Discussion and thinking on factors influencing reliability of high-grade steel pipeline

The construction and development of high-grade steel pipelines have greatly promoted the rapid and efficient allocation of oil and gas resources in China, but new prominent problems such as quality risk of girth weld are also brought. Systematically analyzing the factors influencing the reliability of high-grade steel pipelines and taking effective control measures have become the important subjects to ensure the safe and stable operation of oil and gas pipelines. Based on results of analysis on fracture failure of high-grade steel pipeline girth weld, the problems such as the basic technological research on quality risk of girth weld, site construction management, defect cause analysis, and failure mechanism cognition were focused, and an identification framework of factors influencing the reliability in full life cycle was established from the aspects of metallurgy, plate-making, piping, design, construction, inspection, commissioning and operation. Besides, the main factors affecting the reliability of steel pipes were discussed based on the current manufacturing and construction technology through the statistical analysis results in terms of the chemical composition and mechanical properties data of 1 100×10⁴ steel pipelines, the main factors affecting the reliability of pipe fittings were discussed based on the analysis results of typical failure cases of pipe bends and fittings in gas stations, and the main factors influencing the reliability of girth welds were also discussed based on the performance data of 2 027 sets of girth welds and 1 683 sets of welded materials. In addition, problems concerning the performance matching of welding joints, weld defects, pipe components, welding process, welding material, etc., were analyzed in depth based on the current problem of girth weld failure of high-grade steel pipeline. Meanwhile, appropriate control measures and the research direction were put forward, which could provide technical support and decision-making reference for the subsequent construction of high-grade steel pipelines.