Stab In Re-boiler into ASME Sec. VIII Div 1 Vessel

[AEF]

This one is generating a lot of debate between our pressure vessel engineering consultant and local jurisdiction.
Large new vertical column designed and fabricated to ASME Sec. VIII Div. 1 with a large stab in type re-boiler at the bottom. Re-boiler (LP steam) bundle is inserted into the column through a flanged nozzle and bolted on (tubesheet acts as flange). The PV engineer determined that since the column acts as the shell for the re-boiler bundle, the re-boiler is a chamber of the column and is to be supplied as a Part with a U-2 data sheet. As the owner/user inspector it is my opinion the column bondary ends at the flange, as per U-2(e)(I think; don't have a code book in front of me), and the re-boiler is its own pressure vessel and must be supplied with a U-1A, complete with a shell side hydro, prior to installation. Comments?

 

[apiguy]

In my opinion, the stab-in reboiler gets it's own U-1a form. In most refineries that I have worked, there is usually a spare or two lying around somewhere. Each one normally has it's own data plate as they may have been built by different manufacturers. The reboiler should have it's own National Board number if I'm not mistaken. Check with your local jurisdiction, they should be able to guide you. One other note, Does the exchanger follow your plant's numbering system as a pressure vessel or an exchanger? Richard Schram
Mechanical Integrity Specialist
Pharmacia Global Supply Arecibo-P. Rico
rschram@pharmacia.com

 

[MJCronin]

AEF,

I am pretty sure that this matter has been discussed before with regard to "flanged immersion heaters" installed in Section VIII vessels. This topic was contained in questions to the ASME B&PV Commitee in 1996. ( See Interpretation VIII-95-128) dated 10/24/1996)

A discussion of this topic is contained in the May 1998 edition of the "Pressure Points" newsletter issued by the Hartford Steam Boiler People. Old copies of the newsletter are excellent because there is a clear, rational description of the issue and a reference to the interpretations issues by ASME.

This is clearly in contrast to the "Spynx-like" YES or NO respone of almost all ASME code interpretations....... "YES or NO" formatted questions only insure more questions in the future and are designed only to continue the need for the organization that is answering questions....

See this link:

http://www.nationalboard.org

and review the newsletters...

Hope that this helps


MJC

 

[twjag]

If furnished by vessel mfr, both vessel & reboiler could be documented on a U-2, which provides sections for tubes/tubesheets & channel. The U1-A is not applicable.

Recommend separate U-1A's for vessel & reboiler bundle.
If reboiler is part of vessel U-2, future reboiler replacement would require an NBIC repair & R-1 report, & AI approval.
If reboiler has separate U1-A, future replacement only requires U1-A for new bundle.