API 6A , gap height after flange torque , BX gasket . 1

[rQuestionEngineering]

Referring to BX gaskets.
Why there is no information for gap height after flange torque ?

 

[LittleInch]

rQE,

You've started 9 posts in this forum and only replied to 2. Why?

Typically this is about 5 to 7 mm.

There needs to be some gap to allow the gasket to work.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[jmec87]

While API 6A flanges with type R gaskets are not designed for face-to-face makeup (see API 6A 21st Edition 14.1.2.2.1) and typically have about a 3/16" gap (although there is some variation - see API 6A 21st Edition Table E.9), 6BX flanges were designed based on the assumption that face-to-face makeup would be achieved (see "Design Considerations for AWHEM 15,000 PSI Flanges" by Robert Eichenberg, 1957).

For most 6BX flanges, face-to-face makeup is achieved by torqing the bolts. In some cases (mostly for the smallest 6BX flange sizes and possibly depending on actual machined dimensions compared to tolerances, gasket material, and ring groove inlay material), face-to-face contact cannot be achieved without over-stressing the bolts or damaging the flange. For static pressure testing and normal wellhead service, face-to-face makeup is not necessary for the flange to function. (See notes 1 and 2 in API 6A 21st Edition 14.1.2.3.1.).

However, face-to-face makeup can improve connection resilience in extreme cyclic loading scenarios (i.e. fracking).

 

[EdStainless]

This isn't the dimension that controls the function of the gasket. The compression is.
This gap turns out to be whatever it is.
As LI said, a few mm is typical.
Don't try to use this as a guide though.

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P.E. Metallurgy, consulting work welcomed