Flange bolt chart: ASME B16.5 stud bolts, Class 150 to 2500

A flange bolt chart gives, for each flange size and pressure class, the number of stud bolts in the joint, their diameter and the length they must be. The tables below cover every ASME B16.5 size from NPS 1/2 to 24 in Class 150, 300, 600, 900, 1500 and 2500, with the bolt circle, the bolt hole and the stud length for raised face and ring type joint (RTJ) flanges. For example, a 4 inch Class 150 flange takes eight 5/8 in stud bolts, 3 1/2 in long with a raised face and 4 in long with RTJ.

How to read the chart

• Stud length is the length ASME B16.5 lists for a joint of two flanges of the same size and class with a standard gasket; it does not include the points at the ends of the stud.
• Raised face lengths are for the 0.06 in (1.6 mm) raised face in Class 150 and 300, and the 0.25 in (6.4 mm) raised face that ASME B16.5 uses from Class 400 up.
• Bolt holes are 1/8 in larger than the stud diameter throughout ASME B16.5.
• All flange types of one size and class share the same drilling, so the chart applies to weld neck, slip-on, socket weld, threaded, lap joint and blind flanges.
• Anything between the flanges, such as a spectacle blind, a spacer, a wafer valve, an orifice plate holder or an extra-thick gasket, adds its thickness to the stud length.

Class 150 flange bolt chart

Class 300 flange bolt chart

Class 600 flange bolt chart

Class 900 flange bolt chart

Class 1500 flange bolt chart

Class 2500 flange bolt chart

Threads, nuts and stud bolt grades

ASME B16.5 calls for stud bolts threaded to ASME B1.1: the coarse thread series (UNC) for 1 in and smaller and the 8-thread series (8UN) for 1 1/8 in and larger, class 2A, with heavy hex nuts to ASME B18.2.2. The grade follows the service:

Coatings, impact testing and the bolt class are set by your piping specification. Matching stud bolts and nuts can be quoted with the flanges: list grade, diameter and length on the same line list.

Tightening sequence

Tighten flange bolts in a star (cross) pattern, not around the circle, so the gasket compresses evenly. ASME PCC-1, the guideline for bolted flange joint assembly, sets out the patterns and the passes: snug the nuts, tighten in several passes at rising torque, then make a final pass around the circle until no nut turns.

The target torque depends on the stud grade and diameter, the gasket and the lubricant, so take it from your assembly procedure or the gasket maker, not from a general chart. For water and glycol loops, see flange gaskets for water and glycol.

Flanges for these joints

We make ASME B16.5 flanges in every class in this chart, from Class 150 utility flanges to Class 2500 high pressure flanges, with raised face or ring type joint facing, drilled to the bolt circle and hole size above and checked before dispatch. Each heat ships with an EN 10204 3.1 mill test report. See ASME B16.5 flanges for the flange dimensions and drawings.

Frequently asked questions

Sources

• ASME B16.5, Pipe Flanges and Flanged Fittings: drilling templates and bolting (stud bolt lengths)
• ASME B1.1, Unified Inch Screw Threads; ASME B18.2.2, Nuts for General Applications
• ASTM A193/A193M, A194/A194M and A320/A320M, bolting and nut materials
• ASME PCC-1, Guidelines for Pressure Boundary Bolted Flange Joint Assembly
• Cross-checked line by line against three published reproductions of the ASME B16.5 bolting tables (a fastener maker's chart, a flange distributor's chart and the Wermac piping reference) and, for Class 150 and 300, against RIC's catalog