Flange Dimensions &
Weight Charts

Match three things: the nominal pipe size (NPS), the pressure and temperature rating your system requires (which sets the class, such as Class 150 or Class 300), and the standard for that size. ANSI/ASME B16.5 covers sizes up to 24 inch, ANSI/ASME B16.47 covers 26 inch and larger, and AWWA C207/C228 covers water service. Then confirm the bolt circle and drilling match the mating flange. API International stocks domestic (AIS) and imported flanges and can help you confirm the right specification.

The bolt circle, also called the bolt hole circle (B.H.C.) or bolt circle diameter, is the diameter of the imaginary circle that passes through the centers of all the bolt holes. It sets where the bolts sit and must match the mating flange exactly, even when two flanges share the same outside diameter. Every dimension table lists the bolt circle along with the number and size of the bolt holes.

No. The dimensions (outside diameter, bolt circle, bore, thickness and drilling) are set by the governing standard, ANSI/ASME or AWWA, and stay the same whether the flange is carbon steel, stainless steel, galvanized, epoxy coated or painted. Material and finish affect corrosion resistance, pressure and temperature limits, and weight, but not the dimensional layout.

Both ANSI/ASME B16.47 Series A and Series B cover large diameter flanges (NPS 26 and up). Series A has a larger outside diameter and bolt circle with fewer, larger diameter bolts, while Series B uses a more compact bolt circle with a greater number of smaller bolts. The two are not interchangeable, so the flange must match the series of its mating flange. API International supplies both, so share the mating flange details and we will match it.

The class is a pressure and temperature rating. At a given temperature, a Class 300 flange is rated for higher pressure than a Class 150 flange. Class 300 is also physically heavier, with a larger bolt circle and more (and larger) bolts. Select the class that matches the maximum pressure and temperature of your piping system; the two classes are not interchangeable.

We supply AWWA C207 carbon steel waterworks flanges in Class B (86 psi), Class D (150 to 175 psi), Class E (275 psi) and Class F (300 psi), available as steel ring, hub and blind. For stainless water service we supply AWWA C228 flanges in Classes SA, SB, SD, SE and SF, in 304/304L or 316/316L stainless steel.

Yes. API International machines custom bores, facings (raised face, flat face and ring type joint) and nonstandard sizes in house, including flanges outside standard class and size combinations. Send us your specification or drawing for a quote.