延迟焦化装置焦炭塔的焊接修复技术

Welding repair technology for coke drum in delayed coking unit

在延迟焦化装置运行过程中,焦炭塔塔壁B6环焊缝发生了开裂,采用多种检测方法对其开裂原因进行了分析。根据宏观检查、无损检测、金相组织分析、硬度测试和化学成分分析等结果可以得出,B6环焊缝处于塔体壁厚不均匀部位,由于操作温度的剧烈变化,B6环焊缝发生了疲劳开裂。为了消除焦炭塔内壁和外壁的环焊缝缺陷,采用补焊、消氢和焊后热处理等工序对缺陷部位进行了焊接修复。焊接修复技术应用实践表明,通过制定合理的焊接工艺,选择合适的焊接方法,匹配相应的焊接材料,采用焊后消氢处理以及消除应力热处理等预防措施,可有效避免裂纹的产生,同时降低残余应力,使修复后的焊接接头具有良好的综合力学性能。通过采取有效的焊接修复措施,为焦炭塔的长周期平稳运行打下了良好基础。

During the operation of delayed coking unit,the B6 circumferential weld on the wall of coke drum cracked.Multiple detection methods were used to analyze the cause of the cracking.According to the results of macroscopic inspection,nondestructive testing,metallographic analysis,hardness test,and chemical composition analysis,it was concluded that the B6 circumferential weld was located at the tower wall with non-uniform thickness,and fatigue cracking occurred due to the drastic change of operating temperature.In order to eliminate the circumferential weld defects at the inner and outer walls of the coke tower,the defects were fixed by repair welding,dehydrogenation heat treatment,and post weld heat treatment.The application of welding repair technology showed that the cracks can be avoided and the residual stress can be reduced effectively by developing reasonable welding processes,selecting appropriate welding methods,picking corresponding welding materials,adopting preventive measures such as post weld dehydrogenation treatment and stress relief heat treatment,so that the repaired welding joints can achieve good comprehensive mechanical properties.By using effective welding repair measures,a good foundation was laid for the long-term stable operation of the coke drum.