[ Stud Bolts ]
Hastelloy C-22 Stud Bolts
Patriot Bolt machines Hastelloy C-22 stud bolts from certified ASTM B574 round bar. Alloy C-22 (UNS N06022) is a nickel-chromium-molybdenum alloy with tungsten. Its higher chromium content gives it strong resistance to oxidizing media, along with resistance to pitting, crevice corrosion and chloride stress corrosion cracking.
We make C-22 studs to the specification on your purchase order or to your drawing. Every order ships with mill test reports traceable to the heat.
[ Quick Specs ]
Hastelloy C-22 Stud Bolts at a Glance
- Also called
- Alloy C-22 · Alloy 22 · UNS N06022 · W.Nr. 2.4602
- Material specs
- ASTM B574 / ASME SB574 bar · NACE MR0175 / ISO 15156-3
- Strength
- 100 ksi min tensile, 45 ksi min yield (ASTM B574, solution annealed)
- Key elements
- 20–22.5% Cr, 12.5–14.5% Mo, 2.5–3.5% W
- Configurations
- Fully threaded, double-end and tap-end
Why Engineers Specify Hastelloy C-22 Stud Bolts
Flange studs sit in the crevice between flange faces, where process fluid collects and corrosion starts. C-22 is chosen where that crevice sees chlorides together with oxidizing or mixed acids.
- Oxidizing and reducing media. About 22% chromium handles oxidizers, while 13% molybdenum and 3% tungsten handle reducing acids.
- Pitting and crevice corrosion. C-22 is one of the most pitting-resistant nickel alloys in common use.
- Chloride stress corrosion cracking. The high nickel base resists the cracking that limits austenitic stainless studs.
- Matched joint. C-22 nuts on C-22 studs avoid galvanic mismatch in aggressive service.
Hastelloy C-22 Stud Bolt Specifications
C-22 bolting is usually ordered to ASTM B574 bar, which sets one solution-annealed condition for rod and bar.
| Specification and condition | Tensile, min | Yield (0.2%), min | Elongation, min |
|---|---|---|---|
| ASTM B574, solution annealed bar | 100 ksi | 45 ksi | 45% |
Annealed C-22 is much weaker than alloy steel bolting such as B7. Confirm the stud size and preload with your engineer.
Hastelloy C-22 Chemical Composition
| Element | Weight % |
|---|---|
| Nickel | Balance |
| Chromium | 20.0–22.5 |
| Molybdenum | 12.5–14.5 |
| Tungsten | 2.5–3.5 |
| Iron | 2.0–6.0 |
| Cobalt | 2.5 max |
| Manganese | 0.50 max |
| Vanadium | 0.35 max |
| Silicon | 0.08 max |
| Carbon | 0.015 max |
| Phosphorus | 0.02 max |
| Sulfur | 0.02 max |
Limits per the current edition of the specification. The mill test report for your heat is the controlling document.
Stud Configurations
- Fully threaded studs, threaded end to end, for flange bolting where grip length varies.
- Double-end studs, threaded on both ends with an unthreaded center.
- Tap-end studs, with one end made to thread into a tapped hole.
Nickel alloys can gall. Use a compatible thread lubricant or anti-seize on assembly.
Applications and Industries
- Chemical processing: Mixed acids, chlorinated streams and oxidizing chemicals. See Petrochemical & Refining.
- Pollution control: Flue gas desulfurization scrubbers and ducting.
- Pharmaceutical and specialty chemicals: Flanged reactors and piping where contamination matters.
- Sour oil and gas: Flanges in H2S and chloride service, within NACE MR0175 limits. See Oil & Gas.
Certification and Traceability
Patriot Bolt is ISO 9001:2015 certified. Each Hastelloy C-22 order includes mill test reports traceable to the heat, along with a certificate of conformance to the specification on your purchase order.
Studs are marked with the material and our identification.
Compare Hastelloy C-22 with other bolting grades in our Fastener Materials Matrix.
Hastelloy C-22 Stud Bolts FAQ
How is C-22 different from C-276?
C-22 has more chromium (about 22% versus 15.5%), which improves resistance to oxidizing media and pitting. C-276 has more molybdenum and is often chosen for strongly reducing acids.
What specification covers C-22 bar for studs?
ASTM B574 / ASME SB574 covers UNS N06022 rod and bar.
Is C-22 acceptable for sour service?
C-22 is listed in NACE MR0175 / ISO 15156-3 for use within the limits that standard sets. Confirm the limits for your service conditions.
Can you make C-22 studs to my drawing?
Yes. We machine C-22 studs in the diameter, length and thread on your drawing or purchase order.
Request a Quote
Send us the stud configuration, diameter, length, thread, specification and quantity, or upload your drawing. Our team will confirm the material and lead time. Call (281) 581-0176 or request a quote.