Patriot Bolt machines A286 stud bolts from certified round bar for flanged joints that run hotter than B7 or B16 alloy steel can handle. A286, also called Alloy 660, Grade 660 and Incoloy A-286 (UNS S66286), is an age-hardenable iron-nickel-chromium superalloy. It holds 130 ksi minimum tensile strength and keeps its strength and oxidation resistance to about 1300 °F.
We make A286 studs to ASTM A453 Grade 660 (Class A, B, C or D) or to your drawing. Every order ships with mill test reports traceable to the heat.
A286 Stud Bolts at a Glance
- Also called
- Alloy 660 · Grade 660 · Incoloy A-286 · UNS S66286 · W.Nr. 1.4980
- Specification
- ASTM A453 Gr 660 Class A, B, C, D
- Strength
- 130 ksi min tensile; 85 ksi min yield (Class A, B, C) or 105 ksi (Class D)
- Service range
- Cryogenic to about 1300 °F; non-magnetic
- Configurations
- Fully threaded, double-end and tap-end
Why Engineers Specify A286 Stud Bolts
Stud bolts in hot service lose preload as the steel relaxes. Alloy steel grades such as B7 and B16 are limited by tempering and creep, and austenitic stainless studs are not strong enough to hold high preload. A286 closes that gap.
- Relaxation resistance. A286 is precipitation hardened, so it keeps clamp load in gas turbine casings, exhaust flanges and hot valve bonnets.
- Low-temperature toughness. It stays ductile at cryogenic temperatures, so one stud grade can cover cold and hot cycles.
- Corrosion and oxidation resistance. With about 15% chromium and 25% nickel, it resists scaling and general corrosion far better than alloy steel.
- Non-magnetic. Useful near instruments and in aerospace assemblies.
A286 Stud Bolt Specifications
ASTM A453 covers high-temperature bolting with expansion coefficients similar to austenitic steels. Grade 660 is offered in four classes that share the same chemistry and differ in heat treatment.
| Class | Tensile, min | Yield (0.2%), min | Elong. / RA, min | Hardness (HB) |
|---|---|---|---|---|
| A | 130 ksi | 85 ksi | 15% / 18% | 248–341 |
| B | 130 ksi | 85 ksi | 15% / 18% | 248–341 |
| C | 130 ksi | 85 ksi | 15% / 18% | 248–341 |
| D (to 2-1/2 in.) | 130 ksi | 105 ksi | 15% / 18% | 248–321 |
Classes A, B and C also carry a stress-rupture requirement at 1200 °F. Order the class your design or code calls for, and we machine and certify to it.
A286 Chemical Composition
| Element | Weight % |
|---|---|
| Nickel | 24.0–27.0 |
| Chromium | 13.5–16.0 |
| Titanium | 1.90–2.35 |
| Molybdenum | 1.00–1.50 |
| Vanadium | 0.10–0.50 |
| Aluminum | 0.35 max |
| Carbon | 0.08 max |
| Manganese | 2.00 max |
| Silicon | 1.00 max |
| Boron | 0.003–0.010 |
| Iron | Balance |
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.
A286 can gall against itself and stainless nuts. Use a thread lubricant rated for the service temperature.
Applications and Industries
- Power generation: Gas and steam turbine casing, combustor and exhaust flange studs. See Power Generation.
- Aerospace: Engine and test-cell bolting where strength at temperature matters. See Aerospace.
- Oil and gas: Hot and cryogenic flanges and valve bodies. See Oil & Gas.
Certification and Traceability
Patriot Bolt is ISO 9001:2015 certified. Each A286 order includes mill test reports traceable to the heat, along with a certificate of conformance to the specification on your purchase order.
For the full A286 product range, see A286 fasteners.
Compare A286 with other bolting grades in our Fastener Materials Matrix.
A286 Stud Bolt FAQ
Is A286 the same as Grade 660?
Yes. A286, Alloy 660, Grade 660 and Incoloy A-286 all refer to UNS S66286. “Grade 660” is the ASTM A453 bolting designation.
When should I use A286 studs instead of B16?
When the joint runs above the range where alloy steel holds preload, or when you need corrosion resistance or non-magnetic studs. Follow your design code for the exact limit.
Which Grade 660 class should I order?
Classes A, B and C share the same minimum properties and differ in heat treatment. Class D has a higher yield strength and lower maximum hardness. Follow your drawing or code, or send us the application.
Can you supply matching nuts?
Yes. We also machine A286 nuts, so the stud and nut can come from one source.
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.
Also in A286: All A286 fasteners · Socket head cap screws · Nuts · All stud bolts