What are AWWA Flanges?

An AWWA flange is a type of pipe flange designed for waterworks applications. They follow standards developed by the American Water Works Association and are specifically designed for low-pressure water applications.

AWWA flanges fall under standards such as C207 and C228, which govern the design, manufacture and application of flanges in water systems.

Key features of AWWA flanges

Feature	Details
Standards	AWWA C207 (carbon steel), AWWA C228 (stainless steel)
Pressure Ratings	From Class A (up to 50 psi) to Class F (up to 300 psi)
Sizes	Typically available from 2"-144"
Materials	Carbon steel, ductile iron, stainless steel
Types	Slip-on-ring (2"-144"), blind (4"72"), hub ring (4"-96")
Applications	Waterworks piping systems, irrigation, fire protection

There are two AWWA standards for flanges

The American Water Works Association offers two official flange standards for water supply systems: AWWA C207 and AWWA C228. These standards define critical properties such as: bolt patterns and drilling specifications, flange thickness, pressure ratings and acceptable material grades.

The difference between AWWA C207 and C228 ...

AWWA C207 is a standard for steel ring flanges for water utilities and provides guidelines for the design, materials, sizing and testing of flanges used in water systems. The C207 standard includes several classes of flanges, each designed to handle different pressures. These flanges are usually made of carbon steel and are designed to meet the pressure requirements of water piping systems in industrial applications. They are often used in pipelines, water treatment plants and other infrastructure projects.

AWWA C228 is a newer standard that specifies stainless steel pipe flanges for water pipelines. It contains guidelines for the design, material, sizing and testing of stainless steel flanges used in potable and non-potable water systems. Stainless steel offers enhanced corrosion resistance, making C228 flanges suitable for environments where water quality and longevity are critical.

Specification	AWWA C207	AWWA C228
Material	Steel material conforms to the requirements of AWWA C207 specifications.	Dual grade 304/304L 316/316L stainless steel material conforms to the requirements of AWWA C228 specifications.
Dimensions	The flange thickness and bolt circle diameters vary according to pipe size, following specific tables in the standard.	Conforms to the same dimensional criteria as the C207 standard, ensuring compatibility with existing systems.
Pressure Classes	A, B, D, E, F	Various classes are defined in the standard, similar to C207.
Use Case	Standard waterworks systems	Corrosive environments, potable water
Corrosion Resistance	Requires protective coating	High resistance, no coating needed
Availability	Common for large-diameter piping	Ideal for treatment plants and coastal use
Design	Ring-type flange suitable for slip-on or weld-neck connection.	These can be slip-on, weld-neck, or blind types, depending on application requirements.

Pressure Classes of AWWA Flanges

Flange Class	Max Pressure (psi)	Use Case
Class A	Up to 50 psi (3.5 bar)	Low-pressure systems, limited-duty use
Class B	Up to 86 psi (6 bar)	Light-duty water distribution lines
Class D	Up to 175 psi (12 bar)	Standard municipal water systems
Class E	Up to 275 psi (19 bar)	High-flow or elevated pressure zones
Class F	Up to 300 psi (21 bar)	Extra-duty or critical water lines

Application areas for AWWA flanges

Due to their high availability and affordability, AWWA flanges are ideal for..

Water treatment plants
Water distribution systems
Sewer and wastewater systems
Irrigation systems
Pumping stations
Stormwater systems
Water distribution systems

AWWA vs. ASME Flanges

Feature	AWWA Flange	ANSI/ASME Flange
Applications	Waterworks, utility piping	Industrial, chemical, high-temp/pressure
Pressure Range	Up to 300 psi	Up to 6170 psi or more (per ASME B16.5 Class 2500)
Standards	AWWA C207, C228	ASME B16.5, B16.47
Size Range	4" to 144"	1/2" to 24" (larger via B16.47 Series B)
Material	Carbon steel and stainless steel	Stainless steel, alloy, exotic metals
Cost	Lower—ideal for large systems	Higher—engineered for specific tolerances

Concluding Remarks

If a project involves municipal water distribution, irrigation or non-critical wastewater pipelines, AWWA flanges are a smart and reliable choice. Designed for low-pressure environments, they are backed by more than a century of AWWA technology. Therefore, they remain the ultimate solution for water pipeline infrastructure.

Reference(s) ..
www.awwa.org
https://apiint.com