汽包集中下降管管座更换和修复  

Replacement and repair of nozzle stub of concentrated downcomer in steam drum

作　　者：陈忠兵[1] 姚祥宏 张先炼 肖禹 孙志强[1] 钱猛 Chen Zhongbing;Yao Xianghong;Zhang Xianlian;Xiao Yu;Sun Zhiqiang;Qian Meng(Suzhou Nuclear Power Research Institute Co.,Ltd.,Suzhou 215004,Jiangsu,China;Hubei Xisaishan Power Generation Co.,Ltd.,Huangshi 435000,Hubei,China)

机构地区：[1]苏州热工研究院有限公司,江苏苏州215004 [2]湖北西塞山发电有限公司,湖北黄石435000

出　　处：《焊接》2021年第10期48-51,56,63,64,共7页Welding & Joining

摘　　要：针对汽包集中下降管管座更换修复时存在的下降管位移、接头冷裂纹敏感性高、焊后热处理最高温度偏离焊缝等问题,通过理论计算和分析,制订了相应的技术方案。结果表明,以汽包筒体为承力体,采用井字型悬吊固定装置,可以有效防止管座割除与修复过程中下降管过量位移,避免焊缝错口和折口;采用非对称K形坡口、合理布置角接接头与对接接头焊接顺序、提高预热温度和层间温度至180℃、进行中间消氢热处理,有效避免了大厚壁高拘束条件下BHW35钢接头冷裂纹和其他缺陷;采用管座角焊缝主加热并在下降管管孔对应汽包上部区域辅助加热,获得了合理的焊后热处理温度场。修复后各项检验检测合格,其中汽包筒体硬度与修复前无显著变化,修复区域测得的最大残余应力133 MPa。For the problems existing in the replacement and repair of nozzle stub of concentrated downcomer in steam drum,such as displacement of the downcomer,high cold crack sensitivity of welded joints and deviation of the maximum temperature from the weld during post weld heat treatment(PWHT),the corresponding technical schemes were formulated through theoretical calculation and analysis.The results showed that taking cylinder of steam drum as the load-bearing body and adopting the well-shaped suspension and fixing device could effectively prevent the excessive displacement of the downcomer in the process of cutting and repairing nozzle stub,and avoid staggering and folding of weld.Using asymmetric K-groove,reasonably arranging welding sequence of fillet joint and butt joint,increasing the preheating temperature and interlayer temperature to 180℃,and carrying out intermediate eliminating hydrogen heat treatment,the cold crack and other defects of BHW35 steel joint under the condition of large thick wall and high restraint were effectively avoided.The reasonable temperature field of PWHT was obtained with the main heating of the stub fillet weld and the auxiliary heating in the upper area of the steam drum corresponding to the downcomer pipe hole.After repairing,all inspections and tests were qualified,among which the hardness of the drum cylinder had no significant change from that before repair and the maximum residual stress measured in the repair area was 133 MPa.

关 键 词：管座 修复 BHW35钢 冷裂纹 焊后热处理 

分 类 号：TG442[金属学及工艺—焊接]