雙相不銹鋼冷卻器破損分析研究

雙相不銹鋼綜合沃斯田鐵不銹鋼和肥粒鐵不銹鋼兩者材料之特點，具有優良的抗腐蝕性以及很高的機械強度，因此廣泛地應用在煉油廠與化工廠的設備與管線中，本篇研究之破損物件即來自煉油廠中酸水氣提塔上方之冷卻器。根據分析結果研判，雙相不銹鋼冷卻器下方圓錐型胴體的破損主因為沖蝕，而沖蝕流體為酸氣經熱交換後所產生之冷凝液體。大量的酸氣凝結液藉由酸氣氣流速度以及重力效應，使液滴移動沖擊到下方的圓錐型胴體，而產生沖蝕破孔現象。此外，雙相不銹鋼銲接處亦發生腐蝕穿孔現象，這是由於雙相不銹鋼銲接處的兩相組織未能達到與母材相當之相組織比例，即沃斯田鐵相和肥粒鐵相各約佔50 %，使其耐蝕性能及機械強度下降。為避免相似問題重覆發生，文中建議變更冷卻器設計樣式，並提出適當的銲接程序參數，以避免後續可能發生之工安事故與經濟損失。

關鍵字

雙相不銹鋼；冷卻器；破損分析；沖蝕

並列摘要

Duplex stainless steels combining characteristics of both austenitic and ferritic stainless steel have excellent corrosion resistance and high mechanical strength, and they are widely used to make equipment and pipelines of refinery and chemical plants. The failed equipment in this study was the cooler at the top of sour water stripper in a refinery. According to the analysis results, erosion was the root cause of the broken cone of duplex stainless steel cooler and the erosion fluid was the condensate from sour gas through the cooler. When a lot of sour gas condensate impacted the cone of the cooler by the sour gas flow rate as well as the gravity effect, erosion phenomenon occurred. Moreover, there was corrosion cracking in welds of duplex stainless steels, this was because their microstructure failed to achieve a 50:50 phase balance of ferrite to austenite when welding, and then corrosion resistance and mechanical strength were decreased. In order to avoid the possible occurrence of occupational accidents and economic losses, changes in the cone structure of the cooler and appropriate parameters for welding are proposed.

並列關鍵字

Duplex Stainless Steel ； Cooler ； Failure Analysis ； Erosion

國際替代計量

雙相不銹鋼冷卻器破損分析研究

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