Laboratory Tests of Thermoplastic Piping Assemblies Subjected to Water Hammer and Intermittent Hot Water Flow.

摘要

Evaluation procedures are described that were used at the National Bureau of Standards (NBS) for simulating the long-term effects of water hammer (shock pressure) and cycle hot water flow (thermal cycling) on chlorinated polyvinyl (CPVC) thermoplastic pressure piping assemblies. Also included are the procedures used to study the effects of thermal cycling of two (2) polyvinyl chloride (PVC) thermoplastic drainage stack assemblies. The results obtained using these test procedures are presented and,in addition,related work of other investigators is briefly reviewed. The shock pressure results show that a fatigue life curve can be established for CPVC as a function of temperature and pressure. As the temperature is decreased the number of shock pressure applications necessary to produce failure increases. An estimated use-life of at least 50years was indicated at the maximum test temperature of 180 F (82C) with pressures of 150psi (1034kPa). With intermittent hot water flow all test assemblies were performing satisfactorily when the test was terminated after more than 1500cycles had been completed.