Class E Standard Steel Hub Flanges

AWWA C207 Class E steel hub flanges are rated for 275 psi working pressure, serving the higher-pressure end of waterworks applications. The hub design provides the structural integrity needed for these pressures, with a smooth transition from the pipe wall to the flange face that minimizes stress risers.

Class E hub flanges are specified for high-pressure water transmission mains, pump station discharge headers, and treatment plant high-service piping where operating pressures exceed the 150 psi limit of Class D. The dimensional bolt pattern for Class E matches ANSI B16.1 Class 250 for sizes up to NPS 24.

These flanges are typically fabricated from ASTM A105 or equivalent carbon steel plate, with welding performed in accordance with AWWA C207 requirements. Hydrostatic testing of the completed joint to 1.5 times the working pressure is standard practice for Class E installations in critical water infrastructure.