基于BS 7910复合管海底管道对接焊缝ECA评估研究

Engineering Critical Assessment(ECA) of Composite Pipe Submarine Pipeline Butt Weld Based on BS 7910

依据英国标准BS 7910对含缺陷复合管海底管道对接接头进行了工程临界评估(ECA)。根据管体与焊缝拉伸试验结果确定评定曲线;按照DNV-OS-F101标准对管道取样,进行焊缝和HAZ的CTOD试验,选取最低值作为评定断裂韧性值;在评定计算中分别考虑了静态应力、循环应力、残余应力和应力集中等影响,给出了在敷设条件下考虑疲劳和不考虑疲劳时表面裂纹的极限尺寸。评估结果较DNV-OS-F101规定尺寸宽松,可见复合管含缺陷焊接接头安全裕度很高,从而为海底管道敷设过程中的焊接缺陷评估和验收提供了经验和依据。

According to the procedures suggested by BS7910,the Engineering Critical Assessment（ECA） was performed for the butt weld of submarine composite pipe containing defects. In this assessment,the FAD curve was determined by tensile tests results of the pipe body and weld; according to the DNV-OS-F101 standard sampling the pipes,the CTOD tests were performed on the weld and HAZ,and selected the lowest as the fracture toughness value; taking into account the effects of static stress,cyclic stress,residual stress and stress concentration,the extreme dimension of surface cracks under laying condition was provided,in addition to the consideration of the fatigue status or without fatigue status. Moreover,the results of ECA are greater than the size specified in DNV-OS-F101,thus it can be seen that the welded joint containing defects is with high safety margin, consequently, it provides experience and basis for the defect assessment and acceptance during the process of submarine pipeline laying in the future work.