Standards of polyethylene corrugated pipes

Standards of production and quality control of double wall corrugated pipes

Technical specifications and quality of polyethylene corrugated pipes must be in conformity with DIN 16961-2 standard (relevant to dimensional control and ring stiffness of the pipe) and EN13476 (other tests regarding the quality specifications of the product). New generation of corrugated pipes of Pars Ethylene Kish are produced in conformity with all strict standards of the standard institute of Iran and Germany and in accordance with the regulations and technical standards relevant to water and wastewater management and general technical approval no. of Biotechnical - DIBT institute in Berlin DIBt Z 42.1-390. The international standard insists on production of corrugated pipes with mechanical resistance of 16 to 31.5 Newton per meters squared. In Iran, corrugated pipes must have a mechanical resistance of 31.5 newton per meters squared. All inspectors insist that the mechanical resistance of the corrugated pipe manufactured by any company must be equal to 31.5 newton per meters squared in the first place.

This guide points out only the most important and necessary notes and regulations in different standards and includes only a small part of it. So it is recommended to read the original standard (Corrugated pipe Handbook)

The quality requirements and standards of corrugated pipes of Pars Ethylene Kish:

• Double wall corrugated pipes are comprised of two layers both of which are made of polyethylene from the type with the same MFI and suitable Pipe Grade variants and material grade of PE80.
• Technical specifications of corrugated pipes are relevant to dimensional control and ring stiffness according to the standards DIN 16961-2 and INSO 9116-3.
• Other specifications of the tests regarding corrugated pipes must be in accordance with EN 13476 standard.
• The fittings of polyethylene corrugated pipes must be in conformity with the standards DIN 16961-2m EN 13476 and ASTM 849.
• The inner side of corrugated pipes must be completely smooth and covered and also have enough thickness to enable using under pressure system (0.5 bar at most). The inner side of corrugated pips must be very smooth and less rough.
• The pipes are made as in self coupling and with perfect sealing using German sealing washers. The ring stiffness of corrugated pipes must be at least SN=31/5 KN/M2
• Corrugated pipes are made from a raw material the inner and outer surface of which should be in conformity with ISIRI 7174 standard.
• Inner side of polyethylene corrugated pipes must be composed of non-black material and should contain 4 percent anti-UV materials.
• It is not allowed to use minerals in raw material of pipe to produce the inner and outer layers of polyethylene corrugated pipes.
• For production of corrugated pipes, no recycled materials are used, they are rather made entirely of fresh material.

List of standards for double wall corrugated pipes:

• INSO 9116-1 text
• INSO 9116-2 text
• INSO 9116-3 text
• DIN 16961-1 text
• DIN 16961-2 text
• EN 13476 text

In this company, the tests are conducted as follows:

1. Density according to ISIRI 7175-5 standard
Physical properties of polyethylene can be predicted based on its density with good approximation. For this purpose, this test is carried out in this company by flotation on raw materials and products.
2. Melt flow index ISIRI 6980 standard
This test is a method for measuring the mass melt flow rate of soft heat substances under specified temperature conditions and in grams per ten minutes.
3. Long-term cyclic resistance according to DIN 16961 standard
The long-term cyclic strength of the pipe determines the life of a pipe against external pressures imposed on it. 
4. Short-term cyclic resistance according to ISO 9969 standard
This test is a method for measuring the cyclic resistance of pipes.
5. Cyclic flexibility according to EN 1446
When the pipe is pressurized, under a particular tension, the deformation is elastic and it returns to its original shape by reducing the pipe tension. In this test, the pipe is pressurized to be curved to the extent of 30% its diameter. After removal of the force, the pipe must return to its original state and there should be no permanent movement and fracture in the pipe.
6. Measuring soot content according to ISIRI 7175-2 standard
The color of the pipe is effective on the long-term stability of the pipe against wind and sun, the soot that is added to blacken the polyethylene produces a good stability against ultraviolet radiation. This test controls the amount of soot of the raw material and the product. 
7. Soot dispersion according to ISIRI 7175-6 standard 
The precise and fine distribution of soot in polyethylene is important for achieving the desired functional properties, while the proper distribution of soot is very effective in the smoothness of the surface of pipe. This test examines the distribution and dispersion of soot.
8. Thermal return according to ISIRI 7175-3 standard
In this method, a certain length of the pipe is heated to 110 ° C. After the heating stage, the pipe surfaces are examined for defects such as gap, blister or wall separation.
9. Dimensional control according to DIN 16961-ISIRI 9116 standard
With this control, the inside diameter, the thickness of the inner wall and the height of the production profiles are examined.
10. Weld line elongation according to EN1979
This test measures the tensile strength of weld line of the spiral pipes by using tensile test machine. The spiral pipe must withstand the minimum tensile force required for the weld line.
11. Sealing 
In this test, the water pressure of 0.5 bar is applied to the pipe for one minute, and no leakage should be allowed.

The tests performed on the raw materials of corrugated pipes are as follows:

• melt flow index (MFI)
• density test
• oxidative induction times (OIT)
• Humidity test
• soot dispersion test

The following tests are performed on double wall corrugated pipes:

• Density (according to ISIRI 7175-5 standard)
• Melt flow index (according to ISIRI 6980 standard)
• long-term ring stiffness (according to DIN 16961 standard)
• short-term ring stiffness (according to DIN 16961 standard)
• ring flexibility (according to EN 1446 standard)
• measurement of soot volume (according to ISIRI 7175-2 standard)
• soot dispersion (according to ISIRI 7175-6 standard)
• thermal reversion (according to ISIRI 7175-3 standard)
• dimensional control (according to DIN 16961 and ISIRI 9116 standards)
• Weld line elongation (according to EN 1979 standard) Sealing