Hdpe Pipes



GUIDELINES FOR FACTORY INSPECTION OF HDPE PIPES (IS 4984:1995):

  1. Marking

Each straight length of the pipe shall be clearly marked in indelible ink/paint on either end and for coil at both ends or hot embossed on white base every meter throughout the length of the pipe with following information.

  1. Manufacturer’s name / Trade-mark
  2. Designation of Pipe (Grade of material , Pressure Rating & Nominal Diameter)

Ex: PE 63 PN 10 DN 200 indicates a pipe pertaining to material grade 63, pressure rating 1.0 MPa and outside nominal diameter 200 mm .

  1. Lot number/Batch Number:  ( Mentions the date, month and year of manufacture).
  2. Colour: The colour of the pipe shall be black. Three Equispaced longitudinal stripes of width 3 mm (Min) in Blue Colour not exceeding 0.2 mm in depth.
  3. Sampling of HDPE Pipes

1.a ) Scale of sampling for Visual and Dimensional Requirements

No of Pipes in the Lot

Sample No

 

Sample Size

Cumulative Sample Size

Acceptance No

Rejection No

Up to 150

First

13

13

0

2

Second 13 26 1 2

151 to 280

First 20 20 0 3

Second

20

40

3

4

281 to 500

First

32

32

1

4

Second 32 64 4 5

501 to 1200

First

50

50

2

5

Second 50 100 6 7

1201 to 3200

First

80

80

3

7

Second 80 160 8 9

3201 to 10000

First

125

125

5

9

Second 125 250 12 13

10001 to 35000

First

200

200

7

11

Second 200 400 18 19

1.b) Scale of Sampling for  Performance Tests  (Hydraulic  Characteristics, Reversion,  Density , Melt Flow Rate test , Carbon black content and Dispersion Test).

No of Pipes

Sample Size

Up to 150

3

151 to 1200

5

1201 to 35000

8

Physical Measurements  (Tolerance as per IS Code)

  1. Outside Diameter
  2. Wall Thickness
  3. Ovality
  4. Length
  5. Visual Appearance: The internal and external surfaces of the pipes shall be smooth, clean and free from grooving and other defects.

Performance Tests (Hydraulic  Characteristics , Reversion, Density , Melt Flow Rate test , Carbon black content and Dispersion Test)

Hydraulic Characteristics

  • Test Specimen: A Sample of the pipe having free length between end fittings equal to ten times the outside diameter but not less than 250 mm and not greater than 750 mm shall be taken for testing for testing.
  • Testing Temperature – 80 deg c ± 1 deg c
  • Test Duration – 48 hours
  • Test Pressure (p)

P= (2?s) / (d-s)

Where p- Test Pressure in MPa, s-Min wall thickness, ?- induced stress in MPa, d- Outside dia in mm

Induced stress to be maintained (in MPa):

 

PE 63

PE 80

PE 100

Acceptance Test

3.8

4.9

5.7

Reversion Test
-Test Specimen: 3 complete sections of pipe approximately 200 mm long shall be taken as test pieces.  A mark shall be scribed on the external surface approximately 50 mm from the end of the test pieces in the axial direction of pipe. The distance between the two marks (lo) shall be approximately 100 mm and shall measure to the nearest 0.25 mm at ambient temperature

-Temperature to be maintained: 110±2 deg c

-Duration:  For upto 8 mm wall thickness - 60±1 min, over 8 to 16 mm - 120±2 min

Longitudinal Reversion ( T in %) =( (lo-l1)/lo)x100

Where lo and l1 are distance in (mm) before and after the test.

Melt Flow Rate (MFR) Test

Procedure: The apparatus is basically an extrusion plastometer . Polyethylene which is contained in a vertical metal cylinder is extruded through a jet by loaded piston. The temperature of the cylinder and piston is raised to 190±0.5 deg c for 15 minutes which has to be maintained during the extrusion of the polyethylene. The material is allowed to attain temperature equilibrium for a total of 4±0.5 min after which load is placed on top of piston to extrude the polyethylene through the jet. The rate of extrusion is measured by cutting the extrude at regular interval (240 secs) with a suitable sharp edged instrument. Then we weigh at least three successive cut offs and determine the weighted average say W (in gm).

Therefore,

Melt flow Rate= (600 * W)/(240)

The MFR of the material shall be between 0.4 to 1.1 gram/10 min

  • Temperature= 190±0.5 deg c
  • Applied Load = 5 kg
  • MFR shall not differ more than 30 percent of the material used in manufacturing.
  • Confirmation of raw material from the supplier for MFR of the material which shall be between 0.20 and 1.10 gram/10 min.

Carbon Black Content ( CBC)

The carbon black content in the material shall be within 2.5 ± 0.5 %

Temperature – 500 deg c ± 5 deg c

% of CBC =  (W5/W3)*100

Where W5- Residual Weight (W4-W1)

W1- Empty boat weight

W4- Boat+ residual weight

W3- Material weight (W2-W1)

W2- Boat + Sample weight

Density Test

The specific base density shall be between 940.5 to 958.4 kg/m3 at room temperature ( 27 deg c). The value of the density shall not differ from the nominal value by more than 3 kg/m3.

Density = A1/((A3*P)(A4*1000))

Where,

A1= Weight of sample in air

A2 = Weight of sample in N-Butyl Acetate Solution

A3= A1-A2

P= Density of N-Butyl Acetate Solution

A4= % of CBC * 4.5

Confirmation of raw material density from the supplier, the specified base density shall be between 940.0 kg/m3  to 958.4 kg/m3  when determined at room temperature (27 deg c). The value of the arrived density on testing shall not differ from the nominal value by more than 3 kg/m3.

Carbon Black Dispersion Test

Take three specimen of pin head size each weighing about 5 mg and each one cut from separate granules on hot microscopic slide (maintained at 170 to 210 deg c).

The Carbon black dispersion shall be considered as satisfactory if the specimen s show a uniform background free from white streaks.

Confirmation of Material

Melt flow rate

The MFR of the material shall be between 0.20 and 1.10 when tested at 190 deg c with  nominal load of 5 kgs.  The MFR of the material shall be within ± 30 % of the value of manufacturer.

The specified base density shall be between 940.0 kg/m3 to 958.0 kg/m3 when determined at room temperature (27 deg c). The value of the density shall not differ from nominal value by more the 3 kg/m3. 

*****