Hobson tightening torque chart
DIN 985 Nyloc Nut Torque Chart, Property Class 8: Zinc Plated and Galvanised
A two-page Hobson technical sheet for DIN 985 Nyloc (nylon insert) nuts, property class 8, coarse thread. Page one gives the across flats size, nut height, prevailing torque, clamp load and installation torque from M5 to M39; page two explains how to tighten and reuse prevailing torque lock nuts.
What this covers
- Dimensions
- Prevailing torque
- Clamp load and installation torque
- Installing prevailing torque nuts
- Re-use and nylon exposure
For Nyloc Nut.
Key things to remember
The essentials from this document in plain words. Check the full document before you rely on a figure.
- Installation torque, zinc plated / mechanically galvanised: M8 21 / 45Nm; M10 41 / 87Nm; M12 69 / 149Nm; M16 165 / 363Nm; M20 322 / 723Nm.
- Conditions: first installation of a single assembly on its own, clamp load set at 65% of proof stress of a class 8.8 bolt, nut factor 0.14 for zinc plated (yellow or clear) and 0.35 for mechanically galvanised. A guide only.
- Maximum prevailing torque on first install (from ISO 2320): M10 10.5Nm, M12 15.5Nm, M16 32.0Nm. Clamp load: M12 31.78kN, M16 59.19kN.
- Prevailing torque nuts (nyloc, cone lock, deformed thread and similar) need the prevailing torque added to the normal torque: T = F x k x d + Tpr. Using standard torque values alone gives a lower clamp load than expected.
- The bolt needs full thread right through the nylon insert and at least one full thread showing past the nut.
- Nyloc nuts can be reused, but each use reduces their effectiveness; check the prevailing torque with a torque wrench before reusing one. Nuts exposed to strong sun or salt for a long time should not be reused.
Who it helps: Fitters and builders tightening Nyloc lock nuts.
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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.