How much of a pressure vessel can i replace and it still be considered a repair? 1

[jeevesme]

We have a small 8" heat exchanger bonnet that is pretty much shot except for the head. My question is, can we keep the head, and replace the two nozzles, shell portion, the flanges and the pass partition and still have it considered a repair?

 

[jeevesme]

The repair company that we typically use say that there is a certain percentage that is used to determine whether or not it can be repaired. He is checking with his AI. As far as I know, the NBIC doesn't define at what point it's considered a repair and at what point it is considered that a "U" Stamp company has to make it.

 

[weldstan]

Yes.

 

[Duwe6]

You have to keep one 'component'* plus the Code Data Plate. One or more components, not any percentages. Somewhat counterintuitive, but replacing existing components "in kind" is just a repair, because the vessel is not being redesigned/altered. You are only returning the vessel back to its original condition. In the nuclear end of ASME, there is a much better set of terms; Rework or Repair. Rework = make the vessel like new [thus replace a damaged component]. Repair = make the vessel/component fully serviceable, but not necessarily 'as-new'. Weld buildup on a 'wasted' ell is Repair, replacing that ell with a new one is Rework.

*And the next repair can replace that remaining original component.

 

[JStephen]

"*And the next repair can replace that remaining original component."

I remember in the old Dixie Gun Works catalogs, they had a "letter" from a customer relating how they had an antique tomahawk. "It's had 7 new handles and 5 new heads, but it's still in really good shape!". I did not realize you could do that with vessels.

 

[chicopee]

In some of the older NBIC, repairs could not be carried out if the thickness was over 50% depending where the repairs or replacements had to be made.

 

[metengr]

I can tell you that the NBIC committee had wrestled with how much of a pressure vessel can be replaced up to and including having only the original nameplate attached to a piece of the shell and data report. Under current rules, the extent of replacement under a repair is based on two factors; the judgement of the Inspector and concurrence by the Jurisdiction, if applicable. If the object is regulated, the Jurisdiction has final say as to the extent of pressure part replacement.