Analysis of Leakage Cause of L415M Spiral Submerged Arc Welding Pipe Yan Xu, Yinglai Liu, Xianghui Nie, Zhenjun Feng, Liang Li and Fengping Yang E3S Web Conf., 329 (2021) 01071 Published online: 09 December 2021 DOI: 10.1051/e3sconf/202132901071