Hi
The design and fabrication code according to which the exchanger is designed will give you this information. In general, you need to make a calculation regarding the amount of "fibre elongation". If it exceeds a critical amount, heat treatment is required. Sometimes you will need to heat treat due to service requirements. (e.g. Prone to stress corrosion cracking.)
Hope this helps.
Regards
Niekie Jooste
Fabristruct Solutions
Very simple. The Code that governs tubes made to ASME SA-209 Gr T1 is the ASME Boiler and Pressure Vessel Code, Section II: "Material Specifications".
Grab Section II of the ASME Boiler Code, go to SA-209, once in there search for Grade T1 and it'll say whether or not the tubes must be stress relieved after bending.
In the majority of times, ASME material specs. are identical with ASTM ones of the same number (in this case A-209), but sometimes are not, so I don't recommend you to go to ASTM.
What TEMA governs is the mechanical design of the heat exchanger as a whole, while ASME Code Section VIII Div. 1 governs the design and construction of the shell and headers.
The tubes, on the other hand, are under SA-209, as explained above.
Giovanni S. Crisi
Sao Paulo - Brazil