Description
ISO7089 M8-A4 Flat washer,M8 — BOLTON SKU 56364.
About the ISO 7089 M8 A4 Flat Washer
ISO 7089 specifies plain washers of form A in normal series, product grade A, with a 200 HV hardness class. For the M8 nominal size the washer measures 8.4 mm inside diameter, 16 mm outside diameter and 1.6 mm thickness, which are the same dimensions long familiar from DIN 125 type A. The A4 suffix designates the material group: an austenitic stainless steel of the molybdenum-bearing 316 type, commonly described as marine grade, chosen where the joint is exposed to salt air, washdown or other corrosive service rather than a dry indoor environment. The washer’s function is to spread the bearing load of the bolt or nut over a larger area of the joint face, protect the surface finish from being scored during tightening, and provide a consistent bearing surface for torque control.
Key specifications
| Attribute | Value |
|---|---|
| Standard | ISO 7089 (plain washer, form A, normal series, product grade A) |
| Nominal size | M8 |
| Inside diameter | 8.4 mm |
| Outside diameter | 16 mm |
| Thickness | 1.6 mm |
| Hardness class | 200 HV |
| Material | A4 austenitic stainless steel (316-type, marine grade) |
| Dimensionally equivalent to | DIN 125 type A |
Typical applications
A4 stainless plain washers are used throughout structural and equipment assembly where corrosion resistance matters: shelter and enclosure frames, deployable infrastructure, vehicle and trailer fit-out, marine-exposed ground support equipment and general workshop and MRO assembly. They are also specified where mixed-metal joints need a controlled bearing face. Matching A4 bolts, screws and nuts are normally ordered together so the whole joint shares one material group.
Supplied by BOLTON Technical Equipment Supplies against request for quotation. Add this item to your RFQ basket to request pricing, lead time and documentation requirements (e.g. CoC, datasheets or test reports where applicable).
Browse more in MIL-Spec & Coded Fasteners.
Reviews
There are no reviews yet.