Improvement of fracture assessment method for pipe girth weld based on failure assessment diagram

Abstract

The increasing demand for oil and gas resources in China has promoted the rapid construction and development of oil and gas pipeline networks. With an increase in the mileage of high-grade pipeline, the intrinsic safety of pipeline girth weld faces serious challenges, and the existing fracture assessment methods have many shortcomings. The failure assessment diagram of the commonly used fracture assessment method in engineering is taken as the research object. Aiming at deficiency that it cannot accurately consider the strength matching characteristics of girth welds. Based on the failure assessment diagram theory and the equivalent stress-strain relationship method, the influence of crack size, pipeline diameter-thickness ratio, and material parameters on the fracture assessment accuracy of the girth weld is studied. The calculation method of optimized limit load and reference stress is established. Moreover, the improved fracture assessment process of pipeline girth weld is proposed, which makes up for the lack of conservative assessment results in traditional methods and improves the accuracy of fracture assessment girth weld under high-stress conditions.