[ Nuts ]
Monel K-500 Heavy Hex Nuts
Patriot Bolt machines Monel K-500 heavy hex nuts from certified ASTM B865 bar (UNS N05500). K-500 keeps the seawater resistance of Monel 400 and adds age hardening, so the nut can match the strength of a K-500 stud.
We make K-500 nuts to ASTM F467 or your drawing, alone or with matching studs. Every order ships with mill test reports traceable to the heat.
[ Quick Specs ]
Monel K-500 Heavy Hex Nuts at a Glance
- Material
- Monel K-500, UNS N05500
- Specifications
- ASTM F467 (Ni 500) · ASTM B865 bar
- F467 requirements
- 130 ksi min proof stress (hex), 140 ksi (heavy hex), 24 HRC min
- Condition
- Solution annealed and aged
- Matching stud
- Monel K-500 stud bolts
Why Engineers Specify Monel K-500 Nuts
- Strength to match the stud. Aged K-500 nuts carry a 140 ksi heavy hex proof stress under ASTM F467, far above Monel 400.
- Seawater. Same nickel-copper base as Monel 400, with low corrosion rates in flowing seawater.
- Same alloy as the stud. Matching nut and stud material avoids galvanic corrosion in marine joints.
- Galling. K-500 can gall. Use a compatible anti-seize on assembly.
Monel K-500 Nut Specifications
ASTM F467 covers nonferrous nuts from 1/4 to 1-1/2 in, listing K-500 as alloy Ni 500 in the solution annealed and aged condition. Larger nuts are machined from ASTM B865 bar.
| ASTM F467 Ni 500 nut style | Proof stress, min | Hardness, min |
|---|---|---|
| Hex and hex flange | 130 ksi | 24 HRC |
| Heavy hex | 140 ksi | 24 HRC |
Put the specification and condition on your purchase order so the nuts are made and tested to it.
Monel K-500 Chemical Composition
| Element | Weight % |
|---|---|
| Nickel (+ cobalt) | 63.0 min |
| Copper | 27.0–33.0 |
| Aluminum | 2.30–3.15 |
| Titanium | 0.35–0.85 |
| Iron | 2.0 max |
| Manganese | 1.5 max |
| Silicon | 0.5 max |
| Carbon | 0.25 max |
| Sulfur | 0.01 max |
Limits per the current edition of the specification. The mill test report for your heat is the controlling document.
Nut Styles
- Heavy hex nuts to ASME B18.2.2, the standard style for flange studs.
- Heavy hex jam nuts where a thinner nut is needed.
- Threads: UNC through 1 in and 8UN above 1 in, or the thread on your drawing.
Applications and Industries
- Marine and subsea: Seawater flanges, pump and valve bolting. See Oil & Gas.
- Oil tools: Downhole and wellhead components where nonmagnetic, corrosion-resistant hardware is needed.
- Industrial: Pump and valve assemblies in brine and seawater. See Industrial Manufacturing.
Certification and Traceability
Patriot Bolt is ISO 9001:2015 certified. Each Monel K-500 order includes mill test reports traceable to the heat, along with a certificate of conformance to the specification on your purchase order.
Nuts are marked with the material and our identification.
Compare Monel K-500 with other bolting grades in our Fastener Materials Matrix.
Monel K-500 Heavy Hex Nuts FAQ
Which specification covers K-500 nuts?
ASTM F467 covers K-500 nuts as alloy Ni 500, from 1/4 to 1-1/2 in. K-500 bar is covered by ASTM B865.
How strong are K-500 heavy hex nuts?
Under ASTM F467, Ni 500 heavy hex nuts have a 140 ksi minimum proof stress and 24 HRC minimum hardness.
Why not use Monel 400 nuts on K-500 studs?
Monel 400 nuts are much weaker than K-500 studs. K-500 nuts match the stud strength.
Do you make matching K-500 studs?
Yes. We machine Monel K-500 stud bolts, so the stud and nuts can come from one source.
Request a Quote
Send us the alloy, nut style, thread size, specification and quantity, or upload your drawing. Our team will confirm the material and lead time. Call (281) 581-0176 or request a quote.