Tesco Steel & Engineering forges ASTM A182 F22 blind flanges — 2¼Cr-1Mo chrome-moly, the heavy-duty grade of hydrogen and hot steam — to ASME B16.5 Class 150–2500 from ½″ to 24″ NB and to ASME B16.47 up to 60″. Where F11 runs out of headroom, F22 continues: more creep strength for hotter steam, and the Nelson-curve hydrogen resistance that made 2¼Cr-1Mo the defining steel of hydrotreaters and hydrocrackers — where an ordinary steel blind would be quietly eaten from within by high-temperature hydrogen attack. Supplied as Class 3 by default, normalized and tempered; hot sulphur belongs to F5/F9. Facings: BLRF, BLFF or BLRTJ — ring joints rule this world. Every lot with EN 10204 3.1/3.2 MTC. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
ASTM A182 F22 Cl.1/3 · ASME SA-1822¼Cr-1Mo Chrome-MolyHydrogen Service per API RP 941ASME B16.5 ½″–24″ · Class 150–2500ASME B16.47 to 60″RF · FF · RTJ FacingsEN 10204 3.1 / 3.2 · ISO 9001:2015
ASTM A182 F22 Blind Flange — Specifications at a Glance
What is an ASTM A182 F22 Blind Flange?
The hydroprocessing closure. A solid forged disc of 2¼Cr-1Mo alloy steel with no bore, closing pipes, valves and nozzles in hot, high-pressure and hydrogen-bearing service. Double F11's alloying buys two things: creep strength for hotter steam, and the API RP 941 Nelson-curve resistance to high-temperature hydrogen attack that made this steel the standard of hydrotreaters and hydrocrackers. Standard flange grade Class 3: tensile ≥515 MPa, hardness 156–207 HB, normalized & tempered. Dimensions per ASME B16.5 / B16.47 in RF, FF and RTJ facings; EN 10204 3.1 certified.
Also searched as: F22 blind flange, A182-F22 blind, SA-182 F22 blind (the ASME boiler-code twin), F22 Class 3 blind, 2.25Cr-1Mo blind flange — all refer to the product on this page. See also the alloy steel hub, the F22 slip on flanges, siblings F11 / F12 / F5 / F9 / F91 blind flanges, and the facing pages BLRF / BLFF / BLRTJ.
The Hydrogen Story — HTHA and the Nelson Curves
At high temperature and hydrogen partial pressure, hydrogen diffuses into steel and reacts with its carbides to form methane inside the metal — blistering, fissuring, and destroying strength with little outward warning. This is high-temperature hydrogen attack (HTHA), and it retired plain carbon steel from the hydrogen world decades ago.
The Nelson Curves Draw the Map
API RP 941 plots, for each steel, the temperature-and-hydrogen-pressure envelope it survives. Every step up in chromium and molybdenum lifts the curve — and 2¼Cr-1Mo's envelope covers the operating window of hydrotreaters and hydrocrackers, which is why F22 defines that world.
Stable Carbides Are the Mechanism
Chromium and molybdenum lock carbon into carbides that hydrogen cannot readily strip into methane — the same alloying that buys creep strength buys hydrogen immunity, one metallurgy serving both masters.
The Blind Must Hold the Same Line
A closure below the line's Nelson curve becomes the joint's hidden weak point. Specifying the blind in the line's own F22 keeps every part of the hydrogen circuit on the same side of the map.
F22 Class 1 & 3 — Chemistry and Strength
Property
Class 3 (flange default)
Class 1
Carbon
0.05–0.15%
0.05–0.15%
Manganese
0.30–0.60%
0.30–0.60%
Silicon
≤0.50%
≤0.50%
Chromium
2.00–2.50%
2.00–2.50%
Molybdenum
0.87–1.13%
0.87–1.13%
Heat Treatment
Normalized & tempered
Annealed
Tensile Strength
≥515 MPa (75 ksi)
≥415 MPa (60 ksi)
Yield Strength
≥310 MPa (45 ksi)
≥205 MPa (30 ksi)
Hardness
156–207 HB
≤170 HB
An unqualified "F22" order receives Class 3 — the flange standard. The chemistry is common; the classes differ by heat treatment and strength. No F22 class carries a vanadium requirement — the vanadium-modified variant is F22V, a heavy-wall pressure-vessel grade covered in the FAQ below. Elongation is ≥20%, and the certificate states the class explicitly.
Rule of thumb: molybdenum-led F11/F12/F22 fight stress and hydrogen; chromium-led F5/F9 fight hot sulphur. F22 is where the molybdenum side peaks before the modified 9Cr world of F91.
1/2"NB to 24"NB per ASME B16.5; 26"–60" per ASME B16.47; EN 1092-1 in 10CrMo9-10 to order
Class
150#, 300#, 400#, 600#, 900#, 1500#, 2500#
Facings
Raised Face (BLRF), Flat Face (BLFF), Ring Type Joint (BLRTJ) with groove per B16.20
Service
Hydroprocessing & hot steam; allowable stresses to ~600 °C; hydrogen envelope per API RP 941
Modifications
NPT-tapped centre (hydrotest / vent / drain / gauge), lifting provisions — machined & certified at the works
Testing
Tension, chemistry & hardness per heat; PMI routine; UT / MPI where specified
Certification
EN 10204 3.1 (standard) / 3.2 witnessed
Why F22 Blind Flanges Are Specified
On the Right Side of the Nelson Curve
Hydrotreater and hydrocracker closures must survive the same hydrogen conditions as the pipe — F22's envelope covers the hydroprocessing world, and the blind inherits that protection whole.
Creep Strength Past F11
Hotter steam headers and heavy-wall hot services stay code-rated where 1¼Cr has run out — the last stop before the modified 9Cr grades.
Built for the RTJ World
Hydroprocessing runs Class 600–1500 ring joints as a matter of course — F22 BLRTJ blinds with gauged grooves are a signature product of that service.
Bolted, So the Metallurgy Stays Put
Preheat, PWHT and temper-embrittlement discipline are welding problems — a bolted blind arrives normalized, tempered and hardness-verified, and stays that way.
Know the Siblings
Lighter steam duty: F11 / F12. Hot sulphur: F5 / F9. Maximum creep: F91. General duty: A105. Facings: BLRF / BLFF / BLRTJ.
Specification Notes — Getting F22 Right
Three details buyers miss.F22 is not F22V: the vanadium-modified variant is a heavy-wall reactor grade with its own demanding requirement set — if your specification says F22V, say so on the enquiry; an ordinary F22 certificate will not do. State the class: "F22" alone gets Class 3 normalized-and-tempered; Class 1 is annealed and weaker, and the certificate must match. Not a cold-service grade: below about -29 °C ferritic steels need impact testing — cold closures belong to LF2 or stainless, however hot the unit runs in operation.
How Our F22 Blind Flanges Are Manufactured
1
Forging — cut billet of the spectro-verified F22 heat is hot-forged into the solid disc blank, keeping full heat traceability from melt to marking.
2
Normalize & temper — the Class 3 heat treatment, with controlled residual chemistry and hardness verified into the 156–207 HB window; furnace charts retained against the heat number.
3
Machining & facing — faces, OD and drilling to ASME B16.5 / B16.47; RF serrations, flat face or RTJ groove gauged per B16.20; NPT taps machined where ordered.
4
Testing — tension test, chemistry and hardness against the heat; PMI routine on every alloy lot; UT and MPI where specified.
5
Marking — permanent marking of standard, grade (F22 and class), size, class and heat number.
6
Certification & packing — EN 10204 3.1 MTC (3.2 witnessed on request); faces protected, palletised or crated sea-worthy.
Where F22 Blind Flanges Are Used
Hydroprocessing above all — hydrotreaters, hydrocrackers, hydrogen manifolds and make-up circuits — plus superheater headers, HRSG high-temperature sections and heavy-wall hot services generally. Production below:
Example: “Blind Flange, RTJ, 6″ NB, ASME B16.5 Class 900, ASTM A182 F22 Cl.3, groove for R-45 octagonal ring per B16.20, EN 10204 3.1 — 2 pcs.” Quotations normally within 24 hours with price, unit weight and delivery.
An ASTM A182 F22 blind flange is a solid forged disc of 2¼Cr-1Mo alloy steel, drilled to the standard bolt pattern with no bore, used to close pipes, valves and vessel nozzles in hot, high-pressure and hydrogen-bearing service. F22 is the heavy-duty workhorse of the chrome-moly family: double F11's alloying, with the creep strength for hotter steam and the hydrogen-attack resistance that made it the standard steel of hydroprocessing. Dimensions follow ASME B16.5 from ½ inch to 24 inch and ASME B16.47 beyond, in raised face, flat face and ring joint facings.
What kind of steel is A182 F22?
A forged 2¼Cr-1Mo low-alloy steel — in the standard flange grade F22 Class 3, chemistry runs carbon 0.05-0.15%, manganese 0.30-0.60%, silicon 0.50% max, chromium 2.00-2.50% and molybdenum 0.87-1.13%, supplied normalized and tempered. No vanadium is required (that belongs to the F22V pressure-vessel variant) and no impact test — it is a hot-service grade certified for strength at temperature. Roughly double F11's alloying, it is the grade specifications reach for when 1¼Cr runs out of headroom.
What is high-temperature hydrogen attack, and why F22?
At high temperature and hydrogen partial pressure, hydrogen diffuses into steel and reacts with its carbides to form methane inside the metal — blistering, fissuring and quietly destroying strength. The API RP 941 Nelson curves map which steels survive which hydrogen conditions, and each step in chromium and molybdenum pushes the safe envelope higher: 2¼Cr-1Mo became the defining steel of hydrotreaters and hydrocrackers because its curve covers their world. An F22 closure on a hydrogen circuit is not a luxury — it keeps the blind on the same side of the curve as the pipe.
F22 Class 1 or Class 3 — which one?
Class 3 is the flange standard — tensile 515 MPa and yield 310 MPa minimum, hardness 156-207 HB, normalized and tempered — and is what an unqualified 'F22' order receives. Class 1 is a lower-strength annealed variant (415/205 MPa) used mainly for fittings and welding-sensitive components. The certificate states the class explicitly; if your piping class just says F22, Class 3 is almost certainly what it means, and we confirm at enquiry when in doubt.
When should F22 be used instead of F11?
When temperature, hydrogen or wall thickness outruns 1¼Cr. F22 holds useful creep strength meaningfully hotter than F11, its Nelson-curve envelope covers hydrogen conditions F11 cannot, and its through-hardening behaviour suits heavy sections. The price difference is modest; the certificate is different. Specifications draw the line by service — hydroprocessing is F22 territory outright, hot steam splits by temperature — and the flange follows the line class. Our F11 blind flange page covers the lighter grade.
How does F22 differ from F5 and F9?
By enemy. F22 is molybdenum-led: strength at temperature and hydrogen resistance — steam plant and hydroprocessing. F5 and F9 are chromium-led: hot sulphur corrosion in refinery hydrocarbon streams. Refineries use both families side by side, in different units, and the line class decides. One practical overlap: hydrotreater services combining hydrogen with H2S sometimes step past F22 to stainless-clad construction — the blind then follows whatever the specification names.
What is F22V?
A vanadium-modified 2¼Cr-1Mo (nominally 2¼Cr-1Mo-¼V) developed for heavy-wall hydroprocessing reactors — higher strength and better hydrogen resistance in thick sections, with a far more demanding heat-treatment and fabrication regime. It is a pressure-vessel-world grade; ordinary piping closures do not need it, and an F22V requirement will be spelled out explicitly in the specification. If your line class says F22, this page's Class 3 product is what it means; if it says F22V, ask us — it is forged to order against the full requirement set.
What are the mechanical properties of F22 blind flanges?
For F22 Class 3 — the flange standard: tensile strength 515 MPa (75 ksi) minimum, yield 310 MPa (45 ksi) minimum, elongation 20% minimum, hardness 156-207 HB, normalized and tempered. Class 1 delivers 415/205 MPa annealed where specified. The room-temperature numbers again understate the point: F22's advantage is what remains of them at 500°C-plus, and in hydrogen. Results travel on the EN 10204 3.1 certificate.
What temperature range does an F22 blind flange cover?
The hot end of low-alloy practice: useful allowable stresses run to roughly 600°C in the ASME tables, with everyday steam practice working F22 in the band above F11's comfort zone and below the modified 9Cr grades. It is not a cold-service grade — below about -29°C ferritic steels need impact testing, and cold closures belong to LTCS or stainless. Hydrogen service adds its own envelope via the Nelson curves, where F22 covers most hydroprocessing conditions.
What facings are F22 blind flanges made with?
All three: raised face (BLRF) with graphite-filled spiral-wound gaskets, flat face (BLFF) for utility interfaces, and ring type joint (BLRTJ) — prominent in F22 service, because hydroprocessing runs Class 600 to 1500 and above, where ring joints rule, the ring always chosen softer than the groove. Each facing has its own page on this site; the mating flange governs the choice, and for RTJ the ring number follows from size and class.
Does welding or temper embrittlement affect F22 blind flanges?
Welded 2¼Cr-1Mo demands preheat and post-weld heat treatment, and long service in the 370-565°C band can temper-embrittle careless heats — which is why hydroprocessing specifications police chemistry and heat treatment closely. A bolted blind sidesteps the welding half entirely, and the metallurgy half is handled at the works: controlled residuals, proper normalize-and-temper, hardness verified into the 156-207 HB window. The certificate records it; the flange arrives right and stays right.
Can F22 blind flanges be tapped for testing or instruments?
Yes — fill, vent, drain, gauge and injection taps are machined into the centre of the blind at the works and certified with the flange. In F22 service they matter doubly: hydrotest closures on Class 900-1500 hydroprocessing spools carry serious pressure, and field-drilling an air-hardening chrome-moly blind is exactly the improvisation to avoid. State the NPT size on the enquiry and the tap arrives ready to plug.
Where are F22 blind flanges used?
Hydroprocessing above all — hydrotreaters, hydrocrackers, hydrogen manifolds and make-up circuits — plus the hotter end of steam plant: superheater headers, HRSG high-temperature sections and heavy-wall hot services generally. On those lines F22 blinds serve the usual closure duties — isolations, future connections, tapped hydrotest blinds — in the same metal as the pipe, keeping creep life, hydrogen envelope and certificates uniform across the joint.
Which standards cover F22 blind flanges?
The material standard is ASTM A182 grade F22 (Class 1 or 3), with ASME SA-182 as its boiler-code twin; dimensions follow ASME B16.5 for ½"-24" and ASME B16.47 for 26"-60". Pressure-temperature ratings come from the B16.5 tables for the 2¼Cr material group, and hydrogen limits from API RP 941. A complete specification reads: 'Blind Flange, RTJ, 6", ASME B16.5 Class 900, ASTM A182 F22 Cl.3' — and our EN 10204 certificates state dimension standard, grade, class, heat treatment and test results together.
Who manufactures ASTM A182 F22 blind flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, forging ASTM A182 F22 blind flanges in Classes 1 and 3 from ½" to 24" NB per ASME B16.5 in Classes 150-2500 and to 60" per ASME B16.47 — normalized and tempered, hardness-controlled, PMI-verified and certified to EN 10204 3.1/3.2 on every lot — in raised face, flat face and ring joint facings, with NPT-tapped test blinds to order, alongside F11, F12, F5, F9 and F91 chrome-moly, carbon steel, LTCS, stainless and nickel-alloy blinds. Exported to more than 50 countries.
