Washers for preloaded bolting assemblies
Advisory Desk Note 544
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
We connect trusted knowledge to customers' workflows – mitigating risk, increasing efficiency and accelerating innovation For more than 60 years, leading R&D and engineering-intensive organizations have relied on us to achieve on-time, on-budget delivery of complex projects and new products. We deliver an unparalleled combination of technical content and Artificial Intelligence (AI) technologies to surface answers from the vast universe of technical knowledge, both inside and outside the organization. In a single interface, we connect the dots between information scattered across many different sources, allowing technical professionals to make better, more informed decisions faster.