Made-to-order NAB hex bolts, nuts and stud bolts for seawater, naval, and defence applications. Supplied to DEF STAN 02-833, NES 833, NES 834 and customer drawings. M4 to M64 metric and imperial. Full material certification as standard.
Nickel aluminium bronze (NAB) is a copper-based alloy containing approximately 9% aluminium, 5% nickel, and 4% iron. It is widely regarded as the premier material for fasteners, valves, and structural components in seawater environments — and is the material of choice across the Royal Navy, offshore oil and gas, and marine engineering sectors.
NAB's exceptional seawater corrosion resistance comes from a self-healing aluminium oxide layer that forms on the surface and prevents further attack — even in highly oxygenated, turbulent, or biologically active seawater. Unlike stainless steel, NAB is also resistant to crevice corrosion and pitting in seawater, making it ideal for threaded fastener applications where crevice conditions are unavoidable.
NAB is specified under DEF STAN 02-833 and NES 833 for Royal Navy applications, and under ASTM B148 / UNS C95800 for US Navy and international programmes. It is non-magnetic in its heat-treated condition, making it suitable for use on minesweepers and other magnetically sensitive platforms.
NAB outperforms other materials in seawater fastener applications on every critical measure.
The self-healing aluminium oxide film provides outstanding resistance to seawater corrosion — including in turbulent, oxygenated, and biologically active conditions where steel and standard bronze fail rapidly.
Unlike stainless steel, NAB does not suffer from crevice corrosion in seawater — critical for threaded fastener applications where crevice conditions between bolt, nut, and flange face are unavoidable.
In its heat-treated condition, NAB is non-magnetic — essential for minesweepers, degaussing systems, and other naval platforms where magnetic signature must be minimised.
With tensile strength up to 750 MPa, NAB combines excellent corrosion resistance with the mechanical strength needed for high-load fastener applications in naval and offshore structures.
Every fastener sourced to order against your drawing or specification. No minimum order quantity.
Full and part thread to ISO 4014, DIN 933, and customer drawings. DEF STAN 02-833 / NES 833 material cert included.
M4 to M64 — larger on request
Standard, thick and thin hex nuts to ISO 4032 / DIN 934. Matched to bolt order or supplied separately.
M4 to M64 — all thread pitches
Double-ended studs for flanges, seawater valves, and naval piping. Supplied to your specified thread form and length.
M8 to M52 — any length
Countersunk, pan head, and cheese head machine screws to DIN 963, DIN 85, DIN 84, and customer drawings. Material cert included as standard.
M4 to M12 — larger on request
Socket heads, countersunk, UNC/UNF imperial, left-hand thread. If you have a drawing in NAB, we can quote it.
Metric & imperial — send your drawing
NAB fasteners are specified wherever seawater corrosion, biofouling, or magnetic signature are a concern.
The primary material for fasteners in Royal Navy surface ships, submarines, and naval auxiliary vessels. Proven supply into Portsmouth Naval Base programmes.
Widely specified for offshore platform seawater systems, subsea equipment, and marine structures where long-term corrosion resistance is critical.
NAB fasteners are available to all of the following standards. Your drawing will specify which applies.
UK MOD standard for NAB in naval and defence applications. The most commonly specified standard on current defence drawings.
View page →Royal Navy NAB standard. Still actively referenced on legacy surface ship and refit drawings, particularly at Portsmouth.
View page →Heat treatment standard for NAB. Almost always referenced alongside NES 833 on the same drawing.
View page →US equivalent NAB standard. Required for US Navy supply chain and export programmes.
View page →Both are copper-aluminium alloys used in marine fastener applications. Your drawing will specify which is required.
| NAB — Nickel Aluminium Bronze | SAB — Silicon Aluminium Bronze | |
|---|---|---|
| Alloy | CW307G / C95800 | CW118C |
| Seawater corrosion resistance | Outstanding | Good |
| Strength | High — min 620 MPa UTS | High — similar range |
| Machinability | Good | Better — tighter tolerances |
| Non-magnetic | Yes (heat treated) | Yes |
| Primary spec | DEF STAN 02-833, NES 833 HT: DEF STAN 02-862 Para 8.2.4 | Customer drawing / BS 2874 |
| Best for | Naval, seawater, defence | High-tolerance, hydraulic, valve |
Send us your drawing or spec reference and we'll come back with a price and lead time. No minimum order quantity.