Analysis of the Causes of Failure of a Pipeline Welded Joint

Abstract

An annular welded joint of a pipeline from steel 17G1S with diameter 1020 mm transporting natural gas at a pressure of 5.5 MPa is studied. The residual welding stresses are determined after failure of the pipes. Results of a study of fracture surfaces and of a metallographic analysis of the region of the welding defect over which the fracture has developed are presented. Mechanical tests of the pipe metal and of the metal of the welded joint are performed. The causes of failure of the joint are considered and methods for raising the reliability of pipelines are recommended.