Washers for preloaded bolting assemblies

Advisory Desk Note 544

Steel Construction Institute, 2025
Washers for preloaded bolting assemblies Download document

Document Status

Current

Supplement

Civil & Structural Supplement

Series

Advisory Desk Note

Abstract

This SCI Advisory Note provides guidance on the correct use of washers in preloaded bolting assemblies to prevent loss of bolt preload due to washer indentation. It highlights the importance of using hardened washers, as mandated by BS EN 1090-2 and the NSSS, particularly under rotating components of the joint. Requirements vary by bolt property class and steel grade, with specific standards governing washer types and placement. The note also clarifies that standard hardened washers are unsuitable for direct use with oversized or slotted holes, where plate washers with hardened washers above are required to maintain joint integrity.

History

June 2025 edition.

Subjects

  • Building systems/frame
  • Building structure
  • Materials
  • Steel building systems/frame
  • Metal sections/other items
  • Steel

Publisher History

With over 30 years experience, the Steel Construction Institute provide technical expertise and best practice to the steel construction sector.

Information

NBS

NBS has produced specification systems and information products for construction industry professionals for more than 40 years. The National Building Specification is the recognised UK national standard and is used by over 5,000 organisations. NBS is part of RIBA Enterprises Ltd.

Accuris

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