AWWA flanges refer to pipe flanges based on standard specifications from the American Water Works Association (AWWA). This was an association founded way back in 1881 by an assortment of men who represented water supplies and utilities in Illinois, Indiana, Iowa, Kansas, Kentucky and Tennessee states. In the process of carrying out their duties on waterworks systems, they identified certain consistent requirements that mandated uniformity of methods, eventually leading to standardized flanges that we refer to today as AWWA flanges.
Over the years, these flanges have undergone numerous iterations in their standardizations with the current C207 specification for AWWA steel pipe flanges coming to the fore for full-scale adoption in 1955.
It would also be worthy to mention that there are particular flange types only that come under the purview of AWWA flanges, unlike ANSI standards that tend to be more broad-based. Flange types that fulfill AWWA specifications include blind flanges, hub types, threaded iron flanges, and rings.
AWWA flanges are extensively used in piping for potable water. At the same time, they are also used in ancillary water piping such as for slurry, piping within plants, wastewater, and any other piping where the pressure is low, usually within 300 psi. A guiding light in this regard would be that flange ratings for AWWA specifications apply only in atmospheric temperature and not otherwise as is the case with ANSI standards.
Materials commonly used for AWWA flanges include A105 and ASTM A181 forged steel as well as ASTM A-283 and ASTM A-36 plate steel. Both these materials meet specifications for AWWA C207.
At the same time, it would be pertinent to note that flanges meeting AWWA specifications do not always necessitate specific grades of steel.
As mentioned earlier, flanges that meet AWWA specifications are used most extensively for the transportation or movement of potable water. Therefore, any entity that is involved in the passage of drinking water is likely to deploy these flanges. At the same time, there is the ancillary industrial application of flanges that meet AWWA specifications as well such as for moving slurry and wastewater or for usage on pipes within industrial plants.
As far as the different classes of AWWA flanges go Class D is, in fact, most common and most frequently deployed. Pressure ratings for them tend to on the lower side, about 150 psi for 12” and above sizes, and 175 psi for sizes that are below 12”. Other classes covered by flanges that meet AWWA specifications include B, E, and F.
AWWA flanges offer a variety of different benefits. These include:
- Cost benefits – As compared to commonly forged flanges of ANSI standards such as ANSI B16.5 hub type ones, AWWA flanges offer substantial cost savings especially when they are used with low-pressure piping. This cost saving is particularly true since ANSI standard conventional forged flanges are more frequently used in high-pressure piping meant for chemicals, steam, or oil, among others.
- Versatility – Flanges that meet AWWA specifications are known for their versatile nature to the extent that they can be deployed with reasonable ease across a wide array of piping systems, whether concrete or steel ones. Even in case of polyethylene piping, AWWA flanges can be implemented with complete ease, especially as a backup ring.
- Flexibility – Flanges meeting AWWA specifications are also renowned for the flexibility they offer in terms of materials used for their construction. For example, in light of the point mentioned previously, the C 207 AWWA specification does not mandate a particular grade of steel. So within certain guidelines, any grade of steel would serve the purpose for these flanges that prove to be a major advantage.