ISSN:1000-8365 CN:61-1134/TG
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Cracking Analysis of Outlet Pipeline of Demethanizer Reboiler
Author of the article:LU Xuemei;JIA Yani;LI Yanjiao;WAN Liang;WU Xuegang;SONG Wenming;GUO Zhijun
Author's Workplace:Machinery Industry Shanghai Lanya Petrochemical Equipment Inspection Institute Co.Ltd.,Shanghai 201518,China;Lanpec Technologies Limited,Lanzhou 730070,China
Key Words:reboiler of demethane tower pipeline cracking intergranular corrosion cracking original defects welding stress
Abstract:Cracking occurred in the outlet pipeline of the reboiler of a demethane tower in a factory.The cracking reason was analyzed by means of macroscopic inspection,metallographic structure analysis,chemical composition analysis,fracture morphology analysis and EDX analysis.The results show that the failure pipe conforms to the characteristics of intergranular corrosion cracking,the chemical composition is unqualified,the grain size is coarse,the grain boundary sensitization and so on,the original defect is the root cause of pipe cracking,the existence of water phase is the direct cause of pipe cracking,the heat affected zone stress caused by welding is the indirect cause of pipe cracking.It is suggested to strengthen incoming inspection of raw materials.At the same time,avoid the accumulation of water phase in the shell,including gas phase water;Improve welding process,reduce welding joint stress,it can slow down the occurrence of cracking.