Industry Specification for Pipe Flange

There are four types of industry standards covering different flange types;

1. ANSI Flange, also called ASME B16.5 Flange

2. ASME Flange, also called ASME B16.47 Flange (Series A and Series B)

3. Industry Standard Flange (ASME B16.1 Flange)

4. AWWA Flange

AWWA Flange

This standard covers slip-on and blind flanges for waterworks service in sizes 4" through 144" nominal (100mm through 3600 mm).

Difference between ANSI and AWWA flange

We have already covered that ANSI flange means ASME B16.5 flange. ANSI and AWWA standard for flanges differ in several ways. The AWWA standard is intended for potable water use. Where as ANSI/ASME standard is aimed at industrial application. AWWA flange rating are applicable only at atmospheric temperature whereas ANSI rating covers from -20°F to 1500°F.

The two standards also differ in the scope of application. ANSI standard includes information for welding auxiliar connections while AWWA does not cover the installations. The AWWA standard only covers hub-type, ring, blind and threaded flange whereas ANSI standard has more types such as weld neck, lap joint, socket weld flange etc.

Standards covering AWWA and ANSI flanges are;

1. ANSI/AWWA C115/A21.15-99: “American National Standard for Flanged Ductile-Iron Pipe with Ductile-Iron or Gray-Iron Threaded Flanges”

2. ANSI/AWWA C207-94: “AWWA Standard for Steel Pipe Flanges for Waterworks Service-Sizes 4 In. Through 144 In.”

3. ANSI / ASME B16.5-1981: “Pipe Flanges and Flanged Fittings”.