AWWA C207 Versus ASME B16.5 flanges

[districtguy]

Application: Treated chlorinated water about 100 psi working pressure.

I would like to know the correct application of flanges when joining a 4 inch steel flanged nozzle to a flanged steel butterfly valve. The butterfly valve would probably have a raised face. Is a ASME B16.5 Class 150 identical to a AWWA C207 Class E flange or does one have a raised face and the other not? What is the difference? Is a raised face necessary or is a flat face more desireable? I would be using a EPDM gasket material. Previously a flat faced flange has been specified for the nozzle flange but I want to know if this is optimum. Is a serrated surface needed in both at flat face and raised face application. I realize a flat face should be used with a cast iron flange. Also, what type of serrations, concentric or spiral, is best for this application.

 

[bimr]

Flange Facing

As per AWWA C207-01 Sec 4.2.2, all AWWA flanges shall be flat-faced without projection or raised area of face. Either a serrated concentric or serrated spiral finish having from 24 grooves per inch to 470 grooves per inch shall be used. The cutting tool employed shall have an approximate 0.06 inch or larger radius. The resultant surface finish shall have a 250 to 500-uin. roughness.

http://www.pacificflange.com/AWWA_general_info.htm

AWWA C207-01 Class E Hub Flanges are identical to ANSI/ASME Class 150 flanges and Large Diameter Class 125.

AWWA Flanges
These flanges can allow you to mate a flat face ductile iron valve to your steel piping system, among other applications.

Flat face vs. Raised face
Typical high pressure steel flanges have a raised segment of the gasket sealing face. This aids in the sealing process, allowing more pressure to be exerted in the tightening process. Flat face flanges by definition lack this feature.