大型离心式压缩机成品机壳补焊技术

Repair welding technology of large centrifugal compressor finished casing

某大型离心式压缩机机壳有多处焊接缺陷,且机壳已是成品状态。根据壳体材料成分、结构特点、缺陷分布、除应力难等情况,设计了合理的防变形措施、补焊顺序及焊接参数来控制焊接变形,采用振动时效去除焊接残余应力,成功完成壳体补焊。结果表明,焊缝质量符合NB/T 47013—2015标准Ⅱ级的质量要求;振动时效效果明显,大部分焊缝的残余应力降低约30%~40%,部分焊缝更消除了约57%的残余应力;机壳焊后变形较小,壳体水平中分面最大高度差约4~5 mm,中分面各处沿径向外侧最大扩张变形不超过2 mm。文中研究结果为压缩机、汽轮机等大型壳体成品阶段的大面积补焊及变形控制提供了宝贵的经验。

Several weld defects were found in the casing of a large centrifugal compressor,and the casing was already in the finished state.According to the materials composition,structural characteristics,defect distribution,stress relieving difficulties,etc.,the reasonable anti-deformation measures,repair welding sequence and welding parameters were used to control welding deformation,the vibratory stress relief method was used to relieve welding residual stress.The results showed that,the quality of the weld met the quality requirements of NB/T 47013—2015 standard Ⅱ,the vibratory stress relief effect was obvious,most of the weld residual stress was reduced by about 30% to 40%,and the residual stress of some welds was eliminated by about 57%,the deformation of the casing after welding was small,the maximum end-face run-out of the horizontally middle plane in the casing was about 4 to 5 mm,and the maximum expansion deformation along the radial outside of the horizontally middle plane was not more than 2 mm.The results provided valuable experience for large-area welding and deformation control in the finished stage of large casing products such as compressors and steam turbines.