B16.47 Flanges T - P ratings confusion

gr2vessels · Sep 16, 2007

Gents,

Here we go again.

Pls note that ASME VIII (2007 Edition) in Clause U-3 states that the "acceptable editions" of standards are nominated in Table U-3, and this Table references the superseded 1996 Edition of ASME B16.47 (large diameter steel flanges)and not the current 2006 version (which was published prior to the latest ASME VIII). We have had serious problems re-designing equipment because the AI required adherence to the ASME code requirements and the nominated editions in the ASME VIII did not allow the use of latest B16.xx edition.

I am unable to locate an errata to the ASME VIII (2007), which addresses this error. Would anyone know and be kind to advise, if ASME has issued some correction or at least a note about the incorrect reference, to be revised in a formal way?

cheers,
gr2vessels

eliebl · Sep 17, 2007

gr2vessels,

I think that your AI is probably correct. Just because there is a newer edition of the standard available does not mean that it can be used in the construction of vessels. It took over 2 years to incorporate the new edition of B16.5 in to the vessel codes.

If you go back to the early 70's there was one edition of B16.5 which was never referenced by the Boiler and pressure vessel code. It took so long to try and change the referenced edition that a newer edition had already been released.

The various ASME committees do not communicate as frequently as I would have expected. From the release of a new standard to it being referenced in other ASME codes takes much longer than I expect.

EJL

gr2vessels · Sep 17, 2007

EJL,
The pressure-temp ratings of the 1996 Ed of ASME B16.47 were different to those in the current 2003 edition of ASME B16.5 and the 2006 version of ASME B16.47 now mirrors the 2003 Edition of ASME B16.5 press-temp ratings (for Group 1.1 materials which is the one I have checked, but presumably both now have same press-temp ratings for ALL material groups). This rating miss-alignment was the reason for the earlier re-design, so here we go again. Is it reasonable to assume different rating for the same material and different flange size, as nominated by the ASME VIII ed 2007, or use common sense and assume same rating for the same material, proven now on the new ASME B16.47 ed 2006, but unacceptable to the AI because the edition 2006 is not listed...
Am I the only one having this problem or it's simply matter of arrangement with the AI to overlook the rating issue?
gr2vessels

eliebl · Sep 18, 2007

gr2vessels,

I raised this concern a few years ago. There is an obvious disconnect between the ratings of the multiple standards. From a practical perspective it is unlikely that there will be leakage at the joint using either of editions. The changes in MAWP of the flanges is small. It's not a safety issue but I doubt that the AI would permit the use of the newer edition. If the vessel is to be attached to B31.3 piping built to the 2004 or earlier edition of 31.3 then the referenced ratings are from B16.5-96(r98) and B16.47-96 anyways.

If application is made to a Canadian Jurisdiction for a CRN then they certainly will not permit the use of an edition which is not listed in table U-3.

EJL

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