ASME VIII DIV 1 Section Y: Flange Thickness Formulae

[gvalves0164]

ASME Section VIII DIV 1 Appendix Y states that the rules apply to flat Face, Identical and Non-Identical Flange Pairs where uniform metal to metal contact occurs outside bolt circle. The rules apply for negligible gasket loads (ie. Pressure Energized O-ring Body Seal) HG=0. In addition, Section VII DIV 1; Appx Y-1(b)states ".....It assumes that the seal generates a neglible axial load under operating conditions. If this is not the case, allowance shall be made for a gasket load HG dependent on the size and cnfiguration fo the seal and design pressure...". I interpret this to cover non-pressure energized sealing methods (ie. spiral wound gaskets vs o-rings).
My question is if spiral wound gaskets are utilized for Body Sealing on two piece ball valves (resulting in metal to metal contact outside the bolt circle), do rules apply for using HG*hg in the formula for Flange Thickness Calculations?

 

[prex]

I can't see anything against your position: formulae of App.Y do include the effect of H[sub]G[/sub].
What should be the meaning of the foreword in Y-1 is that H[sub]G[/sub] should not be greater than a fraction (50%?) of H[sub]D[/sub]+H[sub]T[/sub] and similarly for the moment.

prex

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[gvalves0164]

Y-1 refers to statement in VIII Div 1 Appendix Y; Y-1 (under General) paragraph b, where it states the allowanace of HG if using a non-pressure energized seal.

 

[saplanti]

I think you need to read Y-1 (e), for the flange separation. It clearly says that ".....flange separation occurs. The rules in this appendix provide little insight into the problem except ....."

Leak tightness in the flange connection with spiral wound gasket mainly relies on the gasket seating force, and this force is very large with the selected gasket. You can not prove that you provide the required force for the spiral wound gasket in accordance with the code values by tightening and obtaining face-to-face contact of the flanges all the time. If you do have both at the same time this a real luck of yours.

These type flanges are for flat faced and in uniform metal-to-metal contact accross their entire face DURING ASSEMBLY before the bolts are tightened or after a SMALL amount of preload is applied to compress a gasket as indicated in Y-1 (a).

Your case does not match any of these.

You either change your gasket design or use Appx 2 for the flange calculation if you insist on the spiral wound gasket application.

Additionally, please do not duplicate your posts in the forum.

Regards,

Ibrahim Demir

 

[gvalves0164]

Thanks for your feedback Ibrahim. Please do not take the duplication of my question into another forum personally, or that I disregarded your response. I merely wanted to get additionally feedback from alternate fields of expertise.I apologize if I affended you in anyway.

 

[saplanti]

I do not expect anyone looking for answers to their problem will offend personally or any other way.
We are trying to see other views to our problem, or contribute with our views. That is all.

Ibrahim Demir