Flange Bolt-Up Torque
Target preload, per-bolt torque, and the star tightening sequence for a bolted flange.
Example
You enter
- Bolt nominal diameter (in) 0.75
- Thread series UNC
- Bolt count 8
- Target preload (% of yield) 50
- Bolt yield (ksi, B7 = 105) 105
- Nut factor K 0.18
You get
- Preload per bolt (lb) 17535
- Torque per bolt 197.27
Checked against published worked examples from: ASME PCC-1 / B16.5 (by name).
Details, formula, and sources
ScopeTarget preload and short-form torque (T = K*D*F) per bolt plus the cross/star tightening sequence for a bolted flange joint.
Formula or tableF = stress * A_tensile; short-form torque T = K * D * F (D nominal bolt diameter). Cross/star tightening sequence per the ASME PCC-1 legacy pattern for the bolt count.
Source and editionBolt-preload torque by the short-form T = K*D*F and the cross/star tightening sequence, per ASME PCC-1 Guidelines for Pressure Boundary Bolted Flange Joint Assembly and the ASME B16.5 flange classes, by name.
Free accessPublic first-principles short-form torque. The nut factor K, gasket seating stress, and target preload are joint- and lubricant-specific and user-supplied.
What governsEstimate. AHJ and licensed professional govern.
API field namesbolt_diameter_in, thread_series, bolt_count, target_percent_yield, yield_ksi, nut_factor_k, preload_lb, torque_ftlb
- Nut factor K lubricated about 0.16-0.20, dry about 0.20-0.25; user-supplied, default flaggedASME PCC-1 / fastener data