Repaire of 6000 psi rated Pressure Vessel 1

[rkurtz61]

Hello everyone,

We are a small shop with R, S and U stamps, however we don't do much code work. The vessels we have built have never exceeded a 600 psi rating.
We have been asked to submit a bid to repair a pressure vessel built in 1964 which is rated at 6000 psi with MAWP of 5850. I do not want us to get involved with this for obvious reasons but need to submit a detailed explanation to upper management as to why it would be in our best interest not to. We do, however, want to bid on further work from this client. Can anyone give a substantive answer as to why we should not attempt this repair?

 

[unclesyd]

If you have all the material information about the vessel and the welding procedures to cover this material and understand what needs to be done I can see no reason not to work on it.
There is essentially no difference in working on a 600lb vessel or a 6000 lb vessel if you go by the rules.

 

[metengr]

Since you did not mention any background information regarding this vessel, the scope of repair may be out of your handling capability regarding welding material thickness and handling (weight).

 

[LSThill]

I aggree with Metengr
additional information
1) Material
2) Div 1, or Div 2
3) U1 Form

 

[jte]

Well, considering that it was built in 1964, we know that it is neither Div. 1 nor Div. 2. It's "pre-Division" vintage.

As others have stated, more details on materials, dimensions, process service, etc would provide more data for folks to provide commentary.

I suppose one reason to not work on this vessel is that it is "rated" at 6000 psi but has a MAWP of 5850 psi. Makes one wonder exactly what a "rating" is, and do the folks who are responsible for this vessel understand what a MAWP is.

I guess the main reason I would not send such a vessel to your shop for repair is that your shop doesn't do much code work, and I would prefer to see my vessels repaired by outfits with substantial experience. Although the basics of working on a vessel don't change with design pressure, a vessel of this high of a MAWP is worthy of substantial engineering competence. After all, someone has to decide what is necessary to meet the U-1(d) clause ...deviations from and additions to these rules usually are necessary... So, perhaps a question you could ask of your management is whether your shop has sufficient engineering ability to make ...technical judgments made by knowlegable designers experienced in the application of the Code. [from the Foreword of Div. 1] This vessel has been in service for over 40 years. Does your shop have sufficient materials engineering expertise to be comfortable with evaluating the need for dehydrogenation heat treatments or other service related materials issues? As I mention above, more data would provide more feedback.

jt

 

[waskillywabbit]

A substantial reason: You have no previous experience repairing such vessels.

 

[PVinspector]

rkurtz61 wrote:
I do not want us to get involved with this for obvious reasons...

Apparently from the replies they are not obvious to anyone else. What are the "obvious reasons?"

 

[metengr]

Apparently from the replies they are not obvious to anyone else. What are the "obvious reasons?"

The obvious reason is risk. If you go back to the OP, the repair contractor stated they perform very little code work and their experience has been on vessels that are rated for much lower pressure.

 

[rmw]

This isn't said to be ugly; just to put it into proper perspective. If I were to be the one responsible for the repair of a 6000 PSI vessel (and I've done a few already) and someone told me your crew was the one coming, I'd be calling somebody pronto e.g. top management within your customer's organization or their insurance carrier's AI.

You have two choices. One is to not bid it at all with an explanation as to why you don't wish to and a statement that you still desire to bid work that you are more qualified for OR (2) bid it not to get it-and make sure you don't get it. The latter will make you look ridiculous and the former should stand you in good stead if this customer has any character at all. If they don't get it, you are better off without them as a customer anyway.

The operative words to use with your management are "risk" and "liability". Tell them they should run it by your insurance carrier after using the context of those two words. They won't want to make that call and expose themselves to the scrutiny of the insurance carrier. You should be able to sell your case easily enough.

rmw