Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Monel 400 Fasteners - UNS N04400 Bolts, Nuts, Studs, Screws & Washers
Monel 400 fasteners (also UNS N04400 fasteners, Alloy 400 fasteners, Nickel 400 fasteners, Werkstoff 2.4360 fasteners) are the nickel-copper family of bolting used where the joint sees hydrofluoric acid, flowing seawater, sour gas at NACE MR0175 limits, caustic, or a non-magnetic spec on a naval bulkhead. The bolting set covers bolts, nuts, stud bolts, washers, screws, threaded rod and anchor bolts. Bolts run to ASTM F468; nuts to ASTM F467; bar input per ASTM B164; forging stock per ASTM B564; alloy registers as UNS N04400. F468 caps hardness at 25 HRC, tighter than the NACE MR0175 35 HRC sour-service ceiling, so the bolting clears sour qualification by design. Monel® is a trademark of Special Metals Corporation.
Monel 400 Fastener Categories
Five product families ship from Mumbai stock. Every variant has its own page with sizing, mechanicals, threading and ordering data; click through the table to the variant you need.
| Family | Standard | Variants | Service |
|---|---|---|---|
| Bolts | ASTM F468 Class A / B | Bolts, hex bolts, heavy hex bolts, socket cap screws | HF alky flanges, sour gas, marine bolting |
| Nuts | ASTM F467 Class A / B | Nuts, hex nuts, heavy hex nuts, lock nuts | Mated to F468 bolting, identical alloy |
| Stud bolts | ASTM F468 / ASME B16.5 | Stud bolts, threaded rod | Flanged joints, HF alky, sour service |
| Washers | DIN 125 / 9021 / 127 / 6798 | Washers (plain, fender, spring, serrated) | Load distribution, vibration retention |
| Specials | To drawing | Anchor, foundation, eye, U-bolts, cap screws, screws | Civil anchorage, lifting, pipe clamps |
PMI on every heat at receipt; verify Ni and Cu against MTC. Free-machining Monel R-405 (N04405) at 0.025 to 0.060 percent S is bar only, used for nuts and unwelded joints.
Monel 400 Bolts to ASTM F468
F468 covers Monel 400 bolts in two classes - Class A (Ni 400, weldable) and Class B (Ni 405, free-machining). Imperial 1/4 in. through 1-1/2 in. is the F468 envelope; metric M6 through M40 standard, M48 through M64 on indent through B564 forging stock with mechanicals matched to F468 Heavy Forged Equivalent. Head forms in stock: hex cap (most common), heavy hex, socket head cap (DIN 912 / ISO 4762) and stud (full thread, double end). Threading per ASME B1.1 UNC and UNF, DIN 933 fully threaded, DIN 931 partial thread. Full sizing, torque and chemistry on the Monel 400 bolts page.
| F468 Marking | Class | Tensile (MPa) | Yield min (MPa) | Hardness | Use case |
|---|---|---|---|---|---|
| F 468U | A (N04400) | 552 to 896 | 276 | 75 HRB to 25 HRC | HF alky, sour, marine bolting |
| F 468U4 | A (N04400) | 552 to 896 | 276 | 75 HRB to 25 HRC | Higher-yield variant, 0.875 to 1.5 in. |
| F 468HF | A (N04400) | 483 to 827 | 207 | 60 to 95 HRB | Soft annealed, HF flange gasketing |
| F 468V | B (N04405) | 483 to 862 | 207 | 60 HRB to 20 HRC | Free-machining, unwelded joints |
Monel 400 Nuts to ASTM F467
F467 is the nut counterpart to F468 - Class A (Ni 400) and Class B (Ni 405). Nut chemistry must match the bolt to avoid galvanic discontinuity in the clamped joint. Standard stocked forms: hex nuts (ASME B18.2.2), heavy hex nuts (ASME B18.2.2 / B18.2.4.6M) for pressure-rated flange joints, and lock nuts (DIN 982 / DIN 985) for vibration-prone bolting. Heavy hex is the default for ASME B16.5 flanges. Hardness floor B70 HRB; ceiling 35 HRC, well inside NACE MR0175 for sour service. Detail and sizing on the Monel 400 nuts page.
Monel 400 Stud Bolts and Threaded Rod
Stud bolts are the dominant Monel 400 form on ASME B16.5 flanges in HF alkylation, sour gas and refinery duty - full-thread or thread-runout-with-shank, double-end, length specified bolt-to-bolt across the flange. F468 mechanical envelope applies; thread per ASME B1.1 UNC or UNF, ISO metric coarse on European drawings. Lengths from 1.5 in. to 36 in. ex stock, longer on indent. Threaded rod (all-thread stud) ships in 1 m and 3 m mill lengths for site cut-to-length, or in 3 ft / 6 ft / 12 ft imperial. Detail on the stud bolts page and threaded rod page.
Monel 400 Washers
Monel 400 washers seat the bolt against galvanically identical material across the joint; mixing the washer alloy from carbon steel or austenitic stainless restarts the galvanic cell that the Monel bolting was specified to avoid. Stocked forms: DIN 125 plain, DIN 9021 fender (oversize OD), DIN 127 spring lock, DIN 6798 serrated lock, plus ASME B18.22.1 imperial plain. Thickness and OD picked from the bolt diameter table. Full sizing on the Monel 400 washers page.
Specials - Anchor, Foundation, Eye and U-Bolts
Outside the F468 standard envelope, Monel 400 ships as specials to drawing from B164 bar or B564 forging stock with mechanicals held to F468 Class A:
- Anchor bolts - L-form, J-form, headed, swedged. Mumbai marine jetty, FPSO topside anchorage.
- Foundation bolts - pre-embedded grade 5 anchorage for chemical-plant skids handling HF or seawater.
- Eye bolts - DIN 580 lifting, marine pump removal in salt-spray duty.
- U-bolts - pipe clamping on Monel 400 / Cu-Ni heat-exchanger tube banks.
- Cap screws and socket cap screws - DIN 912 / ISO 4762 internal hex drive for instrument and pump-cover bolting.
- Machine screws - small-diameter slotted / cross-recess heads (DIN 84, DIN 7985) for instrument enclosures.
All specials ship with EN 10204 type 3.1 (3.2 on indent) MTC carrying heat number, mechanicals, hardness and NACE compliance statement where the duty calls for it.
Service Applications
The bolting runs where austenitic stainless, low-alloy steel and copper alloys fail. Four core service envelopes drive Monel 400 fastener demand:
| Application | Failure mode avoided | Standard reference | Detail page |
|---|---|---|---|
| HF alkylation | HF attack on austenitic stainless, copper | API RP 751 | HF alkylation |
| Sour gas (H2S) | Sulphide stress cracking | NACE MR0175 / ISO 15156 | Sour service |
| Marine and seawater | Pitting, crevice, biofouling | NORSOK M-501, MIL-S-1222 | Marine engineering |
| Naval non-magnetic | Magnetic signature on hulls and mine countermeasures | Permeability < 1.05 | Magnetic permeability |
| Caustic and chloride | Caustic stress cracking, chloride pitting | NACE / ASM Vol 13 | Corrosion resistance |
Monel 400 is the default bolting on HF-wetted flanges in HF alkylation units. The nickel-copper film resists HF attack across the alkylation acid concentration band (70 to 95 percent) where austenitic stainless and copper alloys fail. Detail on HF acid resistance.
Certification, Testing and Sour Service Compliance
Documentation runs to EN 10204 with two grades:
- EN 10204 type 3.1 - default. Mill test certificate signed by the manufacturer's authorised inspection representative independent of production. Carries heat number, chemistry, mechanicals (tensile, yield, elongation), hardness, heat-treat condition and dimensional report. Cross-referenced to the F468 / F467 marking on the bolt head and the bag tag.
- EN 10204 type 3.2 - on indent. Same content as 3.1, witnessed and counter-signed by a third-party inspection authority (Lloyd's, DNV, BV, TUV, customer's TPI) or a customer-empowered representative. Mandatory for NORSOK M-650 qualified scope, ASME Section VIII Div 2 Class 2 vessels and most subsea / offshore tenders.
Sour-service shipments carry the NACE MR0175 / ISO 15156-3 compliance statement on the MTC. F468 caps hardness at 25 HRC; the NACE ceiling for nickel-copper is 35 HRC; the bolt clears the hardness gate by design. PMI per heat at TorqBolt's Mumbai mill verifies Ni and Cu against the MTC. Third-party witness on request - DNV, Lloyd's, BV, TUV, SGS, IRS, BIS. ISO 9001:2015 quality system, PED 2014/68/EC for European pressure-equipment duty. Detail on sour service applications and NACE MR0175.
Frequently Asked Questions on Monel 400 Fasteners
What Monel 400 fasteners do you stock? TorqBolt stocks the full nickel-copper bolting set in Mumbai - hex bolts, heavy hex bolts, socket cap screws, stud bolts, hex nuts, heavy hex nuts, lock nuts, plain and spring washers, threaded rod, anchor and foundation bolts. Bolts to ASTM F468 Class A or B; nuts to ASTM F467 Class A or B; bar input per ASTM B164; specials forged from ASTM B564 stock.
What size range is available? Imperial 1/4 in. through 1-1/2 in. ex stock, 1-3/4 in. and 2 in. on indent from B564 forging billet. Metric M6 through M40 standard, M48 through M64 on indent. Threaded rod in 1 m / 3 m and 3 ft / 6 ft / 12 ft mill lengths. Studs from 1.5 in. to 36 in. length, longer on indent. Threading per ASME B1.1 UNC, UNF or ISO metric coarse / fine.
Are Monel 400 fasteners NACE MR0175 certified for sour service? Yes. F468 caps hardness at 25 HRC across all classes and diameters, tighter than the NACE MR0175 35 HRC sour-service ceiling for nickel-copper. The bolting clears the hardness gate by design. Sour-service shipments carry EN 10204 type 3.2 with the NACE MR0175 / ISO 15156-3 compliance statement on the MTC. Verify H2S partial pressure and chloride concentration against ISO 15156-3 Annex A.4 for the full sour qualification.
Why are Monel 400 fasteners priced higher than stainless steel? Monel 400 carries 63 to 70 percent nickel and 28 to 34 percent copper against 10 to 14 percent nickel in SS 316L, so raw-material input cost runs 4 to 6 times higher per kilogram, with smaller bolting heats adding conversion cost. The premium pays back in HF acid, sour gas and marine duty where stainless and copper alloys fail in service. See pricing and vs stainless.
Related Pages
Bolting: bolts, hex bolts, heavy hex bolts, socket cap screws, cap screws, screws, stud bolts, threaded rod, anchor bolts, foundation bolts, eye bolts, U-bolts. Mating components: nuts, hex nuts, heavy hex nuts, lock nuts, washers. Standards: ASTM F468, ASTM F467, B164, B127, B165, B163, B564, NACE MR0175, DIN 17743, UNS N04400. Properties: chemistry, mechanical, density, melting point, magnetic permeability, machinability, welding, heat treatment, corrosion, seawater, HF acid. Forms: round bar, plate, sheet, pipe, tubing, wire, forging, flanges, fittings. Applications: HF alkylation, sour service, marine, nickel-copper, what is Monel 400, vs stainless, vs C276, vs K-500, data sheet, specifications, pricing, main reference.
Request a Quote. For Monel 400 fasteners (UNS N04400) - bolts, nuts, studs, washers, screws, threaded rod - send diameter, length, thread (UNC / UNF / ISO metric), head form, applicable spec, quantity and certification grade (EN 10204 type 3.1 or 3.2) to info@torqbolt.com or WhatsApp +91-22-66157017. Ex-Mumbai price and lead time returned within one working day. Domestic India 3 to 7 working days; export through JNPT.
References. ASTM F468 (Bolts, Hex Cap Screws, and Studs of Nickel Alloys). ASTM F467 (Nickel Alloy Nuts). ASTM B164 (Nickel-Copper Alloy Rod, Bar, Wire). ASTM B564 (Nickel Alloy Forgings). NACE MR0175 / ISO 15156-3. EN 10204. API RP 751. ASME B16.5 (Pipe Flanges). ASME B1.1 (Unified Inch Screw Threads). ASME B18.2.2 (Nuts for General Applications). DIN 933 / 931 / 912 / 125 / 9021 / 127 / 6798. PED 2014/68/EC. ISO 9001:2015.
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