吴广仁 袁晓君 梁军智 戴兴东 张磊

摘 要：汽轮机主蒸汽管道温度保护套管安装涉及异种钢的焊接工艺，若焊接工艺不合理，在长时间运行后会因为交变应力造成疲劳断裂问题。本文针对某机组主蒸汽温度套管裂纹问题展开分析，探讨了造成套管裂纹的主要原因：异种钢焊接、选材及工艺执行不当，使得保护套管经历长周期运行后产生裂纹并扩张。根据上述分析，组织编制焊接修复工艺并格执行各项工艺措施。分析结果表明，该方法在优化施工工艺的同时保证了焊接位置的材料特性，为同类型异种钢焊接管座隐患排查及处理提供了可借鉴的方案。

关键词：保护套管 异种钢 焊接裂纹 主汽管道

Abstract： The install processing of the temperature protection casing on the main steam pipe of steam turbine involves the welding process of dissimilar steel. If the welding process is not reasonable， the fatigue fracture problem will be caused by alternating stress after a long operation time. In this paper， the crack problem of main steam temperature casing of a unit is analyzed， as well as the main reasons for the cracks in the casing： Dissimilar steel welding， material selection and process execution make the protective casing crack and expand after long-term operation. According to the above analysis， organize the preparation of welding repair process and implement various process measures. The analysis results show that this method not only optimizes the construction process， but also ensures the material characteristics of the welding position， which provides a reference scheme for the troubleshooting and treatment of hidden dangers of welded pipe sockets of the same type of dissimilar steel.

Key Words： Protection casing; Dissimilar steel; Weld crack; Pipe of main steam

电力生产过程中，依赖众多的测点监测设备的运行状态，并用于指导整个生产过程的安全平稳运行[1-3]。以汽轮机为例，温度、压力、振动等参数依靠传感器获取相关信息。因此，针对各重要參数的测量方法、安装工艺得到了广泛关注。以汽轮机主蒸汽管道温度测点为例，若要测量管道内蒸汽温度，需要将传感器伸入到管道内部且焊接到管道壁面上，并保证焊接位置的封闭性，这就需要相应的安装工艺保证高温高压的蒸汽不能从测点位置泄露造成安全事故[4-6]。而整个过程涉及材料、焊接、结构等多个领域，需要从多个方面展开研究分析[7，8]。有研究[9]利用试验方法对P91钢在蠕变和疲劳相互作用下的断裂特性进行研究，指出应力幅与平均应力的关系直接反映了断裂处的主要因素。……