Reinforcing Pads Vs. Design Temperature

[keens]

Gentlemen,

Does anyone know wherein Section VIII, Div. 1, it recommends not using Repads above 800 degrees F? Thanks...

 

[gr2vessels]

keens,

I cannot imagine that ASME VIII is recommending the limit of 800 deg F(or even higher)for the use of reo plates, since is recommending 1000+ deg F post weld heat treatment for certain materials and thicknesses. There are various vessel specifications preventing the use of reo plates in specific services (low temp, hydrogen service, etc..), but not really related to operating or design temperatures. However, there are materials which cannot be used over 800 deg F, or operating conditions with significant themperature variations. These are cases with large temperature differentials, when the shell plate rapid expansion and slow expansion of the reo plate could cause excessive stresses, thus preferred option would be the use of integral nozzles, rather than reo plate.
Could you please expand a bit your question over the specifics of your vessel?

Cheers,

gr2vessels

 

[ijzer]

It is not mentioned in the ASME Code but more a common practice . Using reinforcement pads or other plates welded to a high temperature vessel can lead to cracking. This is due to temperature difference between vessel wall and plate.

 

[waskillywabbit]

Reinforcing pads are not recommended for temperatures where time dependent material properties govern. (creep regime) It is a warning in COMPRESS above 800F.




Brian