关键词: 加氢装置, 高压空冷器, 碳钢, 湿H2S应力腐蚀开裂, 显微硬度,

Abstract:

High pressure air cooler is the key equipment of hydrogenation unit in petrochemical enterprises. In recent years, leakage problems have occurred many times during start-up and operation, seriously affecting the production safety and economic benefits of enterprises. The carbon steel high pressure air cooler of hydrogenation unit in two domestic refining and chemical enterprises is selected to analyze the metallographic structure and microhardness of the pipe joint. The results show that there is widmanstatten structure in the fillet welds, and the highest hardness is about 250 HV10. For the heat affected zones on the tubesheet side, there is martensite structure and the highest hardness even exceeds 330 HV10. This is mainly due to insufficient or even no postweld heat treatment in the manufacturing process. Combined with the harsh service condition of high pressure air cooler, there is a high risk of wet H₂S stress corrosion cracking. In view of the manufacturing status of carbon steel high pressure air cooler pipe joints, the improvement measures such as correct measurement of microhardness of welded joints, effective postweld heat treatment and strengthening process control are put forward.

Key words: hydrogenation unit, high pressure air cooler, carbon steel, wet H2S stress corrosion cracking, microhardness