Slow Crack Growth Test to ISO 13479

The determination of resistance to slow crack growth (SCG) is conducted on pre-notched PE and PEX pipes. The ISO 13479 test method demonstrates one of the most critical performance criteria for PE and PEX pressure pipes at room temperatures and above.

The SCG test is part of Elements global Plastic Pipes & Fittings Testing program, provided to resin manufacturers, pipe extruders, certification bodies and utility companies worldwide, where independent, reliable and reproducible test data is required for product classification and life time evaluation.

Testing to ISO 13479

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 and EN 12201 Plastic piping systems – Polyethylene (PE) pipes and fittings for water supply
• ISO 4437 and EN 1555 Buried polyethylene (PE) pipes for the supply of gaseous fuels
• ISO 14531 Cross linked polyethylene (PEX) pipe systems for the conveyance of gaseous fuel

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.