ISO/WD 25301

Thermoplastics piping systems for non-pressure underground drainage and sewerage — Test method for the determination of the stress crack resistance of structured-wall polyethylene (PE) pipe materials with recyclates using Un-notched Constant Ligament Stress (UCLS) test

Scope

This test method determines the slow crack growth (SCG) behaviour (also known as the stress crack resistance) of polyethylene (PE) materials, incorporating recyclates, used in structured-wall Type B corrugated pipes (ISO 21138-3) for non-pressure gravity flow drainage applications. The test method is appropriate to post-consumer recyclates (PCR) of PE materials, post-industrial recyclates (PIR) of PE materials, and blends of such materials with virgin and/or reworked PE , respectively. The test method can also be used for Types A1 and A2 pipe (ISO 21138-2) materials. 
The test method is conducted on un-notched specimens in deionized water and evaluates the time until brittle failure, which is governed by both the crack initiation and crack propagation phases of the SCG mechanism.
The test method utilizes standard testing equipment utilized for other stress crack tests in the drainage pipe industry. Specifically, the test method utilizes a lever-arm loading mechanism, typically with a 5:1 mechanical advantage, to apply a constant load to a dog-bone shaped test specimen immersed in an elevated temperature water bath.