Regarding shell and tube heat exchangers, API 660 specifies the thickness of sealing strip as below.
"Para.7.6.5.5. The nominal thickness of seal strips shall be the nominal thickness of the transverse baffles or 6mm, whichever is less."
However I doubt why API 660 specifies the maximum...
dear mrsteam;
I have seen the contents in a kind of instruction as "~ greater than 1000 cycles of pressure variation exceeding 20% of the design pressure.".
Refer to www.PDHonline.org (M205)
Best Regards,