Analysis of Cracking Reasons for a Corrugated Pipe in Balance Safety Valve

A leakage phenomenon appeared on the corrugated pipe of a balance safety valve after 1 year of service. Macroscopic and microscopic observation, metallographic examination and chemical composition analysis of the failed corrugated pipe were carried out by metallographic microscopy, scanning electron microscopy and energy dispersive spectroscopy. The results show that the corrugated pipe failed as tearing from outside to inside. The main reason for the failure of the corrugated pipe was ductile fracture because of instantaneous overloading on the outlet of the corrugated pipe.