Hi,
This post is regarding the change in axial stress allowbles when we change the piping pressure which directly changes hoop stresses.
As per ISO 14692- there are separate allowables for hoop and axial stress.The allowbles hoop and axial stress determine the failure envelope for GRE piping.This is in accordance with ISO 14692.
My question is why do allowable axial stresses change with the pressure(hoop stress.) if we have fixed axial stress allowbles defined.
i have observed only axial allowbles change with change in pressure.With increase in pressure axial allowbles also get increased till value reaches the hoop stress allowbles.Once hoop stress allowbles are shown in static out put no more change in allowbles occurs.
Can some one explain why it is so.