Nozzle Repads

[Bobfromoh]

I have a question about nozzle repads for pipe stress purposes. The stress group says putting a note in the spec adding pads on process nozzles will reduce overall analysis time. A pad should be added wheather or not the Code requires one.

All the projects and companies I previousy worked for, pads were never added so I'm reluctant to agree. Besides, it increases the cost of the vessels and I'm not given any proof that analysis time will actually be saved.

Does anyone have an opinion as to when a pad should be used even before any analysis is done? Is this a new trend/fad?

 

[waskillywabbit]

Some companies in their specs have nozzle loadings to apply for all nozzles, some have predetermined neck thicknesses and repad sizes based on design criteria and others just do it on a per tank/nozzle basis...and then there are all sorts of other combinations of the above and/or additions.

My answer is "it just depends".

Brian

 

[jte]

Bob-

I agree with your sentiments - it is not clearly evident that the client gets better value from indiscriminately adding repads (and who specifies their size?) rather than... ahem... engineering the situation and making a defensible decision.

jt

 

[TGS4]

Bob - I too agree with your sentiment. I have tried working jobs either way (additional repads OR engineer the situation) and I can honestly say that I didn't notice a difference in the pipe stress hours either way. For the most part, a good stress engineer will be able to meet reason nozzle loads without significant additional effort. Only the lazy ones will require more time .

 

[DSB123]

Bob,
I agree with TGS4 and jte. Sounds to me like your pipe stress guys want an easy time no matter what the additional cost is. A good pipe stress engineer should be able to meet realistic vessel nozzle loads providing the vessel engineer has not designed the vessel right on the knuckle. I would go back and challenge them on their requirement for re-pads willy-nilly being used.

 

[JoeTank]

DSB, "designing right on the knuckle" is exactly what a successful vessel fabricator has to do on a competitive bid.

All, I agree that adding repads does cost more and it gets darn hard to get them all to fit in on a vessel.

Joe Tank