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 Flanges
A286 flanges are forged precipitation-hardening superalloy flanges used as bolted-joint termination of A286 pipe and pressure-vessel connections in high-temperature service. TorqBolt manufactures A286 flanges to ASTM A182 grade A286 (forged or rolled alloy steel pipe flanges, extended for A286 chemistry), ASME B16.5 (pipe flanges and flanged fittings — NPS 1/2 to 24), and ASME B16.47 (large-diameter pipe flanges — NPS 26 to 60). Pressure classes 150 / 300 / 600 / 900 / 1500 / 2500 per ASME B16.5. Heat-treated per AMS 5731 / 5732 / ASTM A638 grade 660 to deliver 130 ksi tensile / 95 ksi yield, retained mechanical properties to 700 °C continuous service. Distinguished from A286 fittings by attachment method (flanges = bolted face with gasket; fittings = welded). See parent A286 bar stock, related A286 pipe, A286 fittings, A286 stud bolts (flange bolting).
About A286 Flanges
A286 flanges are produced by hot forging from VIM-VAR ingot or large-diameter A286 forged bar — the forging operation aligns grain flow radially in the flange face for optimal tension capability under bolt preload. Each flange is forged at 1095-1150 °C in closed-die or open-die operation, then 5-axis CNC-machined to the final ASME B16.5 geometry: bolt-circle diameter, bolt-hole pattern, raised-face dimensions, weld-neck taper (for WN flanges), and gasket-face surface finish. Solution-treated 1650-1800 °F and aged 1325 °F × 16 hours per AMS 5732 / ASTM A638. Hydrostatically pressure-tested per ASME B16.5 (1.5× design pressure), ultrasonically inspected per ASTM A388. Each flange ships with EN 10204 3.1 mill cert; 3.2 third-party witness available for nuclear, offshore and aerospace applications. Mating bolts and gaskets are A286 stud bolts + spiral-wound gaskets typically.
A286 Flange Types & Pressure Classes
TorqBolt produces A286 flanges in seven primary configurations:
- Weld-neck (WN) flange (ASME B16.5) — Tapered neck butt-welded to pipe — the dominant high-pressure flange type. Best fatigue performance + lowest stress concentration. Used for jet-engine, gas-turbine, and pressure-vessel applications.
- Slip-on (SO) flange — Slipped over pipe end + double-fillet welded — easier installation than weld-neck but lower fatigue performance. Used for moderate-pressure service.
- Blind flange — Solid flange used to terminate (close off) a flanged opening — pressure-vessel access ports, instrumentation tap-off ports, future-expansion connections.
- Socket-weld flange — Pipe inserted in a socket recess + fillet-welded — used for small-bore (1/8-2 inch NPS) instrumentation and process piping.
- Lap-joint flange — Two-piece: stub-end butt-welded to pipe + lap-joint flange that rotates around the stub. Used for alignment-critical service and frequent-disassembly maintenance applications.
- Threaded flange — Internal threads engage external pipe threads — used in low-pressure NPT service, generally avoided for A286 due to thread-galling concerns.
- Reducing flange — Bolt-circle and outer dimensions of larger NPS, but bore matching smaller pipe — used to transition from larger header to smaller branch piping.
A286 Flange Sizes & Pressure Class Reference (Selected ASME B16.5)
| NPS | Class 150 OD | Class 300 OD | Class 600 OD | Class 900 OD | Class 1500 OD | Class 2500 OD |
|---|---|---|---|---|---|---|
| 1/2 inch | 88.9 mm | 95.3 mm | 95.3 mm | 120.7 mm | 120.7 mm | 133.4 mm |
| 1 inch | 108.0 mm | 123.8 mm | 123.8 mm | 149.4 mm | 149.4 mm | 158.8 mm |
| 2 inch | 152.4 mm | 165.1 mm | 165.1 mm | 215.9 mm | 215.9 mm | 238.1 mm |
| 4 inch | 228.6 mm | 254.0 mm | 273.1 mm | 292.1 mm | 311.2 mm | 355.6 mm |
| 6 inch | 279.4 mm | 317.5 mm | 355.6 mm | 381.0 mm | 393.7 mm | 482.6 mm |
| 8 inch | 342.9 mm | 381.0 mm | 419.1 mm | 469.9 mm | 482.6 mm | 552.5 mm |
| 12 inch | 482.6 mm | 520.7 mm | 558.8 mm | 609.6 mm | 638.2 mm | 762.0 mm |
| 24 inch | 812.8 mm | 914.4 mm | 1041.4 mm | 1085.9 mm | 1187.5 mm | — |
A286 Flanges Manufacturing Process
Every a286 flanges TorqBolt ships traces back to a vacuum-induction-melted plus vacuum-arc-remelted (VIM-VAR) ingot meeting AMS 5731 / 5732 chemistry. Process route:
- VIM-VAR ingot input: AMS 5731 / 5732 chemistry. Aerospace lots double-melted (VIM + VAR) for inclusion control. Ingot weight matched to flange final weight + forging losses.
- Hot forging: Closed-die forging at 1095-1150 °C — radial grain-flow alignment in the flange face for tension capability. Open-die forging for sizes > 24 inch NPS.
- 5-axis CNC machining: Forged blank machined to ASME B16.5 dimensions: bolt-circle ⌀, bolt-hole pattern, raised-face dimensions, weld-neck taper (WN), gasket-face geometry.
- Drilling bolt-hole pattern: Precision drilling per ASME B16.5 bolt-circle and bolt-hole pattern — typically 4, 8, 12, 16 holes depending on size and class.
- Solution treatment: Vacuum or atmosphere furnace 1650 °F (AMS 5737) or 1800 °F (AMS 5732). 1 h per inch of section, oil-quench.
- Precipitation aging: 1325 °F for 16 hours, air-cool. Hardness 29-32 HRC.
- Gasket-face surface finish: Raised-face machined to ASME B16.5 spiral / serrated finish per gasket type. Smooth (Ra ≤ 3.2 µm) for spiral-wound gaskets; serrated for ring-type joints.
- Hydrostatic pressure test: Each flange tested per ASME B16.5 — 1.5× design pressure for 30 seconds, no leakage. Aerospace and nuclear: 2× pressure.
- Ultrasonic test + magnetic particle: 100 % UT per ASTM A388 + magnetic-particle inspection per ASTM E1444 (not magnetic, so liquid penetrant per E1417 used for A286).
A286 Flanges Inspection & Certification
Each lot ships with a signed inspection certificate. Aerospace orders default to AS9100D first-article reporting per AS9102. Industrial orders default to EN 10204 type 3.1; sour-service and offshore step up to type 3.2 with third-party witness. Inspection scope:
- Dimensional check per ASME B16.5 — bolt-circle ⌀, bolt-hole pattern, raised-face geometry, weld-neck taper.
- Surface roughness Ra at gasket face verified by profilometer per ASME B16.5 — typically ≤ 3.2 µm for spiral-wound gasket service.
- Hydrostatic pressure test 100 % per ASME B16.5 — 1.5× design pressure.
- Ultrasonic test 100 % per ASTM A388 — internal flaw detection. Class 1 for aerospace / nuclear.
- LPI per ASTM E1417 on every aerospace lot — surface defect detection.
- Hardness sample 1 per heat per ASTM E384.
- Tensile coupon from each heat per ASTM E8 + elevated-temperature per E21.
- Magnetic permeability < 1.005 per ASTM A342.
- AS9102 first-article on aerospace heats; EN 10204 3.2 third-party witness for nuclear and offshore.
A286 Flanges Installation & Service Practice
A286 flanges are bolted-joint pressure connections — preload follows ASME PCC-1 calculation. For an 8 inch NPS Class 600 A286 flange, typical preload is 12 × M24 A286 stud bolts at 75 % yield → 4.0 MN total preload. Above 540 °C apply nickel anti-seize per AS5272 to stud bolt threads. Spiral-wound gaskets per ASME B16.20 with PTFE / graphite filler are the preferred gasket for A286 flange service. Pressure-cycling fatigue: A286 flanges retain 90 % preload through thermal cycle from 20-700 °C — re-torque at first start-up only. For ASTM A453 grade 660 stud bolt + A286 flange combination, matching thermal expansion eliminates differential expansion stress at the joint.
A286 Flange Applications by Industry
A286 flanges serve high-temperature bolted pressure-vessel and piping connections:
- Jet-engine bleed-air system flanges: Weld-neck A286 flanges on jet-engine bleed-air manifold connections, anti-ice system bolted joints. A286 jet engine fasteners + matching A286 stud bolts.
- Industrial gas turbine combustor casing: Weld-neck Class 600 / 900 A286 flanges on combustor liner-to-casing bolted joints. A286 gas turbine applications.
- Petrochemical hydrogen-service vessels: Class 1500 / 2500 weld-neck A286 flanges on hydrogen-service refinery pressure vessels — HTHA-resistant at 540-700 °C operating temperatures.
- Oil & gas downhole wellhead: Class 1500 / 2500 A286 weld-neck flanges on subsea wellhead and Christmas-tree connections — NACE MR0175 sour-service compliant.
- Cryogenic LNG storage-vessel man-way: Class 600 / 900 A286 blind and weld-neck flanges on LNG storage-vessel access ports + hydrogen-storage manifold flanges. Retains 85 % toughness at -196 °C.
- Nuclear pressure-vessel access ports: ASTM A453 grade 660 / ASME III A286 weld-neck flanges on nuclear pressure-vessel man-ways, instrumentation access ports, control-rod-drive housing flanges. A286 nuclear applications.
Governing Standards & Material Specifications
Every A286 product is released against the applicable industry standard. EN 10204 type 3.1 mill certificates ship with every order. See A286 AMS / ASTM specifications hub.
| Authority | Specification | Coverage |
|---|---|---|
| ASTM | A453 grade 660 Cl. A/B/C/D | High-temperature bolting material |
| ASTM | A638 grade 660 Type 1/2 | Forged stock |
| AMS | 5731 | Bar / forging — solution-treated |
| AMS | 5732 | Bar / forging — solution-treated and aged |
| UNS | S66286 | Material designation |
| DIN | 1.4980 / X5NiCrTiMoVB25-15-2 | European designation |
| EN | 10204 3.1 / 3.2 | Mill / third-party-witness certification |
| NACE | MR0175 / ISO 15156-3 | Sour-service hardness limit ≤ HRC 35 |
A286 Flanges vs Alternative Materials
Engineers compare A286 against three alternatives: A286 vs Inconel 718, A286 vs 17-4 PH, and A286 vs Waspaloy. See A286 equivalent grades.
How to Specify A286 Flanges
A complete a286 flanges callout should include all relevant elements. Example callout:
A286 flange, ASTM A182 grade A286, ASTM A453 grade 660 chemistry, sol-treated and aged, weld-neck, NPS 6 inch × Class 600, raised-face per ASME B16.5, hydrostatic pressure tested 1.5×, EN 10204 3.1, ultrasonic tested per ASTM A388.
A286 Flanges — Frequently Asked Questions
What ASTM standard covers A286 flanges?
ASTM A182 grade A286 — forged or rolled alloy steel pipe flanges extended for A286 chemistry. ASME B16.5 defines flange dimensions for NPS 1/2-24; ASME B16.47 for NPS 26-60. Reference ASTM A453 grade 660 / ASTM A638 grade 660 for material chemistry.
What pressure classes are available for A286 flanges?
ASME B16.5 standard pressure classes: 150 / 300 / 600 / 900 / 1500 / 2500. Class 150 = 285 psig at room temp; Class 2500 = 3700 psig at room temp. Pressure rating decreases with temperature — at 700 °C, A286 flange pressure rating is approximately 50 % of room-temp rating.
What's the difference between weld-neck and slip-on flanges?
Weld-neck: tapered neck butt-welded to pipe — best fatigue performance + lowest stress concentration. Used for high-pressure and high-temperature service. Slip-on: slipped over pipe + double-fillet welded — easier installation, lower fatigue performance. WN dominant for A286 service.
Can A286 flanges be welded in field?
Yes for weld-neck — TIG / GTAW with matching A286 welding rod (AMS 5853). Pre-heat NOT required for thicknesses ≤ 50 mm. Post-weld solution-treatment + aging recommended for full-strength weld zone.
What gasket for A286 flange?
Spiral-wound gaskets per ASME B16.20 with PTFE or graphite filler — the standard for high-temperature austenitic-stainless flanges. For very high temperature (≥ 540 °C), use graphite-filled SWG. For cryogenic, use PTFE-filled SWG. Ring-type joints per ASME B16.20 also acceptable for Class 1500 / 2500.
Are A286 flanges magnetic?
No. Magnetic permeability < 1.005 verified per ASTM A342. Compatible with non-magnetic stud-bolt assembly — see A286 stud bolts.
Are A286 flanges NACE MR0175 compliant?
Yes — when supplied with hardness ≤ HRC 35 per NACE MR0175 / ISO 15156-3. Specify on PO; each heat receives Vickers traverse before release for sour-service oilfield wellhead applications.
What stud bolts to use with A286 flange?
Matched A286 stud bolts per ASTM A453 grade 660 + A286 hex nuts per ASTM A453 grade 660 + A286 spiral-wound gaskets. Matching A286 bolt + flange + nut eliminates differential thermal expansion stress at temperature. See A286 stud bolts.
What's the lead time on A286 flanges?
Standard sizes 1/2-4 inch NPS Class 150-600: 8-12 weeks from heat release. Larger sizes 6-12 inch NPS or higher class (900-2500): 12-16 weeks. Custom 14-24 inch NPS: 14-20 weeks. Aerospace AS9102 first-article + EN 10204 3.2: add 2-3 weeks.
Why TorqBolt for A286 Flanges
Three reasons aerospace and industrial OEMs place a286 flanges orders with us:
- Vertically integrated supply — VIM-VAR melt sourcing, in-house forging + machining + vacuum heat-treatment.
- Aerospace AQMS — AS9100D-certified factory in Mumbai with published quality manual.
- Lead time discipline — 4-6 weeks for ASTM A453 grade 660 standard sizes, 8-12 weeks for custom-drawing aerospace parts.
30+ years of manufacturing track record. Active certifications: ISO 9001:2015, AS9100D AQMS, PED 2014/68/EU and NORSOK M-650 QTR.
Recent A286 Flanges Order Patterns
Active A286 flange orders cover 1-2 inch NPS Class 900 weld-neck for jet-engine bleed-air manifold connections, 4-6 inch NPS Class 600 for industrial gas-turbine combustor casing, custom 8-12 inch NPS Class 1500 for petrochemical hydrogen-service refinery vessels, and 4 inch NPS Class 900 weld-neck + blind sets for nuclear pressure-vessel access ports.
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