某钢厂输送液压油API管道失效分析

Failure Analysis of API Pipes Used for Hydraulic Oil in an Integrated Steel Plant

某钢厂输送液压油API级无缝钢管在一个月中发生了两次失效,第一次失效出现了4.7 m长的纵向裂缝,第二次失效时管道出现了少量泄漏。管道输送液压油的压力为3~14 MPa,环境温度为25~40℃,该无缝管的失效可能是高应变率或氢致开裂(HIC)等因素导致的管体开裂。采用化学分析、拉伸试验、硬度测试、宏观观察、光学和电子显微镜以及能谱分析(EDS)等方法对其失效原因及其机理进行分析。结果表明,管道中输送液压油分解产生的氢与管材内部中的硫化物夹杂相结合,导致管体因氢致开裂而失效。

API grade pipes used for hydraulic oil in an integrated steel plant has failed twice in a month.The first failure appeared 4.7 m long longitudinal cracks,the second failure of the pipeline appeared a small amount of leakage.The pressure of the pipeline transporting hydraulic oil is 3~14 MPa and the ambient temperature is 25~40℃.The failure of the seamless pipe may be caused by high strain rate or hydrogen induced cracking(HIC).Chemical analysis,tensile test,hardness test,macroscopic observation,optical and electron microscopy and energy spectrum analysis(EDS)are used to analyze the failure causes and mechanisms.The results show that the combination of hydrogen produced by the decomposition of hydraulic oil in the pipeline and sulfide inclusion in the pipe leads to the failure of the pipe body due to hydrogen induced cracking.