How To Find Out Torque Specifications for Screws and Bolts: An Outstanding NASA Reference Guide

We’ve all been there – you’re working on a project and wondering how much to torque something so either we don’t bother or just take a guess. What I only found out recently was that in 2017, NASA published a really cool guide called “Installation Torque Tables for Noncritical Applications” – with the document ID as NASA/TM—2017-219475.

The document provides the torque specifications for a ton of general purpose fasteners that do not have an exact specification assigned – hence the term non-critical. As you can imagine, they get very specific in critical/risky situations.

At any rate, given the size of the bolt or screw, the thread pitch, the material and the depth, they provide a reference torque specification you can follow for both metric (M6, M8, M10, etc.) and SAE (#8, #10, 1/8, 1/4, 3/8, etc.) fasteners. Note, they provide an assembly torque (which is a 65% load from failure) and 100% torque. I use the assembly torque spec.

They also recommend that the depth of thread engagement be 1.5x the diameter of the fastener. So a 1/4″ (0.25″) fastener should have at least 0.25″ x 1.5 = .375″ (3/8″).

Here’s an example table. This is for fasteners going into 6061-T6 aluminum with a thread depth of 3/16″. If we go down for a 10-32 UNF screw, the assembly torque is 22.2 inch pounds. I’d use that lacking any other detailed information. I could go up to 34.2 inch pounds but I have stripped so many fasteners I don’t risk it. I’m a huge fan of Loctite so I go with that and the assembly spec.

Kudos to the two authors and to NASA for making it available. The PDF is a cool reference document and one I use whenever I can’t find a specific torque value for a given application. All you machinists and engineers – you know way more than me so please let me know if you have other resources you recommend.

To access this cool guide, click here for the NASA link or click here for the copy on our server.

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