合成气／锅炉给水预热器管口裂纹原因与修复

合成气／锅炉给水预热器投用10月后，众多列管管口部位出现裂纹。经过分析，认为问题出在设备方面：主要是制造焊接时受高温影响时间长，焊后金属组织晶粒大，应力大，且管口硬度高。通过采取减小管板上管口倒角半径，重新制定焊接工艺并严格实施，焊后采取换热器管板整体热处理工艺，解决了换热管与管板焊接后管口硬度高、应力大、易产生裂纹的问题。修复后的使用效果证明，对问题症结的分析正确，修复方案有效。

Cracks Created Reasons at Tube End of Ammonia Converter Effluent Boiler Feed Water Pre-heater and Restoration Methods

The Cracks were created at tube end of ammonia converter effluent boiler feed water pre-heater after it was put on stream for only ten months. The real reasons are found out through metallographie examination. It is incorrect design of weld throat that makes the time influenced by high temperature during welding prolonged, making metal grain over growth and high residual stress and hardness existed at tube end. The problems are successfully solved after restoration in which the measures, reducing the radius of external fillet weld throat of tube, welding by newly made weld procedure, and relieving the stress by post weld heat treatment with integral tube plate, are adopted.