UPVC PIPES

GUIDELINES FOR FACTORY INSPECTION OF  UPVC PIPES (IS 15328:2003):

1) Marking

The following information shall be clearly marked on each pipe  

a) Manufacturer’s Name/ Trade mark

b) Designation of Pipe (Outside diameter & stiffness)

Ex: 125mm SN 4 KN/sqm indicates a pipe having 125mm outer dia and

Nominal Ring Stiffness 4 KN/sqm 

c) Lot Number/ Batch Number

d) ISI Mark

e) Colour: The colour of the pipe shall be dark (any shade of brown). The pipe shall be uniformly coloured throughout the entire wall.

2) Sampling of U PVC Pipes

a) Scale of sampling for Visual appearance and Dimensional Requirements

b) Scale of sampling for Reversion and Vicat Softening Temperature Tests

For nominal diameters up to and including 110 mm

For nominal diameters above 110 mm

c) Scale of sampling for Resistance to External Blows

For all sizes

Note:- The numbers mentioned in col (3) to (6) in the above table represents the number of times the test is to be

carried out and do not represent either the number of pipe samples or the number of blows or the number of failures.

I) Physical Measurements

a)  Outside diameter at any Point

b) Mean Outside Diameter

c) Wall Thickness :

Socket Internal Diameter

Elastomeric Sealing Ring Sockets and Spigot Ends

Sockets and Spigot Ends for Solvent Cement Joints :

Socket Length

f) Effective Length

g) Visual Appearance: The internal and external surfaces of the pipe shall be smooth, clean  and free from grooving, blistering and any other defects.

II) Performance Tests (Longitudinal reversion, Ring stiffness, External blows, Vicat Softening Temperature& Internal Hydrostatic Pressure)

a. Longitudinal Reversion Test  :

• The test specimen shall consist of a length of pipe approximately 200 mm long.
• Two circumferential marks shall be scribed on the test specimen 100 mm apart and in such a way that one of these marks is approximately 15 mm from one end of the specimen.
• Temperature to be maintained : 150 ± 2deg c
• Duration : For Immersion method : up to 8.6 mm wall thickness – 15 min, over 8.6 to 14.1mm -30 min and over 14.1 mm -60 min
• For Air oven  method : up to 8.6 mm wall thickness – 60 min, over 8.6 to 14.1mm -120 min and over 14.1 mm -240 min
•  Longitudinal Reversion (T in %) =((L0-L)/L0)x100
• Where L0 and L are the distances in mm before and after the test.

b. Ring Stiffness Test:

Marking

-The pipe from which the specimens are to be cut shall be marked on the outside along its full length with a line parallel to the pipe axis. Three test specimens, marked a, b, and c, shall be tested for each sample of pipe. The ends of the test specimens shall be reasonably square to the axis of the pipe, free of burrs and jagged ends 

The length : For pipes with nominal diameter less than or equal to 1500 mm, the average length of each test specimen shall 300±10 mm. For pipes that have a nominal diameter, dn, greater than 1500 mm, the average length of each test specimen shall be 0.2dn.

Inside Diameter

Measure the inside diameter, dia, dib, dic, of each test specimen as the arithmetic mean of four measurements made at 45° intervals along one cross section of the test specimen. Finally, calculate the average internal diameter, di, of all three test specimens as

di = (dia+ dib + dic.)/3

Conditioning

Conditioning the pipe samples for at least 24 h in air, at a temperature of 27± 2 deg C, and conduct the test at the same temperature.

Procedure       

1) Locate the pipe specimen with its longitudinal axis parallel to the bearing plates and centre it  laterally in the testing machine.

2) If an orientation of minimum wall thickness has been found, place the first specimen with the thinnest portion on top. Rotate each successive specimen 35°and 70°. If no minimum wall thickness has been found, use any base line.

3) With the deflection indicator in place, bring the upper plate in contact with the specimen with no more load than necessary to hold it in place. This establishes the beginning point for the measurement of subsequent deflections.

4) Compress the specimen at a constant speed specified in Table below, while continuously  recording the force and deflection.

5) Typically, the force and deflection measurements are generated continuously by measuring the displacement of one of the plates, but if, during the test, the pipe-wall height (ec)  changes by more than 10 percent, generate force/deflection plot by measuring the change in  the inside diameter of the test.

6) If the force/deflection plot, which is typically a smooth curve, indicates that the zero point may be incorrect extrapolate back the initial straight-line portion of the curve anduse the intersect with the horizontal axis as the (0,0) point (origin).

7) Calculate the ring stiffness, Sa, Sb, Sc, of each of the three test specimens using the  following equations:

Sa= {0.0186+0.025 (ya/di)}(Fa/La ya)

Sb= {0.0186+0.025 (yb/di)}( Fb/Lb yb)

Sc= {0.0186 + 0.025 (yc/di)}( Fc /Lc yc)

where

F = force, in kN, corresponding to 3.0 percent pipe deflection;

L = length, in metres, of the test specimen; and

Y = deflection in metres, corresponding to 3.0 percent deflection, that is, y/di = 0.03

Calculate the ring stiffness of the pipe, in kN/sqm, as  the mean of these three values, using the following equation:

S = (Sa+Sb+Sc)/3

c. Resistance to External Blows :

Test Specimen :

-Test specimens of length 200 ±10 mm shall be cut from pipe selected at random from the  batch, or the production run from an extruder.

- The cut ends shall be square to the axis of the pipe, clean and free from damage.

- For pipes with outside diameters greater than 40 mm, a straight line shall be drawn along the  length of each test specimen at a random position.

- Further lines shall be drawn at equal distances around the pipe piece so that each test specimen has a number of lines given below

- Conditioning:

The test specimens shall be conditioned in a liquid bath or in air at a temperature of O ± 1°C for at least the period given below:

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