ASME VIII-1 (UG-11/UG-44) Mandatory Standard Flange Gasket Dimensions

[Morts81]

Firstly, I understand there has been a number of queries submitted previously on similar topics, however, I couldn't find the ultimate answer I was looking for plus I also wanted to add some further code clauses, etc to the question to ensure no ambiguity.

ASME VIII-1 (Clauses UG-11 & UG-44) allows the use of B16.5 & B16.47 standard flanges within the nominated pressure-temperature ratings. Alternatively, VIII-1 flanges can be designed in accordance with Mandatory Appendix 2.

My question revolves around the acceptable gasket dimensions for use with either B16.5 or B16.47 before the flange is no longer covered by UG-11/UG-44 and instead requires Appendix 2 analysis? Gasket dimension requirements are rather vague in ASME B16.5-2017.
[ul]
[li] Firstly, paragraph 2.3 states pressure-temperature ratings apply to flanged joints that conform to the limitations on bolting in para. 5.3 and on gaskets in para. 5.4. Section 5.4 purely relates to the material of the gaskets and requires compliance with B16.20.[/li]
[li]Section 6.11.1 nominates mandatory dimensions as per B16.20 for RTJ flanges only, not for standard raised face (SWG, fibre sheet, kammprofile, etc).[/li]
[li]Nonmandatory Appendix B-2 states reference to a dimensional standard for gaskets is recommended and then goes on to say that the selected dimensions should be based on the type of gasket and it's characteristics.[/li]
[li]Nonmandatory Appendix B-1 which relates to material does state that other gaskets that result in no increase in bolt loads or flange moment are acceptable, however, my understanding is that this relates to material substitution and not dimensional changes.[/li]
[/ul]
Reading through these clauses in B16.5, I don't see a clear requirement to comply with the dimensions nominated in either B16.20 or B16.21. However, I fully understand how a change in gasket dimensions can affect stresses in a flange.

B16.47 does give a little more guidance in section 6.6 stating nonmetallic gasket dimensions should conform to ASME B16.21 and spiral wound gaskets should conform to ASME B16.20 however my interpretation of this is that it is not a mandatory requirement as the code does not say they shall comply. Further to this, Nonmandatory Appendix B states the same as B16.5.

So, to re-word my question. To comply with ASME VIII-1 UG-11/UG-44, do B16.5/B16.47 flanges need to have installed gasket dimensions as per B16.20/16.21? (And if so, where is this clearly outlined for reference.)

Thanks in advance for feedback.

 

[TGS4]

Your reference to B16.5, paragraph 6.11.1 incorrectly assumes RTJ for ring joint. It refers to ring joint gasket dimensions, which is their term for gaskets that are not cut from sheet. B16.5 flanges must have gaskets that comply with B16.20.

 

[Morts81]

Thanks for the response TGS4, appreciate it.

So when the code refers to Other Than Ring Joints (ie in Appendix B-1 & B-2) am I correct in assuming this refers to tongue-in-groove and other types?

For info I've always mandated Appendix 2 calcs for any change in standard flange gasket dimension but was looking to back this up with clear guidance from the code.