Hobson did you know flyer
K2 Class 10.9 HR Structural Bolt Assembly, Hot Dip Galvanised (Did You Know)
A three-page Hobson flyer for its premium K2 class 10.9 HR structural bolt assembly, hot dip galvanised, to EN 14399-3:2005. It covers the sizes, how to read the carton label, the quality documents behind each batch, and how K classification lets torque be used to tension the bolts.
What this covers
- Sizes
- Carton label and torque method
- Head markings
- Required documentation
- K classification
- Torque and tension
Key things to remember
The essentials from this document in plain words. Check the full document before you rely on a figure.
- Hot dip galvanised class 10.9 HR bolt assemblies to EN 14399-3:2005, K2 class. Sizes: M16 (40mm to 50mm long), M20 (50mm to 150mm), M24 (70mm to 130mm), M30 (80mm to 200mm) and M36 (130mm to 200mm).
- Each carton label gives the batch's k-factor (km) and its variation (Vk), and a two-step torque method to EN 1090-2: a first torque to bring the steel into firm contact, then a second to reach the correct tension. Use the figures on your own label.
- EN 14399 allows torque to be used to tension structural bolts only for K1 and K2 assemblies, where the torque-tension relationship is calibrated. For K2, km is between 0.10 and 0.23 and Vk is no more than 0.06.
- The flyer states that EN 14399 8.8 and 10.9 HR assemblies with K2 classification comply with AS 1252:2016 and can be used directly in Australia.
- Torque and tension are linked by M = F x k x d: torque on the nut equals the bolt tension needed, times the k-factor (mostly friction loss), times the thread diameter. Friction must be calibrated, which is what the k-factor does.
- Each head carries a unique batch trace code linked to the test certificate, plus the property class and the manufacturer's mark. Batch documents include the CE certificate, factory production control, inspection certificate and declaration of performance.
Who it helps: Steel fabricators, erectors and engineers specifying or tightening high strength structural 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.