Leakage Failure Analysis of Some Gas Transportation Pipeline Girth Weld

The leak causes of girth weld of a L415M gas pipeline were analyzed by means of macroscopic morphology observation, non-destructive testing, chemical composition analysis, corrosion product analysis, metallographic structure analysis and scanning electron microscope analysis. The results show that the tensile properties of girth weld do not meet the standard requirements, and the impact toughness is low. There are defects such as pores and slag inclusion in the welded joint, and the misalignment leads to a large stress concentration at this position, and cracks are easy to form around the weld defects. The fluid produces turbulence at the misalignment, which intensified the metal loss and crack propagation under the action of fluid erosion, and finally the perforation failure occurs on the weld.