Localized PWHT for Repair Job as per NBIC Part-3 & UW-40

[MUHAMMAD FAHAD RANA]

Back Ground:

PWHT is not required by construction code ASME Sec VIII Div-1, however PWHT is required as per client requirement. This is alteration job in which 7 nozzles has to replaced with new one and one nozzle resize from 20 inch to 30 inch. So, only nozzle to shell joint has to be PWHT.

Question:

Localized PWHT calculations (Soak band, Heating band and Gradient control band) covered only Nozzle with pad area (Sketch 01) OR Nozzles including circumferential area (Sketch-02).

Pls respons as per UW-40 & NBIC part-3

Reference Attached Sketchs (01 & 02) and NBIC Part-3 Screen Shot.

Thanks


Fahad

 

[weldstan]

For a 30" nozzle, I would recommend heating the whole circumference as in no.2. The bulls eye technique in no. 3 will be quite difficult to achieve from first hand experience but that was a number of years ago.

 

[Cobra17]

I base my bands on WRC 452, Recommended Practices For Local Heating of Welds.

 

[TGS4]

If the purpose of your PWHT is to reduce residual stress, then a whole-circumference PWHT is the only technique that will actually achieve that purpose. There have been many papers that have demonstrated that bulls-eye PWHTs result in worse residual stress states than what you would have started with (just the weld residual stress).

 

[r6155]

Agree with your client how the PWHT is suitable. Consider PWHT of the entire equipment, depending on the dimensions.

Regards