Experiment-Based Reliability Analysis of Girth Welds on Different Grade Steel Pipelines

The welding of high-grade steel pipeline is difficult. Its quality control is not easy, which makes it easy to become a weak link of the pipeline. In order to ensure the safety of girth weld, the experiment-based reliability analysis of pipeline girth weld is carried out. The girth weld materials of different batches of several natural pipelines are collected for tensile, Charpy impact, and fracture toughness tests. Based on the tests results, the optimal distributions of yield strength, the ratio of yield to ultimate tensile strength (Y/T), impact energy, and fracture toughness of pipeline girth welds are recommended. The limit state functions of pipeline girth weld with crack defects based on stress and strain are established. The reliability calculation method of natural pipeline girth weld based on Monte Carlo is proposed. The sensitivity analysis of the influencing factors of girth weld is conducted. The results show that external load, defect depth, fracture toughness, and yield strength have a great impact on the failure probability of pipeline girth weld. The reliability of girth weld can be enhanced by controlling external load, reducing the size of pipeline defect, and improving yield strength and fracture toughness to ensure the safe operation of pipeline.