海底管道X56与F70级钢对接焊接工艺试验研究

旅大油田开发工程中双层油气混输管道立管段外管材料为API5L X56级钢,而锚固件为ASTM A694F70级钢,二者强度级别相差较大,焊接困难。针对上述问题进行了对接焊接工艺试验研究。通过计算碳当量(Ceq),分析了钢材焊接性,选择了焊接方法和焊接材料,设计了对接试件坡口形式,进行了焊接工艺试验与分析。根据API1104标准和旅大油田开发工程项目焊接检验规格书(SPC-S/G-SP-003)的要求,对试验研究所确定的焊接工艺进行了评定,结果表明:焊缝外观检查、超声波探伤和X射线探伤质量合格,拉伸试验、刻槽锤断试验、弯曲试验及低温冲击试验等各项性能指标良好。按照试验研究所确定的焊接工艺施工的旅大油田开发工程海底管道焊接接头质量合格,满足施工技术要求。依据API1104标准的规定,本次试验研究所确定的焊接工艺可以推广到X52-X70(F70)、X56-F70、X56-X70(F70)等不同强度级别海底管道的对接焊接工程。

Welding process analysis for butt joint of X56 to F70 grade steels in sub-sea pipeline

In dual oil-gas sub-sea pipeline of LD oil field development project,the material of external pipe is API X56 grade steel in riser section,while the material of bulkhead connecting internal and external pipes is ASTM A694 F70 grade steel.The two kinds of steels are different greatly in the grade level and difficult to be butt welded.Herein,the research of welding process was made for X56 to F70 butt joint.Based on the calculation of their carbon equivalence(Ceq),the weldability of two base metals was analyzed,the proper welding mate-rial was chosen,the pipe bevel preparation was designed,and the welding process test and analysis were conducted.The welding process determined by the test research was evaluated according to API 1104 Code and the Weld Inspection Specifications for LD Oil Field Development Project.The test weld joint passes NDE visual inspections,UT and X-ray tests,and the results show good properties,including tensile test,bend test,nick-break test and low-temperature impact test.The weld joint made in the project by this proposed welding procedure is acceptable and meets the technical requirements of the project.According to API 1104 Code,this welding process/procedure can be expanded to the welding of X52-X70(F70),X56-X70,X56-X70(F70) steels.