Description
Washer M12-A4 12×24 Steel Grade A ISO 7089 — BOLTON SKU 56361.
About the Washer M12-A4 12×24 Steel Grade A ISO
This is a normal-series plain washer manufactured to ISO 7089 in product grade A, the international standard for flat washers without chamfer (equivalent to DIN 125-1 Form A). The M12 size carries a 13 mm clearance hole, a 24 mm outside diameter and a nominal thickness of 2.5 mm, matching the 12×24 designation in the product name. The A4 material class denotes an austenitic, acid-resistant stainless steel commonly selected where chloride exposure or general corrosion would degrade plated carbon-steel hardware. Its function is to spread the clamping load of an M12 bolt head or nut over a larger bearing area and to protect the joint surface during tightening. Grade A denotes the standard’s tighter-tolerance product grade, giving consistent flatness and hole size for controlled assembly and inspection work.
Key specifications
| Standard | ISO 7089 (plain washer, normal series, without chamfer) |
|---|---|
| Product grade | A |
| Nominal size | M12 |
| Inside diameter (d1) | 13 mm |
| Outside diameter (d2) | 24 mm |
| Thickness (h) | 2.5 mm nominal (2.3–2.7 mm) |
| Material | A4 austenitic stainless steel |
| Cross-reference | DIN 125-1 Form A |
Typical applications
M12-size A4 washers are used in bolted joints that face humidity, wash-down or saline atmospheres — structural brackets, ground-support frames and equipment enclosures fastened with M12 A4 bolts and nuts. Selecting the washer in the same A4 class as the mating fastener avoids galvanic mismatch within 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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