Determination of resistance to slow crack growth (SCG) of notched pipes
ISO 13479 specifies a test method for determination of resistance to slow crack growth (SCG) of polyolefin pipes, applicable to pipes of wall thickness greater than 5 mm.
Principle and test procedure
Four notches are introduced on a minimum of three pipes. The notched pipes are then subjected to hydrostatic pressure in tap water, and the result is expressed in terms of time to failure. The system standards below specify the test conditions and requirements for each material.
· ISO 4427 Plastic piping systems – Polyethylene (PE) pipes and fittings for water supply
· ISO 4437 Buried polyethylene (PE) pipes for the supply of gaseous fuels
· ISO 14531 Cross linked polyethylene (PEX) pipe systems for the conveyance of gaseous fuels
The test conditions for different PE and PEX materials are shown in table below. All testing is performed using tap water at 80°C as test media. The pressures in the table are based on SDR 11 pipes.
|Material||PE 80 / PE 100||PEX 80 / PEX 100 / PEX 125|
|Pressure||8.0 bar||8.0 / 9.2 / 10.8 bar|
|Failure||> 500 h||> 5 000 h|