Class F Standard Steel Ring Flanges

AWWA C207 Class F steel ring flanges are the highest pressure class in the AWWA waterworks flange standard, rated for 300 psi working pressure. These flanges are specified for the most demanding water transmission applications, including high-head pump stations, force mains with significant elevation changes, and long-distance transmission pipelines.

Class F ring flanges use the heaviest bolt patterns and thickest plates in the AWWA C207 series. Despite using the flat ring construction, the increased plate thickness and bolt loading provide adequate clamping force to maintain gasket seal integrity at 300 psi. Full-face gaskets rated for the service pressure are essential.

These flanges are less commonly specified than Class B or D, as most municipal water systems operate well below 300 psi. When required, Class F flanges are typically found at pump station discharge connections, pressure-reducing valve stations, and connections to high-pressure industrial water users served by the municipal system.