A specification designed for generally lower pressure applications (300 psi or less), American Water Works Association flanges are the exact opposite of the API flanges and can be found in a variety of assemblies in which temperature is ambient and media is not corrosive. In most cases, this is simply for the transportation of well water and wastewater, but can also be utilized for slurry and plant piping with minimal pressure requirements.
^^^ ( A standard AWWA ring flange dimensional template ) ^^^
AWWA C207 steel flanges are usually of a mild carbon steel or stainless variant and are most often either of the ring slip on or blind disc style. Due to their intended design, they do not have ring joint or raised faces, and are typically sealed with rubber gaskets. Due to their cost and weight compared to other flange types, they are also becoming more popular with project work for structural steel types which require mating or filling a gap between existing flanges.
More Specifically, the American Water Works Association has published specification C207 to provide a standard for carbon steel rings and blinds (and formerly, also hubs). The OD and bolt pattern matches that of B16.1 class 125 flanges. They will also match B16.5 class 150 flanges up to 24” nominal pipe size and B16.47 Series A up to 60” NPS. The main dimensional difference is thickness and the lack of a raised face or hub (except in legacy systems).
AWWA is slightly more lenient in what kind of steel can be used as well. C207 limits Carbon, Phosphorus, and Sulfur contents to 0.35%, 0.04%, and 0.05%, respectively. The lower minimum yield and tensile strength requirements (32ksi and 50ksi, respectively) allows several commercially abundant grades of carbon steel such as A36, A516-70, A181-60, A105. All AWWA flanges that Texas Flange supplies will have MTRs showing actual physical and chemical properties for each heat lot. When you do not have to meet ASME code, but need a large flange, send us your requirement for AWWA Ring or Blind flanges!
^^^ ( a standard AWWA Class D blind flange ) ^^^
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*AWWA stands for “American Water Works Association” and more information can be found on their website: https://www.awwa.org/