Flange bolt and stud dimensions to ANSI/ASME B16.5 and B16.47 standards, plus torque values by gasket type for ASME and AWWA classes.
Instant per-flange weight
Dimensions and weights
Dimensional tolerances
Request a Product Catalog
Each table lists, per nominal size: gasket contact area, number of bolts, bolt size, and torque per bolt, a minimum to reach a safe seal and a preferred (maximum) value not to exceed. Bolts are typically brought to a snug fit, then tightened in the numbered cross pattern shown in the example image, in two or three passes, ending within the min/preferred range. This even sequence helps the gasket compress uniformly rather than over-stressing one side of the flange. Re-check torque once the system reaches operating temperature.
We manufacture to your specifications and stock domestic AIS/Buy America and imported materials, with galvanized, epoxy, and additional coatings available. Rubber expansion joints and gaskets are also supplied on request.
A bolt and stud chart tells you how many bolts a flange uses, what diameter, and how long the stud should be, values set purely by the flange standard, series, and pressure class. A torque chart tells you how tight to make those bolts, which depends on the gasket as well as the flange, so it has its own chart per class and gasket type.
No. Bolt count, bolt diameter, and stud length are set by the standard, series, and pressure class, and stay the same whether the flange is slip-on, weld neck, or blind, and whether it's carbon steel or stainless. Material and flange type affect the flange itself, not the bolting.
Bolt count and bolt size are set by the flange standard and class alone, but torque is a joint calculation: it depends on the gasket's contact area, its minimum and maximum recommended compressive stress, and the bolt's own stress limit. Two different gaskets on the identical flange can call for very different torque, which is why this chart is organized by gasket type first.
Unless noted otherwise, the torque values on this page are for ASTM A193 Grade B7 studs at 60,000 psi bolt stress. If your project specifies a different bolt grade, confirm the correct torque with your bolting or gasket manufacturer before assembly.
Start with your flange standard, ANSI/ASME B16.5 for sizes up to 24 inch, ANSI/ASME B16.47 for 26 inch and up, or AWWA for waterworks flanges. Use the B16.5 Bolt & Stud Chart or B16.47 Bolt & Stud Chart to confirm bolt count and size, then use the matching torque chart, filtered by your facing and gasket, to confirm how tight to make the joint.
API International stocks the flanges you need for your project, and our machine shop can modify stock products for special requirements. Contact API International’s experienced sales team, and we will help you select the right flange for your application.
