Weld Neck Dimensions

Dimensions That Matter for Weld Neck

Beyond the standard bolt-pattern dimensions (OD, BC, bolt count, bolt hole size), weld neck flanges have hub-specific dimensions that the order needs to specify:

• Outside diameter (OD): across the flange face. Drives bolt circle and clearance.
• Bolt circle (BC): diameter through bolt hole centers.
• Bolt count and diameter: how many bolts and what size.
• Flange thickness (t): from back face to raised face transition.
• Hub length (Y): from back face to small end of hub.
• Hub diameter at small end (A): at the weld bevel.
• Hub diameter at face end (X): at the flange face.
• Bore (B): matched to mating pipe schedule.
• Weld bevel: angle and root face matched to pipe wall thickness.

ASME B16.5

B16.5 covers weld neck and other flange types in nominal pipe sizes 1/2 inch through 24 inch in pressure classes 150, 300, 400, 600, 900, 1500, and 2500. Each type-class-size combination has tabulated dimensional values.

ASME B16.47

B16.47 covers 26 inch through 60 inch in Series A and Series B. Series A is the heavier MSS-style pattern. Series B is the lighter API 605 pattern. The two series are not interchangeable.

Detailed Tables

For the full ASME B16.5 and B16.47 dimensional tables, see the parent dimensional library at texasflange.com/products/flange-dims-weights. Tables are organized by class with weld neck dimensions and hub geometry called out per size.

For a specific dimension or to verify a tolerance, call (281) 484-8325 with the line spec.