A More Reliable Detergent for Cone and Full Notch Creep Testing of PE Pipe Materials [PE]


Posters - Additional Information # 2001 Munich

Detergents of the type nonylphenol ethoxylate (NPE) are often used in PE pipe tests at 80°C like the Full Notch Creep Test, Cone test and Constant Load test. However, evidence is presented that this class of detergents is very vulnerable to oxidation by oxygen from the air surrounding the tests baths. This leads to a lower concentration of active detergent and hence to unreliable failure times and failure rates. Although excluding oxygen from the tests baths can stop this oxidation, effective protective chemicals like antioxidants are not available. Moreover, discussions about environmental problems caused by metabolites of NPE detergents in the aquatic environment have caused a very large reduction in the use of these substances. They may become less readily available in future. An alternative detergent TeepolTM is presented which shows a constant activity in Cone tests on PE pipe materials during more than 1600 hours at 80°C. Consequently this detergent is recommended for use in FNC, constant load and Cone tests. A discussion in standardisation committees involved in these types of tests is proposed.

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