变换气管道开裂原因分析

REASONS FOR CRACKING OF SHIFT GAS PIPE

对水煤浆净化装置低温变换炉泄漏的出口管材质、裂纹进行宏观和微观的检测和分析,结果表明:焊接管是用720 mm×18 mm板材沿轧制方向卷制而成,这种轧制方法使横焊缝具有极高的残余应力,大于AISI321奥氏体不锈钢在含有Cl-水溶液中的应力腐蚀的临界应力,故在运行400 d后发生Cl-溶液中应力腐蚀,引起泄漏。同时对H2S的作用进行讨论,提出一些解决方案并应用于实际,取得成效。

In this paper, macro and micro analysis was done to the material and cracks of the leaked exit pipe of low pressure shift furnace of water-coal slurry purification plant. It was indicated that the welded pipe was made by rolling φ720mm × 18 mm steel plate along pressing direction. This kind of pressing resulted in very high residual stress of crossrange welds, which is bigger than the critical stress of stress corrosion of AISI321 Austenite stainless steel in Cl-containing solution; therefore, stress corrosion in Cl^-containing solution happened to the pipe after 400 d operation, resulting in the leakage. Meanwhile, this paper discussed the function of H2S, presented some measures and put them into practice, achieving good results.