Hydrogen damage of carbon steel pipe under hydrogen atmosphere

• Main Authors: Chao-hsien Lai, 賴兆賢
• Other Authors: Hsien-Jung Tsai
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/s8qj7s

碩士 === 國立臺灣科技大學 === 機械工程系 === 94 === The main objective of this work was to study the hydrogen damage of carbon steel pipe under hydrogen atmosphere in the naphtha crack plant. The ASTM A53 Gr. B low carbon steel pipe damaged after 16 years at a temperature of 260°C (500°F) and a hydrogen partial pressure of 32kgf/cm2 (480psig). Four fractures being at heat affected zone of weld with weld defects could be found in the pipe. Microstructure observations showed that the fissuring being accompanied by a significant amount of decarburization occurred in the heat affected zone. According to API 941 and 571, the existence of fissures and internal decarburization could be attributed to the result of high temperature hydrogen attack (HTHA) resulting from exposure to hydrogen at elevated temperature. High temperature hydrogen attack has been found in carbon steel operating at hydrogen partial pressure and temperature conditions above the Nelson Curve of carbon steel. Although the hydrogen partial pressure and temperature conditions in this case was slightly below the Nelson Curve of carbon steel, high temperature hydrogen attack took place due to the stress concentration caused by weld defect, leading to failure of pipe.