Richard
In Caesar II's flange calculator, an effective gasket modulus is used and suggests using values between 3016 and 2392 MPa in the absence of better data.
Pressure Vessel Design Manual by Dennis R Moss suggests 5690 psi for spiral wound gaskets without any qualification.
The two figures are miles apart..appreciate if you enlighten me on the basis of arriving at Caesar II's figures.

Back in 1991 when we developed the leakage module, we found some gasket modulus values in a text. If I recall correctly (?) it was the Piping Handbook, by Crocker and King. Values were on the order of (I think) 300,000 psi.

I'd have a hard time buying a number that low as a MODULULS for anything, especially considering that the seating STRESS alone for a spiral wound gasket it typically on the order of 10,000psi. The STRAIN would be on the order of 2 to make that equation work.

I'm not a vessel engineer, but I'm pretty sure that I've heard that the Moss book has lots of errors in it. Most of the guys I know use the Megyesy hand book instead.

A corroborating reference to Mr. Rich Ay's above remark can be found in WRC 271, entitled "Gasket Leakage Behavior Trends: Results of 1977-79 PVRC Exploratory Gasket Test Program." In this 1981 Bulletin, for spiral-wound, asbestos-filled gaskets it lists a stiffness of 471,000 psi/in for 300-lb class, and 695,000 psi/in for 600-ln class. No one uses asbestos anymore, and compressed asbestos is a hard material. CAESAR II's suggested numbers of 347,000 t0 437,000 sound about right.