STEEL & ALUMINIUM WORKS -2



STEEL, IRON AND ALLUMINIUM WORKS

6.  Fabrication

6.1. Frames - Both the fixed and opening frames shall be constructed of sections which have been cut to length and mitred.  The corners of fixed and opening frames shall be welded to form a solid fused welded joint conforming to the requirements given in 6.1.1.  All frames shall be square and flat.  The process of welding adopted may be flash butt welding or metal arc welding any other suitable method.  The weld shall fulfill the requirements given in 6.1.1, 6.1.1.1, 6.1.1.2, and 6.1.1.3.  

6.1.1. Requirements of welded joints

6.1.1.1. Visual inspection test – When two opposite corners of the frames are cut, paint removed and inspected, the joint shall conform to the following:

(a)  Welds should have been made all along the place of meeting the members, (b) Welds should have been properly ground, and  (c) Complete cross section of the corner shall be checked up to see that the joint is completely solid and there are no visible cavities. 

Fig. 2-C Ventilators

6.1.1.2. Micro and macro examinations – From the two opposite corners obtained for visual test as in 6.1.1.1, the flanges of the sections shall be cut with the help of a saw.  The cut surfaces of the remaining portions shall be polished, etched and examined.

The polished and etched faces of the weld and the base metal shall be free from cracks and reasonably free from undercutting, overlaps, gross porosity and entrapped slag. 

Fig. 2-D Fixed-Lights

Fig. 2 Type and overall sizes of steel doors, windows, Ventilators and fixed lights

6.1.1.3. Fillet weld test – the fillet weld in the remaining portion of the joint obtained in 6.1.1.2, shall be fractured by hammering.  The fractured surfaces shall be free from slag inclusions, porosity, crack, penetration defects and fusion defects.

6.1.2. Tee sections for glazing shall be tennoned and riveted into the frames and where they intersect, the vertical tie shall be broached and the horizontal tee threaded through it, and the intersection closed by hydraulic pressure. 

6.1.3. Casements shall be fitted to their frames so as to provide continuous contact for weathering on the inside and outside and shall be secured in closed position by the fittings which shall have been properly checked and adjusted.

6.1.4. Window and doors may have holes in webs of the bars other than those required during manufacture and fixing. 

6.1.5. The location of the parts of the doors, windows, ventilators and fixed-lights for which details of fabrication are described in 6.1.6 are indicated in Fig.5. 

6.1.6. Details of construction of doors, windows, ventilators and fixed-lights shall be indicated in Fig.6 to 12.

6.2. Side hung shutter – For fixing steel hinges, slots shall be cut in the fixed frame and the hinges inserted inside and welded to the frame at the back.  The hinges shall be normally of the projecting type, with wall thickness of not less than 3.15 mm and width not less than 65 mm and not more than 75 mm (see Fig.13) the hinge pin and washer shall be of galvanized steel or aluminium alloy 51 S-WP of suitable thickness. 

For fixing hinges to inside frame, the method described for fixing to outside frame may be adopted but the well shall be cleaned or holes made in the inside frame and hinge riveted. 

6.2.1. Friction hinges may be provided for side hung shutter windows, in which case peg stay as mentioned in 6.2.3 may not be required.  The working principle of the friction hinge is illustrated in Fig.14.

Fig. 3 Size of steel doors, windows, ventilators or fixed lights In relation to size of opening

6.2.2. The handle for side hung shutters shall be of pressed brass, cast brass, aluminium or steel protected against rusting and shall be mounted on a steel handle plate.  The handle plate shall be welded, screwed or riveted to the opening frame in such a manner that it could be fixed before the shutter is glazed and may not be easily removed after glazing.

6.2.2.1. The handle shall have a two-point nose which shall engage with a brass or aluminium alloy striking plate on the fixed frame in a slightly open position as well as in a fast position (see Fig.15). The pin of 4 mm dia shown in the figure shall be considered as optional. The height of the handles in each type of side hung shutter shall be fixed in a position as indicated in Fig.16 with tolerance of ± 10 mm alternatively; handle with only one point nose may be used, if agreed to between the purchaser and the manufacturer. 

6.2.2.2. The height of the handle plate in each type of standard window having horizontal glazing bar shall be at the centre of the second pane from the bottom of the window.  This dimension shall remain same for the standard windows having no glazing bars also. 

6.2.2.3. The boss of the handle shall incorporate a friction device to prevent the handle from drooping under its own weight and the assembly shall be so designed that the rotation of the handle may not cause it to unscrew from the pin.  The strike plate shall be so designed and fixed in such a position in relation to the handle that with the latter bearing against its stop, there shall be adequate tight fit between the casement and the outer frame. 

Fig. 4 Detail of weather bar with steel plate

Table 1 Glass sizes (Clearance allowed)

(Clause 5.3)

Designation

Quantity

Glass sizes

(Width & Height)

No. of glazing clips against each pane

Doors (See Fig. 2A)

Side Hung type – Horizontal Glazing Bars

 

 

mm

 

6HS20

1

466 x 249

-

 

4

466 x 283

-

 

1

362 x 283

-

8HS20

1

666 x 249

-

 

4

666 x 283

-

 

1

362 x 283

-

10HS20

2

407 x 240

-

 

9

407 x 283

-

 

1

303 x 283

-

12HS20

2

507 x 249

-

 

9

507 x 283

-

 

1

403 x 283

-

6HS21

1

466 x 249

-

 

4

466 x 283

-

 

1

362 x 283

-

8HS21

1

666 x 249

-

 

4

666 x 283

-

 

1

362 x 283

-

10HS21

2

407 x 249

-

 

9

407 x 283

-

 

1

303 x 283

-

12HS21

2

507 x 249

-

 

9

507 x 283

-

 

1

403 x 283

-

6NS20

1

466 x 833

4

 

1

362 x 283

-

 

1

466 x 575

2

8NS20

1

666 x 833

4

 

1

562 x 283

-

 

1

666 x 575

2

10NS20

1

407 x 283

-

 

1

303 x 283

-

 

2

407 x 833

4

 

2

407 x 575

2

12NS20

1

507 x 283

-

 

1

403 x 283

-

 

2

507 x 833

4

 

2

507 x 575

2

6NS21

1

466 x 833

4

 

1

362 x 283

-

 

1

466 x 575

2

8NS21

1

466 x 833

4

 

1

362 x 283

2

 

1

466 x 575

-

10NS21

1

407 x 283

-

 

1

303 x 283

-

 

2

407 x 833

4

 

2

407 x 575

2

12NS21

1

507 x 283

-

 

1

403 x 283

-

 

2

507 x 833

4

 

2

507 x 575

2

 

Windows (See Fig.2B)

Side Hung Type – Horizontal Glazing Bars

5HS9

1

407 x 273

-

 

2

407 x 258

-

6HS9

1

507 x 273

-

 

2

507 x 258

-

10HS9

2

425 x 273

-

 

4

425 x 258

-

12HS9

2

525 x 273

-

 

4

525 x 258

-

15HS9

2

425 x 273

-

 

4

425 x 258

-

18HS9

3

475 x 273

-

 

2

525 x 273

-

 

4

525 x 258

-

 

3

575 x 273

-

5HS12

2

407 x 277

-

 

2

407 x 263

-

6HS12

2

507 x 277

-

 

2

507 x 263

-

10HS12

4

425 x 277

-

 

4

425 x 263

-

12HS12

4

525 x 277

-

 

4

525 x 263

-

15HS12

4

425 x 277

-

 

4

425 x 263

-

 

4

475 x 277

-

5HS15

2

407 x 277

-

 

2

507 x 263

-

 

1

435 x 275

-

6HS15

2

507x 277

-

 

2

507 x 263

-

 

1

535 x 275

-

10HS15

4

425 x 277

-

 

4

425 x 263

-

 

2

454 x 275

-

12HS15

4

527 x 277

-

 

4

527 x 263

-

 

2

554 x 275

-

15HS15

4

425 x 277

-

 

4

425 x 263

-

 

2

454 x 275

-

 

4

475 x 277

-

 

1

475 x 275

-

18HS15

4

527 x 277

-

 

4

527 x 263

-

 

2

554 x 275

-

 

4

575 x 277

-

 

1

575 x 275

-

5NS9

1

407 x 807

4

6NS9

1

507 x 807

4

10NS9

2

425 x 807

4

12NS9

2

525 x 807

4

15NS9

2

425 x 807

4

 

1

475 x 835

4

18NS9

2

525 x 807

4

 

1

575 x 807

4

5NS12

1

407 x 1107

6

6NS12

1

507 x 1107

6

10NS12

2

425 x 1107

6

12NS12

2

525 x 1107

6

 

15NS12

2

425 x 1107

6

 

1

475 x 1135

6

18NS12

2

525 x 1107

6

 

1

575 x 1135

6

5NS15

1

407 x 1107

6

 

1

435 x 275

-

6NS15

1

507 x 1107

6

 

1

535 x 275

-

10NS15

2

425 x 1107

6

 

2

454 x 275

-

12NS15

2

425 x 1107

6

 

2

554 x 275

-

15NS15

2

425 x 1107

6

 

1

475 x 1135

6

 

2

454 x 275

-

 

1

475 x 275

-

18NS15

2

525 x 1107

6

 

1

575 x 1135

6

 

2

554 x 275

-

 

1

575 x 275

-

VENTILATORS (See Fig.2C)

 

 

 

Top Hung Type – Horizontal glazing bars

5HT6

2

407 x 249

-

6HT6

2

507 x 249

-

10HT6

4

449 x 249

-

12HT6

4

549 x 249

-

15HT6

4

463 x 263

-

 

2

430 x 249

-

18HT6

4

563 x 263

-

 

2

530 x 249

-

5HT9

2

407 x 259

-

 

1

435 x 273

-

6HT9

2

507 x 259

-

 

1

535 x 273

-

Centre hung type – Horizontqal glazing bars

5HC6

2

360 x 226

-

6HC6

2

460 x 226

-

10HC6

4

426 x 226

-

12HC6

4

526 x 226

-

15HC6

4

464 x 263

-

 

2

420 x 226

-

18HC6

4

564 x 263

-

 

2

520 x 226

-

Top hung type – No horizontlqa glazing bars

5NT6

1

407 x 507

2

6NT6

1

507 x 507

2

10NT6

2

449 x 5076

2

12NT6

2

549 x 507

2

15NT6

2

463 x 535

2

 

1

430 x 507

2

18NT6

2

563 x 535

2

 

1

530 x 507

2

5NT9

1

407 x 526

2

 

1

435 x 273

-

6NT9

1

507 x 526

2

 

1

535 x 273

-

Centre hung type – No horizontal glazing bars

5NC6

1

360 x 460

2

6NC6

1

460 x 460

2

10NC6

2

426 x 460

2

 

12NC6

2

526 x 460

2

15NC6

2

464 x 536

2

 

1

420 x 463

2

18NC6

2

564 x 536

2

 

1

520 x 563

2

Fixed Lights (See Fig. 2D)

Door height – Horizontal glazing bars

6HF20

6

535 x 283

-

6HF21

6

535 x 283

-

Door height – No glazing bars

6NF20

1

535 x 867

4

 

1

535 x 283

-

 

1

535 x 575

2

6NF21

1

535 x 867

4

 

1

535 x 283

-

 

1

535 x 575

2

Window height – Horizontal glazing bars

5HF9

3

435 x 273

-

6HF9

3

535 x 273

-

10HF9

6

463 X 273

-

12HF9

6

563 x 273

-

15HF9

6

463 x 273

-

 

3

491 x 273

-

18HF9

6

563 x 273

-

 

3

591 x 273

-

5HF12

4

435 x 277

-

6HF12

4

535 x 277

-

10HF12

8

463 x 277

-

12HF12

8

563 x 277

-

15HF12

8

463 x 277

-

 

4

491 x 277

-

18HF12

8

563 x 277

-

 

4

591 x 277

-

5HF15

4

435 x 277

-

 

1

435 x 291

-

6HF15

4

535 x 277

-

 

1

535 x 291

-

10HF15

8

463 x 277

-

 

2

463 x 291

-

12HF15

8

563 x 277

-

 

2

563 x 291

-

15HF15

8

463 x 277

-

 

4

491 x 277

-

 

2

463 x 291

-

 

1

491 x 291

-

18HF15

8

563 x 277

-

 

4

591 x 277

-

 

2

563 x 291

-

 

1

591 x 291

-

Window height – No glazing bars

5NF9

1

435 x 835

4

6NF9

1

535 x 835

4

10NF9

2

463 x 835

4

12NF9

2

563 x 835

4

15NF9

2

463 x 835

4

 

1

491 x 835

4

18NF9

2

563 x 835

4

 

1

591 x 835

4

5NF12

1

435 x 1135

6

6NF12

1

535 x 1135

6

10NF12

2

463 x 1135

6

 

12MF12

2

573 x 1135

6

15NF12

2

463 x 1135

6

 

1

491 x 1135

6

18NF12

2

563 x 1135

6

15NF12

2

463 x 1135

6

 

1

491 x 1135

6

18NF12

2

563 x 1135

6

 

1

591 x 1135

6

5NF15

1

435 x 1135

6

 

1

435 x 291

-

6NF15

1

535 x 1135

6

 

1

535 x 291

-

10NF15

2

463 x 1135

6

 

2

463 x 291

-

12NF15

2

563 x 1135

6

 

2

563 x 291

-

15NF15

2

463 x 1135

6

 

1

491 x 1135

6

 

2

463 x 291

-

 

1

491 x 291

-

18NF15

2

563 x 1135

6

 

1

591 x 1135

6

 

2

563 x 291

-

 

1

591 x 291

-

Ventilators height – Horizontal glazing bars

5HF6

2

435 x 263

-

6HF6

2

535 x 263

-

10HF6

4

463 x 263

-

12HF6

4

563 x 263

-

15HF6

4

463 x 263

-

 

2

491 x 263

-

18HF6

4

563 x 263

-

 

2

591 x 263

-

Ventilator height – No horizontal glazing bars

5NF6

1

435 x 535

2

6NF6

1

535 x 535

2

10NF6

2

463 x 535

2

12NF6

2

563 x 535

2

15NF6

2

463 x 535

2

 

1

491 x 535

2

18NF6

2

563 x 535

2

 

1

591 x 535

2

Fig. 5 – Location of parts of steel doors, windows, ventilators

And sub-lights for which details are shown

Fig. 9 Detail through bottom of top hung ventilator

Fig. 10 Transome coupling bar fitted with fixed-lights on top of windows

Fig. 11 Weather bar over external opening shutter with fixed light above

6.2.3. In cases where non-friction type hinges are provided, the widows shall be fitted with peg stays which shall be either of pressed brass, cast brass or steel protected against rusting and shall be 300 mm long with steel peg and locking bracket.  The peg stay shall have three holes to open the side hung casements in three different angles (see Fig. 17).  The peg stay shall be of minimum 2 mm thickness in case of brass or aluminium and 1.25 in case of mild steel.  Side hung casements fitted with friction hinges shall not be provided with a peg stay. 

Fig. 12 – Details of double shutter door

Fig. 13 Typical projecting type hinge for side hung shutter

Fig. 14 Illustration showing working principles of friction hinges

6.2.4. Alternatively, and if specifically required by the purchaser, side hung and top hung shutters may be fitted with an internal removable fly proof screen (see 1.40 x 0.710 mm MS wire cloth of IS: 1568 – 1970) in a 1.25 mm thick sheet steel frame applied to the outer frame of the shutter by brass or aluminium turn buckles at the jambs (see Fig. 18) and brass or aluminium studs at the sill to allow the screen being readily removed.  The windows with removable fly-proof screen shall be fitted with a through-the-screen lever operator at the sill to permit the operation of the shutter through an angle of 90º without having to remove the fly-proof screen. The lever shall permit keeping the shutter open in minimum three different positions. 

Top hung windows fitted with removable fly-proof screen shall be fitted with a through-the-screen operator to enable operating and keeping the shutter open in minimum three different positions.

6.3. Top hung ventilator – The steel butt hinges for top hung ventilators shall be riveted to the fixed frame or welded to it at the back after cutting a slot in it.  Hinges to the opening frame shall be riveted or welded and cleaned off. 

6.3.1. Top hung casements shall be provided with a peg stay with three holes (see Fig.17) which when closed shall be held tightly by the locking bracket.  The locking bracket shall either be fitted to the fixed frame or to the window. 

Fig. 15 A typical handle for side hung shutter

Fig. 16 Position of handle plates in relation to heights of ‘HS’ type of windows

6.3. Top hung ventilator – The steel butt hinges for top hung ventilators shall be riveted to the fixed frame or welded to it at the back after cutting a slot in it.  Hinges to the opening frame shall be riveted or welded and cleaned off. 

6.3.1. Top hung casements shall be provided with a peg stay with three holes (see Fig.17) which when closed shall be held tightly by the locking bracket.  The locking bracket shall either be fitted to the fixed frame or to the window. 

6.4. Centre hung windows and ventilators – Centre hung window ( see Fig.19) shall be hung on two pairs of brass or aluminium cup pivots riveted to the inner and outer frames of the windows to

Fig. 17 A typical peg stay for side hung shutters and top hung ventilators permit the window to swing to an angle of approximately 85º. The opening portion of the window shall be so balanced that it remains open at any desired angle under normal weather conditions. 

Fig. 18 Detail through jamb showing turn buckle

Fig. 19 Details of horizontal centre hung windows and ventilators

Fig. 20 Spring catch for opening centre hung windows and ventilators

6.4.1. A brass or aluminium spring catch shall be fitted in the centre of the top bar of the centre hung window for the operation of the window.  This spring catch shall be secured to the frame with MS Screws and shall close into a mild  steel or malleable iron catch plate riveted, screwed or welded to the outside of the outer window frame bar ( see Fig.20). 

6.4.2.  A brass or aluminium or malleable iron cord pulley wheel in galvanized mild steel or malleable iron bracket shall be fitted at the sill of the centre hung window with mild steel screws or alternatively, welded to the bottom inner frame of the window in a position corresponding to that of the pulley ( see Fig.21). 

Fig. 21 Cord eye and pulley arrangement for closing centre hung windows and ventilators

Fig. 22 Typical projecting type hinge for doors

6.5. Door – Details of construction of the door shall be as indicated inFig.12. 

6.5.1. The kick panels shall be in double tray construction, and shall be of 1.25 mm thick mild steel sheets.  The kick panels shall be welded or screwed to the frame and the glazing bar (see detail ‘A’ in Fig.12).

Fig. 23 Typical non-projecting type hinge for doors

6.5.2. Hinges – Steel hinges for doors shall be of the same type as for the windows but of larger size.  The hinges shall be of 50 mm projecting type (see Fig.22).  Non-projecting type of hinges (see Fig.23) and self-aligned type door hings (see Fig.24) may also be used.  The hinge pins and washers shall be of galvanized steel or aluminium alloy of suitable thickness.

6.5.3. The handle for doors may be of the design indicated in Fig.25. 

6.5.4. A mortice lock with not less than 4 levers or pins shall be provided for the door.  It shall be openable with its key both from the outside as well as from the inside but in addition a bolt shall be provided on the inside so that when door is locked from the inside and bolted, it cannot be opened from the outside with its key.

6.5.5. . In the case of double doors, the first closing leaf shall be at the left hand leaf looking at the door from the push side.  The first closing shutter shall have a concealed brass extruded aluminium or steel bolt at top and bottom (see Fig.26) the bolt shall be so constructed as not to work loose or droop by its own weight. 

 Fig. 24 Mild steel aligned type hinge for doors

6.5.5. In the case of double doors, the first closing leaf shall be at the left hand leaf looking at the door from the push side.  The first closing shutter shall have a concealed brass extruded aluminium or steel bolt at top and bottom (see Fig.26)  the bolt shall be so constructed as not to work loose or droop by its own weight. 

Fig. 25 Typical door handle

6.5.6. Single and double shutter door may be provided with a three-way bolting device (see Fig.27).  Where this device is provided in the case of double shutter doors, concealed brass or steel bolts may not be provided. 

6.6. Composite units – Composite units are to be assembled at site, using coupling sections as illustrated in Fig.28, (see also Fig. 8, 10 And 12).

Weather bar – Where fixed light occurs over external opening shutter, a push fit weather bar as shown in Fig.11 shall be provided. 

7.  Position of holes, fixing screws and lugs

7.1. Outer frames shall be provided with fixing holes centrally in the web of the section as indicated in Fig.29.  The position of the fixing lugs shown should be followed, with minor variation where necessary. Additional holes are provided in certain types of doors and windows for manufacturing purposes but only the holes indicated in Fig.29, are for the use for fixing.  Fixing lugs and fixing screws are to be supplied for the positions shown in Fig.29. 

7.2. The fixing screws and lugs shall be as given in Table 2. 

8. Finish

8.1. All the steel surfaces shall be thoroughly cleaned free of rust, mill-scale, dirt, oil, either by mechanical means, for example, stand or shot blasting or by chemical means, for example, pickling and then finished either with painting only (see 8.1.1) or phosphate and painting (see 8.1.2); or by hot dip galvanizing (see 8.1.3) as may be agreed to between the purchaser and the manufacturer. 

8.1.1. Painting only – After pretreatment of the surfaces two coats of paint shall be applied on the units by any of the following methods:

(a) By brushing, using ready mixed paints (see IS: 102-1962); (b) By spraying with suitable primers in accordance with the requirements laid down in Appendix D of IS: 1477(Part II)-1971; or (c) By dipping the complete unit in bath of suitable primer paint, such as red oxide zinc chrome primer (see IS: 2074 – 1979) and then air drying.

 

Fig. 26 Typical vertical bolt for double shutter door

 

Fig. 27 Typical three-way bolting device for doors

 

8.1.2. Phosphate and painting – After pretreatment of the surfaces, the units shall be dipped in phosphate solution in accordance with the requirements laid down in IS: 1477(Part I)-1977.  This shall be followed by one coat of paint which shall be air-or stove-dried after applying.

8.1.3. Hot dipped galvanizing – After pretreatment of the surface the units shall be dipped in a bath of molten zinc in accordance with the requirements laid down in IS: 1477(Part I)-1977.  The thickness of coating shall be uniform and not less than 0.5 kg/m2

 

Fig. 28 Coupling door to window or side-light

 

Table 2 - Fixing screws and lugs(Clause 7.2)

Sl

No

Place of fixing

Size of the screw or lug

i)

To wooden frames rebated on the outside.

35 mm No. 10 galvanized wood screws conforming to IS: 451-1972 (See Fig.30)

ii)

To plugs in concrete work or brick work rebated on the  outside.

-do-

iii)

To plugs in concrete work or brick work rebated on the outside (that is, plain or square jambs)

65 mm No.10 galvanized wood screws conforming to IS: 451-1972.

iv)

Direct to brick work or masonry (that is, plain or square jambs)

Slotted steel adjustable lugs (natural finish) not less than 70 x 14 x 3.15 mm countersunk galvanized machine screws and nuts 12 x 6 mm (see Fig.31)

v)

To steel work

Fixing clips and 8 mm galvanized bolts and hexagonal nuts (see Fig.32)

9. Glazing

9.1.   Glazing shall be provided on the outside of the frames. 

9.1.1. Glazing clips (see Fig.33) for putty glazing shall be provided as standard fittings.  The quantity of glazing clips required for each glass pane of doors, windows, etc, shall be as given in Table 1.  The method of fixing glazing clips shall be as given in 9.1.1.1.

9.1.1.1. The portion ‘A’ of the glazing clip shall be fitted into the slot in the window frame leaving the clip resting on the glass.  The portion ‘B’ shall then be pressed along the glass towards the frame until it springs into position in the clearance between the edge of the glass and the steel frame.

Note:  1 – Glazing clips usually not provided for normal size glass panes, where large size glass panes are required to be used or where the casement of the window is located in heavily exposed situation, holes for glazing clips will have to be drilled during fabrication.

Note: 2 – Where the glass pane size does not exceed 600 x 300 mm, glazing clips not considered necessary (for inside glazed windows for special use only two spring glazing clips per pane should be provided).  In case of doors, windows and ventilators without horizontal glazing bars, the glazing clips may be spaced according to the slots in the vertical members, provided the spacing does not exceed 300 mm.  The quality of glazing clips required for each for standard size window shall be as given in Table 1.  

9.1.2. Windows may also be prepared for bead glazing made from either 9.5 x 9.5 mm, aluminium channel of 1 mm thickness or 9.5 x 9.5 mm pressed steel channel of minimum 0.45 thick galvanized sheets.  Self-tapping screws shall be used for fixing bead or alternatively bead fixing can be done with concealed screws.  Back putty or ‘V’ shaped rubber channel wall be provided for glazing.  No spring glazing clip shall be required for bead glazing. 

10.  Sampling and criteria for conformity

10.1. The sampling and criteria for conformity for steel doors, windows, ventilators and fixed-lights shall be as given in Appendix B.

11. Marking

11.1. All doors, windows, ventilators and fixed-lights shall carry an identification of the manufacturer or trade-mark, if any and the process of welding adopted.

11.1.1. Each unit may also be marked with the ISI Standard Mark.

Note: The use of the Standard Mark is governed by the provisions of the Bureau of Indian Standards

Act, 1986 and the Rules and Regulations made there under.  The Standard Mark on products covered

 

Fig. 29 Chart showing approximate position of fixing holes and number of fixing lugs

 

Fig. 30 Fixing screws for wooden frames or plugs in concrete

by an Indian Standard conveys the assurance that they have been produced to comply with the requirements of that standard under a well defined system of inspection, testing and quality control which is devised and supervised by BIS and operated by the producer.  Standard marked products are also continuously checked by BIS for conformity to that standard as a further safeguard.  Details of conditions under which a license for the use of the Standard Mark may be granted to manufacturers or producers may be obtained from the Bureau of Indian Standards.

12.  Supply

12.1. All doors, windows and ventilators shall be dispatched with the opening parts suitably secured to preserve alignment when fixing and glazing. 

12.2. Fixing lugs, couplings, fittings and all hardware shall be dispatched separately. 

12.3. Composite windows shall be dispatched uncoupled. 

APPENDIX    A (Clause 4.4 )

INFORMATION TO BE SUPPLIED BY THE PURCHASER WHILE PLACING THE ORDER

A – 1    The purchaser shall furnish information to the manufacturer or the supplier in regard to the following points:

a) Type and size of door, window or composite unit quoting the designation as given in 4.3;

b) Whether the units are to be fixed in brick masonry, stone masonry, concrete or steel;

c) Type of hinges required, for example, whether projecting, non-projecting or friction type;

d) Details of fittings required including couplings, weather bars, etc;

e) Whether the mullions and transoms are to be cut to suit masonry or steel work;

f) Whether removable fly-proof screens are required;

g) Whether the shutters are required to be opened from inside or outside;

h) Type of finish to be provided conforming to the requirements laid down in 8;

i) Whether wood or metal bead is to be provided in place of putty glazing; and

j) Any other relevant information. 

APPENDIX   B (Clause 10.1)

SCALE OF SAMPLING AND CRITERIA FOR CONFORMITY FOR STEEL DOORS, WINDOWS, VENTILATORS AND FIXED-LIGHTS

B-1.     Sampling

B-1.1.   Lot – In any consignment all the doors/ windows /ventilators / fixed-lights of similar raw-materials under relevantly uniform conditions of manufacture shall be grouped together to constitute a lot. 

B- 1.1.1. Sample shall be selected and inspected for each lot separately for ascertaining its conformity or otherwise to the requirements of the specification. 

 

Fig. 31 Slotted fixing lug (for brickwork and masonry)

B-1.2. The number of doors / windows / ventilators / fixed-lights to constitute the sample, to be selected from a lot shall depend upon the size of the lot and shall be in accordance with col 1 and 2 of Table 3. 

Table 3 Scale of sampling

Lot size (No. of doors / windows / ventilators  /fixed lights in the lot)

Sample size   (No. of Doors / windows  /ventilators / fixed lights to be selected in the sample

Permissible No. of defectives

Sub- sample size

Permissible No. of defectives in the sub -sample.

Upto 50

5

0

2

0

51 to 150

8

0

3

0

151 to 300

13

1

5

0

301 to 500

20

2

8

0

501to 1000

32

3

13

1

1001 to 3000

50

5

20

2

B-1.3.   The doors / windows / ventilators / fixed-lights for the sample shall be selected at random from the lot.  In order to ensure the randomness of selection of the sample procedures given in IS: 4905 – 1968 may be followed.

B-2.  Criteria for conformity

B-2.1.     The doors / windows / ventilators / fixed-lights selected in the sample under B-1.2 and B-1.3 shall be inspected for dimensions (4.1.1), tolerances (4.2), materials (5), fabrication (6) [except (6.1.1)], positioning of holes, fixing screws and lugs (7), finishing (8) and glazing (9).  Any door / window ventilators / fixed-light not satisfying any one or more of the requirements inspected for shall be classified as defective.  A lot shall be considered having satisfied the requirements of the standard with regard to these characteristics if the number of defectives in the sample is less than or equal to the corresponding number given in col. 3 of Table 3. 

Fig.32 Fixing clip (for steel work)

 

Fig. 33 Pictorial view with image of spring glazing clip and its method of fixing

 

B-2.2. The lot having satisfied the requirements listed in B-2.1 shall be inspected for requirements of welded joints.  For this purpose a sub-sample of the size given in col. 4 of Table 3 shall be selected from the doors / windows / ventilators / fixed-lights which have been found non-defective under B-2.1.  The doors / windows/ ventilators / fixed-lights in the sub-sample shall be tested according to 6.1.1.1, 6.1.1.2 and 6.1.1.3.  A lot shall be considered having satisfied the requirements of welded joints if the number of doors windows / ventilators / fixed-lights tested above from the sub-sample does not exceed the corresponding number given in col. 5 of Table 3.

Annexure 7-A.7.

SPECIFICATIONS FOR METAL DOORS, WINDOWS AND VENTILATORS  

 (Steel and aluminium)

1 General

1.1 The dimensions and other details of steel doors, windows, and ventilators shall conform to IS 1038 - 1983.  The hot rolled steel sections shall conform to IS 7452 - 1990. Fire check doors shall conform to IS: 3614(Part I)-1966 and IS: 3614 (Part 2)-1992.

1.2. Fixing of aluminium doors, windows and ventilations is also covered in this part.

2. Installation

2.1. General - Fixing and glazing of metal doors, windows and ventilators refer to securing them in structural or masonry surrounds and securing glass to the metal frame. The method adopted should be such that movement of the structure to which the securing is done does not transmit strain to the metallic units.  Special requirements of manufacturer shall be taken care of while installing fire check doors.

Every installation presents its own problems and different surround details may require different techniques. Further, doors, large composite windows, bay windows are rather complicated to install and wherever special windows are being fixed, a careful study of the drawings and specialized training and skill are called for.  A trained fitter in metal window fixing knows how to make adjustments to bring window out of wind and to take out any twist or bend in the section.

2.2. Type of openings - Metal doors windows and ventilators may be required to be fixed to either masonry openings (including brick, concrete, stone and marble) or timber openings or steel work openings.(a)Masonry openings – Masonry openings may either be rebated or flush and in either case, they may have either external rendering applied or be ‘fairfaced’ (that is, without external rendering).  It is usual for stone or marble masonry to be fairfaced.(b)Timber openings – Timber openings are invariably rebated.( c)Steel work openings – Steel work openings vary in detailed design but shall be so designed that the outer frames of the door, window or ventilator frame sections overlap a steel surface either externally or internally.

2.2.1. Size of openings - The overall size of both flush and rebated openings to which the units have to be fixed shall allow a clearance between the frame and opening and the amount of clearance depends on whether the opening is externally rendered or fairfaced. (a)Flush openings – Rendered flush openings shall allow a clearance between frame and opening equal to thickness of rendering (see Fig. 7.22 A and Fig. 7.22 B).  Fairfaced flush openings shall allow a clearance of 3 mm between frame and opening (see Fig. 11). (b)Rebated openings

1) Fair – faced masonry openings and timber openings shall allow a clearance of 3 mm between the opening and the inner flange of the frame as well as between the opening and the outer flange of the frames. The depth of rebate shall therefore be equal to the distance between the inner and outer flanges of the frame of the unit.  The rebate shall be 12.5 mm in the case of general building and industrial windows (see Figs. 12 and 13).

2) Rendered masonry openings shall allow a clearance of 3 mm between opening and the inner flange of the frame and a clearance equal to the thickness of rendering between the opening and the outer flange of the frame.  The depth of rebate shall therefore be adjusted accordingly (see. Fig. 14).

3) Steel work openings shall be designed to allow the outer flange of the window frame section to overlap the steel surface by 10 mm (see Fig. 15).

The size of the Indian Standard units both for building and industrial purposes are designed for modular openings which are larger by 12.5 mm all round than these units.  This gap of 12.5 mm is for fixing those units.  In case of masonry the gap is filled with mastic cement and plaster after the unit is in position.  In the case of steel and timber openings, extra steel or timber fillets will be necessary to cover this gap of 12.5 mm (see Fig. 16).

2.3. Installation of single units (a)The units shall be fixed into prepared openings. They shall not be ‘built – in’ as the walls go up as this practice often results in brick work being brought right up to the frame with no clearance allowed and usually distorts the units and increases the likelihood of damage being done to the unit during subsequent building work.  Placing of scaffolding on frames or glazing bass shall on no account be done.

(b)The size of the opening shall be checked and cleaned of all obstructions. Suitable markings may be done to fix the unit in the proper position, including the fixing hole positions.  In case of masonry, holes for fixing lugs shall be cut 5 cm2 and 5 cm to 10 cm deep or to fix rawl plugs.

(c)The units shall be checked to ensure that they are square and working satisfactorily before fixing.

(d)The units shall then be put in position and the lugs screwed on tight.

(e)When fixing to flush surrounds without rendering the 3 mm gap shall be pointed with mastic on the outside before the internal plaster and rendering ; the plaster and rendering shall be applied to the surrounds after the lugs have firmly set.  When fixing to rebated surrounds without rendering the frame shall be bedded in mastic.  When fixing to rebated surrounds with rendering, after bedding in mastic, plaster shall be applied from outside. (f) In concrete, dressed stone and marble surrounds, the units shall be fixed with legs. (g) Wood surrounds are generally rebated and mastic be applied to the sill of the opening and units placed on it, and screwed on to the openings.  In case of steel openings, special clips may be used to fix the unit. (h)In case of aluminium frames, the surfaces shall be anchored in direct contact with the surrounds and shall be protected with two coats of alkali-resistant paints, to avoid chemical attack from the materials of surround.

2.4. Installation of composite units

(a) Composite units shall follow the procedures as described and in addition shall conform to the following. (b) Mullions and transom of composite units shall be bedded in mastic to ensure weather tightness. Mastic shall be applied to channels of the outside frame sections before assembly. (c)If there is a cross joint of mullion and transom, the shorter coupling unit shall run through unbroken. (d) Mullions normally project 2.5 cm at head and sill into the surround; transom also project 2.5 cm into surround where appropriate they shall be cut.

2.5. Hardware - Hardware shall be fixed as late as possible just before the final coat of paint is applied.

Annexure-7.A.8

STEEL TUBES FOR STRUCTURAL PURPOSES 

Nominal bore (mm)

Outside diameter (mm)

Class

Wall thickness (mm)

Weight (kg/m)

15

21.3

H

3.25

1.43

20

26.9

H

3.25

1.90

25

33.7

M

3.25

2.46

 

 

H

4.05

2.99

32

42.4

M

3.25

3.15

 

 

H

4.05

3.86

40

48.3

M

3.25

3.61

 

 

H

4.05

4.43

50

60.3

L2

3.26

4.57

 

 

M

3.65

5.10

 

 

H

4.50

6.17

65

76.1

L

3.25

5.84

 

 

M

3.65

6.53

 

 

H

4.50

7.92

80

88.9

L

3.25

6.86

 

 

M

4.05

8.48

 

 

H

4.85

10.10

90

101.6

L

3.65

8.82

 

 

M

4.05

9.75

 

 

H

4.85

11.60

100

114.3

L

3.65

9.97

 

 

M

4.50

12.40

 

 

H

5.40

14.50

110

127.0

L

4.50

12.20

 

 

M

4.85

14.60

 

 

H

5.40

16.20

125

139.7

L

4.50

14.90

 

 

M

4.85

16.20

 

 

H

5.40

17.90

135

152.4

L

4.50

16.40

 

 

M

4.85

17.70

 

 

H

5.40

19.50

150

165.1

L

4.50

17.80

 

 

M

4.85

19.20

 

 

H

5.40

21.20

150

168.3

L

4.50

18.10

 

 

M

4.85

19.60

 

 

H-1

5.40

21.70

 

 

H-2

6.30

25.30

175

193.7

L

4.85

22.60

 

 

M

5.40

25.00

 

 

H

5.90

27.30

200

219.1

L

4.85

25.70

 

 

M

5.60

29.40

 

 

H

5.90

31.00

225

244.5

H

5.90

34.20

L means - Light         M means - Medium      H means -  Heavy

Annexure-7.A.9

SPECIFICATIONS FOR STEEL CONSTRUCTION 

Part 1   Use of hot rolled sections

1.  General

1.1. This part covers use of hot rolled steel sections including tubes in general building construction, in particular fabrication practices and connections. The requirements do not completely cover those of bridges, chimneys and other special steel structures.  This is in line with the design codes, one for general building construction and others for individual structures depending loads, service conditions, etc.

1.2. There are three basic methods of connecting steel members through rivets, bolts and welding.  Thus, the fabrication and practices differ. In addition high strength grip bolts are being used in construction which reduces noise during fabrication on site, and is based on the principle of friction through grip.

2. Materials

2.1. Structural steel - Structural steel shall conform to IS: 1977-1975, IS: 2062 -1992 and IS: 8500  -1992 and any other structural steel as specified with minimum guaranteed yield point.

Note: IS: 226 and IS: 961 have been superseded by IS: 2062 and IS: 8500 respectively.

2.2. Rivets - Rivets shall conform to IS: 1929-1982 and IS: 2155-1982 as appropriate. High tensile steel rivet bars shall conform to IS: 1149-1982.  Hot rolled rivet bars shall conform to IS: 1148 - 1982.

2.2.1. Friction grip bolts - High tensile friction bolts shall conform to IS: 3757-1985 high tensile friction grip nuts shall conform to IS: 6623-1985 and high tensile friction grip washers shall conform to IS: 6649 -1985.

2.3. Welding consumables - Covered electrodes shall conform to IS: 814-1991 or IS: 1278-1972.  Bare wire electrodes for submerged arc welding shall conform to IS:  7280-1974. Combination of wire and flux shall satisfy IS: 3613-1974.  Filler rods and bare electrodes for gas shielded metal arc welding shall conform to IS: 6419 -1971 to IS: 6560 -1972 as appropriate.

2.4. Steel castings - Steel castings shall conform to grade 2345 of IS 1030 -1989.

2.5. Bolts and nuts - Bolts and nuts shall conform to IS: 1363 (Parts 1, 2, 3) 1992, IS: 1364 (Parts 1, 2, 3) 1992, IS: 1367 (Part 3) 1991, and IS: 3640 - 1982 as appropriate.

2.6. Washers - Washers shall conform to IS: 5369-1975, IS: 5370-1969, IS: 5374-1975 and IS: 6610 - 1972, as appropriate.

2.7. Cement concrete - Cement concrete used in association with structural steel shall conform to IS: 456-1977.

2.8. Hot rolled - Hot rolled sections shall conform to Indian Standards listed in Annexure 7-A.1. It also lists other relevant Indian Standards and Handbooks prepared so far in relation to steel construction.

3. Fabrication and erection 

3.1. General - As much fabrication work as is reasonably practicable shall be completed in the shops where steel work is fabricated.  Tolerances for fabrication of steel structures shall conform to IS: 7215

- 1974. Tolerances for erection of steel structures shall conform to IS: 12843-1989. For general guidance on fabrication by welding reference may be made to IS: 9595-1980.

3.1.1. Minimum thickness of metal – corrosion protection

  1. Steel work exposed to weather – Where steel work is directly exposed to weather and is fully accessible for cleaning and repainting, the thickness shall be not less than 6 mm ; and where steel is exposed to the weather and is not accessible for cleaning and painting, the thickness shall not be less than 8 mm.  This shall not apply to hot rolled sections covered by Indian Standards.
  2. Steel work not directly exposed to the weather – The thickness of steel work not directly exposed to the weather shall be not less than 6 mm.  The thickness of steel in secondary members shall be not less than 4.5 mm.  For hot rolled sections to Indian Standards the mean thickness of flange be considered and not the web thickness.
  3. These requirements of (a) and (b) do not apply to light structural work or to sealed box section or to steel work in which special provision against corrosion has been made; also in case of steel work exposed to highly corrosive industrial fumes or vapour or saline atmosphere, the minimum thickness shall be as agreed to between the customer and designer.

3.2 Fabrication procedures

Straightening – All material shall be straight and, if necessary, before being worked shall be straightened and/or flattened by pressure, unless required to be curve linear and shall be free from twists.

Clearances The erection clearance of cleated ends of members connecting steel to steel should preferably be not greater than 2.0 mm at each end. The erection clearance at ends of beams without web cleats should be not more than 3 mm at each end, but where, for practical purposes, greater clearance is necessary, suitably designed seatings should be provided.

Where block bolts are used, the diameter of holes shall be generally 1.5 mm more than the diameter of permanent bolts, and 3 mm more than diameter of erection bolts.

Cutting

1. Cutting may be affected BY shearing, cropping or sawing.  Gas cutting by mechanically controlled torch may be permitted for mild steel only.  Gas cutting of high tensile steel may also be permitted provided special care is taken to leave sufficient metal to be removed by machining so that all metal that has been hardened by flame is removed.  Hand flame cutting may be permitted subject to approval by the engineer.

2. Except where material is to be subsequently joined by welding, no loads shall be transmitted into metal through a gas cut surface.

3. Shearing, cropping and gas cutting, and free from any distortions, and should be the engineer find it necessary, the edges shall be ground afterwards.

Holding

1) Holes through more than one thickness of material for members, such as, compound stanchion and girder flanges shall, where possible, be drilled after the members are assembled and tightly clamped or bolted together. Punching may be permitted before assembly, provided the holes are punched 3 mm less in diameter than the required size and reamed after assembly to the full diameter. The thickness of material punched shall not be greater than 16 mm. For dynamically loaded structures, punching shall be avoided.

2) When holes are drilled in one operation through two or more separable parts, these parts, when so specified, shall be separated after drilling and the burrs removed.

3) Holes in connecting  angles and plates other than splices, also in roof members and light framing, may be punched full size through material not over 12 mm thick, except when required for close tolerance bolts or barred bolts.

4) Matching holes for rivets and black bolts shall register with each other so that a gauge of 1.5 mm or 2.0 mm (as the case may be depending on the diameter of rivet or bolt is less than or more than 25 mm) less in diameter than the diameter of the hole will pass freely through the assembled members in the direction at right angle to such members. Finished holes shall be not more than 1.5 mm or 2.0 mm

(as the case may be) in diameter larger than the diameter of the rivet or black bolt passing through them, unless otherwise specified.

5) Holes for turned and fitted bolts shall be drilled to a diameter equal to the nominal diameter of the shank or barrel subject to H8 tolerance specified in IS 919 (Part 1) - 1993. Parts to be connected with close tolerance or barrel bolts shall preferably be tightly held together through all the thickness at one operation and subsequently reamed to size. All holes not drilled through all the thickness in one operation shall be drilled to a smaller size and reamed out after assembly.  Where this is not practicable, the parts shall be drilled and reamed separately through hard bushed steel jigs.

6) Holes for rivets or bolts shall not be formed by gas cutting process.

3.3. Assembly

The comparison parts shall be assembled and aligned in such a manner that they are neither twisted nor otherwise damaged, and shall be so prepared that the specified cambers, if any, are provided.

3.4. Riveting

  1. Rivets shall be heated uniformly throughout their length without burning or excessive scaling, and shall be of sufficient length to provide a head of standard dimensions. They shall, when driven, completely fill the holes, and if countersunk, the countersigning shall be fully filled by the rivet; any protrusion of the countersunk head being dressed off flush, if required.
  2. Riveted members shall have all parts firmly drawn and held together before and during riveting, and special care shall be taken in this respect for all single riveted connections. For multiple riveted connections, a service bolt shall be provided in every third or fourth hole.
  3. Wherever practicable, machine riveting shall be carried out by using machines of the steady pressure type.
  4. All loose, burned or otherwise defective rivets shall be cut out and replaced before the structure is loaded, and special care shall be taken to inspect all single riveted connections.
  5. Special care shall be taken in heating and driving long rivets.

3.5. Bolting

  1. Where necessary, washers shall be tapered or otherwise suitably shaped to give the heads and nuts of bolts a satisfactory bearing.
  2. The threaded portion of each bolt shall project through the nut by at least one thread.
  3. In all cases where full bearing area of the bolt is to be developed, the bolt shall be provided with a washer of sufficient thickness under the nut to avoid any threaded portion of the belt being within the thickness of the parts bolted together.

3.6. Welding

  1. Welding shall be in accordance with IS:  816 - 1969, IS: 819 - 1957, IS: 1024 - 1979, IS: 1261 - 1959, IS: 1323 - 1982 and IS: 9595 - 1980 as appropriate.
  2. For welding any particular type of joint, welders shall give evidence acceptable to the engineer of having satisfactorily completed appropriate tests as described in any of the Indian Standards, namely, IS: 817 (Part 1)  1992, IS: 1393,  1961, IS: 7307 (Part 1)  1974, IS: 7310 (Part 1) and IS: 7318 (Part 1)  1974 as appropriate.

3.7. Machining of butts, caps and bases

  1. Column splices and butt joints of struts and compression members depending on contact for stress transmission shall be accurately machined and close butted over the whole section with a
  2. clearance not exceeding 0.2 mm locally at any place. In column caps and bases, the ends of shafts together with attached gussets, angles, channels, etc, after riveting together should be accurately
  3. machined so that parts connected butt over entire surfaces of contact. Care should be taken that these gussets, connecting angles or channels, are fixed with such accuracy that they are not reduced in thickness by machining more than 2.0 mm.
  4. Where sufficient gussets and rivets or welds are provided to transmit the entire loading, the column ends need not be machined, the design of column members should cover this.
  5. Ends of all bearing stiffness shall be machined or grounds to fit tightly both at top and bottom.
  1. Slab bases and caps, except when cut from material with true surfaces, shall be accurately machined over the bearing surfaces and shall be in effective contact with the end of the stanchion. A bearing surface which is to be grouted direct to a foundation need not be machined if such face is true and parallel to the upper face.
  2. To facilitate grouting, holes shall be provided where necessary in stanchion bases for the escape of air.

3.8. Solid round steel columns

  1. Solid round steel columns with shouldered ends shall be provided with slab caps and bases machined to fit the shoulder, and shall be tightly shrunk or welded in position.
  2. The tolerance between the reduced end of the shaft and the hole in case of slabs welded in position shall not exceed 0.25 mm.
  3. Where slabs are welded in position, the reduced end of the shaft shall be kept just sufficiently short to accommodate a fillet weld around the hole without weld metal being proud of the slab.  Alternatively, the caps and bases may be directly welded to the column without bearing or shouldering. All bearing surfaces of slabs intended for metal – to – metal contact shall be machined perpendicular to the shaft.

3.9. Painting

Painting shall be done as prescribed in IS: 1477(Parts 1 and 2)-1971.

  1. All surfaces to be painted, oiled or otherwise treated shall be dry and thoroughly cleaned to remove all loose scale and loose rust.
  2. Shop contact surfaces need not be painted unless specified. If so specified, they shall be brought together while the paint is still wet.
  3. Surfaces not in contact, but inaccessible after shop assembly shall receive the full specified protective treatment before assembly. This does not apply to the interior of hollow sections (see IS: 3502-1981).
  4. Chequered plates (see IS: 3502-1981) shall be painted but the details of painting shall be specified by the engineer.
  5. In case the surfaces are to be welded, the steel shall not be painted or metal coated within a suitable distance of any edges to be welded, if the paint specified or metal coating would be harmful to the welders or impair the quality of welds.
  6. Welds and adjacent parent metal shall not be painted prior to deslugging, inspection and approval.
  7. Parts to be encased in concrete shall not be painted or oiled.

3.10. Marking - Each piece of steel work shall be distinctly marked before delivery, and bear such other marks as in accordance with a marking diagram as well facilitate erection.

3.11 Shop assembly

  1. The steel work shall temporarily shop assembled complete or as arranged with the engineer so that accuracy of fit may be checked before dispatch.  The parts shall be shop assembled with sufficient numbers of parallel drifts to bring and keep the parts in place.
  2. In case of parts drilled or punched, through steel jigs with bushes resulting in all similar parts being interchangeable the steel work may be shop erected in such position as arranged with the engineer.

3.12. Packing - All projecting plates or bars and all ends of members at joints shall be stiffened, all straight bars and plates shall be bundled, all screwed ends and machined surfaces shall be suitably packed; and all rivets, bolts, nuts, washers and small loose parts shall be packed separately in cases so as to prevent damage or distortion during transit.

3.13. Inspection and testing

  1. The engineer shall have free access at all reasonable times to those parts of the manufacturers’ works which are concerned with the fabrication of steel work and shall be afforded all reasonable facilities to satisfy that the fabrication is being undertaken in accordance in with the specifications.
  1. Unless specified otherwise, inspection prior to dispatch shall not interfere with the operation of the work.

3.14. Site erection

  1. Plant and equipment – The suitability and capacity of all plant and equipment used for erection shall be to the satisfaction of the engineer.
  2. Storing and handling – All structural steel should be so stored and handled at the site that the members are not subject to excessive stresses and damage.
  3. Setting out – The positioning and leveling of all steel work, the plumbing of stanchions and the placing of every part of the structure with accuracy shall be in accordance with approved drawings and to the satisfaction of engineer.
  4. Security during erection – Safety precaution during erection shall conform to IS: 7205-1974. During erection, the steel work shall be securely bolted or otherwise fastened and, when necessary, temporarily braced to provide for all load to be carried by the structure during erection including those due to erection equipment and its operation.

No riveting, permanent bolting or welding should be done until proper alignment has been obtained.

3.15.  Field connections - All field assembly by bolts, rivets and welding shall be executed in accordance with the requirements for shop fabrication excepting such as manifestly apply to  shop conditions only.  Where the steel has been delivered painted, the paint shall be removed before field welding, for a distance of 50 mm at least on either side of the joint.

3.16. Painting after erection

  1. Before painting of such steel which is delivered unpainted is commenced, all surfaces to be painted shall be dry and thoroughly cleaned from all loose scale and rust.
  2. The specified protective treatment shall be completed after erection. All rivet and bolt heads and site welds after deslugging shall be cleaned. Damaged or deteriorated paint surfaces shall be first made good with the same type of paint as the shop coat. Where specified, surfaces which will be in contact after site assembly shall receive a coat of paint (in addition to any shop priming) and shall be brought together while paint is still wet.
  3. Where the steel has received a metal coating in the shop, this coating shall be completed on site so as to be continuous over any welds and site rivets and bolts ; but subject to the approval of engineer, protection may be completed by painting on site. Bolts which have been galvanized or similarly treated are exempted from this requirement.
  4. Surfaces which will be inaccessible after site assembly shall receive the full specified treatment before assembly.
  5. Site painting should not be done in frostly or foggy weather, or when humidity is such as to cause condensation on the surfaces to be painted.

3.17. Bedding of stanchion bases and bearings of beams and girders on stone, brick or concrete (Plain or reinforced)

  1. Bedding shall be carried out with cement, grout, or mortar or with cement concrete as in IS: 456 - 1977.
  2. For multistoried buildings, this operation shall not be carried out until a sufficient number of bottom lengths of stanchions have been properly lined, leveled and plumbed and sufficient floor beams are in position.
  3. Whatever method is employed, the operation shall not be carried out, until the steel work has been finally leveled and plumbed, the stanchion bases being supported meanwhile by steel wedges; and immediately before grouting, the space under the steel shall be thoroughly cleaned.
  4. Bedding of structure shall be carried out with grout or mortar which shall be of adequate strength and shall completely fill the space to strength and shall completely fill the space to be grouted and shall either be placed under pressure or by ramming against fixed supports.

4. Connections

4.1. General - As much of the work of fabrication as in reasonably practicable shall be completed in the shops where the steel work is fabricated.

4.2. Rivets, close tolerance bolts, high strength friction grip fasteners, black bolts and welding - Where a connection is subject to impact or vibration or to reversal of stress (unless such reversal is solely due to wind) or where for some special reason, such as continuity in rigid framing or precision in alignment of machinery, rivets or close tolerance bolts, high strength friction grip fasteners or welding shall be used.  In all other cases, bolts in clearance holes may be used provided that due allowance is made for any slippage.

4.3. Composite connections - In any connection which takes a force directly transferred to it and which is made with more than one type of fastening, only rivets and turned and fitted bolts may be considered as acting together to share the load.  In all other connections sufficient number of one type of fastening shall be provided to transfer the entire load for which the connection is designed.

4.4. Members meeting at a joint  - For triangulated frames designed on the assumption of pin jointed connections, members meeting at a joint, shall, where practicable, have their centroidal  axes meeting at a point ; and wherever practicable the centre of resistance of a connection shall be on the line of action of the load so as to avoid eccentricity moment on the connections.

  1. However, where eccentricity of members or if connection is present, the members and the connections shall provide adequate resistance to the induced bending moments.
  2. Where the design is based on nonintersecting members at a joint all stresses arising from eccentricity shall be calculated and this stress within limits specified.

4.5. Bearing brackets - Wherever applicable, connections of beams to columns shall include a bottom bracket and top cleat. Where web cleats are not provided, the bottom bracket shall be capable of carrying the whole of the load.

4.6. Gussets - Gusset plates shall be designed to resist the shear, direct and flexural stresses acting on the weakest or critical section.  Reentrant cuts shall be avoided as far as practicable.

4.7. Lug angles - Lug angles connecting a channel shaped manner, shall as far as possible, be disposed symmetrically with respect to the section of the member.

In case of angle members, the lug angles and their connections to gusset or other supporting member shall be capable of developing a strength not less than 20 per cent in excess of the force in the outstanding leg of the angle and the attachment of the lug angle to the angle number shall be capable of developing 40 per cent in excess of that force.

In the case of channel numbers and the like, the lug angles and their connections to the gusset or other supporting member shall be capable of developing a strength of not less than 10 per cent in excess of the force not accounted for by direct connection of the member, and the attachment of the lug angles to the member shall be capable of developing 20 per cent in excess of that force.

In no case shall fewer than two bolts or rivets be used for attaching the lug angle to the gusset or other supporting member.

  1. The effective connection of the lug angle shall, as far as possible terminate at the end of the member connected, and the fastening of the lug angle to the member shall preferably start in advance of the direct connection of the member to the gusset or other supporting member.

4.8. Pitch of rivets

Minimum Pitch – The distance between centres of rivets shall not be less than 2.5 times the nominal diameter of the rivet.

Maximum Pitch – The maximum pitch for any two adjacent rivets shall not exceed 32 t where t is the thickness of the thinner outside plate or 300 mm.

In tension members the distance between any two adjacent rivets, in a line lying in the direction of stress, shall not exceed 16 t or 200 mm ; and 12 t or 200 mm for compression members. In case of butting compression members, the distance shall not exceed 4.5 times the diameter of the rivets for a distance from the abutting faces equal to 1.5 times the width of the member.

The distance between centres of any two consecutive rivets in a line adjacent and parallel to an edge of an outside plate shall not exceed (100 mm + 4 t) or 200 mm; whichever is less in compression or tension members.

When rivets are staggered at equal intervals and the gauge does not exceed 75 mm, the distances specified herein between centres of rivets, may be increased by 50 per cent.

Edge distances – The minimum edge distance from the centre of any hole to the edge of the plate shall be not less than as given below :

ia of hole

 

Distance to sheared or hand flame cut edge

Distance to rolled, machine flame cut, sawn or planed edge.

mm

mm

mm

13.5 and below

19

17

15.5

25

22

17.5

29

25

19.5

32

29

21.5

32

29

23.5

38

32

25.5

44

38

29.0

51

44

32.0

57

51

35.0

57

51

when two or more parts are connected together, a line of rivets or bolts shall be provided at a distance of not more than (37 mm + 4 t) the nearest edge. In case of work not exposed to weather, this may be increased to 12 t.

Tacking rivets – Tacking rivets not subject to calculated stress shall be used, in case the maximum distances as specified is exceeded. The pitch of tacking rivets in line shall not exceed 33 t or 300 mm whichever is less.  When the plates are exposed to weather, the pitch in line shall not exceed 16 t or 200 mm, whichever is less. In both cases, the lines of tacking rivets shall not be apart at a distance greater than the pitches.

In tension members composed of two angles, flats, channels or tees in contact back-to-back or separated back-to-back by a distance not more than the aggregate thickness of the connected parts, tacking rivets shall be at a pitch not exceeding 1000 mm.

For compression members as above, the pitch shall not exceed 600 mm.

4.9. Pitch of bolts - They shall be as for rivets including edge distances and tacking bolts.

5. FABRICATION AND CONNECTIONS FOR DESIGN BY PLASTIC THEORY

5.1. Fabrication

All the requirements of fabrication shall apply for fabrication for design of steel structures by plastic theory subject to the following

  1. The use of sheared edges shall be avoided in locations subject to plastic hinge rotation at factored loading. If used they shall be finished smooth by grinding, chipping, or planning.
  2. In locations subject to plastic hinge rotation at factored loading, holes or rivets or bolts in the tension area shall be sub punched and reamed or drilled full size.

5.2. Connections

  1. All connections which are essential to the continuity, assumed as the basis of design analysis shall be capable of resisting the moments, shears and axial loads to which they would be subjected by either full or factored loading.
  2. Corner connections (haunches), tapered or curved for architectural reasons shall be so proportioned that the full bending strength of the section adjacent to the connection may be developed.
  3. Stiffeners shall be used, as required, to preserve the flange continuity of interrupted members at their junctions with other members in a continuous frame. Such stiffeners shall be placed in pairs on opposite sides of the web of the member which extends continuously through the joint.

6. Fabrication and connections for tubular structures

6.1. General - The use of tubular steel in structural work would result in considerable savings, particularly in case of roof trusses, latticed girders and compression members in general. This clause on fabrication and connections for tubular structures is complimentary to the provisions of 1 to 5. Requirements which are of special application to construction using steel tubes are included here.

6.2. Materials

a) Steel tubes shall be hot rolled finished tubes conforming to IS: 1161-1979.  Tubes made by other than hot finishing processes or which have been subjected to cold working, shall be regarded as hot finished, if they have subsequently been heat treated and are supplied in normalized conditions.

Note: Grade ERW YST 22 tubes specified in IS: 1161-1979 with carbon content less than 0.30 per cent, may be considered as hot finished for this purpose.

b) Electrodes used for welding of steel tubes shall conform to IS: 814-1991.

c)  Minimum thickness

1. For tubular steel work painted with one priming coat of red oxide and zinc chromate paint after fabrication and periodically repainted and maintained regularly, the wall thickness of tubes used for construction exposed to weather shall be not less than 4 mm (see 2); for construction not exposed to weather; it shall be not less than 3.2 mm and; where structures are not readily accessible for maintenance, the minimum thickness shall be 5 mm.

2. Steel tubes used for construction exposed to weather shall be not less than 3.2 mm thick and for construction not exposed to weather shall be not less than 2.6 mm thick provided that in each case the tube is applied with - one coat of zinc primer conforming to IS: 104-1979, followed by a coat of paint conforming to    IS: 2074-1992; or two coats of paint conforming to IS: 123-1962.

This painting schedule should be reviewed after every two years in the case of tubes exposed to weather.  In case some other metallic corrosion protecting material is used, such as aluminium painting, the renewal of coating may be done after longer intervals.

6.3. Fabrication

  1. As mentioned provisions of 1 to 5 apply to construction using tubes also.  Where welding is adopted provisions of IS: 816-1969 shall apply, as appropriate.
  2. The component parts of the structure shall be assembled in such a manner that they are neither twisted nor otherwise damaged and be so prepared that the specified cambers, if any, are maintained.
  3. Straightening – All material before assembly shall be straightened, if necessary, unless otherwise required to be a curvilinear form and shall be free from twist.
  4. Bolting

1. Washers shall be specially shaped where necessary, or other means used, to give the nuts and the heads of bolts a satisfactory bearing.

2.I n all cases where the full bearing area of the bolt is to be developed, the threaded portion of the bolt shall not be within the thickness of the parts bolted together, and washers of appropriate thickness shall be provided to allow the nut to be completely tightened.

  1. Cut edges – Edges should be dressed to a neat and workman like finish and be free from distortion where parts are to be in contact metal-to-metal.
  2. Caps and bases for columns – The ends of all tubes from columns, transmitting loads through the ends, shall be true and square to the axis of the tube and should be provided with a cap or base.
  3. accurately fitted to the end of the tube and screwed, welded or shrunk on. The cap or base plate should be true and square to the axis of the columns.
  4. Sealing of tubes – When the end of a tube is not automatically sealed by virtue of its connection by welding to another member, the end shall be properly and completely sealed.  Before sealing, the inside of the tube should be dry and free from loose scale.
  5. Flattened ends – In tubular construction, the ends of tubes may be flattened or otherwise formed to provide for welded, riveted or bolted connections, provided that the methods adopted for such flattening do not injure the material.  The change of section shall be gradual.
  1. Oiling and painting – If not galvanized, all tubes shall, unless otherwise specified, he painted or oiled or otherwise protectively coated before exposure to the weather. If they are to be painted with any special requirements, this shall be arranged.

6.4. Connections

  1. General – Connections in structures using steel tubes shall be provided by welding, riveting or bolting. Wherever possible, connections between tubes shall be made directly tube to tube without gusset plates and other attachments. Each tube may be flattened as specified or otherwise formed to provide for welded, riveted or bolted connections. When loads are required to be carried from one tube to another or are required to be distributed between tubes, diaphragms which may be tubular, designed with sufficient stiffness to distribute the load between tubes, shall be used.
  2. Eccentricity of Members – Tubes meeting at a point shall, wherever practicable, have their gravity axes meeting at a point so as to avoid eccentricity.  Wherever practicable, the centre of resistance of the connections shall lie on the line of action of the load so as to avoid eccentricity of the connection.
  3. Welded connections

1. A weld connecting two tubes end-to-end shall be full penetration butt weld.  The effective throat thickness of the weld shall be taken as thickness of the thinner part joined.

2. A weld connecting the end of one tube (branch tube) to the surface of another tube (main tube) with their axes at an angle of not less than 30 degree shall be of the following type:

  • butt weld throughout,
  • fillet weld throughout, and
  • fillet butt weld, the weld being a fillet weld in one part and a butt weld is another with a continuous change from the one form to another form in the intervening portions.

A butt weld throughout may be used whatever the ratio of the diameters of the tubes joined, provided complete penetration  is secured either by the use of backing material, or by depositing a sealing run of metal on the back of the joint, or by some special method of welding.  When butt weld running throughout is not employed, a fillet running throughout should be used where the diameter of the branch tube is less than one third of the diameter of the main tube.  The combined fillet butt weld should be used when the diameter of the branch tube is equal to or greater than one third of the diameter of the main tube.

1. A weld connecting the end of one tube to the surface of another, with axes of tubes intersecting at an angle less than 300 shall be permitted only if adequate efficiency of the junctions has been demonstrated.

2. Connections where the axes of the two tubes do not intersect – A weld connecting the end of one tube to the surface of another, where the axes of the tubes do not intersect, shall be subject to the provision provided that no part of the curve of intersection of the eccentric tube with the main tube lies outside the curve of intersection of the corresponding largest permissible eccentric tube with the main tube (see Fig. 7.1).

3. Connections of tubes with flattened ends – Where the end of the branch tube is flattened to an elliptical shape, the provisions of above shall apply and the diameter of the flattened tube for this purpose shall be measured in a plane perpendicular to the axis of the main tube

LIST OF INDIAN STANDARD AND HANDBOOKS RELEVANT TO STEEL CONSTRUCTION

(Clause 2.b)

A-1 Hot rolled steel sections

IS No.

Title

808: 1989

Beam, column, channel and angle sections

1161: 1979

Steel tubes

1730: 1989

Dimensions of steel plates, sheets, strips and flats for general engineering purposes.

1732: 1989

Dimensions of round and square steel bars for general engineering purposes.

1852: 1985

Rolling and cutting tolerances for hot rolled steel products.

3443: 1980

Crane rail sections.

3954: 1991

Channel sections for general engineering purposes.

12778: 1989

Parallel flange - beam and column sections - Dimensions

12779: 1989

Rolling and cutting tolerances for parallel flange beam and column sections.

A-2 Design codes and handbooks

800: 1984

Use of steel in general building construction.

806: 1968

Use of steel tubes in general building construction

4000: 1992

Assembly of structural joints using high tensile bolts

Handbook for structural engineers

SP 6(1): 1964

Steel sections

SP 6(2): 1962

Steel beams and plate girders

SP 6(3): 1962

Steel columns and struts

SP 6(4): 1969

High strength friction grip bolts

SP 6(6): 1972

Plastic theory

A-3 Welding codes/handbooks

10801: 1984

Recommended procedures for heat treatment of welded fabrication

11991: 1986

Recommended practice for flash butt welding of tubes, rods and other sections in carbon and alloy steels

SP 6(7): 1972

Simple welded girders

 

ISI handbook for manual metal arc welding for welders

Sp 12: 1975

Handbook for gas welders

Part 2 - Use of cold formed sections

General - The design of cold formed sections is covered by IS: 801-1975.  The fabrication is largely by resistance spot welding and by site bolting. This is because of extremely thin sections used in cold forming.  IS: 819-1957 for resistance spot welding of light assemblies in mild steel covers the fabrication practices of cold formed sections.

Materials - Cold formed gauge sections shall conform to IS: 811-1987.

Design code using cold formed sections shall conform to IS: 801-1975. SP 6 (5) 1980 is the handbook for cold formed light gauge sections.

Annexure 7-A.10

 SPECIFICATIONS FOR WELDING – COLD-WORKED STEEL BARS FOR REINFORCED CONCRETE CONSTRUCTION   (Extract of IS: 9417-1989)

1. Scope

1.1. This standard lays down recommendations for welding cold-worked steel bars conforming to Grade Fe 415 and Fe 500 of IS: 1786 -1985 'Specification for high strength deformed steel bars and wires  for  concrete  reinforcements ( third revision )' by flash butt welding, shielded metal arc welding and gas pressure welding processes.

2. References

2.1. The Indian Standards listed in Annex A are necessary adjuncts to this standard.

3. Terminology

3.1. For the purpose of this standard, definition given in IS: 812-1957 shall apply.

4. Plans and drawing

4.1. Plans and drawing for welding reinforced steel bars shall be prepared in accordance with SP: 46- 1988.

5. Symbols

5.1. Symbols for welding used in plans and shop drawings shall conform to IS: 813-1986.

6. Welding equipment and accessories

6.1. Welding equipment and accessories used in welding of steel bars for concrete reinforcement shall conform to the requirements of the appropriate Indian Standards where available. Where an Indian Standard is not available, equipment and accessories shall be of the best available quality.  Their capacity shall be adequate for the welding procedure.  A general guidance for selection of equipment and accessories is included in Annex B.

7. Parent metal

7.1. The parent metal shall be of guaranteed weldable quality of steel conforming to IS: 1786-1985.

8. Safety and health requirements

8.1. Safety and health requirements as prescribed in IS: 818-1968 shall be applicable.  Fire pre-cautions shall be as given in IS: 3016-1982.

9. Electrodes

9.1.Electrodes used shall conform to IS: 814 (Part 1)-1974.

10. Welding processes and procedures

10.1. General

10.1.1.Cold-worked steel bars shall be either butt-welded or lap welded.  Butt-welding may be carried out either by flash butt, gas pressure or by shielded metal arc welding process.  Lap welding may be carried out by shielded metal arc welding process.

10.1.2. Bars of unequal diameter may be welded. However, in case of butt welding, the difference in diameter of bars shall not exceed 5 mm.  Where unequal diameter bars are welded, the dimension ‘d' mentioned in this standard refers to the diameter of the smaller bar.

10.1.3. The untwisted ends must be removed before welding and the surface of the ends of the bars to be welded shall be clean and free from rust, paint, grease and/or other contaminants which are likely to affect the quality of weld.

10.2. Flash Butt welding of cold worked bars

10.2.1. General - Flash butt welding may be adopted if a large number of welding has to be done at the same place and when the electric supply is available of the required capacity in respect of the cross sectional area of the maximum size of the bar to be welded.

10.2.2. Procedure

10.2.2.1. The ends of the bars to be welded should be placed in proper alignment in clamps so that bent or eccentric joints do not result. The clamps should be cleaned before each welding operation to avoid current loss and to eliminate harmful notches or grooves due to burning in of spots of arcing.

10.2.2.2. The bar ends shall be uniformly pushed against each other from the moment of contact to the up setting.  The transformer regulator should be so set that the current at the contact area is between 85 to 90 A / mm2.

10.2.2.3. If the capacity of butt welding machine or the available power is not sufficient to take the load for welding from cold, welding may be done after preheating. By making and breaking of the contact arc repeatedly, heat can be made to spread over the entire cross section of the bar.  The number of short-circuits (contacts and reversing) should be kept to the minimum possible so that the welding time and spread of heat in the longitudinal direction in the bar is minimum. Satisfactory joints with only slight reduction in original strength of the bar can be achieved with a current density up to 25 A/mm2.

10.2.2.4. In automatic machines, the flash rate should be so set that a continuous flash without interruption can be achieved. If the rate is set, too high additional short-circuits are required leading to heat spread. If the rate is too low, the flash will be interrupted and consequently air penetrating into the joints will form oxides. If the machine is hand-operated, the flash should be maintained to avoid interruption. Too long flashes lead to generation of large quantities of heat thus removing the effect of cold-working in the bar.

10.2.2.5. For bars with sheared ends, a bum-off (flash-off) length of about 5 to 7 mm is required (this length is practically independent of the bar diameter).  Very short burn-off lengths lead to defective welding because all the impurities may not have been removed from the place of welding. Increase in the burn-off length will spread heat along the length of the bar thus reducing the strength of the bar.

10.2.2.6. The up setting should result from the burning off, that is, without interruption in the rain of sparks. The electric supply should be switched off about 1/3 to 1 second after the start of the up setting or in the case of automatic machine after 1 to 3 mm of up-set travel.

The voltage and frequency of the current should be checked before commencing the welding operation. Deviations from the nominal value or large fluctuations during the operation may lead to gross defects in welding.  Wherever possible, welding should be done during daytime when the total load on the network is fairly balanced.

10.3. Butt-welding by shielded metal arc welding process

10.3.1. General - Butt-welds by metal arc welding process are normally adopted to join bars of thickness more than 20 mm.

Fig 1. Edge preparation

10.3.2. Preparation for welding

10.3.2.1. The preparation of the edges of the rods shall be as shown in Fig 1. Shearing, machining, or oxy-acetylene flame cutting shall prepare the edges.  Machining, grinding oxy-acetylene cutting may make beveling. The fusion faces and the surrounding material shall be free from scale, dirt, greases, paint, rust and contaminants.

10.3.2.2. When it is not possible to rotate the bars for carrying out all welding in flat position, the edge preparation shall be such that welding is done on both sides in the vertical position.

10.3.2.3. All the bars to be butt welded should be aligned and set up in position with their axis

in one straight line.  This may be done in a jig or by means of a clamp or by using guides. Rotation of the bars should be avoided until they arc adequately welded 80 that no disturbance to the alignment is caused and no twist is introduced in the bars during the process of welding.  The joints may not be out

of alignment by more than 25 percent of the thickness of the thinner material for material up to and including 12 mm thick or by more than 3 mm for thicker material.

10.3.3. Electrode

10.3.3.1. Welding electrodes with flux covering of Type3 or Type 6 of IS 815: 1974 are recommended for better results depending on the size of the bar to be welded. Storage of the latter type and their drying immediately prior to use must be strictly in accordance with the recommendation of the electrode manufacturer.

10.3.3.2. The size of electrodes depends upon the position of the bead and thickness of the bar to be welded. The root runs should be made with electrodes of size not exceeding 2.5 mm. For successive beads, the size of the electrodes should be progressively increased so that in the top bead, the electrode size does not generally exceed 3.15 mm for 20-mm bars and S mm for 40-mm bars.

10.3.3.3. Proper welding sequence and manipulation of electrodes shall avoid concentration of heat.

10.3.4. Procedure

10.3.4.1. The sequence of welding beads is shown in Fig. 2.  The runs 1 to 4 are made in the position of welding best suited for the quality of the weld.  Besides the interruption in welding required for cleaning of each bead, a pause shall be made after every second bead and the bar is allowed to cool.  The temperature of the bars at a distance of about one bar diameter from the joints shall not exceed 3000C immediately after the bead is made.  Before commencing the next bead, the temperature shall not exceed 2500C. The temperature may be checked approximately by using temperature indicating crayons. However, in the absence of temperature indicating devices, the bar may be allowed to cool down to hand hot temperature before the next bead is deposited.

After completing bead 4, the bars are turned through 1800 and the beads 5 to 7 are made in the same manner as described above.  The top bead 8 is deposited as the joint is continuously rotated and the size of the reinforcement should be approximately as indicated in Fig.2.

Fig 2 Sequence of welding

10.3.4.2. In the case of non-rotatable bars, the beads 1 to 4 should be made as explained in 10.3.4.1.  The welder then moves to the other side and beads 5 to 7 are similarly made.  It is difficult to deposit a uniform top bead for non-rotatable bars and it may be necessary to make two or more separate annular runs so that the joint is approximately axisymmetric and has sufficient reinforcement as shown in Fig. 2.

10.4. Butt welding by gas pressure welding

10.4.1. Gas pressure welding is basically a hot forging process of joining the two bars end to end.  The bar ends arc heated by a multi-nozzle burner using oxy-acetylene flame and fused by forcing the two bar ends against each other under pressure to effect a solid phase welded joint.

10.4.2 Recommendations in regard to the preparation for welding procedure and equipment are given in Annex C.

10.5. Lap welding of cold-worked bars

10.5.1. General - Lap joints may be made in cold-worked bars of all sizes. They are preferred when access for welding is from one side only, and while connecting prefabricated units.  Use of electrodes with flux covering of Type 3 or Type 6 of IS: 815-1974 arc recommended for better results depending on the size of bar being welded.  Storage of the latter type and their drying immediately prior to use must be strictly in accordance with the recommendations of the electrode manufacturer.

10.5.2. Preparation for welding - Edge preparation is not necessary for lap welds. The joint faces and the surrounding material shall be free from scale, dirt, grease, paint, rust and contaminants.

10.5.3. Electrodes - The size of electrodes according to the diameter of the bar to be welded shall be as follows:

Nominal Diameter of Bar, d (Mm)

Size of electrode, Max (mm)

Up to and including 10

2.5

Over 10 upto and including 18

3.15

Over 18 up to and including 28

4.0

Over 28

5.0

10.5.4. Procedure – the arc should be struck as shown in Fig.3 somewhere in the middle of the joint and not at its beginning. 

The movement of the electrode for welding lap joints in the horizontal and vertical position is indicated in Fig.3.

 

Fig 3B Welding in the horizontal position

Strike the electrode here; the arc striking point must lie in the groove which will be subsequently welded-over.Welding directions for horizontal and near-horizontal lap joints; in the case of vertical lap

joints, the welding shall be performed from bottom to top (rising) Lift off electrode.

 

 

Fig 3B Welding in the vertical position

Fig 3 Welding of lap joints

 

The various lap joints used to connect cold worked bars are shown in fig.4 to 7.

 

Fig 4 Lap joint

 

Fig 5 Lap joint (variant)

Fig 6 Strapped joint (d= nominal diameter of butted joint)

 

1. Strike the electrode here; the arc striking point must lie in the groove, which will be subsequently welded-over.

2. Welding directions for horizontal and near-horizontal strapped joints; in the case of vertical strapped joints, the welding shall be performed from bottom to top (rising)

3.  Lift off electrode

4. Butted bar

 

 

Fig 7 Strapped joint (variant)

 

In Fig.4 to 6, the dimensions indicated as ‘5d’ for single side welding should be halved to ‘2.5d’ if the welds are deposited from the opposite side also.  The single strap arrangement shown in fig.7 is not recommended where access is from one side only.  In the case of joints illustrated in fig.6 and 7, the strap material must also conform to 7 and the strap cross sectional area must, at least, equal that of the bar to be joined.

11. Visual inspection - Each welded joint shall be visually inspected for the following.

11.1. Shape of profile - The profile of the welds shall be uniform, slightly convex and free from overlap at the toes of the welds.

11.2. Uniformity of surface - The weld surface shall be uniform in appearance throughout its length and shall show no pronounced hump or crater.

11.3. Degree of undercut - The welded joint shall be free from undercut but slight intermittent occurrences may be disregarded.

11.4. Freedom from surface defects - The surface of the weld shall be free from cracks, cavities, solid inclusions and other visible defects.

11.5. Misalignment - The misalignment of the bars welded shall not exceed one-fourth of bar diameter or 5 mm whichever is less.

Note: Misalignment shall be evaluated on the basis of smaller diameter in case of bars of unequal diameters are used.

12. Initial tests

12.1. Prior to production welding, test welds shall be carried out under the local production conditions to establish that the proposed joints can be made satisfactorily.  For the purpose, the tests shall be the same as for 'Quality Control Tests' in 13 but only 3 test pieces will be required for tensile test and 3 for bend test. Such initial tests shall be repeated if there is any change in:

(a) the welding process;(b) the grade of cold-worked steel bars;(c) the type or size of electrode;(d) the welder, and (e) the position  of welding, unless the  new position is an easier one.

13. Quality control tests

13.1. Butt welds - Test pieces containing butt welds at the centre in the as-welded condition shall be selected at the rate of one for tensile test and one for bend test for every 100 joints or as decided by the engineer-in-charge.

13.1.1. Tensile text – Un-machined specimens with a free length between grips about 20d should be used.  The selected pieces when subjected to a tensile test shall have tensile strength not less than 90 percent of the actual tensile strength of the bar but in no case less than 485 MPa for grade  Fe 415 and 545 MPa for grade Fe 500 of IS 1786 : 1985. The fracture shall not take place in the weld joint.

13.1.2. Bend test - The welding flash or reinforcement shall be removed at the point where contact is made with the mandrel.  The welded joint shall be capable of being bent to an angle of 600 around a mandrel of diameter specified below, before any crack appears:

Nominal Diameter of Bar, d

mm

Diameter of Mandrel

mm

Up to 10

5 d

Over 10

7 d

13.2. Lap joints - Test pieces containing lap joints at their centre in the as-welded condition shall be selected at the rate of one sample for tensile test for every 100 joints or as decided by the engineer-in-charge.

13.2.1. Tensile test - The free specimen length between grips must be between 25 d and 30 d where d is the nominal diameter of the bar. The breaking load shall not be less than the guaranteed load in accordance with IS 1786; 1985 required to fracture the bar.

14. Retests

14.1. If a sample selected for testing fails to meet the requirements given under 13.1 and 13.2, the purchaser or his representative shall take two further samples from the same lot.  If on testing, either of the samples fails to meet the specified requirements, the whole lot shall be rejected.

ANNEX A (Clause 2.1)

List of referred Indian standards

IS No.

Title

SP 46-1988

Engineering ,  drawing practice for schools and colleges 

IS: 812-1957

Glossary of terms relating to welding and cutting of metals

IS: 813-1986

Scheme of symbols for welding (first revision )

IS: 814(Part 1)-1974

Specification for covered electrodes for metal arc welding of structural steels : Part 1 For welding products other than sheets ( fourth revision )

IS: 815-1974

Classification and coding of covered electrodes for metal arc welding  of structural steels (second revision)

IS: 818-1968

 

Code of practice for safety  and  health  requirements  in electric and gas welding and cutting operations     ( first revision )

IS: 1179-1967

Specification for equipment for eye and face protection during welding ( first revision )

IS: 1786-1985

Specification  for  high strength deformed steel bars and wires for concrete reinforcements (third revision)

IS: 1851-1975

Specification for single operator type arc welding  transformers  ( second revision )

IS: 2635-1975

Specification   for  DC electric welding generators ( second revision )

IS: 2641-1964

Specification for electric welding accessories

IS: 2751-1979

Code of practice for welding of mild steel plain and deformed bars for reinforced concrete construction (first revision )

IS: 3016-1982

Code of practice for fire precautions in welding and cutting operations

IS: 9595-1980

Recommendations  for metal arc  welding  of carbon   and   carbon manganese steels

IS: 9857-1981

Specification for  welding cables

 

ANNEX B (Clause 6. 1)

Selection of equipment and accessories for welding cold-worked bars used for reinforced concrete construction

B-1. General

B-1.1. The methods of welding covered in this annex are:

(a) Flash butt welding, and (b) Shielded metal arc welding with covered electrodes.

B.2. Flash butt welding equipment

B - 2.1. The efficiency of the flash butt welding equipment, manifested by its conjunctive efficiency for cold-worked steels should be about 8 kVA/cm2 of the cross sectional area of the bar in order that sufficient cold weld maybe accomplished.

B - 2.2. The jaws for clamping the bars should preferably be long and pin shaped in order to assume a rectilinear central feeding of the bar ends.  The joint should preferably be of copper to assume a smooth and uniform flow of current from the jaws into the bar.

B – 3. Shielded metal arc  welding equipment

B - 3.1. In its simplest form, the equipment required for shielded metal arc welding of cold-worked steel bars for concrete reinforcing consists of:

(a) Welding power source;(b) Accessories, such as, electrode holders, earth clamp, welding cable, connectors, chipping hammer and wire brush;(c) Protective equipment for the operator, such as, hand screen or helmet, gloves, apron, etc; and(d) Suitable electrode storage and drying equipment, where necessary.

B - 3.1.1. Welding power source - The current for welding may be alternating or direct.  There is little to choose between them for work involving mild steel welding.  Electricity from the mains is usually at too high a voltage for arc welding. Various types of equipment arc used for reducing this voltage and delivering a welding current of right characteristics.

B - 3.1.1.1. Alternating current transformer oil-cooled or air-cooled type has the advantage of being low in initial cost and requiring very little maintenance.  Various types of controls for varying the current to suit conditions in common use.  Some of these are:  

 (a) Static choke with tapings, (b) a choke the value of which may be varied by means of the movement of the core, (c) a choke with a saturable core, and (d) a variable flux linkage transformer.

Being essentially a single-phase load, welding transformers when connected to 3-phase supply mains may cause slightly unbalanced load conditions.  Condensers of adequate rating may also be connected across the input lines for improving the power factor.

B - 3.1.1.2. Rotary machines, such as, motor generators suitable for use on alternating-current mains give a direct current output of the required characteristics.   They have the advantage that they impose a balanced load on 3-phase bar supply mains. They are, however, initially more expensive and require more maintenance than transformers.

B - 3.1.2. Where the mains supply is direct current, a motor generator designed for direct current bar main use has to be selected.

B - 3.1.3. Rectifier welding sets which arc relatively high in initial cost, require very little maintenance because of elimination of most moving parts. They also impose a balanced load on 3-phase supply, mains.

B - 3.1.4. For work at sites where mains power supply is not available, a petrol or diesel engine driven welding generator may be selected.  Such machines are often mounted on trailers for easy portability.

B - 3.1.5. Other points to be considered when selecting the equipment are:

(a) that the machine is designed to work  satisfactorily in the climatic conditions that will be met with during service;(b) that it is well made and conforms to relevant  Indian Standards, wherever these exist; and(c) that the current capacity is adequate for welding with the sizes of electrodes expected to be used.

B-3.1.5.1. IS: 1851-1975 covers transformer welding equipment and IS:  2635-1975 covers motor generator equipment for manual metal arc welding.

B-3.1.5.2. Electrode holders shall conform to the requirements laid down in IS: 2641-1964 and shall be of suitable rating for welding with electrodes in sizes expected to be used.

B-3.1.5.3. Welding cables shall conform to the requirements laid down in IS: 9857-1981, if cables with copper conductors are used.  Cables are with aluminium conductors shall be of a quality proved for performance.  Two lengths of cables are required, one from the welding set to the electrode holder and the other from the work piece to the welding set.

B - 3.1.5.4. All cable terminal connections, such as, sockets-earth clamp, shall also conform to the requirements specified in IS: 2641-1964.

B - 3.1.5.5. A well made chipping hammer with a hardened and tough cutting edge and a narrow type wire brush which may reach the root of the weld would also be required for deslagging and cleaning the weld.

B-3.1.6. Protective equipment - A non-conducting hand screen or helmet fitted with protective filter lens will be required to protect the face and eyes of the operator from the ultra-violet and infra-red rays emitted by the arc.  The filter lens has the double function of securing good vision of the arc and giving effective protection by cutting off the harmful rays.  The eye and face protection equipment should conform to the appropriate stipulations laid down in IS: 1179-1967.

B-3.1.6.1. Aprons and leather gloves should be of a standard that has been proved adequate for welder's use.  Shoulder guards, leggings and other such protective garments may be necessary when the operator has to do positional welding in conditions where freedom of movement is restricted.

B - 3.1.7. Storage - The conditions of the electrodes used have an important bearing on the ultimate quality of the weld produced.  Particularly, when moist ambient conditions are envisaged, for instance, at site work, the storage of electrodes has to be given much attention.  Heated storage cabinets or drying ovens arc a must when low hydrogen type electrodes are being used for site work. Other types of electrodes also are preferably stored before use in such cabinets when ambient conditions are unfavorable.

ANNEX C   (Clause 10.4.2)

GAS PRESSURE WELDING

C-1. Gas pressure welding process

The gas pressure welding process may be used for butt welding of reinforcing bars.

C- 1.1. Preparation for welding

C- 1.1.1. The ends of bars and the extreme untwisted ends of new bars shall be cut by shearing or

machining to make the face approximately normal to the axis of the bar.  Care should be taken to ensure that the bar ends do not twist while shearing.

C- 1.1.2. Rust, oil, paint, cement paste and any other coating over the bar-ends shall be removed and the surfaces to be, welded shall be finished as flat as possible.

C-1.2. Procedure.

C-1.2.1. Bars are clamped securely in the clamping unit with no misalignment keeping the gap between the bar ends less than 3 mm.

C-1.2.2. To begin with, the bar ends arc heated by a reducing flame to avoid any oxide formation.  The flame shall be directed at the joint and the burner shall be rotated to ensure uniform heating of the bar ends. On sufficient heating, the gap between the bar ends shall be

closed by the application  of axial  pressure (preliminary or first stage pressurization).

C-1.2.3. After preliminary pressurization and complete closing of the gap, the bar ends shall be heated by a neutral flame.  The heating shall be done for an appropriate period ensuring that the bar ends do not melt.

C-1.2.4. On sufficient heating of the bar ends, appropriate axial pressure (final or second stage pressurization) is applied  so that the bulge at the weld interface is about 1.4 times  the bar diameter.  Heating shall be stopped at this stage.  However, pressure application shall be maintained for some time even after the flame is put off.

C-1.2.5. The bars shall be unclamped after the glow of the heated area vanishes.

C-1.2.6. In case the flame dies out during heating the affected area shall be cut off and the welding procedure begun afresh,

C.2. Gas pressure-welding equipment

C-2.1. The equipment for gas pressure welding comprises or:

(a) Oxygen and acetylene gas cylinders with regulating values, etc; (b) Multi-nozzle burner;(c) Clamping unit; and (d) Pressurize.

C-2.1.1. The burner consists of a blow pipe with four or more nozzles. The nozzles shall be so arranged to ensure uniform heating of the bar surface.  The burner shall provide stable flame during heating and the heating capacity shall be appropriate to the size of the bar.

C-2.1.2. The clamping unit shall grip the bars well, be easy to handle, capable of being used in horizontal or vertical position of welding, and have such mechanism that no misalignment develops at the welded portion.

C-2.1.3. Pressurize shall be either hydraulic or mechanical and may be either manually operated or electrically driven. The pressurize shall be capable of maintaining uniform axial pressure.

Annexure 7-A.11

SPECIFICATIONS FOR INSPECTION OF WELDS OF STEEL AND ALLUMINIUM WORKS

(Extract of IS: 822-1970)

1. Scope

1.0 This standard has been prepared to serve as a guide to inspection of welds.  It covers the various stages of inspection and the methods, which may be adopted.

During inspection of welds reference may have to be made to other Indian Standards.  A list of such standards is given in Appendix A.

This standard keeps in view the practice being followed in the country in this field.  Assistance has also been derived from the following:

Weld quality control and inspection.  Canadian Welding Bureau, Toronto.

Welding inspection, 1968.  American Welding Society, New York.

1.1. This standard covers the recommended procedures for the inspection of welds.

1.1.1. This code is not limited to any specific process, method of manufacture or type of fabrication or type of fabrication, but is intended to be a general guide, from where the provisions should be selected for individual applications.

1.2. This standard does not stipulate any acceptance standards. These shall be subject to mutual agreement and would depend upon the nature and end use of the weldments.

2. Terminology

2.1. For the purpose of this standard, the definitions given in IS: 812-1957 shall apply.

2.2. Terms relating to methods of mechanical testing of metals shall be as defined in IS: 50 -1969.

3. Symbols

3.1. Symbols for welding used as working drawings shall be as given in IS: 813-1956. If other symbols are used, a complete explanation of their meaning shall be given.

4. Stages of inspection

4.1. Inspection for welding shall be carried in three stages :

a) Preliminary stage - Before commencing fabrication by welding

b) In process stage - During fabrication by welding

c) Final stage - Alter welding

5. Inspection before commencing fabrication by welding

5.0 Inspection before the commencement of the job should cover all aspects of the job with a view to eliminating all potential sources of defects.

5.1. Drawings and specifications

5.1.1. The contract specifications should be studied to ascertain the standard of quality required, and the end use of the products.

5.1.2. The standard specifications prescribed for the contract, and the general standard specifications applicable to the class of work should be examined carefully.

5.1.3. All the relevant drawings should be studied in respect of weld details, dimensional tolerances, process specifications, and any special requirements specified.

5.1.1. Where the contract specification does not indicate all the standard specifications applicable, or where it has been left partly or wholly to the discretion of the inspector, the standard specifications to be applied on the job shall be decided in consultation with the customer. The fabricator should be informed about such decisions and the standards of inspection and acceptance should be clearly laid down at the preliminary stage.                            

5.2. Selection of welding process

5.2.1. The process or welding proposed to be adopted by the fabricator shall be in accordance with the job specification and, where necessary, should be proved capable of producing welds of the required quality.

5.3. Material specifications

5.3.1. The materials to be used shall be in accordance with the job specification or approved  drawings and  any deviation  shall  be duly approved,

5.3.2. Only tested materials shall in general be used for welded work where the job permits the .use of untested material, separate tests should be carried out to ensure that satisfactory welds can be produced consistently with the material used.

5.4. Inspection of material

5.4.1. The material shall be examined and compared with the manufacturer’s test certificates, in respect of cast numbers, ISI Certification Marks, where applicable, inspection stamps, etc,

5.4.2. The material shall be examined for surface defects, rust and corrosion products presence of contaminants and any oilier factor may hamper the production of a satisfactory weld.

5.4.3. Since laminations are deleterious in welding, it is essential that the cut edges and weld preparations be examined for their presence. It is an advantage to use some non-destructive method such as liquid penetrate or magnetic particle flaw detection on the edges or to subject to ultrasonic flaw detection.

5.5. Selection of consumables

5.5.1. The welding electrodes, welding wire, flux, gases, or other consumables proposed to be used  for the job shall conform to the requirements of the relevant Indian standard specifications or to the job specifications.

5.5.2. Conformity with the standard may not however be adequate, since a wide range of products may be covered by a standard. It is, therefore, necessary to ensure that the specific selection made gives welds of the necessary quality.  In particular this applies to jobs where the welds are completely or partially free from inclusions and porosity (commonly known as radiographic quality welds) are demanded, since only some types or electrodes covered by the standard may give the required quality.

5.6. Inspection of consumables

5.6.1. The consumables to be used on the job shall be examined to ensure that they have not deteriorated, and are stored as recommended by the manufacturer with a view to preclude potential damage.

5.6.2. Manufacturer’s labels should be examined to ensure that the consumables conform to the latest specifications.

5.6.3. For important jobs it is advisable to get a test certificate for each batch of consumables supplied to the user, and to verify that these tests show conformity with the required standards.

5.7. Welding procedures

5.7.1. Complete welding procedure should be laid down by the fabricator unless the procedure to be adopted corresponds to the relevant Indian Standard code of procedure.

5.7.2. Tile procedure selected by the fabricator shall conform to all the relevant drawings and specifications and it shall be capable of producing welds of the required quality consistently under actual working conditions. The procedure shall lay down only such preparations and tolerances that may be achieved during production work.

5.7.3. Welding procedures, which are specially laid down, should be qualified (that is, proved acceptable) by a qualification test carried out by operators of requisite skill using the approved consumables and materials under conditions closely    approximating    to  those   during fabrication.  These test pieces shall lie subjected to all the tests, which will apply to the actual weld and to any other tests which may be required to demonstrate the quality of the weld.

5.7.4 Procedures conforming to the relevant Indian Standards do not normally require procedure qualification tests.  But these may be carried out, if desired by the inspector, especially when the standard provides wide latitude of choice.

5.8. Welding equipment

5.8.1. The welding equipment to be used on the job shall be in satisfactory operating condition and appropriate for the job in question.

5.8.2. It is advisable to ensure that all welding equipment and accessories used by the fabricator conform to the relevant Indian Standard specifications.

5.8.3. The functioning of the welding plant shall be examined, and accessories used by the tests shall be carried out to ensure that the plant capable of consistently producing welds of the required quality.

5.9. Welders and operators

5.9.1. Welders - All welders employed shall be trained, tested and certified according to the appropriate Indian Standards applicable to the job.

5.9.2. Operators - Operators employed for mechanized welding shall be trained and tested to executed to execute the required job.

5.9.3. Such qualifying tests shall be made using the consumable and equipment approved for the job under conditions closely approximating to those during production.

5.9.3.1. The validity of the certificate of welder or operator shall lapse if for any reason he has not worked as a welder or operator for period of six months.

5.9.4 A record shall be maintained of the welders and operators who are qualified by certificates or tests for the respective categories of world on the job.  Tins record shall be made available to all concerned so that it can be ensured that duly qualified welders do all welding.

5.10. Testing facilities

5.10.1. The fabricator should have facilities for performing all the tests required on the job or shall be able to call upon the facilities of any outside agency or testing establishment.

5.10.2. Testing equipment should be in good condition and shall be calibrated and certified as required.

5.10.3. The testing equipment shall be operated by staff conversant with the testing techniques and able to operate the equipment properly and reliably,

5.11. Ancillary equipment and facilities

5.11.1. The fabricator should have adequate and suitable equipment for cutting, straightening, rolling, planing and other methods of preparation required for different classes of welded fabrication.

5.11.2 The fabricator should possess Jigs, fixtures, clamping device manipulators, handling equipment, etc, to suit the class of work.

5.11.3 There should be adequate facilities for storage of materials and consumables.

5.11.4 There should be adequate facilities for drying the welding consumables.

5.11.5 Where preheating or other heat treatment is required, the fabricator shall possess adequate equipment for the operations and for indicating and controlling the temperature.

6. Inspection during fabrication by welding

6.0. Inspection during fabrication by welding is done from the following points of view:

a) Ensuring that the procedures, consumables, operators, etc, on the job have been previously approved.

b) Examining assemblies, weld preparations, etc, prior to welding to ensure that they arc in conformity with the approved procedures and conducive to good welding.

c) Visual inspection during welding to ensure that, the work in process produces .a good finished weld, and that defects in initial stages are removed prior to further work,

d) Testing of welds which may become inaccessible or more difficult to inspect at a later stage.

e) Permitting modifications, additions or permissible alternatives to procedures, consumables and welders previously approved.

6.1. Inspection of prepared materials

6.1.1. The materials previously inspected and approved should be re-examined just before avoiding is commenced with special emphasis on the weld zone.  Tile weld and (lie adjacent area shall be free of dirt, rust, oil or ether following material, which may affect the quality of the welding.

6.1.2. The edge preparation for the weld and the weld zone should be checked for conformity with the requirements of the approved welding procedure, and shall be within acceptable tolerances.

6.1.3. The cut Faces shall be examined for nick marks, cracks, scale, burrs, etc, and these shall be rectified prior to welding.  Where the material is gas cut and by virtue, of its thickness and composition; is susceptible to cracking during cutting, particular attention should be paid to crack detection on the cut surface, preferably using some method of non-destructive testing.  This would apply even if subsequent machining has been carried out, since cracks may not have been removed completely by machining.

6.2.1. The method and sequence of assembly and the jigs and fixtures shall correspond to those previously approved, and shall permit welding according to the approved procedure.

6.2.2. The fit-up, gaps, orientation and welding position should correspond to those on the approved welding procedure.

6.2.3. Due precautions to minimize distortion and ensure dimensional accuracy of the finished fabrication shall have been taken without imposing undue stresses on the welds.

6.2.1. Tack welds shall be adequate size, length and pitch and carried out using the correct welding procedures and by qualified welders (see ISI Handbook on Manual Metal Arc Welding for Welders).

6.2.5. Temporary fittings, clamps, fixtures, stiffeners, etc, where used shall not   interfere with the  welding,    and   shall   conform   to accepted practices for the particular class of work.

6.3. Welding consumables

6.3.1. Electrodes and other welding consumables shall be of types previously approved, and shall be in good condition.   In particular it shall be ensured that these arc clean, and have been dried according to the manufacturers' recommendations.

6.3.2. If during fabrication it is found necessary or desirable to alter amend or make additions to the list of consumables previously approved, the new consumables proposed shall be duly approved.  Whereas strict equivalents or identical types of alternative brands may be approved without further

tests, change of type or category of consumable will in general require further tests to ensure that these will produce acceptable results when used wish the approved procedures.

6.3.3. If during fabrication there is an incidence of defects which may be attributed to the consumables, the defective consumables should be replaced by another batch of consumables or by another brand of identical type, subject to the approval of the inspector.

6.4. 0perators and welders

6.4.1. All operators and welders used on the job shall be persons who have been previously approved by virtue of certificates or qualification tests.

6.4.2. If any addition to the list of approved operators and welders for various categories is to be made, such additions shall be approved on the same basis as for initial approval. This will apply to inclusion of more operators and welders for a given class of work, to transfers from one class to another and to the approval of welders for class in addition to those for which they have been previously approved.

6.4.3. If at any time during the job there is any reason to question the capability of an operator or welder, for example, due to the incidence of defects in welds made by him, the inspector may, at his discretion, withdraw approval previously granted to him and demand tests for re-approval.  Such operators shall not be used on the job until they are re-qualified.

6.5. Welding procedure

6.5.1. The welding procedures followed shall conform to those laid down and duly approved in respect of all the relevant details.

6.5.2. Where it becomes desirable or necessary to amend alter or deviate from the approved procedures, the revised procedures shall be fully laid down and approved on the same basis as for initial approval Where the changes are of such a nature that they are not likely to affect the quality adversely, the tests for qualification may be waived provided that it is demonstrated that welds of satisfactory quality can be producer after incorporating the changes.

6.5.3. If it is found that; despite conformity to approved welding procedures, welds of acceptable quality are not produced, such approval may be withdrawn.  The same procedure may be submitted for re-approval, however, If it could be demonstrated that the procedure was not responsible for the defective weld.

6.5.4. Particular attention shall be paid to the observance of special requirements such as sequence of welding, preheating, peening, heat treatment, etc.

6.5.5. It shall be ensured that test coupons, extension pieces, etc, are provided as required by the job or as specified in the relevant Indian Standard.  Additional test coupons shall be provided if demanded by the inspector.

6.6. Inspection during welding

6.6.1. Besides ensuring that the approved welding procedures are being followed, it should be seen that the techniques conform to good welding practice. For example, the thorough removal of slag from an arc weld, of the dressing of spot avoiding electrodes although implied in the procedure will fall in the category of good practice.

6.6.2. Welds which would become inaccessible or more difficult to inspect at a later stage shall be inspected completely at this stage.

6.6.3. For important welds, inspection during the welding process, and in between runs, is essential.  

With careful inspection during welding it is possible to identify potential sources of defects and eliminate them at the early stage.

6.7. Deviations

6.7.1. If any deviations from approved procedures or from approved lists of consumables, processes or operators are detected, the welding shall be stopped pending an appraisal of the consequences of such deviations.

6.7.2. It is essential that the fabricator be made to understand the importance of approvals and the dangers of unauthorised deviation.

6.7.3. If such deviations are detected after completion of a part or the whole of a job, suitable rectification should be made or remedial measures are taken at the discretion of the inspector.

6.7.4. Where such deviations have produced welds of doubtful quality the fabrication would not be deemed as acceptable unless adequate test show that the quality achieved is satisfactory, or unless necessary rectification’s carried out subsequently to achieve this quality.

7. Inspection after welding

7.0. Inspection after welding is done with a view to assessing:

a) the quality of the weld  by tests on extension pieces or the actual fabricated component; and

b) the correctness of the whole weldment  ( that is,  the fabricated component) by visual and dimensional inspection, by leak and load tests on the actual fabricated component.

7.1. Visual inspection

7.1.1. The completed weld and the welded fabrication as a whole should be examined visually, preferably with the assistance of a magnifying lens or a magnifying torch.

7.1.2. Visual inspection should cover all the visible aspects of the weld and the weldment.

7.1.3. The following types of weld defects may be detected during visual examinations:

a) Weld defects occurring at the surface such as blowholes, pipes exposed porosity, exposed inclusions, unfilled crate, unfused welds, etc.

b) Surface cracks in the weld metal or in tile parent metal adjacent to it;

c) Damages to the parent metal such as undercut, burning, overheating, etc;

d) Profile defects such as excessive convexity or concavity, overlap, unequal leg lengths, excessive reinforcement, incompletely filled grooves, excessive penetration bead, root grooves, shrinkage grooves, etc; and

e) Incorrect finish, for example ripple marks, weaving faults, chipping and peening marks, spatter, under-flushing (excessive grinding), excessive indentation of spot welds, uneven welds etc.

7.1.4. The following types of faults on the weld may also be detected by visual examination:

(a) Distortion due to welding, that is, local shrinkage, camber, bowing twisting, rotation, buckling, waviness, etc;(b) Linear, eccentric, angular and rotational misalignment of parts;(c) Incorrect location of components; and (d) Visible dimensional errors.

7.2. Inspection of weld dimensions

7.2.1. Inspection for the correct dimensions shall be carried out in the case of fillet welds, spot welds, seam welds, etc where the size is specified. They shall be inspected using suitable gauges and taking into consideration the permissible tolerances.

7.2.2. Dimensional inspection of the completed weldment shall be carried out using tools and measuring instruments appropriate to tile type of fabrication and the dimensional accuracy required.

7.3. Mechanical testing

7.3.0. Mechanical tests (often described as destructive tests because their application will destroy the weldment) can be performed on:

a) prototype or sample welds, and b) extension pieces or test coupons.

7.3.0.1. Mechanical tests may comprise of all or some of the following:

a) Tests for determining strength and ductility - Tensile test, bend test, impact test load test, etc;

b) Tests for determining continuity, fusion and soundness – Bend test, slug test for spot welds, etc;

c) Tests for determining penetration and internal weld configuration – Macro section, etching, etc; and

d) Tests for determining metallurgical properties and local variations in the weld and the heat affected zone – Microscopic examination, hardness surveys, chemical analysis of borings from the cross sections, etc.

7.3.1. Prototype

7.3.1.1. For small weldments a prototype is welded and tested to destruction.  This test may comprise

an overload of the type of load to which the weldment is subjected in service or some form of fatigue test.

7.3.1.2. For larger weldments in repetitive work a prototype is welded and sectioned at various places.  Such sections would he subjected to the required mechanical tests.

7.3.2. Sample welds

7.3.2.1. Sample welds are normally required only for establishing the correct welding procedure and would be part of the inspection before fabrication.

7.3.2.2. In certain types of welds additional sample welds are made on test pieces using the same machine settings, operators and oilier conditions that would be obtained on the job.  These test pieces are subjected to various tests, and may lie deemed be equivalent to testing the actual weldment.

7.3.3. Extension pieces find test coupons

7.3.3.1. Many specifications specify extension pieces or test coupons, which would be welded as part of the main weld and subsequently detached for testing. In fusion welds such extension pieces would serve the additional function of run-on and run-off pieces required to ensure the soundness of the full length of the weld.

7.3.3.2. Extension pieces and coupons should be of the same composition and with the same weld preparation as the parent material of the mail weld.  It would be ideal if they are off-cuts from the parent material and attached so that the direction of rolling is the same as that on the parent material.

7.3.3.3. Extension pieces are subjected to mechanical tests and the results of such tests shall be deemed to indicate the properties of the main weld.

7.3.4. Tests for determining strength and ductility

7.3.4.1. Tensile tests:

a) Transverse tensile test

b) Reduced section transverse tensile test (with a reduced section at the weld to cause tensile failure in the weld) c) Longitudinal tensile test, d) All weld metal tensile test, e) Tensile (shear) test for spot vvelds, f) Cruciform tensile test for fillet welds, and g) Tensile tests, on lap welds (shear on longitudinal and transverse fillet welds).

7.3.4.2. Bend tests

a) Free transverse bend test, b) Guided transverse bend lest, c) Longitudinal bend test, d) Side bend test and e) Fillet weld bend test.

7.3.4.3. Impact tests:

a) Charpy V - notch impact test, and

b) Explosive impact test.

7.3.4.4. Load tests - Loads may be applied on the weldment by jacks, weights, pulley blocks, or universal testing machines until failure takes place.                            '

7.3.5. Tests for determining continuity, fusion and soundness of welds

7.3.5.1. Bend tests

(a) Free transverse bend test,(b) Guided transverse bend test,(c) Longitudinal bend test,(d) Side bend test, and(e) Fillet weld bend test.

7.3.5.2. Nick break tests for butt and fillet welds.

7.3.5.3. Slug tests for spot welds.

7.3.6. Tests for determining penetration and internal weld configuration

7.3.6.1. Macro-examination.

7.3.6.2. Etching of macro section with proper etching solution.

7.3.7.1. Microscopic examination

(a) Examination of microstructure,(b) Number, and size of inclusions, and (c) Grain size measurements.

7.3.7.2. Hardness surveys

a) Hardness survey of weld and heat affected zone on macro section, and b) Measurement of micro-hardness.

7.3.7.3. Chemical analysis

a ) Chemical analysis of borings taken from the macro section or the surface of tile weld, and

b) Chemical analysis by spectrographic method.

7.4. Non-destructive testing

7.4.1. General - Non-destructive testing covers the examination of welds by all the processes which do not require destruction of weldment by sectioning or cause damage to it or render it unusable. 

While this includes methods such as visual and dimensional inspection non-destructive testing will normally cover the use of the following methods:

(a) Radiographic examination,(b) Ultrasonic testing,(c) Magnetic particle flaw detection, (d) Liquid penetrate flaw detection, and (c) Eddy current testing.

The general application of the methods, their advantages and limitations are given in Table 1.

7.4.1.1. Before selecting the method of non-destructive testing, it is necessary to consider the following factors:

a) Portions of tile weldment to be inspected; b) End use of the weldment and the functional significance of discontinuities or flaws in the weld; c) Material, thickness, shapes and surfaces condition of the weld; d) Possible or expected defects, their type, size and location; and e) Acceptable standards.

Table 1 – Guidelines for use of different methods on destructive examination of welds

Sl. No

Method

Application

Types of faults Indica

Advantages

Limitations

I

Radiography

Aircraft structures, structural steel work, ship building, pressure vessels and boilers, penstocks, electronic parts, etc.

All types of internal flaws such as piping, porosity, inclusions, fusion, incomplete penetration

a)provided permanent record on film

b)Techniques standardised

c)Reference standards for defects available

d)Adjustable energy level gives high sensitivity, and

e)Fluoroscopy techniques available.

a)Trained technicians needed

b)Radiation hazards

c)High cost of equipment, and

d)Power source needed.

a) X-rays

 

b) Gamma rays

Pipe work, penstocks, pressure vessels and boilers, structural steelwork, ship building, etc

All types of internal flaws such as piping, porosity, inclusions, fusion, incomplete penetration

a)provided permanent record on film

b)Techniques standardised

c)Reference standards for defects available

d)Low initial cost,

e)Portable and indepen-dent of power supply (for site work), and

f)Makes panoramic exposures (ideal for jobs like pipe work)

 

a)Trained technicians needed

b)Radiation hazards

c)Fixed energy levels per source,

d)Source loses strength continuously,  and

e)Generally lower sensitivity and

definition than X-rays

 

ii

Ultrasonics

All types of welded work in metallic and non-metallic materials

Internal defects such as cracks, inclusions, lack of fusion, in penetration

a)safe to use.  No radiation hazards

b)Fast, results available immediately,

c)Sensitive,

d) Indicates presence of laminations and other planner defects missed by radiography,  and

e)Indicates depth of flaw also.

a)Entirely dependent on the interpretation skill of operator who requires much experience  and training

b)Unsuited to the examination of weld -ments of complex shape or configuration (e.g. backing rings)

c)Requires surface contact or immersion, and

d)Surface must be ground smooth and clean.

iii

Magnetic particle

Welds (particularly fillet welds) in all ferro-magnetic materials

Cracks, porosity, inclusions antinuities at or close to the surface

a)simple to use and interpret

b)relatively inexpensive, and

c)portable

a)Material must be ferro-magnetic

b)Demagnetization may be needed, and

c)Power source required

Sl.No

Method

Application

Types of faults Indica

Advantages

Limitations

iv

Liquid-penetrant

All welds in ferrous and non-ferrous materials and in non-metallic materials

Surface defects only, such a cracks and blowholes

a)Simple to use and interpret

b)Relatively inexpensive, and

c)Portable, and requires no elaborate equipment, and

d)Will work on all materials

a)Will only detect surface defects on the accessible surface

b)Surfaces must be clean and dry, and

c)Rust or paint will mask defects.

 

v

Eddy-current

Welds in materials with good electrical conductivity

Defects at or very close to the such as cracks, linear discontinuity

a)Does not require contact with the surface

a)Difficult to set and interpret, and

b)Limited to materials with good electrical conductivity.

7.4.1.2. All the methods of non-destructive examination are comparatively expensive and would increase the cost of inspection.  Their use should, therefore, be limited to the extent actually required in order to assess with reasonable confidence the absence of unacceptable flaws.

7.4.1.3. Used judiciously, non-destructive methods given in 7.4.1 are the most significant and useful among the various methods of inspection available.

7.4.2. Radiographic inspection – In radiography the ability of short wave length radiations, such as X-rays and gamma rays, to penetrate objects opaque to ordinary light is utilized to produce a shadow of any internal defect on the image.  The defects are recorded on a film sensitive to the radiation or may be viewed on fluorescent screen.

7.4.2.1. Radiography may be performed using X-rays generated from X-ray tubes, gamma rays emitted by radioactive isotopes or electron beams emitted by betatrons and linear accelerators.

7.4.2.2. Radiography may be employed for the inspection of welds of all types and thickness ranging from minute welds in electronic components to welds up to half meter thick employed in heavy fabrications.  The maximum thickness of material (in terms of steel thickness) which can be inspected with various industrial X-ray generators are given in Table 2.  In Table 3 are given the optimum range of thickness which may be tested with commonly used radioactive isotopes.

7.4.2.3. For material other than steel, the limits of thickness may be obtained by dividing those shown in Tables 2 and 3 by the radiographic equivalent factors given in Table 4.]

7.4.2.4. Thickness above the range given in Tables 2 and 3 may be penetrated by electron beams emitted by betatron (25 Mev) upto 500 mm and by the electron beams emitted by Linear accelerator (12 Mev) upto 650 mm.

7.4.3. Selection of source 0 selection of source for radiography depends upon:

(a) availability of sources; (b) thickness range to be examined,(c) shape of weldment and its accessibility, (d) availability of power supply, and (e) use of panoramic exposures.

Table 2 Type of conventional industrial X-ray generators and their applications (Clause 7.4.2.2)

Peak kilo voltage kV (peak)

Type of screens

Maximum thickness of material that can be inspected (approx)  mm

50

-

Micro radiography, wood and plastics

100

-

50(aluminium), 75(magnesium)

150

None or lead foil

25 (steel or equivalent)

 

Fluorescent

40 (steel or equivalent)

200

Lead foil

40 (steel or equivalent)

 

fluorescent

60 (steel or equivalent)

250

Lead foil

50 (steel or equivalent)

 

fluorescent

75 (steel or equivalent)

300

Lead foil

65 (steel or equivalent)

 

fluorescent

90 (steel or equivalent)

400

Lead foil

75 (steel or equivalent)

 

fluorescent

100 (steel or equivalent)

1000

Lead foil

125 (steel or equivalent)

 

fluorescent

175 (steel or equivalent)

2000

Lead foil

225 (steel or equivalent)

Table 3 Application of artificial gamma ray sources (Clause 7.4.2.2)

Sl. No.

Element

Isotope

Half-life

Energy of main gamma ray line 

MeV

Optimum thickness of steel

Mm

i

Thalium

Tm  170

130 days

0.084, 0.052

5.15

ii

Iridium

Ir  192

75 days

0.31, 0.47, 0.60

5.20

iii

Caesium

Cs  137

33 years

0.66

20 – 60

iv

Cobalt

Co  60

5.3 years

1.33, 1.17

30 -150

v

Cerium

Ce  144

140 days

1.3

30 -150

Table  4  Approximate radiographic equivalence factors of several metals  (Clause 7.4.2.3)

Sl. No.

Metal alloy

150 kVP

200 kVP

1000 kVP

Gamma rays

i

Aluminium

0.12

0.13

-

-

ii

Magnesium

-

-

-

-

iii

24 ST Alloy

0.13

0.14

-

-

iv

Steel

1.0

1.0

1.0

1.0

v

18-8 Stainless Steel

1.0

1.0

-

-

vi

Copper

1.5

1.4

-

-

vii

Zinc

1.4

1.3

-

-

viii

Brass *

1.48*

1.3*

1.2*

1.1*

ix

Lead

14.0

12.0

5.0

2.3

* tin or lead in the brass will increase these factors.

7.4.3.1. In general, X-ray sources will give more sensitive radiographs of higher contrast and better definition in a shorter time.  Isotopes (gamma ray sources) are more advantageous for work at site, for pipe work and where heavy thicknesses are to be inspected.  Their initial cost is also lower.

7.4.3.2. The source selected for the radiography of a particular weld on the basis of the factors mentioned above shall be able to produce radiographs of the requisite quality (density and sensitivity)

7.4.4. Indication of defects on radiograph – The indication of defects on the radiographs depends upon their nature and orientation with respect to the beam of radiation.  Table 5 shows the types of faults in fusion welds and their radiographic images (see Part VI of IS: 812-1957).

7.4.5. Interpretation of radiographs and assessment of defects – Radiographs should be interpreted by viewing with adequate illumination in a darkened room.  Before interpretation it should

be ensured that the radiograph has adequate density and sensitivity as indicated by a suitable image quality indicator.

Table 5 Radiographic images of defects in fusion welds (Clause 7.5.3)

Defect

Description

Image

Porosity

Gas pockets or voids

Rounded shadows of various sizes and densities, occurring singly, in clusters or scattered

Slag inclusions

Slag entrapped during welding

Elongated or irregularly shaped shadows

Lack of fusion

Lack of side fusion, root-fusion or inter-run fusion

A dark shadow usually elongated

Incomplete penetration

Un-penetrated cavities at the root or between runs

A linear indication straight, dark  and usually at the centre of the weld

Cracks

Narrow discontinuity produced by tearing of the metal when in a plastic or cold condition

Fine dark line, straight or wandering

Capillary pipe

A fine pipe at the fusion face usually caused due to laminations in the parent material

A straight dark but rather diffuse shadow

Pipe (wormhole)

Elongated or tubular gas pocket

Elongated or very dark round shadow (depending upon the orientation of the pipe)

7.4.5.1. Correct interpretation of radiographs requires experience and should be done only by those inspectors who are properly trained and who possess adequate experience.

7.4.5.2. In the interpretation of radiograph and deciding the degree of faults, guidance may be derived from the reference radiographs published by International Institute of Welding.  But these radiographs should not be as acceptance standards.

7.4.6. Ultrasonic testing – In ultrasonic testing a high frequency sound wave is propagated into the metal under test.  Any discontinuity in the metal will result in the reflection of the wave thus indicating the presence of faults.

The initial signal and the reflected signals are usually indicated on a cathode-ray tube and appear as vertical indications (commonly called ‘pips’).  The equipment uses an electronic pulse generator to generate an electrical wave which is converted into a sound wave by using piezo-electric crystals mounted in the ‘probes’, which also pick up the reflected sound waves and convert it into electrical waves to be fed back into the cathode-ray tube.

Ultrasonic testing may be done with straight probes which generate A longitudinal wave perpendicular to the surface of contact, angle probes which give out them waves at the specified angle or special surface wave probes.

Testing may be done using a single probe as transmitter and receiver or by a double probe method with one probe functioning as the transmitter and the other receiving the echoes.

The method can be used successfully on welds in steel from about 10 mm in thickness to over 5 metres.

7.4.6.1. Salient features of ultrasonic testing:

a) Indications – In most of the equipment now in use, the wavy line on the screen has to be interpreted for the presence of echoes indicating discontinuities.  It is necessary to scan tile weld in different directions before the size and the location can be interpreted.  Although new types or equipment are being developed to Indicate the size of flaws, such refinements are in the development

stage and at present the operator has to assess the indications in the form of  'pips' to determine the fault.

b) Sensitivity – Minute faults if oriented normal to the ultrasonic beam will give distinct 'pips' which could be mistaken for echoes from gross faults.  Even a slight increase in the cross-section of the part under examination will register on the screen. Normal discontinuities such as grain boundaries or micro porosity may generate such a degree of background ‘noise’ that a signal from a flaw is

indistinct. This extreme sensitivity of the ultrasonic method to variations in the acoustic impedance is the chief cause of misinterpretation of readings.

c) Operators – In view of the difficulties in interpreting the indications on the screen and identifying the type and size of discontinuity, ultrasonic testing can only be done by experienced and highly skilled operators.

The success of the method depends almost entirely upon the skill of the operator in making the correct settings, eliminating sources of spurious indications and in correctly interpreting the indications,

d) Recording - Usual types of ultrasonic testers do not have any methods of recording the results of the tests apart from photographing the screen, but such photographs only indicate the screen image at a particular setting but not the results of scanning. Other types of recording equipment arc being developed, but most of these can only be used on fully automatic set-ups.

c) Spurious indications -These may arise out of variations in acoustic impedance; grain boundaries, couplant, surface condition or electronic faults in the equipment.   Use of test blocks can identify some of them, but it is dependent on the skill of the operator to detect and eliminate spurious indications.

7.4.6.2. Interpretation and assessment - In view of the features of the process enumerated in 7.4.6.1, the interpretation and assessment of type size of flaw and location should be left to the operator.

The Inspector will only be expected to assess the functional acceptability of the weldment based on the flaw detection report of the ultrasonic operator.

In case the indications of discontinuity by the ultrasonic testing method are doubted, it is preferable to corroborate this by using radiography.  Where such an alternative is not possible, the area which is suspected to contain the defect should be again scanned at other positions and with other probes to confirm the presence of the defect.

7.4.7. Magnetic particle flaw detection - Magnetic particle flaw detection is based on the principle that if a ferro-magnetic object is magnetised, the discontinuities in the material such as cracks and inclusions, lying at an angle to the magnetic lines of force, cause an abrupt change in the path of the magnetic flux flowing through the object.  This results in local flux leakage at the surface over the discontinuity.  If at this stage, fine particles of ferro-magnetic material, either dry or suspended in a liquid, are applied over the surface some of these particles will be attracted towards the leakage field Mid pile up arid bridge the discontinuity setting up a pattern outlining the discontinuity.

7.4.7.1. Methods -The following methods of  magnetization  are available:

a) Magnetic flow method - The job (part to be tested) is placed between the poles of a permanent magnet or an electromagnet,

b) Current flow method - Longitudinal magnetization: Where the passage of electric current through a coil of several turns around the part to be tested produces a longitudinal magnetic field within it.

c) Current flow method – circular magnetization - The passage of electric current through the part or through a straight conductor enclosed by the part creates a circular magnetic field around it.  Current is passed through the part by placing it between the machine contact plates of a current flow type-testing machine, or by using prod type contacts to produce local circular magnetization.

7.4.7.2. The magnetic particles may be applied while the current is flowing (continuous method) or after the current has ceased to flow (residual method).  The use of the latter depends upon the strength of the magnetization force and the capacity of the material to retain the magnetization.

The magnetic particles may either be applied in the form of dry powder ( dry method ) or as a suspension in a suitable liquid medium ( wet method ).  The magnetic particles may be red or black to

providing adequate contrast and should be visible under normal white light.  For increased visibility when working with the wet method, the magnetic particles that are coated, with a fluorescent dye arc rendered visible by 'black light' (near ultraviolet light).

7.4.7.3. The following are the salient features of magnetic particle flaw detection:

a)  Indications - Discontinuities are indicated by the pattern in which the magnetic powder is collected around the leakage fields.  Fine elongated discontinuities, which are parallel to the field, are not indicated, and should be detected by using a field at right angle to them.   Deep discontinuities are indicated by the 'piling up' of the magnetic powder at the lines of the flaws.   

Subsurface discontinuities show fuzzy or indistinct pattern, which may easily remain, undetected.  Change of magnetic permeability, abrupt change of section and over magnetized welds may lead to false indications.

b) Application - The method may be applied only if both the weld metal and the parent metal are ferromagnetic. For satisfactory results, the surface should be clean, dry and reasonably smooth.

c) Demagnetization - For some applications it is necessary to demagnetize the weldment before the test.   This may be done either by some form of heat treatment or by using an alternating current reducing the magnitude of the current gradually to zero.

d) Recording of indications - Defects may either be recorded by photography or by lifting off the pattern with transparent adhesive tap or a piece of adhesive coated tracing cloth.

7.4.7.4. Interpretation and assessment - Defects in the fusion weld generally indicated by magnetic particle flaw detection method and the powder patterns formed are as follows:

Defects

Powder pattern

Surface cracks

Sharp piled-up patterns

Subsurface cracks

Diffused powder patterns

Incomplete penetration

Diffused indication similar to that for subsurface cracks

Subsurface porosity and slag inclusions

Diffused indications

Incomplete fusion

Pronounced accumulation of powder along the edges of the weld

7.4.8. Liquid penetrant flaw detection - In this method of testing a suitable liquid penetrant is applied to the surface of the portion under examination and remains there for a sufficient time to allow the liquid to penetrate into any defects open at the surface.  After the penetrant time, the excess penetrant, which remains on the surface, is removed. Then a light coloured powder absorbent called the developer is applied to the surface.  This developer acting as a blotter draws out a portion of the penetrant which had previously seeped into the surface openings.  As the penetrant is drawn out, it diffuses into the coating of the developer, forming indication of the surface discontinuities of flaws (see also IS: 3658-1966).

7.4.8.1. The following types of penetrants are used:

(a) Thin oil when chalk powder is used as the developer; (b) Dye penetrants which form indications visible in the normal light; and (c) Fluorescent penetrants which make the defects visible in ultraviolet light.                         

7.4.8.2. The components under test may be dipped into the penetrantor, where only a local area of a component is to be tested; the penetrant may be applied by brush. It is necessary that the component to be tested is clean, free from all contaminants and dry.   .

7.4.8.3. After necessary penetration time, the surface film of the penetrant on the component is removed by appropriate means.  Where the penetrant contains an emulsifier or where the penetrant is treated with an emulsifier after penetration, a water spray is used to remove the excess penetrant.  Great care should be exercised to ensure that while the surface is clean, the penetrant from the defect is not removed.

7.4.8.4. On applying the developers the, defects appear as amber coloured lines when the oil and chalk process is used, and as red ( or the colour of the dye ) when dye penetrant has been used.  Where fluorescent penetrant is used the components should be inspected in a dark room under black light.  Defects appear as bright green outlines against a dark purple background.

7.4.8.5. Interpretation and assessment - The indications generally take the shape of the discontinuity and its definition depends upon the depth and size of the defect.

Because of the inherent human factors involved in applying and removing penetrants, faulty indication, and when the cracks are choked with corrosion products, liquid penetrant method of flaw detection should be used with some caution.

7.4.9. Eddy current testing – This process depends upon eddy currents set up in the material under test when a suitable probe is brought close to the material.

The process is difficult to use and interpret, and is seldom used for weld testing.  It has however the advantage of able to fine cracks without touching the weldment.  New types of this equipment are being developed to eliminate some of the difficulties in adjusting the equipment and reducing the spurious indications.

7.5. Leak tests - For certain types of enclosed weldments such as in vessels, tanks, pipe lines, penstocks, etc, it is essential that the weld is leak-free under the working pressure.   Leak tests are usually carried out at a pressure higher than [lie working pressure using some suitable liquid or gas.

7.5.1. While selecting the fluid for leak test, the end use of the component and the substance it has to store or carry should be kept in view. For example, use of a highly sensitive liquid of low viscosity may be more stringent than needed for containers of viscous liquids.

7.5.1.1. Water is very commonly used for leak tests because of its cheapness and moderate viscosity.  But if the vessel or pipe has to carry a fluid of lower viscosity, the absence of leak at a certain test pressure with water does not indicate the absence of leak at the same pressure with the less viscous fluid.   Leak tests with water are therefore normally carried out at pressures higher than the working pressures.

7.5.1.2. The oils, which arc to be contained in the vessel or pipe, may themselves be used at an increased pressure.  Leaks may be detected by coating the welds in the suspected zones with chalk or the developer used in liquid penetrant tests.

7.5.1.3. Liquid penetrants may also be used to detect leaks with or without application of pressure. The liquid penetrant coated on one side of the weld may be examined for leakage by applying the developer on the oilier side of the weld,

7.5.1.4. Compressed air or other gases at pressure are sometimes used for leak tests. Leakage may be detected by the hissing noise of the escaping air or gas or by the drop in the pressure.  Use of air or gas i» not recommended since failure of the vessel or pipe may be disastrous.

7.5.1.5. Certain gases lime ammonia and sulphur dioxide (stable gas) may be used even at normal working pressures since their presence even to the extent of a few parts per million can be detected using concentrated hydrochloric acids which forms white fumes with the gas.

7.5.2. Assessment of test – In the majority of the cases any leakage would be treated as a rejection and would need the rectification (7.5.1). It is advisable to lap with a light hammer approximately 1.5 kg in the vicinity of the weld during leak test, to dislodge the particles, which may be blocking the path of leakage.

7.5.2.1. Before attempting the repair of a leakage it is necessary to examine the whole region of the leak to determine the cause for the leakage. Serious faults on the inside of welds are often detected by small Ieakages through a crevice of an otherwise sound outside weld.

7.5.2.2. Any weldments which is to be subjected to a leak test and on which a leak has been detected and repaired should always be retested to ensure that the repair has eliminated the leak and has not initialed other leakage paths.

7.5.2.3. Leak tests should always be done after the welding is completed, and should not be followed by other  welding  or repair  work unless this is to be subsequently followed by a similar leak test.

7.6. Load test, Proof test and Overload test

7.6.0. ln view of the complexity of the stress pattern in welded components especially  when  residual  stresses  arc  locked  in  these tests  give  a practical and concrete appraisal of the correctness of design calculations. Proof stress causes local yielding to a certain extent and thus results in a degree of stress relief.

7.6.1. Proof tests, load tests and overload tests are carried out on weldments by applying a load greater than or equal to the design load, but no great enough to cause damage to acceptable products. Load may be applied by pressure, weights, jacks, ropes, chains, filling with liquids, or in testing machines. During testing, it may be adequate to inspect for local damage of the weldments and for permanent set or yielding, or it may be necessary to use strain gauges.

7.6.2. The overload and proof tests arc usually carried out at 50 percent overload that is, at pressures or loads 50 percent higher than that encountered in service.   Alternatively these are done at 50 percent higher than the design load or minimum allowable pressure.

7.6.3. The following types or overload tests arc performed:

(a) Pressure tests for vessels, tanks and pipelines;(b) Static overload tests for welded structural members and components;(c) Impact, knocking and hammer tests for completed weldments such as rolling stock;(d) Proof tests for welded chains, ropes, etc; and (e) Load and overload tests or small weldments on universal tensile testing machines or special purpose machines.

7.6.4. Assessment - During and after load, overload or proof tests some of the following would be determined:

(a) Strain at important locations ;(b) Local deformation or deflection under load;(c) Permanent set, yielding, etc, after tile load is released; (d) Cracking or rupture of the Welds; (e) Leakage (if leak tests are combined with these tests); and(f) Evidence of cold working, hardening or embitterment of tile weld zones. The nature and permissible limits of the above factors would defined upon the requirements of the specifications applicable to the class of weldments and its end use,

8. Evaluation of weld quality

8.0. The purpose of inspection before, during and after fabrication by welding is to assess the quality and to exercise control over it.  The weld and the weldments shall conform to the required standards of quality. The inspector should therefore be able to evaluate the quality of the Welding and determine with a reasonable degree of certainty whether the weld or the weldments contains any faults, which would render it unacceptable.

8.0.1. The process of evaluation of weld quality consists of the following steps:

a) Determining the standard of quality, the range of permissible defects, the finish and the dimensional tolerances required in the weld and the weldments.

b) Laying down specifications, where needed, for the procedures to be adopted to achieve the necessary quality.

c) Specifying the methods and the extent of testing required to assess the quality actually achieved in terms of the required quality.

d) Ensuring that adequate precautions have been observed in the process and sufficient tests have actually been carried out.

c) Interpreting the results of the tests and the inspection carried out and inferring from these results whether the required level of quality has been achieved in the welds and the weldment.

8.1. Required quality

8.1.1.The requisite quality standards should be specified in the contract specifications either by reference to the provisions of one or more standard specifications or by mutual agreement between the purchaser and the supplier.

8.1.2. The requisite quality is dependent upon the end use of the weldment.  In assessing the required quality the following factors affecting the service condition of the weldment should be taken into account:

a)  Stress - Maximum stress, nature of the stress whether static dynamic repeated or alternating.

b) Pressure and temperature in service – High pressure or vacuum, high temperature and creep-resistant applications or low temperature and cryogenic applications, fluctuations in pressure and temperature non-uniformity of temperature distribution etc.

c) Effect of failure of a weld in service - Risk to human life and property possibility of explosive or catastrophic failure possible loss of prestige and goodwill, probable financial compensation, other hazards such as radioactivity.

d) Special properties required - Ductility resistance to corrosion, impermeability, electrical or magnetic properties etc.

e) Surface finish and appearance – Smoothness, straightness, conformity to  true  geometric  shape significance  of  deviations  from  the appearance in terms of function and in relation to aesthetic values, etc.

f) Expected life - Useful life, permanence, obsolescence, expendability etc.

g)Customer satisfaction – Goodwill, prestige, salability, dependability, export worthiness, competitiveness, etc.

8.1.3. The required quality should be realistic in terms of the quality that can be achieved at reasonable expense.  The specification of the best possible standard or a 'nil-defect' standard may be idealistic and comer.

8.5.3. It is essential that the area to be repaired is inspected after the defect has been cut out or otherwise removed.  In order to ensure that the defect has been completely removed, and the weld preparation thus formed is conductive to a defect-free repair.

8.5.4. All repairs shall be carried out by qualified welders. They should normally be done by adopting same process and using the same consumables as for the original weld.  A deviation may be permitted if the adequate quality is ensured.

8.5.5. The repaired weld should be subjected to adequate tests to evaluate its quality; the repaired portion should be subjected to as many of the tests made on the original welds as considered reasonable. In general, all the non-destructive tests carried out on the original weld should be repeated on the repaired weld.

8.5.6. After evaluation of the quality of the repaired portion, the overall duality of the weldments should be assessed and used as the basis of acceptance of the weldments.

9. Acceptance

9.1. Acceptance of the finished weldments will be the culmination of the entire process of inspection before, during and after fabrication and of the evaluation of the quality of the weldments in terms of the required quality.

9.2. Such acceptance should be final and unambiguous and should imply that the weldments is of the required quality as far as it was possible to assess on the basis of the inspection carried out.

9.3. Acceptance should in general be documented by the issue of a suitable certificate of acceptance, where necessary suitable permanent markings such as the inspector's personal hard stamp may be used to indicate acceptance of the specific weldments.  Similar steps would be required also in the event of the weldments being totally rejected, where in addition to a document indicating rejection and the reasons for rejection, permanent identification of rejected weldments should be made.

9.4. Whereas the inspection report would contain full details of the inspection carried out, and the findings at each stage of inspection, acceptance certificates will generally not contain such details, but will be confined to certifying that after carrying out the inspection in all respects, the weldments has been found to be of acceptable quality.

APPENDIX A (Clause 0.3)

List of Indian standard specifications and codes of practice relevant to the inspection of welding

a) Materials

1) Rolled steel

IS: 2062-1999

Structural steel (standard quality)

IS: 808-1964

Rolled steel beam, channel and angle sections (revised)

IS: 961-1962

Structural steel (high tensile)(revised)

IS: 1079-1968

Hot rolled carbon steel sheet and strip (second revision)

IS: 1173-1967

Hot rolled and slit steel, tee bars (first revision)

IS:1252-1958

Rolled steel sections bulb angles

IS:1730-1961

Dimensions for steel plate, sheet and strip for structural and general engineering purposes

IS:1731-1961

Dimensions for steel flats and for structural and general engineering purposes

IS:1732-1961

Dimension for round and square steel bars for structural and general engineering purposes

IS:1762-1961

Code for designation of steel

IS: 1852-1967

Rolling and cutting tolerances for hot-rolled steel products

IS:1863-1961

Dimensions for rolled steel bulb plates

IS:1977-1969

Structural steel (ordinary quality)

IS: 2002-1962

Steel plates for boilers

IS: 2049-1963

Colour code for the identification of wrought steels for general engineering purposes

IS: 2062-1969

Structural steel (fusion welding quality) (first revision)

IS: 3039-1965

Structural steel (shipbuilding quality)

IS: 3503-1966

Steel for mariner boilers, pressure vessels and welded machinery structures

IS: 3747-1966

Steel for flanging and pressing

2. Steel castings

IS: 2856-1964

Carbon steel castings suitable for high temperature service (fusion welding quality)

3. Other metals

IS: 737-1965

Wrought aluminium and aluminium alloys, sheet and strip (for general engineering purposes)revised)

IS: 1550-1967

Copper sheet and strip for the manufacture of utensils and for the general purposes (first revision)

4. Tubes

IS: 1161-1968

Steel tubes for structural purposes (second revision)

IS: 1239 (Part I)1968

Mild steel tubes, tubular and other wrought steel fittings Part 1 mild steel tubes (second revision)

IS: 1914-1961

Carbon steel boiler tubes and super heater tubes

IS: 3589-1966

Electrically welded steel pipes for waster, gas and sewage (200 to 2000 mm nominal diameters)

IS: 3601-1966

Steel tubes for mechanical and general engineering purposes

IS: 4310-1967

Weldable steel pipe fittings for marine purposes

IS: 4922-1968

Seamless, steel tubes (suitable for welding) for aircraft purposes

b) Electrodes and consumables

1. Welding Rods and Electrodes

IS: 814-1970

Covered electrodes for metal arc welding of structural steel (third revision)

IS: 815-1966

Classification and coding of covered electrodes for metal arc welding of mild steel and low alloy high tensile steel (revised)

IS: 1278-1967

Filler rods and wires for gas welding (first revision)

IS:1395-1964

Molybdenum and chromium molybdenum low alloy steel electrodes for metal arc welding (revised)

IS: 2680-1964

Filler rods and wires for inert gas tungsten arc welding

IS: 2879-1967

Mild steel for metal arc welding electrode core wire (first revision)

IS: 4972-1968

Resistance spot-welding electrodes

IS: 5206-1969

Corrosion-resisting chromium and chromium nickle steel covered electrodes for manual metal arc welding

IS: 5511-1969

Covered electrodes for manual metal arc welding of cast iron

2. Automatic arc welding wire and flux

IS: 3613-1966

Acceptance tests for wire flux combination for submerged arc welding

3. Gas welding

IS: 5760-1969

Compressed argon

c) Welding equipment and accessories

1. Arc welding

IS: 1851-1966

Single operator type arc welding transformers (first revision)

IS: 2635-1966

dc electric welding generators (revised)

IS:2641-1964

Electrical welding accessories

IS:4559-1968

Single operator rectifier type dc arc welder

2. Resistance welding

IS: 4804(part I)-1968

Resistance welding equipment: Part I Single-phase transformers

IS: 4804 (Part II)-1968

Resistance welding equipment: Part II Single –phase rocker arm spot welding machines

IS: 4804 (Part III) –1969

Resistance welding equipment Part III Single-phase spot and projection welding machines

d) Terminology and symbols

1. Terminology

IS: 812-1957

Glossary of terms relating to welding and cutting of metals

IS: 813-1961

Scheme of symbols for welding (amended)

e) Training and testing of welders

IS: 817-1966

Code of practice for training and testing of metal arc welders (revised)

IS: 1181-1967

Qualifying test for metal arc welders (engaged in welding structures other than pipes) (first revision)

f) Codes of procedure

IS: 819-1957

Code of pratice for resistance spot welding for light assemblies in mild steel

IS: 823-1964

Code of procedure for manual metal arc welding of mild steel

IS: 2811-1964

Recommendations for manual tungsten inert-gas arc welding of stainless steel

IS:4944-1968

Code of procedure for welding at low ambient temperatures

g) Mechanical testing

1. Tensile testing

IS: 1521-1960

Method for tensile testing of steel wire

IS:1608-1960

Method for tensile testing of steel products other than sheet, strip, wire and tube

IS:1663 (Part I)-1960

Method for tensile testing of steel sheet and strip: Part I Steel sheet and strip of thickness 0.5 mm to 3 mm

IS:1663(Part II)-1962

Method for tensile testing of steel sheet and strip: Part II steel sheet and strip of thickness above 3 mm

IS: 1894-1962

Method for tensile testing of steel tubes

2. Impact test

IS: 1499-1959

Method for charpy impact test (U-notch) for steel

IS:1598-1960

Method for izod impact test for steel

3. Bend test

IS: 1403-1959

Method for reverse bend test for steel sheet and strip less than 3 mm thick

IS:1599-1960

Method for bend test for steel products other than sheet, strip , wire and tube

IS: 2329-1963

Method for bend test on steel tubes

4. Hardness test

IS: 1500-1959

Method for Brinell hardness test for steel

IS: 1501-1959

Method for Vickers hardness test for steel

IS: 1586-1960

Methods for Rockwell hardness test (B and C scales) for steel

IS: 5072-1969

Method for Rockwell superficial hardness test (N and T scale) for steel

h) Non-destructive testing

1. Radiography

IS: 1182-1967

Recommended practice for radiographic examination of fusion welded butt joints to steel plates (first revision)

IS:2478-1963

Glossary of terms relating to industrial radiology

IS: 2595-1963

Code of practice for radiographic testing

IS: 2598-1966

Safety code for industrial radiographic practice

IS:3657-1966

Radiographic image quality indicators