Failure Mode and Effects Analysis and Finite Element Simulation of Defective ElectroFusion Joint in Natural Gas Piping Network

The aim of this study was to investigate the source of leaks in the natural gas pipeline network. According to the results obtained from the Failure Mode and Effects Analysis (FMEA), the three defects including lack of proper scraping, the presence of oil and existing of moisture at the welding zone in the installation and execution phase had the highest risk. These defect types studied further using experimental methods. The fracture mechanics analysis for the defects with the highest risk in Abaqus software was performed by XFEM method in three dimensions. According to the results, cracks with initial length of 4mm will grow at pressures higher than 1.4 MPa. To obtain results equivalent stress intensity factor has been used. The results imply the application of suitable nondestructive methods for determination of cracks with lengths higher than 4mm. The results of this research can be employed by inspection engineering of natural gas companies.