Product Description
Metric A4 Marine Grade Stainless Steel Form C Flat Washers — BS 4320
A4 marine grade stainless steel Form C flat washers manufactured to BS 4320. Their larger outside diameter provides a wider bearing surface beneath nuts and bolt heads, helping distribute the clamping load across the component surface.
Available in M4, M5, M6, M8, M10, M12, M16 and M20 sizes. Choose the nominal washer size to match your bolt or screw, and check the outside diameter and thickness against the space available in your assembly.
Technical Specifications
| Product Type | Flat washers |
|---|---|
| Washer Form | Form C — large outside diameter |
| Material | A4 marine grade stainless steel |
| Standard | BS 4320 |
| Size System | Metric |
Available Sizes and Nominal Dimensions
| Nominal Fastener Size | Internal Diameter | Outside Diameter | Thickness |
|---|---|---|---|
| M4 | 4.3mm | 10mm | 0.8mm |
| M5 | 5.3mm | 12.5mm | 1mm |
| M6 | 6.4mm | 14mm | 1.6mm |
| M8 | 8.4mm | 21mm | 1.6mm |
| M10 | 10.5mm | 24mm | 2mm |
| M12 | 13mm | 28mm | 2.5mm |
| M16 | 17mm | 34mm | 3mm |
| M20 | 21mm | 39mm | 3mm |
Dimensions are nominal and subject to manufacturing tolerances. Nominal fastener size identifies the matching bolt or screw diameter; the washer hole is slightly larger to provide clearance. Please check with us before ordering if measurements are critical.
Fitting Information
Position the washer flat beneath the nut or bolt head. Ensure the surrounding surface supports the washer and that the fastener has sufficient thread engagement after allowing for the washer thickness.
