高压加热器管板堵漏工艺的改进

某电厂高压加热器在检修过程中出现部分换热管泄漏,原封堵工艺采用实心0Cr18Ni9钢堵头及不锈钢焊条焊接,由于焊条与管板的钢种不同,膨胀系数差别较大,导致焊接堵漏产生裂纹.改进工艺后采用空心20号钢堵头及J422焊条焊接,堵头及焊条与管板的钢种相同,焊接堵漏后未再产生裂纹.通过有限元法应力分析表明,改进后的空心堵头所产生的焊接残余应力低于实心结构堵头.

IMPROVEMENT OF LEAKAGE-PLUGGING TECHNOLOGY ON TUBE-PLATE OF HIGH-PRESSURE HEATER

The leakage of some heat-exchange tubes in high-pressure heater has appeared during repair process in one power plant.The solid Cr18Ni9 steel plug and stainless steel electrode were used in original plugging process,and cracks have occurred in weld-joints of leakage-plugging due to different materials of the electrode and the tube-plate,thereby,having larger difference in expansion coefficient.After improvement of the technology,the hollow plugs of no.20 steel and J422 electrode are used,the materials are similar to that of the tube-plate,and cracks haven’t occurred after weld-plugging.The stress analysis using finite element method shows that the residual stress of welding with hollow plugs is lower than that of plugs with solid structure.