SA387 Gr.11 Cl.2 1

[LSUME]

I am working on a PV/HE that has 3.25" thick SA387 Gr.11 Cl.2 tubesheet (TS) clad with SA240 304 on the tubeside only. The TS will be welded to a 1.125 thick SA516 70N shell. The TS was tempered at 1178 °F. ASME Sec VIII Div.1 requires a PWHT of 1200 °F. This will be a local PWHT at the shell - TS joint. I'm a bit concerned about a reduction in mechanical properties due to difference in the temps. Can anyone shed some light on this subject?
Take it easy on me guys I'm a recently graduated ME.

 

[metengr]

LSUME;
You should be fine. If you review ASME SA 387, for this class of material, the minimum tempering temperature is 1150 deg F, not the maximum. You have met this requirement for the fabrication heat treatment of the plate. The PWHT should be at or higher than the minimum tempering temperature to assure adequate ductility and toughness for PV applications.

 

[metengr]

One additional comment, if you really want to satisfy your curiosity, look at the weld procedure qualification record. The weld procedure used fro joining the TS to the shell must be done with an ASME Section IX welding procedure. This procedure is qualified using a weld coupon that is subjected to tensile tests and bend testing after PWHT. Look at the tensile test results and compare to the minimum mechanical properties in SA 387.

 

[LSUME]

Thank you for your helpful insight! I was under the impression that it was not wise to PWHT above tempering temp.