Plastic Pipes Conference Association # 1985 York
Marshall, Birch
It is proposed that present Specifications for PE Pressure pipes are essentially undemanding and tests do not simulate service conditions. Perfect pipes are assessed rather than pipes which have sustained handling and installation ‘damage’.
Flaws and defects have caused many problems with other thermoplastics pipes and it is believed that Specifications should be re-modelled to use fracture mechanics test methods and analyses to demonstrate that only pipes with high toughness are produced.
Examination of any current Specification for PE and uPVC pressure pipe shows that the testing specified and background data required are at levels far in excess of those demanded for more "traditional" pipe materials.
The U.K. pipe industry in particular, carries out in-house quality control testing at a high level of assessinent and it is often argued that those wishing to introduce yet further test procedures are not only a nuisance but are imposing cost penalties on finished products such as to render them uncompetitive c.f. other products.
The view here its that much of the present tesing which is Carried out is irrelevant to service performance of pipe systems and new tests should be introduced to model service more closely, at the expense of 'conventional' procedures which tend to assess properties of 'perfect' pipe under idealised loading conditions. The testing should demonstrate the suitability of the pipe for the purpose for which it is intended. That plastics pipes can be supplied to operate at design limits with assured performance, backed by relevant data should be promoted to challenge the laissez-faire attitude adopted for other materials.
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