Beech, Headford, Hunt, Sandilands
Testing Specification Design # 1995 Edinburgh
The guldeUnes g h n in BS CP 312 :Pwt 2 : 1973 w e recommended to the UK toater industryfor the deslgn of polyethylene pfpeline systems to toke inin account the effects of tmnsient [surge) pressurejluctuatlons with respect to fatigue (ref.1). These guIdelInes we based on earlier experience wlth PVC-Usewer h i n g molns and are generally considered too conservativefor moreflexIble polgethylene systems. A group representing the IIK water industry induding a materlal supplier. product ~ ~ e rwid swater. oompanles wasjormed in 199i m discuss and Lnwstlgate thls apparent anomnly. With the aid of measurement on a number of in-service instdatfons known to experience surge pressures. a marlmum rate of change of pressure reaUsttmlly possible durlng a surge event was established. This rate of pressure change was used in high amplitude q d l c pressure tests carried out Ln the laboratory on notched pipe andfftWtg assemblies. Nofailures or dlscemible deterioration occured 01any ofthe products sutJ& to this repeated cydlc testing. designed to slrnulate the number of worst case eventsfeasible Ln theprojected lifetime. In conclusion it is conlffrmed that the current guidelines we indeed w y consenntlw and alternatlw remmmendations are proposed which should be applled to polyethylene pipe systems up to at least 180 mm diameter without delay.
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