Cap / Doom Nuts

Cap Nuts – Dome Nut & Acorn Nut Manufacturer & Supplier in UAE

Asia Bolts Industries LLC is a trusted Cap Nut, Dome Nut, and Acorn Nut manufacturer and supplier based in Dubai, UAE, serving the construction, architectural, oil & gas, food processing, marine, automotive, and general engineering sectors across the GCC and global markets since 1997. Our Cap Nuts deliver a dual-function fastening solution — providing the full clamping performance of a standard hex nut while simultaneously enclosing and protecting the exposed bolt thread end in a precision-formed dome profile that enhances safety, aesthetics, and long-term corrosion resistance in the assembled joint.

What Are Cap Nuts / Dome Nuts?

Cap Nuts — interchangeably referred to as Dome Nuts, Acorn Nuts, Crown Nuts, or Blind Nuts — are hexagonal nuts in which one end is closed by a rounded dome-shaped cap formed integrally with the nut body. The internal thread engages the bolt in the conventional manner, while the external dome covers the protruding bolt thread end completely — protecting it from corrosion, physical damage, and providing a smooth, injury-free external surface on the assembled joint.

The dome profile serves three distinct engineering functions simultaneously:

• Thread Protection — seals the exposed bolt end from moisture, salt spray, process fluids, and corrosive atmospheres that cause thread corrosion and seizure, particularly critical in GCC coastal and offshore environments
• Personnel Safety — eliminates sharp, projecting thread ends in public spaces, architectural installations, walkways, handrails, playground equipment, and food processing plant where personnel contact with fasteners is likely
• Aesthetic Finish — the smooth dome profile provides a clean, professional appearance on visible fastener installations in architectural steelwork, furniture, signage, and decorative metalwork

They are widely used in:

• Architectural and structural steelwork — handrails, balustrades, façade panels, signage frames
• Food and beverage processing — hygienic stainless steel installations requiring no thread crevices
• Marine and offshore — deck fittings, handrails, ladder rungs, equipment guards
• Automotive and transportation — wheel bolts, body panel trim, interior and exterior fittings
• Oil & gas surface equipment — instrument enclosures, junction boxes, access covers
• Playground and public furniture — safety-critical installations requiring no exposed sharp threads
• Electrical enclosures and switchgear — panel cover fastening, terminal box closures
• Plumbing and pipework — decorative and functional cover nuts on visible pipe connections

Types of Cap Nuts / Dome Nuts Available

1. High Dome Cap Nut — DIN 1587
The standard configuration — a full hexagonal nut body with a tall, pronounced dome cap providing maximum thread coverage and the most generous internal thread engagement depth. The most widely specified Cap Nut globally and the reference standard for metric cap nut supply across the GCC. Available across the full M3 to M36 metric size range in carbon steel, stainless steel, and brass.

2. Low Dome Cap Nut
A reduced-height dome profile for space-constrained applications where the full DIN 1587 dome height cannot be accommodated, or where a lower profile aesthetic is required. Same thread protection functionality in a more compact form factor. Common in automotive trim, electrical panel, and architectural applications.

3. Thin Hex Cap Nut
A slim-body version combining a reduced hex nut height with an integral dome cap — for applications where overall fastener stack height must be minimised. Used in precision mechanical assemblies and compact panel fastening.

4. Decorative Chrome-Plated Cap Nut
Carbon steel or brass cap nuts with bright chrome electroplating for decorative architectural, automotive, and furniture applications. The high-gloss chrome dome provides an aesthetically superior finish for visible fastener installations in premium fit-out and design projects.

5. Stainless Steel Polished Cap Nut
AISI 316 stainless cap nuts with a mirror-polished or satin-brushed dome finish for architectural, marine, and food-grade hygienic applications. Combines full corrosion resistance with a premium surface finish quality. Standard specification for handrail systems, balustrades, and food processing installations across the UAE and GCC.

6. Oversized / Custom Dome Cap Nut
For non-standard thread sizes, large diameter applications (M42 and above), or bespoke dome profiles required by project drawings, Asia Bolts manufactures custom Cap Nuts to customer specification — including extended dome depth for long thread protrusion coverage and custom hex body dimensions.

Standards & Specifications

Non-standard dome heights, custom thread depths, and project-specific material and coating requirements are handled by our in-house engineering team.

Materials & Grades Available

Surface treatment and finish options include zinc electroplating, bright chrome plating, nickel plating, mirror polishing, satin brushing, hot-dip galvanising, PTFE coating, black oxide, and passivation for stainless grades.

Dimensions & Size Range