Nickel Fasteners
Manufacturer
India · Mumbai
Why Pure Nickel — When No Alloy Is Enough
Pure Nickel 200 and 201 fasteners occupy a unique position in the exotic alloy fastener landscape: they are specified not where the process fluid is the most aggressive, but where it is the most specific. Caustic soda (NaOH) at high concentration and temperature is the primary application — above approximately 50% NaOH concentration and 70°C, even the best stainless steels, Hastelloy C276, and Monel 400 corrode rapidly by stress corrosion cracking or intergranular attack. Pure nickel, with its face-centred cubic structure and high stacking fault energy, is immune to stress corrosion cracking in caustic at all concentrations up to molten sodium hydroxide.
The second niche is hydrofluoric acid (HF) and fluorine-containing media. Pure nickel forms a stable, adherent nickel fluoride surface film in HF that prevents further attack — making it the preferred material for HF alkylation unit flanges at temperatures and concentrations where Monel 400 (the standard HF acid alloy for piping) is unavailable in fastener form or where pure nickel is contractually specified.
A third application is dry fluorine gas (F₂) and fluoride salt service — pure nickel’s fluoride film is the barrier that permits handling of elemental fluorine in uranium hexafluoride (UF₆) processing, fluorination reactors, and fluoropolymer synthesis equipment. No other common engineering alloy forms a stable fluoride protective film.
Nickel 200 vs Nickel 201: The two grades are chemically identical except for carbon content. Nickel 200 has ≤0.15% carbon. Nickel 201 has ≤0.02% carbon. Below 315°C (600°F), both grades perform identically — use Nickel 200. Above 315°C, carbon in Nickel 200 can precipitate as grain boundary carbides causing embrittlement; Nickel 201 is mandatory for service above 315°C. This temperature boundary is the only criterion for grade selection between the two.
For ASME B16.5 pressure flange stud bolt applications in caustic soda plant, the matching nut must also be Nickel 200 or 201 — a stainless steel nut in a Nickel 200 stud bolt assembly will corrode preferentially in hot concentrated NaOH service. Akbar Fasteners supplies matched Nickel 200/201 assemblies (stud bolt + heavy hex nut + washer) from the same ASTM B160 certified heat.
PMI XRF verification is particularly important for pure nickel because it has a higher unit value and is more commonly substituted than other exotic alloys. Every bar of Nickel 200/201 from Akbar Fasteners is PMI-verified by XRF spectrometer before machining, confirming ≥99.0% Ni and compliance with ASTM B160 composition limits. NABL-accredited tensile and hardness test reports are dispatched with every order.
Nickel 200 vs Nickel 201 — The Temperature Rule
The grade selection between Nickel 200 and Nickel 201 has one criterion only: service temperature. Below 315°C — Nickel 200. Above 315°C — Nickel 201. Both grades from ASTM B160 certified Akbar Fasteners stock with full MTC, PMI, and COC.
Nickel 200
| Element | Limit | Typical |
|---|---|---|
| Nickel (Ni + Co) | ≥99.0% | ~99.5% |
| Carbon (C) | ≤0.15% | ~0.08% |
| Manganese (Mn) | ≤0.35% | — |
| Iron (Fe) | ≤0.40% | — |
| Silicon (Si) | ≤0.35% | — |
Nickel 201
| Element | Limit | Typical |
|---|---|---|
| Nickel (Ni + Co) | ≥99.0% | ~99.5% |
| Carbon (C) | ≤0.02% | ~0.01% |
| Manganese (Mn) | ≤0.35% | — |
| Iron (Fe) | ≤0.40% | — |
| Silicon (Si) | ≤0.35% | — |
Why Pure Nickel — Where No Other Alloy Works
Hot Caustic Soda Immunity
Unique SCC resistance in concentrated NaOH above 50% and 70°C — where stainless steel, Hastelloy C276, Monel 400, and all other standard exotic alloys fail by stress corrosion cracking or intergranular attack. Caustic soda evaporators, neutralisation vessels, NaOH concentration plant, electrolytic cell bolting — the only correct fastener material is pure nickel.
Stable Fluoride Film in HF
In hydrofluoric acid (HF) at concentrations and temperatures where Monel 400 has insufficient corrosion resistance, pure nickel forms an adherent nickel fluoride (NiF₂) surface film that provides outstanding corrosion protection. HF alkylation unit process flanges, HF gas scrubbers, and fluoride salt handling equipment where Nickel 200 is the contractually specified fastener material.
Dry Fluorine and Fluorides
The only engineering alloy that can be used in dry elemental fluorine gas (F₂) service — the nickel fluoride passive film is stable in anhydrous fluorine. Uranium hexafluoride (UF₆) processing, fluorine gas distribution, fluorination reactor bolting, and fluoropolymer synthesis equipment where no other common alloy provides adequate service life.
Non-Magnetic & Food-Grade
Pure nickel is non-magnetic in the solution-annealed condition — a critical property for MRI equipment fastening, mineral processing electromagnetic separation systems, and scientific instrumentation. Also specified for food-grade NaOH and lye handling in food processing caustic wash systems where iron contamination from stainless steel is unacceptable.
Nickel 200 / 201 Fastener Types
All forms machined from ASTM B160 certified UNS N02200 / N02201 annealed bar. PMI-verified before production. Matched sets from the same heat for single-MTC assembly documentation.
Stud Bolts
Fully threaded and double-end. Nickel 200 (below 315°C) and Nickel 201 (above 315°C). Class 150–2500, M12–M100, lengths to 3,000mm. Caustic soda concentrator flanges, NaOH electrolyser cell bolting, HF alkylation unit pressure flanges, and fluorine gas system connections.
Hex Bolts
Full thread and partial thread. M6–M100. Nickel 200/201 hex bolts for caustic evaporator cover bolts, NaOH plant equipment connections, HF acid plant structural bolting, and all non-flange bolted connections in hot concentrated caustic service where stud bolt assembly is not used.
Hex Nuts
Standard hex, heavy hex. M6–M100. Matched from same ASTM B160 certified heat as stud bolts — same grade (Nickel 200 or 201 per service temperature). Zero galvanic potential at the nut bearing face in caustic and HF acid service. One MTC covers the complete stud bolt set.
Washers
Plain flat and spring helical. M5–M100. Nickel 200/201 washers for matched-grade assembly in caustic soda plant — eliminating the galvanic corrosion risk at the washer-nut bearing face in hot NaOH where a stainless washer under a Nickel 200 nut would corrode first.
Threaded Rods
Full thread and end-thread. M6–M100, lengths to 3,000mm. Nickel 200/201 threaded rods for NaOH plant hanger systems, caustic evaporator structural rods, and HF acid plant structural tie-rods where threaded rod material must match the process environment.
Socket Cap Screws
Hex socket cylindrical head in Nickel 200 for confined-access bolting in caustic plant — electrolyser cell internal fittings, NaOH handling equipment internal fixtures, fluorine gas system instrument connections where hex head clearance is unavailable. M4–M24.
Coupling Nuts
Long hex coupling nuts in Nickel 200/201 for joining threaded rods and extending stud bolts in NaOH plant expansion joints and caustic evaporator structural connections. M6–M100. From same certified ASTM B160 heat as threaded rods.
Matched Assembly Sets
Nickel 200/201 stud bolts + heavy hex nuts + washers from the same ASTM B160 certified heat. Single MTC, PMI XRF, and COC for the complete caustic or HF acid flange assembly — single-source documentation for EPC TPI hold plans.
Nickel Fastener Corrosion Environment Guide
Pure nickel fasteners have a narrow and specific application range. This table identifies the correct grade and alternative alloys where pure nickel is or is not the correct choice — avoiding misspecification.
| Service Environment | Nickel 200 | Nickel 201 | Alternative Alloy |
|---|---|---|---|
| PRIMARY NICKEL FASTENER APPLICATIONS | |||
| Caustic NaOH ≥50% concentration below 315°C | ✔ Correct Grade | ✔ Acceptable | — |
| Caustic NaOH at any concentration above 315°C | ✗ Risk of embrittlement | ✔ Required Grade | — |
| Molten NaOH / KOH (above melting point) | ✗ Not suitable | ✔ Only Option | — |
| HF Acid high concentration / elevated temp | ✔ Preferred | ✔ If >315°C | Monel 400 (lower temp) |
| Dry Fluorine Gas (F₂) service | ✔ Only Option | ✔ If >315°C | — |
| Fluoride Salts (NaF, KF, HF vapour) | ✔ Correct | ✔ If >315°C | Monel 400 (some) |
| WHERE OTHER ALLOYS ARE PREFERRED | |||
| Dilute caustic NaOH below 50% below 70°C | Acceptable (but costly) | Acceptable | SS 316L sufficient |
| HCl at all concentrations | ✗ Poor | ✗ Poor | Hastelloy B3 / B2 |
| Mixed / undefined acid media | ✗ Not suitable | ✗ Not suitable | Hastelloy C276 |
| Seawater / marine service | Acceptable | Acceptable | Monel K500 / 400 |
| Oxidising acids (HNO₃, H₂SO₄ hot conc.) | ✗ Not suitable | ✗ Not suitable | Hastelloy C22 / C276 |
Grade selection queries: sales@akbarfasteners.in · HCl: Hastelloy B3 · Mixed acids: Hastelloy C276
Industry Applications
The caustic, HF acid, fluorine, and non-magnetic applications where no other alloy is an acceptable substitute for pure nickel fasteners.
Caustic Soda Plant
caustic evaporator covers
Chlor-Alkali / Electrolysis
electrolyser internal fittings
HF Alkylation Units
high-temp HF pressure joints
Fluorine Gas Processing
UF₆ processing bolts
Fluoropolymer Production
fluorination reactor flanges
Nuclear Industry
non-magnetic radiation zones
Food & Pharma
caustic wash system
MRI & Instrumentation
MRI equipment fasteners
Standards We Manufacture & Test To
Same quality system as our Hastelloy B3 stud bolts. NABL-accredited testing and full heat traceability on every Nickel 200/201 order.
Complete Documentation Package
Heat & Lot Traceable
Conformance
100% Lots Verified
Tensile · Hardness
TÜV · BV · Lloyds
Compare Related Fastener Alloys
Pure nickel for caustic and HF. Monel 400 for seawater and dilute HF. Hastelloy B3 for reducing HCl. Hastelloy C276 for mixed acids.
Monel 400 Fasteners
Ni-Cu alloy for seawater, dilute HF acid, and brine service below temperatures where pure nickel is required. Standard HF acid fastener alloy for room-temperature to moderate-temperature HF service.
View Page →Hastelloy B3 Stud Bolts
For HCl at all concentrations — where neither pure nickel nor Monel 400 performs adequately. The 28% Mo Ni-Mo alloy for reducing acid service completely different from the caustic / fluorine niche.
View Page →Hastelloy C276 Fasteners
For mixed or undefined acid media where pure nickel is unsuitable. C276 covers the broadest range of corrosive environments — the correct default when the process chemistry is not precisely characterised.
View Page →Exotic Alloy Fasteners India
Complete exotic alloy fastener range from Akbar Fasteners — Hastelloy, Monel, Inconel, Nickel, Titanium, Duplex. Grade selection guidance from our Mumbai facility for any corrosive service.
View Full Range →Need Nickel 200 or
Nickel 201 Fasteners?
Grade · product form · size · quantity · service temperature · documentation. Akbar Fasteners Pvt. Ltd. responds within 24 hours with pricing, lead time, and MTC documentation list.
Export: +91 8696 32 4646 · Support: +91 800 9315 333 · export@akbarfasteners.in