Demagnetization of gas pipeline during welding and safety measures and reliable of welded pipe construction in exploitation

Abstract

When welding some alloy steels with high nickel and carbon steel, greater thickness may cause magnetic fields on the working piece. Magnetism causes problems and difficulties in establishing the arc, leading to elimination of the blowing port in the desired direction, does not melt the edges of the groove uniformly, and causes a lack of fusion, non-penetrating root errors, or even completely prevents welding. Due to the complexity of problems of construction and welding of pipelines and the importance of safety and reliability of the entire pipeline, prescribed welding technology will provide the best features of welded joints. Preliminary tests were made of welded samples for welding procedure qualification. The paper presents a welding gas pipeline with a high concentration of magnetic lines of force. The base material is carbon steel resistant to low temperatures, A333 Gr.6, which has dimensions of φ 406.4 x 12.7 mm and (API) 5L X Gr. 52, φ 406.4 x 6.35 mm. The demagnetization pipeline was determined by winding the cable around the workpiece (pipes). After demagnetization and providing arc welding, it was done on schedule and welding parameters were given in technological lists. Since gas pipelines carry a high risk to safety in operation, leaking gas can cause sudden explosions and fires, so the welds are tested using the radiographic method, and the regulation requires it.