Is overall stress relief heat treatment necessary for stainless steel fixed tubesheet heat exchangers?
Thread Content
Liquid ammonia on the shell side and carbon dioxide on the tube side. The temperature is minus 40. The materials are all 0Cr18Ni9. The expansion coefficient of the material is large. After heat treatment, there is still a problem when repairing the tube-sheet welding joint. Some of the posts I posted may have been posted to the wrong place. Please transfer them to the original post, which has caused trouble to you.
Stainless steel generally does not require heat treatment, even if it is used at low temperatures above -196°. If it is done, it may not be handled well and problems may arise. Pay special attention to the sensitization temperature zone of 600~850°.
Stainless steel equipment does not require heat treatment
First of all, we must understand that the purpose of heat treatment of low-temperature equipment is to improve the toughness reserve of materials and prevent low-temperature brittle fracture. The toughness of stainless steel is very good. Even at minus 196 degrees, it can still be considered as a low-temperature container. Therefore, stainless steel equipment is not heat treated. At the same time, stainless steel materials have sensitization temperature problems. If heat treated, it is easy to reduce the corrosion resistance of stainless steel. I have never encountered stainless steel equipment for heat treatment until now. Even for composite plate equipment, the base layer meets the heat treatment requirements. In view of the anti-corrosion requirements of the surface layer, you must choose carefully.