Weld try support to overlay

[jamesl]

We have a weld overlayed carbon steel vessel. Is it acceptable to weld the tray support rings directly to the weld overlay surface if the calculated stress at weld joint is below the allowable stress of overylay material (304 stainless)? Thanks.

 

[abbver98]

You had to recalculate the vessel as it's requested in UG-22. See if you add pads or reinforcement for local stresses.

 

[jamesl]

Thanks for reply. The intention of my original question was to find out whether we can weld supports to weld overlay surface, or we have to weld supports to base metal and restore the overlay.

 

[vesselguy]

Jamesl,

The answer to your question is both yes and no.

Yes, you can weld tray support rings to clad plate or to W.O. provided the local stress is less than some value. This value changes with the kind of Client you have. I had been using 5000 psi local stress as a rule of thumb. This low stress dictates these attachments are consider to be "minor" supports. Major supports MUST never be welded to clad or W.O. as it WILL tear later on.

No, you cannot weld to the clad or W.O. if you are in H2 or sour service. In these cases, you can only weld to the base metal and then do W.O. restoration.

If you have W.O. vessel, I think you have something going on in the process which you must investigate before you do it.

I don't think you are doing PWHT since you are only using T304. But if you are, if I may suggest, you should weld on the rings only after PWHT to minimize the risk of cracking your attachment welds.

Hope this helps.