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HV and HR sets are frequently used in steel construction applications throughout Europe. The systems consist of bolts, pre-lubricated nuts and washers. The radius under the bolt head is a particular characteristic of these sets. It is larger than for normal standard bolts in order to decrease the notch effect.

Until recently there was no satisfactory way to secure HV/HR sets used in structural steel construction. When bolts came lose due to vibration or dynamic loads, there was no solution apart from the time consuming and expensive process of retightening.

Based on the leading Nord-Lock wedge-locking technology, the Nord-Lock Group has now developed the Nord-Lock Steel Construction (SC) washers specially designed for use in structural steel parts and to fit HV sets and HR sets (bolts and nuts in accordance to the European standard EN 14399-4 and EN 14399-3). The purpose of SC-washers is to replace standard chamfered washers according to EN 14399-6 in order to add safety to high-strength structural preloaded assemblies encountered in steel construction, when exposed to dynamic loads or vibration. Nord-Lock wedge-locking technology secures the bolt with tension instead of friction preventing the bolt from rotating loose.

Nord-Lock SC-washers are CE-marked for use with HV bolts. Safe usage with high-strength bolts has been confirmed by the General Building Supervisory Approval No. Z-14.4-629 and by the European Technical Approval 13/0246 issued by DIBT.