Flanged Connection with Two Gaskets: One Within Bolt Circle, One Outside Bolt Circle

[PressEquip]

Hello,

There is an existing piece of pressure equipment built to the ~1968 Edition of ASME Sect. VIII, Div. 1 that has a flanged connection with two gaskets: one within the bolt circle, one outside the bolt circle. One of the flange sides is drilled and tapped with threads. The two gaskets are there to prevent process fluid from reaching the studs and escaping.

The 2015 Edition of ASME Sect. VIII, Div. 1, Appendix 2 only addresses cases where the gasket is contained within the bolt circle.

Taylor Forge Modern Flange Design Bulletin 502 has an example of a flange where the gasket is outside the bolt circle "Sheet E: Reverse Welding Neck Flange Design"

Does anyone know of a ASME publication Taylor Forge publication or other industry literature that addresses the design of this style of flanged connection where there are two gaskets: one inside the bolt circle, one outside the bolt circle?

Thank you for taking the time to read my post

A Fan of EngTips, share the knowledge

 

[Compositepro]

Only the inside gasket would actually be a seal. The benefit of an outside gasket is to prevent the flanges from going out of parallel during stud tightening (cocking). The outside gasket acts as a shim rather than a seal. The bolt circle will communicate with the ambient environment through the threads of the studs.

 

[KVdA]

En1594
En13445
is equivalent to a full face gasket
Don't know any asme codes though but there must be one.
I would gues asme viii div2?