On the heat treatment of low-temperature condensers
Thread Content
The 09MnNiDR low-temperature condenser features a fixed tube sheet, with a design temperature of -45 degrees. The shell has a thickness of 20 mm and requires heat treatment based on that thickness; then, does the tube end also need heat treatment? How should the tube ends be treated during the heat treatment of the shell? If the heat exchange tubes are welded to the tube sheet, could this cause the welds to crack? ； If welding is not done, will the heat exchange tubes contract into the tube holes of the tube sheet? I would be grateful for any advice from those who are familiar with this topic.
This is indeed challenging; it’s recommended to leave one end of the heat exchange tube unwelded while welding the other end. Two weld evaluations are required for the pipe ends: one with heat treatment and one without heat treatment.
It seems this problem is quite difficult; heat treatment for exchangers with fixed tube sheets is indeed challenging.
Has the original poster found a good solution?
Can the shell be heat-treated, and then local heat treatment be applied to the welds with the tube sheet, while leaving the tube ends and the tube sheet alone?
Consider the method of local heat treatment for the welded joint; overall heat treatment carries a higher risk.
What has been done is mainly heat treatment of the shell before molding, along with internal support; after molding, local heat treatment is applied to the last two ring seams and the pipe ends