Hobson tightening torque chart
Class 4.6 Threaded Rod Torque Chart: Metric Allthread Tightening Torque
Hobson's one-page table for metric allthread (threaded rod), class 4.6. For each size from M3 to M64 it gives the pitch, stress area, core area, tensile, proof and shear load, and the recommended tightening torque for plain, zinc plated and hot dip galvanised (HDG) rod.
What this covers
- Tensile, proof and shear load
- Recommended tightening torque: plain, zinc, HDG
Key things to remember
The essentials from this document in plain words. Check the full document before you rely on a figure.
- Covers sizes M3 to M64.
- Recommended torque, plain / zinc / HDG: M10 17.0 / 11.9 / 35.6Nm; M12 29.6 / 20.7 / 62.1Nm; M16 73.5 / 51.4 / 154.3Nm; M20 143.3 / 100.3 / 301.0Nm.
- Loads for M12: tensile 33.7kN, proof 19.0kN, shear 18.3kN. M20: 98.0kN, 55.1kN and 54.0kN. These are strength figures, not working loads.
- Hot dip galvanised rod needs about twice the torque of plain rod, and zinc plated about 30% less, because of the different thread friction.
- Conditions: a guide only, for the first tightening of a single assembly on its own, using a k factor of 0.2 for plain threads (burr-free, lightly oiled), 0.14 for zinc plated and 0.42 for hot dip galvanised.
Who it helps: Builders and fitters tightening everyday class 4.6 threaded rod.
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This document is published by Hobson Engineering, who supply this range to us. We show it here in full so you can read it next to the product; the summary above is ours. Read it on this page or download the PDF. For the most current version, ask us.