天然气长输管道焊口开裂泄漏原因

Reason Analysis on Weld Cracking in Long-distance Gas Pipelines

某天然气长输管道在管道穿越处出土端发生焊口开裂泄漏,根据GB50251-2003《输气管道工程设计规范》对管道的工程设计、工程施工和生产运行等3个阶段进行校核,并结合定向钻穿越出土点的地质特征,对该天然气长输管道焊口开裂泄漏原因进行排查和分析。结果表明:管道的工程设计和施工都符合相关规范,而在生产运行过程中,工作压力波动、高速流体冲击、管内介质温度变化以及管道形变等因素可能导致局部应力集中,并在焊口的薄弱环节发生应力疲劳开裂,从而造成泄漏事故。

Weld cracking in a long-distance natural gas pipeline occurred at the exit point of crossing position.Based on the Gas Pipeline Engineering Design Standard described in GB50251-2003(China National Standard),a technical approval on the engineering design,project construction and commissioning for the pipeline was carried out.Combined with the geologic characteristics,reason of weld cracking in the pipeline at the exit point of crossing position was analyzed.The results showed that the engineering design and project construction of the pipeline were in line with the standard,but the factors in the fluctuation of operating pressure,impact from high-speed liquid and temperature variation of pipe flow as well as pipeline deformation would result in pipe's partial stress concentration in the process of pipeline operation,so fatigue stress cracking produced in the weld with defect,thereby the leakage accident took place.