压缩机管道环焊缝纵向裂纹案例分析

Case analysis of longitudinal crack occurred in girth welds used in compressor pipelines

焊接作为压缩机制造安装的重要环节,焊接质量好坏直接决定着压缩机机组的正常运行。通过压缩机管道环焊缝纵向裂纹,分析了可能引起裂纹的三种情况:(1)管线吊装过程中是否存在暴力吊装;(2)焊接材料是否符合焊接工艺规程要求;(3)焊接母材是否领用正确。结果表明:造成纵向裂纹的原因是由于20钢弯头中混入了50Cr弯头,因50Cr碳当量高,可焊性很差,焊接时出现淬硬马氏体组织,在焊接应力作用下出现裂纹,从而造成焊缝裂纹由弯头根部由内向外扩展。另外针对原材料入场检验提出引入手持式金属化学成分检测仪来快速定性判定其成分,以此来加强钢管、法兰、弯头、三通的入场检验。

Welding is an important part of manufacturing and installation of compressor.The normal operation of compressor unit is determined by the quality of weld.Through the longitudinal crack of girth weld of compressor pipelines,three situations that may cause the crack are analyzed:⑴whether there was violent hoisting in the process of pipeline hoisting;(2)whether the welding consumables meet the requirements of welding procedure specification;(3)whether the welding base metal was received correctly.The results showed that the reason of the longitudinal crack was that 50Cr elbow was mixed into 20 steel elbow.Due to the high carbon equivalent of 50Cr and poor weldability,hardened martensite structure occurred in welding and cracks occurred in the action of welding stress,it was result in the expansion of weld crack from the root of elbow from inside to outside.In addition,it is proposed to introduce a handheld metal chemical composition detector to quickly and qualitatively determine its composition for the incoming inspection of raw materials,so as to strengthen the incoming inspection of steel pipes,flanges,elbows and tees.