Description
Plain Washer 5×10 A4 ISO 7089 — BOLTON SKU 56551.
About the Plain Washer 5×10 A4 ISO 7089
This washer is the M5 size in the ISO 7089 normal series, manufactured in A4 austenitic stainless steel. The standard assigns the M5 washer a 5.3 mm clearance hole, a 10 mm outside diameter and a nominal thickness of 1 mm, which the 5×10 designation reflects. The acid-resistant A4 class is specified where fastened joints face salt-laden air, condensation or frequent wash-down. Placed under an M5 screw head or nut, the washer enlarges the bearing area, protects paint and soft substrates from galling during tightening, and helps the joint hold a stable preload. Grade A tolerances keep flatness and hole size consistent across a batch, which matters when washers are fed in quantity through assembly benches, and the same washer can equally be fitted on the nut side to protect the rear surface of the joint.
Key specifications
| Standard | ISO 7089 (plain washer, normal series, without chamfer) |
|---|---|
| Nominal size | M5 |
| Inside diameter (d1) | 5.3 mm |
| Outside diameter (d2) | 10 mm |
| Thickness (h) | 1 mm nominal (0.9–1.1 mm) |
| Material | A4 austenitic stainless steel |
| Cross-reference | DIN 125-1 Form A |
Typical applications
The M5 size serves equipment covers, rail-mounted accessories and mid-weight brackets assembled with M5 A4 machine screws — common in marine-adjacent, workshop and field-deployed hardware. Keeping washer and fastener in the same A4 grade avoids mixed-metal corrosion inside the joint.
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).
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