AWWA C207
Steel pipe flanges for waterworks service. The default standard for transmission mains, treatment plant interconnects, and large-diameter water and wastewater piping. AIS-compliant supply available for EPA State Revolving Fund and USDA Rural Development projects.
Pressure Classes
AWWA C207 defines four working pressure classes for steel pipe flanges:
- Class B: 86 psi working pressure. Low pressure transmission and distribution.
- Class D: 175 psi working pressure. The waterworks workhorse.
- Class E: 275 psi working pressure. High service and pump station piping.
- Class F: 300 psi working pressure. The highest standard waterworks class.
Working pressure is the static rating. Surge pressure (water hammer from pump trip or valve closure) is allowed up to 150 percent of the working pressure for short duration. Project hydraulic analysis governs the class selection.
Construction
AWWA C207 flanges are plate-cut from rolled steel. Standard plate is ASTM A36 carbon steel for the structural classes and ASTM A516 Grade 70 where pressure-rated plate is specified. Plate thickness scales with flange diameter and class. Bolt circle dimensions and bolt count follow standard tables that match common waterworks connection patterns.
Sizes
The standard covers 4 inch through 144 inch nominal diameter. Custom diameters beyond 144 inch are routinely fabricated to project drawings using the same plate-cut process. Bolt patterns are matched to the mating component on transmission projects where alignment matters.
AIS Compliance
Most EPA Clean Water and Drinking Water State Revolving Fund projects, plus USDA Rural Development water and wastewater projects, require American Iron and Steel compliance. AWWA C207 flanges fabricated from domestic-melt plate qualify when the manufacturing chain stays within the United States. See AIS compliance for documentation scope.