ASTM B164
Monel 400
Fasteners
What Is Monel 400 — Why Use It
Monel 400 (UNS N04400 / DIN 2.4360) is a solid-solution nickel-copper alloy containing 63–70% nickel with copper as the balance. Developed by the International Nickel Company from naturally occurring nickel-copper ore, it is the most widely used alloy in the Monel family — chosen wherever seawater and chloride corrosion would destroy stainless steel, but the elevated strength of Monel K500 is not required.
In fastener applications, Monel 400 delivers near-zero corrosion rate in seawater at all velocities, tidal zones, and splash zones — environments where 316L pits rapidly and duplex corrodes at welds. Its resistance in hydrofluoric acid at all concentrations and temperatures makes it the standard alloy for HF alkylation unit bolting in refineries. Unlike Hastelloy B3 which excels in reducing acids, Monel 400 performs best in reducing and slightly oxidising conditions — seawater, HF, caustics, and marine atmospheres.
Akbar Fasteners Pvt. Ltd. stocks ASTM B164-certified UNS N04400 bar and rod for rapid turnaround. All fasteners are PMI-verified, dimensionally inspected, and dispatched with NABL-accredited test reports. Matching Monel 400 nuts, washers, and studs from the same certified heat ensure galvanic compatibility throughout the joint.
| Element | Min % | Max % | Typical |
|---|---|---|---|
| Nickel + Cobalt | 63.0 | — | ~67% |
| Copper (Cu) | — | Balance | ~31% |
| Iron (Fe) | — | 2.5 | ~1.5% |
| Manganese (Mn) | — | 2.0 | ~1.0% |
| Carbon (C) | — | 0.30 | <0.15% |
| Silicon (Si) | — | 0.50 | <0.3% |
| Sulfur (S) | — | 0.024 | — |
Monel 400 Hex Bolts
Machined from ASTM B164 certified UNS N04400 bar stock. Full thread (DIN 933) and partial thread (DIN 931). Heavy hex available for ASME flange service. Heat-traced, PMI-verified, dispatched with NABL-accredited test reports. The primary choice for marine flange connections in seawater pump systems, ship fittings, and desalination equipment where 316L corrodes in Cl⁻ service.
| Spec | Details |
|---|---|
| Material | UNS N04400 / Monel 400 |
| Standard | ASTM B164 / QQ-N-281 |
| Size Range | M6 — M100 |
| Thread | Metric · UNC · UNF · BSW |
| Head | Hex · Heavy Hex · Flanged |
| UTS | ≥ 480 MPa |
| 0.2% YS | ≥ 170 MPa |
| Elongation | ≥ 35% |
| Condition | Annealed |
Monel 400 Stud Bolts
Fully threaded and double-end stud bolts in Monel 400 for ASME B16.5 flanged joints in seawater, HF acid, and marine service. Similar to our Hastelloy B3 stud bolt range in configuration options — but specified for service environments where Monel’s Ni-Cu corrosion resistance is required. Lengths to 3,000mm.
| Spec | Details |
|---|---|
| Material | UNS N04400 / Monel 400 |
| Standard | ASTM B164 · ASME B16.5 |
| Size Range | M12 — M100 |
| Max Length | 3,000 mm |
| Config | Full Thread · Equal · Unequal End |
| Press. Class | ASME 150# to 2500# |
| UTS | ≥ 480 MPa |
| Condition | Annealed |
Monel 400 Hex Nuts
Standard hex (DIN 934) and heavy hex (ASME B18.2.2) nuts in Monel 400. Manufactured from the same certified B164 heat as matching bolts — identical UNS N04400 composition ensures no galvanic couple in seawater or HF service. Coupling nuts (DIN 6334) available. For higher-strength requirements consider our Monel K500 heavy hex nuts.
| Spec | Details |
|---|---|
| Material | UNS N04400 / Monel 400 |
| Standard | ASTM B164 · DIN 934 · ASME B18.2.2 |
| Size Range | M6 — M100 |
| Types | Std Hex · Heavy Hex · Coupling |
| Thread | Metric · UNC · UNF |
| Condition | Annealed |
Monel 400 Washers
Plain flat (DIN 125) and spring (DIN 127) washers in Monel 400. M5–M100. Using matched Ni-Cu alloy washers throughout the assembly prevents galvanic corrosion from a dissimilar metal washer in seawater. Just as we recommend matched Hastelloy B3 washers with B3 stud bolts, Monel 400 washers are essential with Monel 400 bolts in marine service.
| Spec | Details |
|---|---|
| Material | UNS N04400 / Monel 400 |
| Standard | ASTM B164 · DIN 125 · ISO 7089 |
| Size Range | M5 — M100 |
| Types | Plain Flat · Spring · Large OD |
| Condition | Annealed |
Monel 400 Socket Cap Screws
ISO 4762 socket head cap screws in Monel 400 for marine valve bodies, seawater pump covers, and enclosed shipboard equipment. Hex socket drive enables high-torque installation in confined spaces. For subsea and high-load applications requiring ≥1000 MPa, consider our Monel K500 socket screws.
| Spec | Details |
|---|---|
| Material | UNS N04400 / Monel 400 |
| Standard | ISO 4762 · DIN 912 · ASTM B164 |
| Size Range | M3 — M36 |
| Drive | Hex Socket (Allen) |
| UTS | ≥ 480 MPa |
Monel 400 Threaded Rods
Fully threaded rods (DIN 975/976) in Monel 400 for marine structure hanger rods, seawater pipeline supports, and offshore platform cable trays. Cut from ASTM B164 certified bar. Lengths to 3,000mm. Metric and inch thread. Same corrosion immunity in seawater as all other Monel 400 fasteners.
| Spec | Details |
|---|---|
| Material | UNS N04400 / Monel 400 |
| Standard | DIN 975 · DIN 976 · ASTM B164 |
| Diameter | M6 — M100 |
| Max Length | 3,000 mm |
| Thread | Metric · UNC · UNF · BSW |
| UTS | ≥ 480 MPa |
ASTM B164 Monel 400 Full Product Matrix
All products machined from ASTM B164 / QQ-N-281 certified UNS N04400 bar stock. Properties per ASTM A370. Custom sizes to sales@akbarfasteners.in.
| Product | Standard | Size Range | UNS No. | UTS | 0.2% YS | Elongation | Condition |
|---|---|---|---|---|---|---|---|
| MONEL 400 BOLTS | |||||||
| Hex Bolts — Full Thread | DIN 933 / ISO 4017 | M6–M100 | N04400 | ≥480 MPa | ≥170 MPa | ≥35% | Annealed |
| Hex Bolts — Part. Thread | DIN 931 / ISO 4014 | M6–M100 | N04400 | ≥480 MPa | ≥170 MPa | ≥35% | Annealed |
| Heavy Hex Bolts | ASME B18.2.3.6M | M12–M100 | N04400 | ≥480 MPa | ≥170 MPa | ≥35% | Annealed |
| STUD BOLTS | |||||||
| Fully Threaded Stud | ASME B16.5 / DIN 976 | M12–M100 | N04400 | ≥480 MPa | ≥170 MPa | ≥35% | Annealed |
| Double-End Stud | DIN 939 / DIN 938 | M6–M100 | N04400 | ≥480 MPa | ≥170 MPa | ≥35% | Annealed |
| NUTS | |||||||
| Hex Nuts | DIN 934 / ISO 4032 | M6–M100 | N04400 | — | — | — | Annealed |
| Heavy Hex Nuts | ASME B18.2.2 | M12–M100 | N04400 | — | — | — | Annealed |
| Coupling Nuts | DIN 6334 | M6–M48 | N04400 | — | — | — | Annealed |
| WASHERS · SCREWS · RODS | |||||||
| Plain Flat Washers | DIN 125 / ISO 7089 | M5–M100 | N04400 | — | — | — | Annealed |
| Socket Cap Screws | ISO 4762 / DIN 912 | M3–M36 | N04400 | ≥480 MPa | ≥170 MPa | ≥35% | Annealed |
| Threaded Rods | DIN 975 / DIN 976 | M6–M100 ≤3000mm | N04400 | ≥480 MPa | ≥170 MPa | ≥35% | Annealed |
* For ≥1000 MPa strength in the same Ni-Cu alloy family, see Monel K500 (ASTM B865)
Standards We Manufacture & Test To
Full documentation package on every order — same quality system as our Hastelloy B3 stud bolts and all exotic alloy fasteners.
Monel 400 Fastener Applications
Wherever seawater or HF acid would destroy stainless steel and the elevated strength of Monel K500 is not required — Monel 400 is the cost-effective, proven specification.
Marine & Seawater
hull valves · tidal zones
Offshore / Platform
seawater pipe flanges
HF Acid / Alkylation
HF gas scrubbers
Desalination Plants
brine heater bolts
Chemical Processing
sulphuric acid dilute
Pump & Valve Bodies
marine valve internals
Power Generation
condenser tube sheets
Food Processing
brine handling systems
Complete Documentation Package
Heat & Lot Traceable
Conformance
100% Lots Verified
Tensile · Hardness
TÜV · BV · Lloyds
Related Monel & Ni Alloy Fasteners
Same certified heat, same documentation — complete your joint with matched material, or step up to higher-performance alloys for demanding environments.
Monel K500 Fasteners
Age-hardened version — 3× the strength of Monel 400 with identical seawater resistance. For high-load offshore and subsea applications.
View Page →Hastelloy B3 Stud Bolts
When HCl and reducing acid resistance is needed beyond Monel’s range. Near-zero corrosion in HCl at all concentrations. ASTM B335.
View Page →Hastelloy B3 Washers
Plain flat and spring washers in Hastelloy B3 for complete flanged joint documentation from one ISO 9001:2015 certified source.
View Page →All Hastelloy Grades
Full Hastelloy range — C276, C22, C4, B3, X, G-30 — as bolts, studs, nuts, washers. Grade selection guidance for your environment.
View All Grades →Need ASTM B164
Monel 400 Fast?
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