Vessel Alteration Code Edition

[garnet1]

This has probably been beat to death but I need clarification. I have an ASME vessel built in 1962. I want to add a 16" nozzle to it. What code edition can I use to comply with NB-23?

 

[metengr]

You can use any edition of the ASME B&PV Code that is acceptable to the Inspector and the Jurisdiction.

 

[metengr]

Just one point of clarification so that I am not misinterpreted in my post. The words in RC-1020 of the 2004 Edition of the NBIC state.... that repairs and alterations should be performed, insofar as possible, to the section and edition of the ASME Code most applicable to the work being performed…..

So, if you can obtain a copy of the 1962 Edition of the ASME code that applies to your addition of a nozzle that would be great. However, in most cases, later editions of the ASME Boiler and Pressure Vessel Code section would suffice.

 

[unclesyd]

metengr,
What year did some of the stress values change, especially the SS?

I know all our repairs and alterations we used post 1968 editions for the code guidelines.

 

[metengr]

unclesyd;
I believe with the 1998 Edition/1999 Addendum of the ASME B&PV Code.

 

[garnet1]

The way I understand it is that the original stress values must be used however the remainder of the latest code can be used.

 

[unclesyd]

Thanks,

I never did ask why we used the later additions of the code and for some reason it never seemed strange. At the time the majority of our vessels were fabricated 1951-1962.

 

[metengr]

In your situation, since the vessel was built before 1968, you should attempt to obtain ASME B&PV Code stress values for the vessel material from the year that it was built. If the vessel was built after 1968, other rules apply for using higher allowable stress values (see RC-3024). Notice I said attempt and keep in mind that some material stress values prior to 1999 had not changed appreciably. Current stress values can be used for the the nozzle (new) minimum wall calculations.

Check with your Inspector. If you specifically need the allowable stress from the year the vessel was built contact the National Board directly. They have every published edition of the ASME B&PV code. You can provide them the edition, section and material designation, and they will provide you a copy of the stress line.

 

[jte]

garnet1-

I've never had any issues with either the AI or Jurisdiction when in a situation like yours and using the allowable stress used for the original design and calc's per the latest edition of the Code. As metengr pointed out, you can use current allowable stresses for the new components which you are adding.

However... take this approach after due consideration. If you use the original allowable stresses and you have an existing 16" connection with identical reinforcement requirements (etc, etc) then you may install this (with the usual "check with your AI" caveat) as a repair. Since this is a repair, the AI may waive the hydrotest requirement in lieu of alternate testing which may be less painful.

On the other hand, if you use current allowable stresses, then it is an alteration and a hydrotest is mandatory unless otherwise approved by the Jurisdiction.

If you are pondering using a "local hydrotest" approach by putting on a (say 20") weld cap on the inside of the shell to cover the newly installed nozzle, be aware of Interpretation VIII-1-01-139 which prohibits this approach for new construction...

jt

 

[GenB]

jte,
Either way it is considered an alteration.
What the Jurisdiction Inspector approves is another thing,

genb