低温钢冷却器壳体焊缝裂纹原因分析及处理

Cause Analysis and Treatment of Weld Crack of Low Temperature Steel Cooler Shell

甲醇冷却器是化肥厂生产流程中的重要设备。在长期运行过程中,管束多次发生泄漏。为了恢复冷却器功能,必须切开冷却器壳体的上下封头,对管束查漏、堵漏后再对封头实施焊接。封头是低温钢材料,第一次使用A309不锈钢焊条修复,第二次使用Tech-Rod182镍基合金焊条修复。前两次焊完并检验合格后,冷却器均能安全平稳地生产。第三次修复时采用2.5Ni填充材料,焊后检验发现焊缝裂纹。通过分析焊缝裂纹产生的原因,并采取修整焊缝及热影响区后施焊,获得了良好的焊接质量。

Methanol cooler is an important equipment in the production process of chemical fertilizer plant. The leak of tube occurred many times in the long run. In order to restore the function of the cooler, the upper and lower heads of the cooler shell must be cut and the welding of head was implemented after plugging the bundle leak. The head material is low temperature steel. The A309 stainless steels welding rod was used to repair the heads for the first time, and the Tech-Rod182 nickel based alloy electrode was used for the second time. After the two previous welding and qualified inspection, the cooler ran safely and smoothly. The 2.5Ni filling material was used to repair for the third time, weld crack was found in post welding inspection. By analyzing the reason of weld crack, the heads was welded after the weld and heat affected zone was cleaned, and good welding quality was obtained.