August 2020, Vol. 247, No. 8
Tech Notes
CPP Completes Pressurized Pipeline Repair with Mechanized Welding Technology
Special to P&GJ
China Petroleum Pipeline Engineering (CPP) was hired by PetroChina Southwest Pipeline Company to complete the work on the China-Myanmar Oil and Gas Pipeline, a pressurized 40-inch by 80-grade gas pipeline, using mechanized FCAW in-service welding technology.
The poor construction environment was a great challenge to the project, which is located in Guizhou Province China, a region featuring complex landform and frequent geological hazards. The pipeline spans three kinds of terrain, but 80% of it is routed through mountainous areas.
The main task of the project was to install a 1.42-inch thickness Type B sleeve to repair the defective pipe girth weld without shutdown. CPP uses mechanized FCAW in-service welding technology to complete the longitudinal butt welds and circumferential fillet welds.
All welds were inspected more than 48 hours after welding by PT/MT/UT/PAUT, and the results were acceptable. Compared with the SMAW, the mechanized FCAW in-service welding technology developed by CPP has obvious advantages, such as smooth weld shape, high welding quality, reducing the welding time and personnel cost by more than 50%.
CPP believes this it the first time for mechanized FCAW in-service welding technology has been applied in mountain pipeline on large- diameter and high-grade steel in the world.
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