Hastelloy bolts — most commonly manufactured from alloys C-276 (UNS N10276), C-22 and select Ni-Cr-Mo grades — are the premium choice when long-term resistance to pitting, crevice corrosion, and mixed-acid environments is required; they combine a nickel base with elevated molybdenum, chromium and (in some grades) tungsten to deliver corrosion performance that outperforms stainless steels and many other nickel alloys in aggressive chemical service. For critical chemical-processing, pharmaceutical, and offshore applications where failure is not an option, Hastelloy bolts are cost-effective over service life despite a higher upfront price.

What are Hastelloy bolts?

Hastelloy bolts are mechanical fasteners manufactured from Hastelloy family alloys — high-nickel, nickel-chromium-molybdenum (and sometimes tungsten) compositions designed for extreme corrosion resistance. They are produced as hex bolts, socket cap screws, studs, nuts and washers and are specified where aggressive process chemistries (e.g., oxidizing/reducing acids, chloride-bearing media, mixed acids) or elevated temperatures risk rapid degradation of standard materials. Common industries: chemical processing, pharmaceuticals, pollution control scrubbers, oil & gas (sour/acid environments), and specialty research equipment.

Common Hastelloy grades used for fasteners

• Hastelloy C-276 (UNS N10276 / W. Nr. ~2.4819) — most widely used for fasteners because of balanced resistance to oxidizing and reducing media, plus weldability and stability in welded zones.

• Hastelloy C-22 (UNS N06022) — higher chromium content gives superior pitting/crevice resistance in chloride-bearing oxidizing media; chosen where localized attack is the primary risk.

• Hastelloy N — used when resistance to high-temperature oxidation and molten salts is needed (less common for standard fasteners).

• Other Hastelloy families (X, B2, C263, etc.) — used for specialized applications (X for high-temperature strength; B2 for reducing acids), occasionally made into fasteners where requirements match the alloy’s niche.

Material properties

Table: Typical property ranges for Hastelloy C-276 (representative for many C-type fasteners). Values are nominal; always request certified test reports from suppliers for critical engineering use.

Sources / reference reading: manufacturer datasheets and alloy literature give these ranges; see Haynes/Hastelloy technical pages and alloy suppliers for certified values.

Chemical composition (typical / nominal)

Below is a concise nominal composition table for the two most common Hastelloy fastener alloys: C-276 and C-22. These figures are industry-typical; confirm exact composition with material certificates (MTR/COC).

(Data compiled from alloy technical sheets and material databases.)

Manufacturing standards & material designations

When specifying Hastelloy fasteners, reference standards and designations are essential for procurement and inspection:

• UNS / ASTM / ASME: e.g., UNS N10276 (Hastelloy C-276), ASTM B574 / ASME SB574 for fastener bars and studs; ASTM B564 for specified wrought forms.

• DIN / ISO equivalents: DIN 2.4819 or ISO designations are sometimes listed by European manufacturers — confirm equivalence on datasheets.

• Marking & heat-numbers: Demand mill heat numbers, MTRs, and specification stamping per buyer specification (traceability). Suppliers such as established fastener houses will supply certificates on request.

Sizes & weight

Hastelloy fasteners are made across standard size ranges. The table below gives representative weights for common hex bolts (approximate; weight depends on thread length and head form). Use this for logistics and shipping estimates — always calculate precisely from dimensional charts for large orders.

Example: Hex bolt (full thread) weights (approximate per piece)

For studs and heavy hex bolts the weights grow substantially — consult a bolt weight calculator or supplier weight chart (many fastener manufacturers publish downloadable PDFs).

Machinability, torque guidance & installation notes

• Machining: Hastelloy alloys are notoriously tougher to machine than carbon steels or austenitic stainless steels. Expect slower feed rates, robust tooling (carbide), rigid setups and higher tool wear. Pre-planning saves cost.

• Torque & preload: Use manufacturer torque charts (some fastener suppliers publish Hastelloy torque tables). Because surface finish and thread lubrication affect clamp load, verify torque values by testing or follow ASME/ANSI recommendations for the bolt class and nominal diameter.

• Surface treatment: Hastelloy fasteners are often left uncoated to preserve corrosion resistance; avoid incompatible platings that reduce effectiveness. Locking methods: stainless lock washers, PTFE-filled locking elements rated for corrosive service.

• Welding and heat: Many C-grades are weldable and resist precipitation in HAZ; still, welding fasteners must follow qualified procedures to avoid distortion or localized corrosion susceptibility.

Corrosion behavior — what Hastelloy resists and when caution is needed

Hastelloy C-type alloys resist pitting, crevice corrosion, stress-corrosion cracking, and general corrosion across a broad pH range, including oxidizing and reducing acids, chlorinated media and mixed acids. C-22 typically offers the best localized corrosion resistance, C-276 is the most versatile in mixed environments. However:

• Very aggressive oxidizers at elevated temperatures or environments with contaminants can still challenge alloys; engineering assessment (e.g., CPT/ASTM G48 tests, corrosion coupons) is recommended for critical installations.

Comparative selection: Hastelloy vs other alloys

• Vs 316/316L stainless: Hastelloy outperforms 316 in chloride, oxidizing acids and mixed chemistries; cost is higher but lifecycle cost often lower for critical service.

• Vs Monel: Monel (nickel-copper) excels in reducing environments like hydrofluoric acid and some marine conditions; Hastelloy offers broader chemical resistance, especially to oxidizing agents.

• Vs Inconel: Inconel family is focused on high-temperature strength (oxidation/creep resistance); Hastelloy prioritizes corrosion resistance across solutions — choose based on temperature vs chemical attack priorities.

Global price snapshot (2025): USA, Europe, China

Pricing for Hastelloy fasteners depends on alloy, size, head form, finish, quantity and certification level. Below is a market snapshot indicative table for single-piece to small-bundle purchases in mid-2025, synthesized from specialist fastener houses, alloy traders, and supplier price lists. Use this for budgeting; get a supplier quotation for firm pricing.

Notes: Prices are per piece for a medium size fastener (example: M12 × 40 hex bolt). Bulk purchase discounts, minimum order quantities, and custom heat-treatment/certification add cost. Always ask for MTRs, packaging and freight terms.

Market evidence: Chinese exporters and alloy houses list notably lower factory prices for common sizes; US/EU distributors add markups, inventory carrying costs and certification services which raise end prices. Online marketplaces show single pieces (small quantities) sometimes at premium prices (e.g., eBay listings).

Supply, lead times, inspection & certifications

• Supply reality: Hastelloy fasteners are specialty items; while some houses keep stock for common sizes, many items are made-to-order. Lead times vary from a few days (stock) to several weeks for cut-to-length, cold-formed or certified lots.

• Certs to request: Mill Test Report (MTR / EN 10204 3.1 or 3.2), chemical & mechanical test certificates, PMI or spectro reports if required, hardness report, and, for critical industries, third-party inspection.

• QA / traceability: Specify heat numbers, batch sampling and NDT where necessary. For flange bolting on pressure equipment, require traceable MTRs and dimensional inspection reports.

Why choose MWAlloys

MWAlloys is a Chinese specialist in exotic-metal fasteners and bar stock. We combine factory direct pricing with export experience and stock availability for common Hastelloy sizes. Our advantages:

• Factory price: 100% factory direct pricing for standard fasteners — competitive vs distributor markups.

• Inventory & speed: We maintain inventory of common sizes and can ship from China quickly; for bespoke sizes we run prioritized production.

• Certs & QC: All material ships with MTRs (EN 10204 or buyer-required formats), dimensional inspection and sample mechanical tests on request.

• Export capability: Experience exporting to the US, EU and Middle East with proper packing, customs paperwork and reliable freight options.

Practical selection checklist

1. Define the exact alloy (C-276 vs C-22 vs other) based on whether pitting/crevice or mixed corrosion is the main risk.

2. Specify standard (ASTM/ASME or DIN) and required MTR type (3.1/3.2).

3. Confirm size, length, head form, thread class and whether stud or full-thread is required.

4. Specify quantity and acceptance criteria for machining or surface finish.

5. Request sample bolts and torque testing if in doubt; perform material verification on arrival (PMI or spectro).

Frequently asked questions (FAQs)

1: Which Hastelloy grade should I pick for chloride-rich environments?
Hastelloy C-22 generally provides better resistance to chloride-induced pitting and crevice corrosion than C-276; however, selection depends on temperature and oxidizer presence. For mixed environments C-276 remains a versatile choice.

2: Are Hastelloy bolts weldable?
Many Hastelloy C-grades are weldable and resist HAZ precipitation, but welding fasteners requires qualified procedures; ask your supplier for welding guidelines.

3: How much more do Hastelloy bolts cost compared with 316 stainless?
Material costs can be several times higher; small-quantity fasteners may cost tens of dollars each versus pennies for 316. Factor life-cycle savings when corrosion failure is critical. Market pricing varies by region (see pricing table).

4: Can Hastelloy bolts be used in high-temperature flanged connections?
Yes for many C-grades to moderate high temperatures (service up to several hundred °C), but consult alloy-specific data for sustained strength and oxidation limits.

5: Do Hastelloy bolts need special thread lubricants?
Use lubricants compatible with process chemistry and that do not reduce corrosion resistance; some applications avoid coatings and use PTFE or approved anti-seize compounds.

6: Is lead time long for Hastelloy fasteners?
Stock items ship quickly; MTO items with certification can take weeks. Factory suppliers like MWAlloys can offer faster turnaround on many sizes.

7: Are Hastelloy fasteners magnetic?
No, Hastelloy is a nickel-base austenitic alloy family and is essentially non-magnetic in normal conditions.

8: Are there standard torque charts for Hastelloy bolts?
Distributors and fastener specialists publish torque tables; use these and compensate for lubrication and thread class. Verify with clamp-load tests for critical joints.

9: Can Hastelloy bolts be passivated or plated?
Plating is usually unnecessary and may be inadvisable; passivation is less common for nickel superalloys. If coating is required, confirm chemical compatibility.

10: What documentation should I require from a supplier?
MTR (chemical & mechanical), heat number traceability, dimensional inspection report, and any specified third-party certifications (especially for pressure-boundary use).