某输气管线弯管开裂原因分析

某弯管发生刺漏现象，为明确该弯管开裂原因及失效机理，本文采用宏观分析、理化性能、微观分析、腐蚀模拟试验等手段对其进行分析研究。结果表明：该弯管开裂失效机理为硫化氢应力腐蚀，失效的主要原因为，该弯管热煨弯工艺不合理，导致弯曲段产生大量的马氏体组织，马氏体组织硬度较高，对硫化氢应力腐蚀开裂较为敏感；该弯管输送的天然气中含有游离水和硫化氢，硫化氢溶于游离水，对金属基体产生应力腐蚀作用，导致弯管发生开裂。

Analysis on the Cracking of the Elbow of a Gas Pipeline

In order to clarify the cracking reason and failure mechanism of an elbow. this paper adopts macroscopic analysis, physical and chemical properties, microscopic analysis, corrosion simulation test and other means to analyze and study. The results show that the cracking failure mechanism of the bent pipe is hydrogen sulfide stress corrosion, and the main reason for the failure is that the hot bending process of the bent pipe is unreasonable, which leads to a large amount of martensite structure in the bending section. The martensite structure has high hardness and is more sensitive to hydrogen sulfide stress corrosion cracking. The natural gas transported by the bent pipe contains free water and hydrogen sulfide,and hydrogen sulfide dissolves in free water, which causes stress corrosion effect on the metal matrix,leading to cracking of the bent pipe.