高温过热器出口过热蒸汽取样管开裂原因分析  

Cause Analysis of Cracking of Superheated Steam Sampling Tube at Outlet of High Temperature Superheater

作　　者：张保军 赵冰 陈海生 ZHANG Baojun;ZHAO Bing;CHEN Haisheng(Changqing Oilfield Branch Material Supply Department Quality Control Center,Xianyang 712000,China;Tianhua Institute of Chemican Machinery&Automation Co.,Ltd.,Lanzhou 730000,China)

机构地区：[1]长庆油田分公司物资供应处质量管控中心,陕西咸阳712000 [2]天华化工机械及自动化研究设计院有限公司,甘肃兰州730000

出　　处：《山东化工》2024年第23期209-212,215,共5页Shandong Chemical Industry

摘　　要：某石化公司高温过热器出口过热蒸汽取样管因开裂引起介质泄漏。通过宏观检查、化学成分分析、壁厚测定、硬度测试、金相分析、扫描电镜及能谱分析等手段,分析取样管开裂原因。结果表明:失效管段材质为碳钢,金相组织为铁素体+碳化物+石墨,管段服役温度为530℃,处于该类材料球化和石墨化的温度范围,服役约32000 h后,珠光体发生了完全球化,同时稳定性不高的碳化物分解成铁素体和石墨;此外,管段长期运行温度远高于碳钢蠕变阈值温度,组织中出现了蠕变损伤,使材料内部不连续,晶界强度降低。失效管段因材料发生球化、石墨化劣化以及高温蠕变机械损伤,加之管内较大的介质压力,最终因材料强度不足和局部壁厚减薄而发生开裂与局部变形。Medium leakage was caused by cracking of superheated steam sampling pipe at the outlet of high temperature superheater in a petrochemical company.The cracking causes of the sampling tubes were analyzed by means of macroscopic inspection,chemical composition analysis,wall thickness measurement,hardness test,metallographic analysis,scanning electron microscope and energy spectrum analysis.The results show that the failure tube section is made of carbon steel,the metallographic structure is ferrite+carbide+graphite,and the service temperature of the tube section is 530℃,which is in the temperature range of spheroidization and graphitization of such materials.After serving for about 32000 h,the pearlite is completely globalized,and the carbides with low stability are decomposed into ferrite and graphite.In addition,the long-term operating temperature of the pipe section is much higher than the creep threshold temperature of carbon steel,and creep damage appears in the structure,making the internal discontinuity of the material and the grain boundary strength reduced.Due to nodulation,graphitization degradation and high temperature creep mechanical damage of the failed pipe section,coupled with large medium pressure in the pipe,cracks and local deformation occur due to insufficient material strength and local wall thickness thinning.

关 键 词：取样管 开裂 球化 石墨化 蠕变 

分 类 号：TQ055.8[化学工程]