flange facing and 125 arch

[Masoud280]

Dear friends

I supposed falnge facing can be specified by RF,FF or RTJ but in one techincal offer bidder says 125-250 ARCH. Now I am confused by this new term! What is its relation to known catagory for flange facing.

Regards
Masoud

 

[XL83NL]

125-250 ARCH is a measure of surface finish. Facing is something different to surface finish (it tells the geometry onto which the seal is placed and made by means of contact area).
A specified range of min and max surface finish is a requirement to get a good seal between gasket and flange facing.

 

[Masoud280]

Dear Friend

Thank you for reply.Do u mean flange facing and flange finish are different issues? So they shall not be mixed up?

BR
Maoud

best regards
Masoud

 

[XL83NL]

yes, they're 2 different things!
I recommend you read ASME B16.5 (or any other flange standard you're working to) and make sure you know what you're dealing with.
It'll give you an idea of how the standard works and what's what.