輕裂工廠不銹鋼管線裂紋分析探討

Failure Analysis on the Cracking of Stainless Steel Pipe of Ethylene Plant

翁文宏(Wen-Hung Weng) ； 陳孟宏(Meng-Hung Chen) ； 許峰彰(Fong-Chang Sheu)

《石油季刊》 48卷3期 (2012/09) Pp. 45-52

https://doi.org/10.30128/JP.201209.0004

摘要

本研究主要針對某輕裂製程之丙二烯反應器不銹鋼管線裂紋進行分析探討，以期明瞭裂紋產生機制及其可能肇因。根據分析結果研判，其破損機制應是保溫層下腐蝕（Corrosion Under Insulation, CUI）所引發之氯離子應力腐蝕（Chloride Stress Corrosion Cracking, Cl（上標 −）_SCC），氯離子的來源可能來自保溫材本身或外界來源，而觸媒再活化及再生之次數多寡間接影響CUI_氯離子應力腐蝕發生的機率。為防範相似問題再次發生，文中並提出相關之改善對策，以增進設備操作安全，避免後續可能發生之洩漏危險。

關鍵字

不銹鋼304 ； 裂紋 ； 保溫層下腐蝕 ； 氯離子應力腐蝕

並列摘要

Cracks were found in the 304 Stainless Steel transfer line section of propadiene converter in ethylene plant over 25 years service. Metallurgraphic examinations were performed to study the crack mechanisms and the root cause using optical and scanning electron microscopy (SEM) as well as energy dispersive X-Ray spectroscopy (EDS). The observation showed that the branched cracks initiated from the outer surface of pipe and propagated transgranularly into stainless steel pipe with un-sensitized microstructure. It was concluded that the 304 Stainless steel pipe failure was due to environmental stress corrosion cracking caused by chloride concentrated under thermal insulation. Recommendations were also made to mitigate the aforementioned cracking failure.

並列關鍵字

Stainless Steel 304 ； Cracking ； Corrosion Under Insulation ； Chloride Stress Corrosion Cracking