Monel K500
Nuts
UNS N05500
Monel K500 Nuts — The Matched Assembly Case
A Monel K500 stud bolt paired with a 316L nut in seawater forms an active galvanic couple. The stainless nut is anodic to K500 in chloride electrolyte — it corrodes preferentially at the stud-nut thread interface. Within months, thread galling, crevice attack at the nut bearing face, and seizing make the joint non-removable. Using a matched UNS N05500 Monel K500 nut eliminates this failure path entirely.
Monel K500 nuts manufactured by Akbar Fasteners Pvt. Ltd. come from the same ASTM B865 certified bar and heat as the matching stud bolts and washers. This means one mill certificate covers the full assembly — bolt, nut, and washer — simplifying NACE MR0175 documentation for subsea and offshore flange joints. The age-hardened condition (≤35 HRC) also prevents thread galling between matched K500 mating surfaces, a common failure mode when two identical soft alloy fasteners are run together without heat treatment.
Beyond seawater, K500 nuts are specified wherever K500 stud bolts are used — HF alkylation unit flanges, desalination plant pressure vessels, naval non-magnetic assemblies, and offshore platform structural joints. The nut must always match the bolt alloy. Akbar Fasteners Pvt. Ltd. supplies both as a certified matched set with a single documentation package on request.
| Element | Min % | Max % | Typical |
|---|---|---|---|
| Nickel + Cobalt | 63.0 | — | ~65% |
| Copper (Cu) | — | Balance | ~30% |
| Aluminium (Al) | 2.30 | 3.15 | ~2.7% |
| Titanium (Ti) | 0.35 | 0.85 | ~0.6% |
| Iron (Fe) | — | 2.0 | ~1.5% |
| Manganese (Mn) | — | 1.5 | — |
| Carbon (C) | — | 0.25 | — |
| Silicon (Si) | — | 0.50 | — |
| Sulfur (S) | — | 0.010 | — |
Monel K500 Nut Types & Standards
All types manufactured from ASTM B865 certified UNS N05500 age-hardened bar. Every nut PMI-verified and dispatched with MTC and COC. Compare with our Hastelloy B3 matched nut sets.
Standard Hex Nuts
The most common Monel K500 nut type. DIN 934 dimensions — six equal flat sides, standard height. Used on K500 hex bolts and threaded rod assemblies in seawater pump flanges, marine hardware, and chloride service piping. Thread metric DIN 13 or inch UNC/UNF. M6–M100.
Heavy Hex Nuts
Wider across flats and taller than standard hex — the mandatory type for ASME B16.5 stud bolt assemblies in Class 150–2500 pressure flanges. Greater bearing area under the wrench flat, higher thread engagement length. M12–M100. Supplied as certified pairs with matching K500 stud bolts from same heat.
Coupling Nuts (Long Hex)
Extended length hex nuts (typically 3D length) for joining two threaded rods end-to-end, or connecting a stud to a threaded rod in long-reach marine hanger systems. Used in K500 threaded rod assemblies for offshore platform equipment racks and seawater pipe support systems. M6–M48.
Nyloc, Slotted & Custom
Prevailing torque (nyloc) nuts in K500 for vibrating equipment, slotted (castle) nuts for pin-retention applications, and flanged hex nuts. Non-standard across-flats, left-hand thread, and drawing-specific profiles manufactured to order. Send drawing to sales@akbarfasteners.in.
Inch Thread Hex Nuts
Standard and heavy hex nuts in UNC (¼”–4″) and UNF fine thread forms for US offshore and naval projects specified in imperial dimensions. Same UNS N05500 age-hardened material, ASTM B865 certified bar, full MTC and PMI. Across-flats per ASME B18.2.2 inch dimensions.
Stud Bolt + Nut Sets
Matched K500 stud bolt and heavy hex nut sets from the same certified UNS N05500 heat — same MTC, same PMI report, same COC. Simplifies NACE MR0175 documentation for complete flange joint assemblies. Available with matching K500 washers as a complete assembly kit.
DIN 934 & ASME B18.2.2 Nut Dimensions — UNS N05500
Standard dimensions per DIN 934 (standard hex) and ASME B18.2.2 (heavy hex). All sizes in mm. Custom across-flats and thread forms on request to sales@akbarfasteners.in.
| Bolt Size | Thread Pitch | Std AF (mm) | Std Height (mm) | Heavy AF (mm) | Heavy Height (mm) | Standard | Condition |
|---|---|---|---|---|---|---|---|
| METRIC HEX NUTS — DIN 934 & ASME B18.2.2 (UNS N05500 · ASTM B865) | |||||||
| M6 | 1.0 mm | 10.0 | 5.0 | — | — | DIN 934 | Age Hard. |
| M8 | 1.25 mm | 13.0 | 6.5 | — | — | DIN 934 | Age Hard. |
| M10 | 1.5 mm | 17.0 | 8.0 | — | — | DIN 934 | Age Hard. |
| M12 | 1.75 mm | 19.0 | 10.0 | 21.0 | 12.0 | DIN 934 / B18.2.2 | Age Hard. |
| M16 | 2.0 mm | 24.0 | 13.0 | 26.9 | 16.0 | DIN 934 / B18.2.2 | Age Hard. |
| M20 | 2.5 mm | 30.0 | 16.0 | 33.5 | 20.0 | DIN 934 / B18.2.2 | Age Hard. |
| M24 | 3.0 mm | 36.0 | 19.0 | 40.4 | 24.0 | DIN 934 / B18.2.2 | Age Hard. |
| M30 | 3.5 mm | 46.0 | 24.0 | 50.8 | 30.0 | DIN 934 / B18.2.2 | Age Hard. |
| M36 | 4.0 mm | 55.0 | 29.0 | 60.3 | 36.0 | DIN 934 / B18.2.2 | Age Hard. |
| M42 | 4.5 mm | 65.0 | 34.0 | 71.0 | 42.0 | DIN 934 / B18.2.2 | Age Hard. |
| M48 | 5.0 mm | 75.0 | 38.0 | 82.6 | 48.0 | DIN 934 / B18.2.2 | Age Hard. |
| M56 – M100 | 5.5–6.0 mm | Custom | Custom | Custom | Custom | DIN 934 / B18.2.2 | Age Hard. |
| COUPLING NUTS — DIN 6334 | |||||||
| M6 – M48 | Per DIN 13 | Per DIN 934 AF | 3× Bolt Dia. | — | — | DIN 6334 | Age Hard. |
| INCH THREAD — ASME B18.2.2 | |||||||
| ¼” – 4″ UNC | Per ASME B1.1 | Per B18.2.2 | Per B18.2.2 | Heavy Hex Avail. | Per B18.2.2 | B18.2.2 | Age Hard. |
* UNF fine thread, BSW, and non-standard across-flats on request. Matched stud bolt + heavy hex nut sets with single MTC/COC available. Contact sales@akbarfasteners.in
Standards We Manufacture & Test To
Same quality system as our Hastelloy B3 stud bolts and complete exotic alloy range. Full heat traceability from mill to dispatch.
Monel K500 Nut Applications
Wherever K500 stud bolts and bolts are specified — the nut must be K500 too. These are the environments that drive the specification.
Offshore Pressure Flanges
Class 150–2500 joints
Seawater Systems
seawater pump nozzles
Subsea Equipment
manifold flange nuts
Oil & Gas
Xmas tree nut sets
HF Alkylation Units
HF acid flanges
Naval & Defence
minesweeper hardware
Marine Platforms
structural flange nuts
Marine Hanger Systems
equipment support nuts
Complete Documentation Package
Heat & Lot Traceable
Conformance
100% Lots Verified
Tensile · Hardness
TÜV · BV · Lloyds
Matched Monel K500 Assembly Components
Order nuts, stud bolts, washers, and threaded rods together from the same certified UNS N05500 heat — one documentation package covering the complete assembly.
Monel K500 Stud Bolts
Fully threaded and double-end stud bolts. Class 150–2500. M12–M100 up to 3,000mm. Supply with these matching K500 heavy hex nuts from same heat.
View Page →Monel K500 Fasteners
Full K500 range — hex bolts, washers, socket screws, threaded rods. All age-hardened, all from same certified heat as these nuts.
View Page →Monel K500 Washers
Flat and spring washers in K500 to DIN 125 / DIN 127. M5–M100. Complete the assembly with matched galvanic-compatible washers from same heat.
View Page →Hastelloy B3 Stud Bolts
For HCl and reducing acid service where Monel is not specified. Near-zero corrosion in HCl at all concentrations. Matched B3 nuts available.
View Page →Need Monel K500
Nuts Now?
Type · size · quantity · matched set requirement · documentation. Akbar Fasteners Pvt. Ltd. responds within 24 hours with full pricing and documentation list.