Evaluation of Higher Strength E8010 Pipe Root Pass Welding

Abstract

Abstract Recent girth weld failures in newly constructed pipelines in North America have highlighted the issue of the weld strength undermatching the actual pipe strength. The lowest strength region of a manual girth weld is usually the root pass. This project evaluated using higher strength E8010 shielded metal arc welding (SMAW) electrodes for root pass welding on modern API 5L Grade X70 (L485) line pipe, as part of a solution to increase overall weld strength. The operability, weldability, and productivity of E8010 root pass welding were evaluated by welder operability trials, weldability testing, and welding procedure qualification testing and reviews. Feedback from North American pipeline welders support that E8010 electrodes have satisfactory operability for pipeline open root pass welding. Welding Institute of Canada (WIC) weldability test results support that an E8010 root pass does not significantly increase weld cracking susceptibility when properly used. Furthermore, welding qualification tests and production welding procedures using E8010 electrodes for all weld passes were reviewed and found that productivity is similar to current industry practices using E6010 electrodes for root pass welding. Guidance with recommendations and precautions for using an E8010 root pass was developed. In summary, a higher strength E8010 root pass can be part of an effective solution to address pipeline girth weld strength undermatching.