中俄东线天然气管道环焊缝断裂韧性的确定

Determination of fracture toughness for girth weld in China-Russia Eastern Natural Gas Pipeline

中俄东线天然气管道工程的黑河—长岭段干线在国内首次采用大口径(φ1 422 mm)、高压力(12 MPa)输送,同时管道施工环境温度低,环焊缝低温韧性问题需要特别关注。通过对比分析国内外标准对环焊缝冲击韧性的要求,并利用失效评估图FAD计算了本工程含缺陷环焊缝不起裂韧性指标,同时结合相关课题研究成果,确定了中俄东线黑河—长岭段干线φ1 422 mm的X80M管道环焊缝韧性指标,并为避免冬季施工环焊缝低温脆性开裂风险,应进行环焊缝韧脆转变温度曲线测定,并提供不同试验温度下环焊缝冲击吸收功值,根据最终的试验结果确定管道吊装下沟的环境温度下限值。

Large diameter(φ1 422 mm) pipe with high pressure(12 MPa) transportation was first used in domestic in the main pipeline from Heihe to Changling of China-Russia Eastern Natural Gas Pipeline, and the environmen temperature for construction was low. So the girth weld toughness at low temperature needed special attention, namely that the girth welds not only had enough toughness to resist fracture initiation in pipeline operation stage, but also had enough toughness for non-fracture during the process of lifting. Through comparative analysis of standards at home and abroad on the impact toughness of girth weld, and calculation based on the failure assessment diagram(FAD),combined with the researched results, the girth weld fracture toughness of φ1 422 mm X80 M pipe for Heihe Changling pipeline was finally determined. In order to avoid cracking risk in girth weld during construction in winter,ductile-brittle transition temperature curve should be measured, and toughnesses at different test temperatures should be provided, and then the lowest environment temperature that suited for pipeline lifting would be determined according to the test results.