Dome Cap Nut | Nylon Blind Nut A2 A4 Hex Acorn M4-M20

Thedome cap nut — also called cap nut,blind nut, or acorn nut — is a hexagon nut with a closed, domed top that completely covers the protruding bolt thread end. This design serves three practical functions aboard ships: it eliminates the injury hazard of exposed sharp threads on deck equipment and handrails, it shields the bolt end from salt spray and moisture to slow corrosion at the thread tip, and it provides a clean, finished appearance on visible hardware installations. Available in three body materials to match the corrosion environment, the dome cap nut is a low-cost yet effective bolt-end protection solution widely used across marine deck and interior equipment.

Purenylon PA6 cap nuts offer electrical insulation and zero corrosion in splash-zone fittings such as cable tray brackets, navigation light mounts, and plastic-bodied deck fittings. Carbon steel hex bodies with a nylon insert dome provide mechanical strength at low cost for protected-interior applications like engine room panel guards, while A2-70 (304) and A4-80 (316) all-stainless dome nuts deliver full corrosion resistance and structural integrity for exposed topside equipment — winch base brackets, cleat mounts, handrail stanchions, and safety barrier posts — where a protruding bolt tip could snag mooring lines or injure crew.

Ourcap nuts are manufactured per DIN 1587 hexagon domed cap nut specification and DIN 986 prevailing torque type with nylon insert, covering metric sizes M4 through M20. All stainless variants are passivated after machining to restore the chromium oxide layer. Custom non-standard sizes and batch-matched dome nut sets with corresponding hex boltsandflat washers are available on request for marine project procurement packages.

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