Bolting — A325 7/8" Pretension
Installation torque estimate for a325 7/8" pretension via T = K·d·F with the nut-factor entered explicitly.
The 70%-of-tensile pretension rule makes the faying surfaces grip — slip-critical joints transfer load by FRICTION, and the bolt is just the clamp. Paint in the wrong place defeats the joint, not the bolt.
Formula
Note: Erection-planning estimate only. Member weights, connection capacities and tolerances for execution must come from the issued drawings, the EOR and the erection engineer — never from a generic calculator.
Installation torque estimate for a325 7/8" pretension via T = K·d·F with the nut-factor entered explicitly. A free structural steel delivery & erection tool — no sign-up, no upload, instant results in your browser.
About Bolting — A325 7/8" Pretension
Bolting — A325 7/8" Pretension computes the governing relationship T = K·d·F live as you type. The 70%-of-tensile pretension rule makes the faying surfaces grip — slip-critical joints transfer load by FRICTION, and the bolt is just the clamp. Paint in the wrong place defeats the joint, not the bolt. Defaults are pre-filled with realistic values for this exact scenario, and the worked example substitutes your numbers step by step so the math is never a black box.
How to use Bolting — A325 7/8" Pretension
- 1Enter your values — Bolt diameter, Required pretension, Nut factor K (sensible defaults are pre-filled).
- 2Read the live results: Installation torque.
- 3Check the "with your numbers" line to see T = K·d·F substituted step by step.
- 4Adjust inputs until the scenario matches yours, then copy or share the result.
Why use Bolting — A325 7/8" Pretension?
- ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
- ✓Built on the stated formula T = K·d·F with authoritative sources cited on the page (RCSC — Specification for Structural Joints Using High-Strength Bolts; AISC 360 — Specification for Structural Steel Buildings)
- ✓The 70%-of-tensile pretension rule makes the faying surfaces grip — slip-critical joints transfer load by FRICTION, and the bolt is just the clamp.
- ✓SI ⇄ Imperial toggle converts your inputs in place, so you can work in the units your drawings use
Frequently asked questions
What formula does the bolting — a325 7/8" pretension use?+
It evaluates T = K·d·F, exactly as published. Sources: RCSC — Specification for Structural Joints Using High-Strength Bolts; AISC 360 — Specification for Structural Steel Buildings. The substituted worked example on the page lets you verify every step against the textbook.
How should I read the result — and how far can I trust it?+
The 70%-of-tensile pretension rule makes the faying surfaces grip — slip-critical joints transfer load by FRICTION, and the bolt is just the clamp. Erection-planning estimate only. Member weights, connection capacities and tolerances for execution must come from the issued drawings, the EOR and the erection engineer — never from a generic calculator.
When is this calculator the right tool for the job?+
Installation torque estimate for a325 7/8" pretension via T = K·d·F with the nut-factor entered explicitly. A free structural steel delivery & erection tool. Paint in the wrong place defeats the joint, not the bolt. For neighbouring scenarios, the related tools below cover the same engine with different presets.
Does it support both metric and imperial units?+
Yes — the SI ⇄ Imperial toggle converts the values already in the fields, preserving the physical quantity, so you can flip mid-calculation without re-entering anything.
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