Sect VIII Div1 UW-40 (f)(5)(d) Postweld Heat Treatment 3

[suchetw]

Dear sirs,
I have unclear question about the nominal thickness to be used for Postweld Heat Treatment as per UW40. My informations of pressure vessel are as following;
1.Material is SA516-70N
2.Shell and head thickness is 50mm.
3.1(one) Nozzle material is SA350 LF2, connect to shell by grove weld set in type (not set on type)and complete with fillet weld 12 mm.(as per Fig.UW-16.1 (e))
4.Another nozzle connect to shell by groove weld set in type with reinforcing pad (thk.25.4mm)and complete with fillet weld 12mm.
Question is,what is nominal thickness as per UW-40 for PWHT?
1. Is it 50mm as per shell thickness? or
2. Is it 87.4mm (shell 50mm + re-pad 25.mm + fillet 12mm)? because UW40(F)(5)(d)"in Figs.UW-16.1 and UW16.2, the thickness of the weld across the nozzle neck or shell or head or reinforcing pad or attachment fillet weld, whichever is the greater;"

Best Regards,
Suchet

 

[metengr]

My interpretation of UW-40 5 (d) implies the thicker of the two governs nominal thickness taking into consideration the groove weld depth versus groove weld depth + thickness of the repad fillet weld + the external fillet weld. Therefore, it would be 87.4 mm.

 

[codeeng]

Its the greater of each component, not the combined thickness, thus 50mm is the nominal thickness.

 

[metengr]

After further review, 50 mm would be the nominal thickness for PWHT. My own rationale for this is that the combined welds (like the external fillet or repad fillet weld) will be exposed to the same PWHT temperature as the nozzle groove weld. Since the external fillet weld and the repad fillet weld are presumably less in thickness (based on throat dimension) they would be subjected to an adequate stress relief (less time needed at the same PWHT temperature) because the time constraints for the thicker weld would govern.