Research on weld crack model and internal detection signal characteristics of oil and gas pipeline based on weak magnetic method

Weak magnetic technology is an emerging non-destructive testing method with broad application prospects in the internal detection of long-distance oil and gas pipelines. As an important link in the manufacturing and connection of long-distance pipelines, welds play a crucial role in oil and gas transportation. However, during the operation of in-service pipelines, cracks may occur in the welds due to external pressure and cyclic loads, which may lead to catastrophic weld failure. This study comprehensively analyzed the magnetic signals of pipelines subjected to different pressures, helix angles, and crack depths using the weak magnetic method, and experimentally verified the research results. The research results indicate that the operating pressure of pipelines will intensify the stress concentration at the crack location. Under the same state, there are certain differences in the magnetic signal characteristics of spiral welds at different angles. The presence of cracks will damage the integrity of the weld, and the change in crack depth has a significant impact on the effective magnetic charge area. This study can effectively identify the status of weld detection in in-service pipelines and promote the application of weak magnetic technology in the field of non-destructive testing of long-distance oil and gas pipelines.