Effects of Over-Loading on Pressure Vessel Integrity

Abstract

The effect of proof over-pressure on pressure vessels structural integrity is analysed. Risk based approach is applied using Failure Analysis Diagramme to assess likelihood of failure. Special attention is paid to crack-like defects detected by NDT regular testing which are unacceptable by standards, but difficult to be repaired. It was show, using two examples, that such defects can remain if some strict conditions are fulfilled. In any case, with or without crack-like defects, it was shown that testing of pressure vessels with significant over-pressure can cause much more problems than it has benefits, because it acts more like the first step in eventual failure, than being proof to anything.