Printable Flange Bolt Torque Chart
A one-page torque chart for ASTM A193 B7 studs at 50% of yield, with three lubricant values and ASME B16.5 stud sizes. Print it or save it as a PDF.
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Bolt Torque Calculator
Work out bolt load and tightening torque for flange studs from stud size, material, target stress and lubricant.
Target torque––
- Bolt stress
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- Bolt load (per stud)
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- Total joint load
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- Pass 1 (30%)
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- Pass 2 (60%)
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- Pass 3 and check passes (100%)
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Formula: T = K × F × D, where F = target stress × tensile stress area and D = nominal diameter. Results are estimates for planning. Always use the target load approved in your plant procedure, check gasket and flange limits, and convert torque to pump pressure with the chart for your exact wrench.
How the calculator works
The calculator uses the common short-form relationship T = K × F × D. The bolt load F is the target bolt stress multiplied by the stud’s tensile stress area, D is the nominal stud diameter, and K is the nut factor, which depends mainly on the lubricant and thread condition.
A target of around 40% to 70% of bolt yield is typical for many process joints with B7 studs, but the right value depends on the gasket, the flange and the service. ASME PCC-1 explains how to choose a target that seats the gasket without crushing it or overstressing the flange.
Why the lubricant matters
Most of the torque you apply is lost to friction. Change K from 0.16 to 0.20 and the same torque gives about 20% less bolt load. Always use the K value for the lubricant you actually apply, as explained in our flange bolt torque chart guide.
From torque to pump pressure
Hydraulic torque wrenches are set by pump pressure. Convert the torque from this calculator using the chart for your exact wrench model and serial number. For larger or critical joints, consider bolt tensioning instead.
This calculator is a planning aid. Results are not an approved procedure; your plant’s bolting procedure and engineer set the final values.