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
A286 Gas Turbine Applications — Industrial Power and Aerospace
A286 gas turbine applications span industrial power-generation gas turbines (Siemens SGT-A65 / SGT-800, GE 9F-class, Mitsubishi M501F, Solar Mercury), aero-derivative gas turbines (LM2500 / LM6000), and small auxiliary gas turbines. A286 is the dominant precipitation-hardening superalloy material for combustor liner attachment, casing-split flange bolting, exhaust diffuser bolting, and transition-piece retention — operating temperature range 540-700 °C continuous. TorqBolt manufactures the full A286 gas-turbine fastener and component range to ASTM A453 grade 660, ASTM A638 grade 660, AMS 5731-5895, and customer-specific gas-turbine OEM standards (Siemens, GE, Mitsubishi, Solar). See parent A286 stainless steel, related sister applications jet engine, nuclear, aerospace, and product variants A286 bolts, hex bolts, metric bolts.
Why A286 for This Application
Industrial gas turbines run continuously at base load for 8000-32000 hours between major overhauls. Hot-section operating temperatures 700-1100 °C with 100-300 start-stop cycles per year. A286 is selected for retained preload through thermal cycling (gamma-prime precipitation stable to 700 °C), oxidation resistance in hot-gas environments to 982 °C, NACE MR0175 sour-service compliance (offshore gas turbines exposed to sour gas), and cost-efficiency at one-third Inconel 718 cost. For hot-section components above 700 °C (turbine blades, vanes), Inconel 718 / Waspaloy / Nimonic 80A are specified — see A286 vs Waspaloy.
A286 Components Used in This Application
- Combustor liner attach bolting: NAS 1351 SHCS or M10-M16 hex bolts attach combustor liner shell to outer casing. Service temp 540-700 °C cyclic. A286 preferred over carbon steel for retained preload through thermal cycling.
- Casing-split flange bolting: Hex bolts (DIN 933 / ISO 4014 / MS 90725) on compressor / combustor / turbine casing-split flanges. M16-M30 sizes typical. Heavy hex Type 2 for high-preload Class 600+ flange joints.
- Transition piece retention: M12-M20 SHCS attach transition piece (combustor exit / turbine entry interface) to outer casing. Service temp 700-900 °C — A286 acceptable on cooler side; Waspaloy / Inconel 625 on hot side.
- Exhaust diffuser bolting: M12-M24 hex bolts attach exhaust diffuser to outer casing. Operating temp 540-820 °C. Larger flanges use heavy-hex bolts with matching A286 hex nuts.
- Inlet guide vane (IGV) actuator bolting: M5-M10 SHCS attach IGV actuator hardware. Lower temperature than hot section but vibration-critical service — use NAS 1291 / MS 21043 self-locking nuts.
- Generator coupling shaft bolting: M30-M48 hex bolts on generator coupling shaft retention (gas turbine to generator drive coupling). Service temp 200-400 °C. A286 used for non-magnetic instrumentation isolation.
- Combustor fuel manifold bolting: M5-M10 SHCS / DIN 7991 flat head countersunk on fuel manifold attachment. Wet-fuel + 200-400 °C operating environment.
- Stationary blade ring (vanes) attach: M10-M16 SHCS on stationary blade-ring (vane) support attachment. A286 acceptable for cool stages; Inconel 718 / Waspaloy for hot stages.
Governing Standards & Specifications
- ASTM A453 grade 660 Class A/B/C/D — High-temperature bolting material — the canonical gas-turbine bolt spec.
- ASTM A638 grade 660 Type 1/2 — Forged stock for gas-turbine casing forgings, transition piece forgings.
- AMS 5731 / 5732 / 5737 — Bar / forging for fastener manufacture.
- Siemens / GE / Mitsubishi proprietary specs — OEM-specific dimensional, material, inspection requirements — typically reference ASTM A453 grade 660 chemistry + custom inspection scope.
- ASME B16.5 Class 600 / 900 / 1500 / 2500 — Pressure-class flange-bolting requirements for casing-split joints.
- ASME PCC-1 — Bolted-joint preload + assembly procedures for gas-turbine flanges.
- EN 10204 type 3.1 / 3.2 — Material certification — type 3.2 third-party witness for offshore / nuclear gas turbines.
- NACE MR0175 / ISO 15156-3 — Sour-service compliance for offshore gas turbines exposed to sour gas environments.
Manufacturing & Quality Process
- VIM-VAR melt: AMS 5731 / 5732 chemistry from approved aerospace mills. Industrial gas-turbine lots may use VIM-only without VAR for cost efficiency.
- Cold or hot heading: Cold heading for sizes ≤ M16; hot heading for M18-M48 large casing-split bolts.
- Thread rolling 6g / 4g6g: Commercial 6g for industrial gas-turbine; aerospace 4g6g for aero-derivative gas turbines (LM2500 / LM6000).
- Solution treatment: Vacuum or atmosphere furnace 1650 °F (AMS 5737) or 1800 °F (AMS 5732).
- Precipitation aging: 1325 °F for 16 hours, air-cool. Hardness 29-32 HRC.
- Hardness traverse + magnetic permeability: 4-point Vickers per heat-treat batch + magnetic permeability < 1.005 verified per ASTM A342.
- Customer-specific marking: OEM-specific head marking (Siemens / GE / Mitsubishi part numbers in addition to standard A286 + lot stamp).
- EN 10204 3.1 / 3.2 certification: Type 3.1 standard for industrial; type 3.2 with third-party witness for offshore.
Material Selection by Service Condition
- Combustor section bolting (540-700 °C): A286 dominant — cost-efficient, retained preload through thermal cycling, oxidation-resistant. NAS 1351 SHCS or M10-M16 hex bolts with A286 hex nuts.
- Casing-split bolting (200-540 °C): A286 preferred for non-magnetic isolation + corrosion resistance. M16-M30 hex bolts + matched A286 heavy-hex nuts.
- Hot-section vanes / blades (700-1100 °C): NOT A286 — Inconel 718 / Waspaloy / Nimonic 80A required. See A286 vs Waspaloy.
- Aero-derivative gas-turbine bolting (LM2500): A286 NAS / MS aerospace-spec bolts — meets AS9100D AQMS for naval gas-turbine applications.
- Generator coupling shaft: A286 preferred for non-magnetic isolation + thermal-cycling fatigue.
- Offshore gas-turbine sour-service: A286 with NACE MR0175 hardness verification ≤ HRC 35. Specify on PO.
A286 Gas Turbine Applications — Industrial Power and Aerospace — Frequently Asked Questions
What gas-turbine OEMs use A286?
Siemens (SGT-A65, SGT-800, SGT-A35), GE (9F-class, LM2500, LM6000), Mitsubishi (M501, M701), Solar (Mercury, Centaur, Mars), MAN (MGT-6000), and most other industrial and aero-derivative gas turbines. A286 is the dominant precipitation-hardening superalloy fastener material globally.
Which gas-turbine components use A286?
Combustor liner attach bolting, casing-split flange bolting, exhaust diffuser bolting, transition piece retention, IGV actuator bolting, generator coupling shaft bolting, stationary blade ring (vane) attach. Hot-section blades and vanes typically use Inconel 718 / Waspaloy / Nimonic 80A instead.
Why A286 instead of carbon steel for gas-turbine bolting?
Carbon-steel bolts lose preload through thermal cycling — A286 retains 90 %+ of preload through 540-700 °C cycling. Carbon steel also corrodes in hot-gas environments; A286 oxidation-resistant to 982 °C. Cost premium of A286 (vs B7) is justified by overhaul-interval extension.
Can A286 bolts be used in offshore gas-turbine?
Yes — NACE MR0175 / ISO 15156-3 compliance with hardness ≤ HRC 35 verified. Common on Shell / BP / Aramco / Adnoc offshore gas-turbine power-generation modules.
What's the typical bolt-replacement interval on industrial gas turbines?
Combustor liner + transition piece bolts: every C-inspection (~24,000-32,000 hours). Casing-split bolts: at major overhaul (typically 64,000-100,000 hours). A286 retains 90 % preload through these intervals — replacement is per OEM mandate, not material degradation.
Are A286 bolts NACE-compliant for sour gas-turbine fuel?
Yes — A286 grade 660 with hardness ≤ HRC 35 per NACE MR0175 / ISO 15156-3 is sour-service compliant. Specify on PO; each heat receives Vickers traverse before release.
Which is better for gas-turbine bolting — A286 or Inconel 718?
For service ≤ 700 °C — A286 (cost is one-third). For applications requiring tensile > 1240 MPa or extended fatigue life — Inconel 718. See A286 vs Inconel 718 for full comparison.
What's the lead time on Siemens-spec A286 bolts?
Siemens / GE / Mitsubishi proprietary specs: 8-12 weeks from heat release. Custom drawing parts add 2-3 weeks. EN 10204 3.2 third-party witness: add 1-2 weeks. Aerospace AS9102 first-article on aero-derivative applications: add 2-3 weeks.
Are A286 gas-turbine bolts magnetic?
No. Magnetic permeability < 1.005 verified per ASTM A342 on every aerospace and gas-turbine heat. Critical for non-magnetic isolation of speed sensors, vibration sensors, and electromagnetic-sensitive instrumentation in modern gas turbines.
Related Applications & A286 Reference
Other A286 application reference pages: jet engine fasteners · gas turbine applications · nuclear applications · aerospace fasteners.
Canonical A286 reference: A286 chemical composition · A286 mechanical properties · A286 heat treatment · AMS / ASTM specifications hub · alloy comparisons (vs Inconel 718 · vs Waspaloy).
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