Hobson tightening torque chart
Fine Pitch Hex Bolt Torque Chart: Class 8.8 and Class 10.9
A two-page Hobson table for metric fine pitch hex bolts: page one class 8.8, page two class 10.9. For each size and pitch from M8 x 1 to M39 x 3 it gives the stress area, tensile, proof and shear load, and the recommended tightening torque for plain, zinc plated and hot dip galvanised (HDG) bolts.
What this covers
- Class 8.8 fine pitch
- Class 10.9 fine pitch
- Tensile, proof and shear load
- Recommended tightening torque
Key things to remember
The essentials from this document in plain words. Check the full document before you rely on a figure.
- Covers M8 x 1 to M39 x 3, including both M10 x 1.25 and M10 x 1, and M12 x 1.5 and M12 x 1.25.
- Class 8.8 torque, plain / zinc / HDG: M12 x 1.5 79.7 / 55.8 / 167.4Nm; M16 x 1.5 201.5 / 141.0 / 423.1Nm; M20 x 1.5 424.3 / 297.0 / 891.1Nm.
- Class 10.9 torque, plain / zinc / HDG: M12 x 1.5 114.1 / 79.9 / 239.6Nm; M16 x 1.5 288.3 / 201.8 / 605.4Nm; M20 x 1.5 587.0 / 410.9 / 1,232.6Nm.
- 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.
- The document states these figures are not to be used for structural fasteners or structural applications.
Who it helps: Fitters and machinists tightening fine thread hex bolts.
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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.