Postweld heat treatment and R-stamp

[sksmechanical]

have a vessel that has already been postweld heat treated. pipe guide clips are being welded to the shell. i'm pretty sure the vessel doesn't need to heat treated again according to table ucs-56. does the vessel need to r-stamped? please advise.

 

[metengr]

Is the vessel in-service or under construction? If in-service and your Jurisdiction does or does not regulate pressure vessels, I would require an R-Certificate (R-Stamp) for any weld repairs, regardless.

 

[sksmechanical]

the vessel has just finished fabrication and has gone through a postweld heat treatment. the clips will be welded on in the field before plant start up.

 

[metengr]

Ok. Perform the clip attachment using a current R-Certificate (R-stamp).

 

[Christine74]

Using the R-stamp, you should be able to avoid PWHT per NBIC RD-1030.

-Christine

 

[sksmechanical]

okay so let me be sure I understand. we can perform the clip attachments with no PWHT but will have to get the R-stamp correct?

 

[metengr]

This weld repair should be performed using an R-Stamp program. I can't respond if local PWHT is required after welding pipe guide clips because you have not provided enough information. If you say UCS-56 does not require PWHT because the welds meet the exemption requirements you are all set. If you are unsure about the requirements in UCS-056 better get help to interpret them.

Just a side note - let me be perfectly clear about this, the alternative welding methods in the NBIC were never intended to circumvent the requirements in the ASME B&PV Code. They are provided as an option in the event PWHT cannot be performed without harm to the completed vessel or intended service.

 

[sksmechanical]

yes i think we are all set regarding the PWHT. the welds are less that 1/2" which is exempt according to the notes of table UCS-56.

 

[stanweld]

If the vessel has not been hydrostatic tested and the Code data report unsigned, the R-stamp does not apply. You may weld to the vessel without additional PWHT provided the weld sizes do not require PWHT under UCS-56.

 

[sksmechanical]

So basically once the vessel is complete (fabrication, all inspections, pwht, final hydrostatic testing, U-reports signed off) then the R-stamp comes into play.

 

[stanweld]

Yes.

 

[sksmechanical]

Thanks for the help everyone. Much appreciated.

 

[vesselfab]

I would like to add....if the vessel is being PWHT because of service reason, like wet H2S, Amine, Hydrogen, or some other reason besides ASME code, it is always better to consult with the buyer/end user of vessel.
They may want to see the welding,temper bead procedure with the proper preheats.