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
ASTM A453 Grade 660 — A286 High-Temperature Bolting
ASTM A453 grade 660 is the dominant industrial high-temperature bolting specification for A286 (UNS S66286). Issued by ASTM International, the specification covers A286 bolting in four classes (A, B, C, D), each defining a specific solution-treatment + aging combination and resulting mechanical property profile. ASTM A453 is the canonical bolting spec for petrochemical, gas-turbine, nuclear, oil & gas, and industrial flange-bolting applications. Class A is most common (high room-temperature tensile + yield); Class B emphasises stress-rupture; Classes C and D cover specific temperature-controlled property requirements. See parent A286 AMS / ASTM specifications hub, related A286 hex bolts, stud bolts, hex nuts. For the full ASTM A453 grade 660 specification reference covering all four classes, dimensions and applicable products, TorqBolt also maintains a dedicated ASTM A453 Grade 660 specification site.
Spec Scope & Coverage
ASTM A453 grade 660 covers A286 bolting (bolts, studs, screws, nuts) for high-temperature service. Material is hot-worked from VIM-VAR ingot, machined to fastener form, then heat-treated per the specified class. Class A: sol 1650 °F + aged. Class B: sol 1800 °F + aged. Class C: sol-treated only (downstream aging). Class D: alternate sol-treatment for stress-rupture optimization. The spec mandates EN 10204 type 3.1 mill cert minimum; type 3.2 third-party witness for nuclear and offshore applications.
A286 Chemical Composition (UNS S66286)
| Element | Min % | Max % | Notes |
|---|---|---|---|
| Iron (Fe) | Balance | Balance | ~53 % typical |
| Nickel (Ni) | 24.0 | 27.0 | Solid-solution stabilizer |
| Chromium (Cr) | 13.5 | 16.0 | Corrosion + oxidation resistance |
| Titanium (Ti) | 1.90 | 2.35 | Gamma-prime former (Ni3Ti) |
| Molybdenum (Mo) | 1.00 | 1.50 | Solid-solution strengthener |
| Vanadium (V) | 0.10 | 0.50 | Carbide stabilizer |
| Aluminium (Al) | 0 | 0.35 | Gamma-prime former (Ni3Al) |
| Boron (B) | 0.001 | 0.010 | Grain-boundary strengthening |
| Carbon (C) | 0 | 0.08 | Per ASTM A453 |
| Manganese (Mn) | 0 | 2.00 | Per ASTM A453 |
| Silicon (Si) | 0 | 1.00 | Per ASTM A453 |
| Phosphorus (P) | 0 | 0.025 | Trace impurity |
| Sulphur (S) | 0 | 0.015 | Trace impurity |
ASTM A453 Grade 660 — A286 High-Temperature Bolting — Spec Requirements
| Class | Heat treatment | Tensile MPa | Yield MPa | Hardness HRC | Application |
|---|---|---|---|---|---|
| Class A | Sol 1650 °F + aged 1325 °F × 16 h | ≥ 895 | ≥ 655 | 29-37 | Highest room-temperature tensile + yield. Most common. |
| Class B | Sol 1800 °F + aged 1325 °F × 16 h | ≥ 895 | ≥ 585 | 24-37 | Higher stress-rupture; lower yield. Used for hot-section bolting. |
| Class C | Solution-treated only | Per spec | Per spec | 24-32 | Customer ages downstream for specific property profile. |
| Class D | Alternate sol-treatment | ≥ 895 | Per spec | Per spec | Specialty application — typically aerospace bolting. |
When to Specify ASTM A453 Grade 660 — A286 High-Temperature Bolting
- Industrial flange bolting: Class A — the canonical industrial bolting class. Used for ASME B16.5 Class 600+ flange bolting in petrochemical, gas-turbine, oil & gas service.
- Hot-section / stress-rupture critical: Class B — higher stress-rupture strength at temperature. Used for combustor-section and turbine-attach bolting where 1100-1200 °F service requires extended creep life.
- Custom heat-treatment timing: Class C — sol-treated only, customer ages after specific machining or assembly steps.
- Aerospace-spec bolting (non-NAS): Class A or B — for aerospace applications not requiring NAS / MS dimensional spec.
- NACE MR0175 sour-service: Class A or B with hardness verification ≤ HRC 35. Specify on PO.
- ASME III nuclear bolting: Class A — accepted in ASME Section III Subsection NB / NF for primary-pressure-bearing service.
ASTM A453 Grade 660 — A286 High-Temperature Bolting — Frequently Asked Questions
What is ASTM A453 grade 660?
ASTM industrial spec for A286 (UNS S66286) high-temperature bolting. Grade 660 is the A286-specific designation; 'Iron Alloy 660' is the common name. Four classes: A (sol 1650 °F + aged), B (sol 1800 °F + aged), C (sol only), D (alternate sol).
Class A vs Class B — which to specify?
Class A: higher room-temperature yield (655 MPa vs 585 MPa Class B). Class B: higher stress-rupture strength at 1100-1300 °F. Choose A for room-temperature applications and high-load bolting; B for hot-section stress-rupture-critical service.
Is ASTM A453 the same as AMS 5732?
Heat-treatment is essentially identical (sol 1650 °F + aged 1325 °F for ASTM A453 Class A vs AMS 5732). Chemistry is identical (UNS S66286). Difference is scope: ASTM A453 is industrial bolting; AMS 5732 is aerospace bar/forging/tubing under AS9100D AQMS. For industrial, cite ASTM A453; for aerospace, cite AMS 5732.
What's the most common A453 class?
Class A — used for the majority of industrial high-temperature bolting (ASME B16.5 Class 600+ flange, gas-turbine casing-split, petrochemical pressure-vessel). Class B is second-most common for hot-section bolting.
Is ASTM A453 grade 660 ASME III nuclear-acceptable?
Yes — Class A is accepted in ASME Section III Subsection NB (pressure vessels) and Subsection NF (component supports) for primary-pressure-bearing nuclear applications. EN 10204 type 3.2 third-party witness required for nuclear-safety-critical lots.
Can ASTM A453 grade 660 be NACE MR0175 sour-service compliant?
Yes — when supplied with hardness ≤ HRC 35 (HV ≤ 327) per NACE MR0175 / ISO 15156-3. Class A or B with hardness verification by Vickers traverse. Specify on PO.
What head marking on ASTM A453 grade 660 bolts?
Per ASTM F788: head-stamped 'A286' or 'GR 660' for ASTM A453 traceability + lot number + manufacturer ID 'TB'. Specific class (A/B/C/D) typically not stamped — verified via mill certificate.
What's the lead time on A453 grade 660 bolts?
Standard sizes M6-M30: 4-6 weeks from heat release. Larger sizes M36-M64: 6-10 weeks. EN 10204 type 3.2 third-party witness: add 1-2 weeks. NACE MR0175: no lead-time impact (verified during normal heat-treat cycle).
Is ASTM A453 grade 660 magnetic?
No. Magnetic permeability < 1.005 verified per ASTM A342. Critical for non-magnetic instrumentation, MRI, and aerospace electromagnetic-sensitive applications.
Mechanical Properties per This Spec
| Class | Tensile (MPa) | Yield (MPa) | Hardness HRC |
|---|---|---|---|
| Class A (Sol 1650 °F + aged) | ≥ 895 | ≥ 655 | 29-37 |
| Class B (Sol 1800 °F + aged) | ≥ 895 | ≥ 585 | 24-37 |
| Class C (Sol only) | Per spec | Per spec | 24-32 |
| Class D (Alternate sol) | ≥ 895 | Per spec | Per spec |
A286 Products Manufactured per This Spec
TorqBolt manufactures the following A286 products to this specification:
- A286 Hex Bolts
- A286 Stud Bolts
- A286 Hex Nuts
- A286 Self-Locking Nuts
- A286 Lock Nuts
- A286 Cap Screws
- A286 Threaded Rod
- A286 Tie Rod
Mating & Related Specifications
Common mating and related A286 specifications used alongside this spec:
- AMS 5732 — Aerospace bar / forging equivalent.
- ASTM A638 grade 660 — Forgings spec — for forged bolting stock.
- ASTM B637 — Industrial bar alternative.
Drawing Call-Out Example
A286 stud bolt, ASTM A453 grade 660 Class A, sol-treated and aged, M16 × 2.0 × 100 mm length, 6g class, NACE MR0175 hardness ≤ HRC 35 verified, EN 10204 3.2.
Related A286 Specifications & Reference
Other A286 specifications: AMS / ASTM hub · AMS 5525 · AMS 5731 · AMS 5732 · AMS 5737 · AMS 5853 · AMS 5895 · ASTM A453 grade 660 · ASTM A638 grade 660 · ASTM B637 · DIN 1.4980 · UNS S66286.
Canonical A286 reference: A286 chemical composition · A286 mechanical properties · A286 heat treatment · alloy comparisons (vs Inconel 718 · vs Waspaloy).
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