Technical resources

The BoltCore blog.

Bolt calculation, preload, safety margins, ECSS methodology — technical articles for engineers who justify critical bolted joints.

Published

Bolt Calculation per ECSS-E-ST-32-19C: The Complete Guide

Preload, safety margins, geometric parameters, and justification methodology — the reference guide for sizing a critical bolted joint.

The Fv,min/Fv,max bracket, in-service losses, and how tightening method accuracy directly impacts your safety margins.

Indicative tightening torques M4 to M24, classes 8.8/10.9/12.9, with the full formula and calculation assumptions.

Definitions, M3 to M24 reference table, and where to find each value depending on the reference standard.

µ th, µ uh, values by surface treatment, and how this uncertainty impacts the preload bracket.

Common CTE values, effect on preload, and the specifics of cryogenic applications.

How to read a bolt class, strength/brittleness trade-offs, and how to choose between steel and stainless.

Why fatigue is a distinct failure mode, preload's protective role, and the most common calculation pitfalls.

Checklist of the most common mistakes: geometry, preload, external loads, traceability, and methodology.

The vibration loosening mechanism, how to detect it, and the real prevention solutions versus common misconceptions.

Comparison of the three bolted joint calculation references, and how to know which applies to your project.

Geometry, materials, tightening, loads, environment — everything to have on hand before you begin.

Series wrap-up: the real time cost of a manual calculation, where errors hide, and what automation doesn't replace.

Want to apply this methodology directly to your assemblies?