Flange Surface Finish for Sheet Gasket

[onrush]

Dear ladies and gentlemen,

I urgently need your help!

Regarding the surface finish of flanges,
ASME B16.5 requires 125~250 AARH unless otherwise
agreed between purchasers and manufacturers.

However many piping guys say that rougher surface finish
like 500 microinch is more suitable for sheet gaskets.

With thinking the structure of gasket seating on flange surface,
I think they may be correct.

But now I must explain this to Client technically.

How can I explain this to Client technically
and with background material like code or standard?

Your help would be highly appreciated.

 

[dtn6770]

http://www.lamonsgasket.com/html/design.html

http://www.flexitallic.com/products/techsupport/design_criteria/design_criteria.htm

Flexitallic
soft cut sheet gaskets<1.5mm thick - 125-250 microinch RMS
soft cut sheet gaskets>1.5mm thick - 125-500 microinch RMS

Lamons
Flat, non-metallics gaskets - 250-500 microinch AARH