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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