DIN 7989-1 Washers for Steel Structures

DIN 7989-1 is a thick flat washer for steel structures, specified as product grade C with a hardness class of 100 HV. It is intended for structural bolted connections where a substantially thicker washer is required than a conventional plain washer. The washer has a large outside diameter relative to the bolt hole, creating a broad bearing surface beneath the bolt head or nut.

A defining characteristic of DIN 7989-1 is its 8 mm nominal thickness across the standard size range. This heavy section gives the washer greater resistance to deformation under the clamping force of a bolted connection and helps distribute the load over the supporting steel surface. The dimensional series covers metric structural fastening sizes, with standard dimensions including M10, M12, M16, M20, M24, M27 and M30.

DIN 7989-1 washers are commonly referred to as washers for steel structures, structural flat washers, or thick structural washers. They are typically installed beneath structural bolt heads or nuts to provide a stable bearing interface between the fastener assembly and the connected steel member. Their greater thickness and relatively large bearing area distinguish them from general-purpose flat washers used in lighter fastening applications.

The standard specifies steel as the material and a 100 HV hardness class, with Vickers hardness HV 10 specified within the standard’s technical delivery conditions. The standard also provides requirements for dimensional tolerances and product acceptance, making DIN 7989-1 a defined structural washer specification rather than a generic thick washer description.

DIN 7989-1 washers are used in structural steelwork, steel frames, fabricated steel assemblies, and other bolted connections where the specified washer dimensions and mechanical properties are required. Commercially supplied DIN 7989-1 washers are available in plain steel as well as with zinc-plated or hot-dip galvanized finishes, depending on the required corrosion protection.