ASME VIII-1 Appendix 2 question

[lostsailor]

Gentlemen,
In the 2005 Addenda to the Code, paragraph 2-14 has been moved from nonmadatory Appendix S to mandatory Appendix 2.
I have been presented with the following:a flanged head with bolt circle-->filter element(similar to a floating tubesheet)-->flanged shell with a bolt circle. Within the bolt circle there is metal to metal contact on either side of the filter element. Inside the metal to metal contact, also on either side of the filter element, is a machined step for an EPDM gasket configured to press outwards as pressure builds for leak tightness. Is paragraph 2-14 intended to apply to a joint of this type? If so, the thickness of the flange will have to nearly double in order to satisfy J, rigidity index. Based on my reading of the scope in paragraph 2-1, I would have to say yes but I have been presented with compelling arguements to the contrary. Any and all opinions would be most helpful
Regards,
RLS

 

[deanc]

Maybe not---See 2-1(e). Would need to see a drawing,but maybe Appendix 14? You can always go back to U-2(g).

 

[PVGuy]

I do not believe that the rigidity equations given in Appendix 2-14 apply to flanged heads. If you look at the equations in Table 2-14 you see that you are given three different flange types: integral, loose with hub, and and loose without hub (and optional). The integral flanges and the loose flanges with hubs are more rigid then just a loose flange and that is why the equations are different. I believe that the integral flange, and the loose with hubs are modeled as rings attached to a cylinder, with more credit given to the integral flange (KI is 0.3 while KL is 0.2). The loose type is simply considered a ring to determine rigidity. In the case of a flanged head, if the the flange is considered integral with the head, the rigidity should consider the head as well, which is a different shape than a cylinder and would have a different rigidity. You might look at Article 4 of SC VIII-II for some guidance on how to determine the rigidity. Roark is another option.

 

[lostsailor]

PVGuy,
Mistake on my part. I should have said a head welded to an integral flange.
Regards,
RLS