Dear All,

In U-tube heat exchanger, I am using SB 395 UNS C71500 material.
But I am confused whether to go for annealed tubes or stress relieved tubes (Refer SB 395, UNS C71500 O61 for annealed & HR58 for stress relieved) because there i found huge stress difference

UTS : 72 ksi (Stress Relieved), 52 ksi (Annealed)
Yield Stress: 50 ksi (Stress Relieved), 18 ksi (Annealed).

There is no such criteria mentioned by client & process about use of stress releived tubes.

So, please anybody can guide me to choose the correct type of tube.....

In addition to above query one more query I have.
Why there is so much difference in the UTS & Yield values for annealed and stress relieved tubes???