What Are AWWA Flanges?
An AWWA flange is a type of pipe flange designed for waterworks service. It follows standards developed by the American Water Works Association and is specifically intended for low-pressure water applications. AWWA flanges are governed by standards such as C207 and C228, which guide the design, manufacturing, and application of flanges used in water systems.
Main 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 |
Two AWWA Standards for Flanges
The American Water Works Association provides two official flange standards for water utility systems: AWWA C207 and AWWA C228. These standards define critical properties such as: bolt patterns and drilling specs, flange thickness, pressure classifications, acceptable material grades.
The Difference Between AWWA C207 and C228:
AWWA C207 is a standard for steel ring flanges for waterworks service, providing guidelines for the design, materials, dimensions, and testing of flanges used in water systems. The C207 standard includes several classes of flanges, each designed to handle different pressure ratings. These flanges are typically made from carbon steel and are designed to handle pressure requirements of waterworks systems in industrial applications. They are commonly used in pipelines, water treatment plants, and other infrastructure projects.
AWWA C228 is a newer standard that specifies stainless-steel pipe flanges for water service. It includes guidelines for the design, material, dimensions, 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.
Example Specifications for AWWA C207 and C228 Flanges:
| 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. |
AWWA Flange Pressure Classes
AWWA flanges are classified based on their pressure ratings and strength.
| 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 |
Where AWWA Flanges Are Used
Due to their large size availability and affordability, AWWA flanges are ideal for:
Water Treatment Plants
Water Distribution Systems
Sewage and Wastewater Systems
Irrigation Systems
Pump Stations
Stormwater Systems
Water Distribution Systems
- Stormwater Systems
AWWA vs. ANSI/ASME Flanges
While AWWA flanges (both C207 and C228) are specifically designed for waterworks applications, ANSI flanges cater to a broader range of industries, including oil and gas, chemical, and power generation. Here are some key differences:
| 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″ | ½” 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 |
Read more about the differences between AWWA and ANSI flanges in our blog.
Why Choose AWWA Flanges?
For engineers, contractors, and utility providers, AWWA flanges deliver:
Affordable, large-diameter options
Proven long-term performance in water systems
Compatibility with multiple pipe sizes and fittings
Compliance with trusted AWWA engineering standards
Final Thoughts
If your project involves municipal water distribution, irrigation, or non-critical wastewater piping, AWWA flanges are a smart and reliable choice. Designed for low-pressure environments and backed by over a century of AWWA engineering, they continue to be the go-to solution for waterworks infrastructure across North America.
Our sales team at API can answer any questions about your flange requirements. Depending on its application, they can also recommend alternative products that may be better suited for your system. We also provide custom flange solutions tailored to your project specifications. Get connected with a dedicated sales representative today! Or call us: 503.692.3800
