Why is there a difference in pressure class (PC) and working pressure rating (WPR) between HDPE pipe and PVC pipe?
PVC is more than three times as stiff as PE. The magnitude of a pressure wave caused by the same hydraulic event is about 50% higher in a PVC pipe. And the pipe has a lower built in tolerance to surge stresses. So it is desirable to determine the remaining steady state pressure capacity of a pipe (its’ working pressure rating) once the hydraulic operating conditions are known.
