Tesco Steel & Engineering manufactures ASTM A182 F22 socketweld flanges — 2¼Cr-1Mo alloy steel, Class 3, UNS K21590, W.Nr. 1.7380 — to ASME B16.5 from ½″ to 3″ NB in Classes 150–1500 (2500 and 4″ to order). F22 is the top of the ladder's creep rungs and the strongest of them — 515/310 MPa — the grade of high-energy steam headers, and the same 2¼Cr-1Mo chemistry the hydroprocessing world builds its reactors from (the Nelson-curve sweet spot). Matches P22 pipe and T22 tube systems. One class detail worth knowing up front: F22 comes in Classes 1 and 3 — there is no Class 2, and the FAQ explains the confusion. Socket seated, one external fillet weld, firm preheat/PWHT discipline stated honestly below. Facings: SWRF, SWFF, SWRTJ. Milder steam? F11/F12. Advanced steam? F91. Every lot with EN 10204 3.1/3.2 MTC. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
A182 F22 Cl.3 · UNS K21590 · W.Nr. 1.73802¼Cr-1Mo — High-Energy Steam GradeThe Hydroprocessing World's Steel515 / 310 MPa — Strongest Creep RungClasses 1 & 3 — No Class 2The P22 / T22 System MatchASME B16.5 ½″–3″ · Class 150–1500EN 10204 3.1 / 3.2 · ISO 9001:2015
ASTM A182 F22 Socketweld Flanges — Specifications at a Glance
What is an ASTM A182 F22 Socketweld Flange?
The strongest creep rung's small-bore flange. A forged 2¼Cr-1Mo alloy steel flange (ASTM A182 F22 Class 3 / UNS K21590) with a machined socket: pipe seated square by geometry, one external fillet weld, through-bore matched to the pipe schedule. Chromium and molybdenum both doubled against the 1Cr grades — the recipe of high-energy steam headers and the hydroprocessing world's construction steel per the Nelson curves. Tensile ≥515 MPa, yield ≥310 MPa, 156–207 HB, normalized & tempered; Classes 1 and 3 only — no Class 2. Sized by ASME B16.5 at ½″–3″ NB, Classes 150–1500; EN 10204 3.1 on every lot.
Also searched as: A182 F22 socket weld flange, F22 Class 3 flange, F22 CL3 SWRF flange, 2.25Cr socket weld flange, K21590 flange — all the same product family. Related pages: the facings — SWRF / SWFF / SWRTJ — the socketweld hub, the other F22 types — blind, weld neck, slip-on, F22 grade hub — the ladder neighbours F11 / F12 / F5 / F9, and the alloy steel hub.
F22 is where the creep half of the ladder tops out: beyond it, hotter steam belongs to the vanadium generation (F91), not to more plain chromium.
What Doubling Both Elements Buys
The Hot End of the Steam Band
Cr and Mo both doubled against the 1Cr grades: higher creep-rupture ratings that carry high-energy steam headers where F11/F12 fall off the allowable-stress tables.
The Nelson-Curve Sweet Spot
2¼Cr-1Mo resists hot high-pressure hydrogen attack well enough, cheaply enough, that hydrotreater and hydrocracker plants have been built from it for seventy years — their small bore specifies F22 to match.
The Strongest Creep Certificate
515/310 MPa — a full step above F11/F12's 485/275, with the carbon floor (0.05–0.15%) that keeps the carbide engine supplied.
Classes 1 and 3 — No Class 2
An A182 quirk that generates real purchase-order errors: F22 Class 2 does not exist. Class 3 (N&T) is the flange default; Class 1 (annealed, softer) serves weldability-led specs. The FAQ has the history.
ASTM A182 F22 Chemical Composition (UNS K21590)
Element
C
Mn
Si
Cr
Mo
P
S
Weight %
0.05–0.15
0.30–0.60
≤0.50
2.00–2.50
0.87–1.13
≤0.040
≤0.040
Identity marks: Cr and Mo both roughly doubled against the 1Cr grades — the creep-plus-hydrogen recipe — with the carbon floor lowered to 0.05% (2¼Cr builds its carbides efficiently enough to afford it, keeping weldability in hand). PMI reads the Cr-Mo signature on every piece.
Mechanical Properties (Class 3, N&T)
Property
ASTM A182 F22 Class 3 Requirement
Tensile Strength
≥ 515 MPa (75 ksi) — the creep family's strongest
Yield Strength (0.2%)
≥ 310 MPa (45 ksi)
Elongation
≥ 20%
Hardness
156–207 HB — tempering proof and PWHT baseline
Other Class
Class 1 — annealed, lower strength, maximum weldability — to order; there is no Class 2
Why It's Bought
Creep-rupture ratings at the hot end of the steam band, plus Nelson-curve hydrogen standing
Class 900–1500 steam, feedwater & hydrogen circuits — F22's home classes
ASTM A182 F22 Socketweld Flange Specifications
ASTM A182 F22 Socketweld Flanges are available in the following specifications:
Material Grade
ASTM A182 F22 Class 3 (default — an unqualified 'F22' order is supplied as Class 3); Class 1 to order; no Class 2 exists; UNS K21590, W.Nr. 1.7380
Heat Treatment
Normalized and tempered (Class 3); hardness verified 156–207 HB; furnace records certified
Size
1/2"NB to 3"NB per ASME B16.5; 4″ and larger to order
Class
150#, 300#, 600#, 900#, 1500# (900# shares 1500# dimensions in most sizes); 2500# on request — duty concentrates in 600–1500
Facings
Raised Face (SWRF), Flat Face (SWFF), Ring Type Joint (SWRTJ) with groove per B16.20
Bore
Socket bore to pipe OD; through-bore matched to pipe schedule (Sch 40/80/160 — 80/160 dominate)
Welding
Single external fillet per B16.5/B31.1/B31.3 with 1/16″ expansion gap; preheat ~150–200 °C, PWHT normally required — see the FAQ
Service Span
High-energy steam and hydrogen-unit auxiliaries in P22/T22 systems; advanced steam → F91, sour heat → F5/F9
Testing
Tension, chemistry and hardness per heat; PMI on every piece; socket depth and bore gauged
Certification
EN 10204 3.1 with heat-treatment records (standard) / 3.2 witnessed
Specification Notes — Getting F22 Sockets Right
Four honest notes.There is no F22 Class 2: the classes are 1 and 3 — a purchase order saying 'Cl.2' has imported plate nomenclature (A387 Gr.22 has Classes 1 and 2), needs correcting at source, and we will flag it rather than guess. PWHT is normally required: 2¼Cr hardens more than the 1Cr grades — preheat ~150–200 °C and code-mandated PWHT are the rule, not the exception, and small-bore sockets are where crews get tempted. The 1/16″ gap stands — expansion against a bottomed socket cracks weld roots. And hydrogen-unit line classes often mandate RT: a fillet weld cannot give volumetric examination — where the class demands it, the F22 weld neck is the right escalation.
How Our A182 F22 Socketweld Flanges Are Manufactured
1
Forging — cut billet of the spectro-verified F22 heat — the Cr-Mo windows and the carbon floor confirmed — is hot-forged into the flange blank with full heat traceability.
2
Heat treatment — normalized and tempered to the Class 3 requirement; furnace charts retained against the heat number.
3
Hardness & testing — hardness verified in the 156–207 HB band; tension and chemistry per heat; PMI reads the Cr-Mo signature on every piece.
4
Machining — faces, OD and drilling to ASME B16.5; socket counterbore and depth gauged piece by piece, through-bore matched to the ordered schedule; RF serrations, flat face or RTJ groove per B16.20.
5
Marking — laser-marked with grade, class, size, schedule and heat number.
6
Certification & packing — EN 10204 3.1 MTC with heat-treatment records (3.2 witnessed on request); packed sea-worthy.
Where ASTM A182 F22 Socketweld Flanges Are Used
The hot end of steam, and everything around the hydrogen unit: high-energy steam header drains and vents, boiler and superheater instrument connections, attemperator and feedwater auxiliaries — and in refineries, the small-bore auxiliaries of hydrotreaters, hydrocrackers and hot hydrogen piping; fertiliser and methanol plants lean on the same chemistry. Production below:
A182 Alloy Steel Flanges — Face-Capped, Export CratedThe Socket Weld Joint — Note the Expansion Gap (X)Steel Flanges — Black-Coated, Crated at Our Works
A182 F22 Socketweld Flange Dimensions
Socket weld flange dimensions are class-governed per ASME B16.5 — identical across material grades (pressure-temperature ratings follow the 2¼Cr material group). Full charts:
An ASTM A182 F22 socketweld flange is a forged 2¼Cr-1Mo alloy steel flange — UNS K21590, supplied as Class 3 unless another class is named — whose back carries a machined socket: the pipe end seats inside, self-aligned square to the face, and is secured with a single external fillet weld. F22 is the top of the chrome-moly ladder's creep rungs and the strongest of them — 515 MPa tensile, 310 MPa yield — the grade of high-energy steam headers, and the same 2¼Cr-1Mo chemistry the hydroprocessing world builds its reactors from. Dimensioned to ASME B16.5 for ½" to 3" NB in Classes 150 to 1500, in raised face, flat face and ring joint facings — the natural match for P22 pipe and T22 tube systems.
Where does F22 sit on the chrome-moly ladder?
At the top of the creep rungs. The ladder climbs F11/F12 (1Cr class) → F22 (2¼Cr-1Mo) → F5 (5Cr) → F9 (9Cr), and the mission changes at F22's doorstep: below it the chromium buys creep strength for steam, above it the chromium becomes corrosion armour for sour refinery streams. F22 is the last and strongest of the steam grades — the standard answer when subcritical conditions outgrow the 1Cr window — and beyond it, hotter steam belongs not to more plain chromium but to the vanadium-microalloyed F91 branch. Each rung has its own pages on this site; this page is the F22 socket weld.
What are F22 Class 1 and Class 3 — and why is there no Class 2?
F22 comes in exactly two classes, and the numbering skips: Class 1 is the annealed, lower-strength condition — maximum weldability and softness, appearing mainly in fittings practice — while Class 3, the flange default, is normalized and tempered to 515 MPa tensile / 310 MPa yield. There is no F22 Class 2 in A182; the designations carried over from historical plate practice (A387 Grade 22 Classes 1 and 2 exist, which fuels the confusion), and purchase orders occasionally invent an 'F22 Cl.2' that no standard defines. If a specification reaching you says Class 2, it needs correcting at source — we quote Class 3 against it and say so. An unqualified 'F22' order is quoted and certified Class 3.
What is the chemical composition of ASTM A182 F22?
Carbon 0.05-0.15% (a deliberate range with a minimum — creep strength is carbide strength), manganese 0.30-0.60%, silicon ≤0.50%, chromium 2.00-2.50%, molybdenum 0.87-1.13%, phosphorus ≤0.040%, sulphur ≤0.040%. Two identity marks against the 1Cr grades below it: chromium roughly doubled, and molybdenum doubled to a full 1% — the combination that buys both the higher creep-rupture ratings and the hydrogen-service standing. Note the carbon floor sits lower than F11/F12's (0.05 versus 0.10): 2¼Cr steel builds its carbides efficiently enough to afford it, keeping weldability in hand. Chemistry is verified per heat and travels on the EN 10204 3.1 MTC.
What are the mechanical properties of A182 F22 socketweld flanges?
In the Class 3 normalized-and-tempered condition A182 requires tensile strength 515 MPa (75 ksi) minimum, yield strength 310 MPa (45 ksi) minimum, elongation 20% minimum, with hardness controlled at 156-207 HB — the strongest certificate of the low-chrome creep family, a full step above F11/F12's 485/275. As with the whole family, the room-temperature numbers understate the purchase: F22 is bought for its creep-rupture ratings at the hot end of the steam band, where the allowable-stress tables separate it decisively from the 1Cr grades. The hardness band is the mill's proof of tempering and the baseline your site PWHT should return the weld zone to.
Why is 2¼Cr-1Mo the hydroprocessing world's steel?
Because it sits at the sweet spot of the Nelson curves. Hot high-pressure hydrogen attacks carbon steel by converting its carbides to methane inside the metal; chromium and molybdenum carbides resist that conversion, and 2¼Cr-1Mo resists it well enough — at economical cost, in weldable heavy sections — that hydrotreater and hydrocracker reactors, exchangers and hot piping have been built from it for seventy years. For the small-bore buyer the consequence is simple: the drains, vents, instrument taps and injection points of hydrogen-unit auxiliaries specify F22 flanges to match the system, and both the flange certificate and the weld procedures inherit the qualified 2¼Cr-1Mo pedigree. Where sulphur dominates over hydrogen, the ladder's corrosion half — F5 and F9 — takes over instead.
How is an F22 socketweld flange welded — preheat and PWHT?
With a firm middle-of-the-ladder discipline. Joint geometry is standard socket weld practice: pipe bottomed, withdrawn 1/16" (1.6 mm) per the code so thermal expansion cannot crack the weld root, single external fillet sized to B16.5/B31.1/B31.3 rules. 2¼Cr hardens more than the 1Cr grades: typical preheat runs around 150-200°C, and PWHT is normally required for F22 joints in code work — B31.1's tables for power piping, B31.3's for process — returning the zone toward the 156-207 HB band. It is not yet the near-absolute regime of 5Cr and 9Cr, but skipping it on small bore is how cracked F22 sockets happen. Our flanges arrive normalized and tempered with records; the joint's pedigree is the fabricator's half of the contract.
F22 or F11/F12 — when does the duty move up?
Via the allowable-stress tables, when the steam conditions outgrow the 1Cr window. F11 and F12 carry the classic subcritical band economically; F22's higher creep-rupture strength takes over at the hot end — commonly in the 540-565°C region for long-life duty, though the governing code's tables and the owner's design margins set the real crossover, not a catalogue number. F22 also inherits duties the 1Cr grades never see: hydrogen-unit auxiliaries per the Nelson curves, and the heavy-section steam headers of high-energy plants. All three grades ship as socket welds from our works; when an enquiry names the design temperature and service, the quotation names the economical rung.
F22 or F91 — what is the difference?
F22 is the last of the classic creep grades; F91 is a different generation. F91 (9Cr-1Mo-V, UNS K91560) adds vanadium, niobium and nitrogen to create a creep-strength-enhanced ferritic with roughly double F22's creep-rupture strength — the grade of modern supercritical and ultra-supercritical steam plants — but at the price of a strict normalize-and-temper window, unforgiving weld and PWHT rules, and well-documented failures where fabricators treated it like ordinary chrome-moly. The practical rule: conventional subcritical and early-supercritical conditions stay F22 country; advanced steam conditions name F91, and a specification naming either must be supplied with that grade exactly. Both have full page families on this site.
What facings are A182 F22 socketweld flanges made with?
All three, each with its own page on this site: raised face (SWRF) — the default, with graphite-filled spiral wound gaskets for the hot services F22 lives in — flat face (SWFF) for the rare lined or brittle mate, and ring type joint (SWRTJ) for high-pressure steam, feedwater and hydrogen circuits in Classes 900-1500, where F22 small bore concentrates. The socket, the welding discipline and the schedule-matched bore are identical across the three; only the gasket face changes, and the piping class decides which you order.
What sizes and pressure classes do F22 socketweld flanges come in?
ASME B16.5 standardises socket weld flanges from ½" to 3" NB in Classes 150, 300, 600, 900 and 1500 — Class 900 sharing Class 1500 dimensions in most small-bore sizes — with 4" and Class 2500 made to order. F22's duty profile pushes orders toward the high end: Class 600-1500 boiler-proximate and hydrogen-unit connections are routine. As with every socket flange, put the pipe schedule on the enquiry — Sch 80 and 160 dominate high-pressure small bore — so the through-bore matches the pipe ID. B16.5 pressure-temperature ratings for the 2¼Cr material group govern the limits; our quotations state them per class.
When should I not use a socket weld flange?
The standard socket weld limits apply, with the emphasis of F22's services. As always: the socket gap is a crevice (corrosion-sensitive stagnant duty prefers butt welds), fillet welds cannot be radiographed (mandatory-RT and lethal-service classes escalate to weld necks), and hygienic duty excludes sockets. Two sharpened cautions here: high-energy steam small bore that cycles — attemperator drains, cycling drain pots — is a documented socket-weld failure mode utilities often butt-weld as policy; and hydrogen-unit line classes frequently mandate volumetric examination, which a fillet cannot give. Where your line class says so, our F22 weld neck page has the matching flange.
Where are F22 socketweld flanges used?
At the hot end of the steam plant and around the hydrogen unit: high-energy steam header drains and vents, boiler and superheater instrument connections, attemperator and feedwater auxiliaries, turbine drain systems — and in refineries, the small-bore auxiliaries of hydrotreaters, hydrocrackers and their hot hydrogen piping, wherever the line itself is P22 or 2¼Cr-1Mo equivalent. Power stations, fertiliser and methanol plants (hot syngas services lean on the same chemistry) and hydroprocessing complexes are the volume homes. Wherever the line is P22, the closures should match the alloy — same certificate, same expansion, same PWHT behaviour.
What details are needed to get an accurate F22 socketweld flange quotation?
Six elements plus commercial terms: (1) size — ½" to 3" NB; (2) pressure class — 150 to 1500; (3) facing — SWRF, SWFF or SWRTJ with ring number; (4) the pipe schedule — Sch 40, 80 or 160, so the through-bore matches the pipe ID; (5) grade detail — F22 Class 3 (the default) or Class 1 where the specification names it — and if a document says 'Class 2', flag it, because A182 defines no such class; (6) certification — EN 10204 3.1 with heat-treatment records (our standard) or 3.2 witnessed, PMI as applicable. Add quantity and destination and we return price, weight and delivery — normally within 24 hours.
Who manufactures ASTM A182 F22 socketweld flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, producing ASTM A182 F22 Class 3 socket weld flanges from ½" to 3" NB (larger to order) in Classes 150-1500 — each forged from certified heats, normalized and tempered with furnace records, hardness-verified in the 156-207 HB band, machined with gauged socket depth and schedule-matched bore, PMI-checked and laser-marked with grade, class, size, schedule and heat number. Supplied with EN 10204 3.1/3.2 certification, alongside the full chrome-moly ladder — F1, F11, F12, F5, F9 and F91 — and the complete socket weld range in carbon, stainless and nickel alloys. Exported to more than 50 countries.
