PWHT for Low Alloy Steel.

[mandarkardekar]

PWHT, is it mandatory for low alloy steels such as SA-387 Gr.5, Cl.2 plates for all thicknesses?

In my project vendor has provided PWHT for all such cases for entire vessel. please someone guide.

 

[Mech2325]

Define all cases??

 

[Mech2325]

See UCS 56 of ASME Sec VIII Div. I. It clearly states the PWHT requirements for carbon and low alloy steels

 

[mandarkardekar]

Mech2325, thank you. As I see in Table UCS-56-4 applicable in this case, General Note (a) says PWHT is mandatory in all conditions, exempted for certain pipe and tube cases and ERW case.

Which means other than exemptions it is PWHT mandatory for vessel made up of SA-387 Gr.5, Cl.2.

please help me on my Code interpretation.

 

[mandarkardekar]

Adding to above, which means my vessel shell, dished head, girth flange and blind cover entire to be PWHT.

Is there any more conditions which can exempt PWHT for this situation?

 

[Mech2325]

Yes. But SA-387 Gr5 has a chromium content of 5% which is more than the 3% limit mentioned there. So this material is not exempted from PWHT as per my understanding

 

[david339933]

Is there welding on the blind flange? If not, no need for PWHT...unless a service requirement.

 

[weldstan]

There is no exemption in ASME VIII for P 5B materials.

 

[Mech2325]

I checked it on COMPRESS software and found out that it gives you a message that "PWHT" is mandatory for all thickness for this material. Although i dint find any reference in the code.

 

[mandarkardekar]

Thank you all for response.

Mech2325, Table UCS-56-4, General Note (a), in ASME Sec.VIII, Div.1 has reference for PWHT mandatory.

 

[Mech2325]

mandarkardekar: Yes i read it but in this also it is exempting a certain limit of thickness from PWHT. Guess, COMPRESS should change its warning message of "PWHT mandatory for ALL thicknesses"

 

[mandarkardekar]

COMPRESS gives warning for plate material only. Exemptions in Code are for circumferential welding of pipe and tubes for certain cases and thermocouple attachment weld.

Do you have any interpretation about plate material where it is exempted? I think for all thickness of plate material PWHT is mandated by Code.

 

[Mech2325]

Mandarkardekar: Thanks for the correction. I was using the plate material