Tesco Steel & Engineering forges ASTM A182 F11 slip on flanges — the 1¼% chromium, ½% molybdenumalloy steel that is the entry grade of elevated-temperature piping — to ASME B16.5 Class 150–2500 from ½″ to 24″ NB, larger patterns to order. The first step when carbon steel runs out of temperature: steam lines, boiler external piping, hot hydrogen services per API RP 941. Supplied as F11 Class 2 (Cl.1/Cl.3 on request), heat treated per ASTM A182, faced SORF (flat face or RTJ where specified), alongside the complete chrome-moly family F5, F9, F22 and F91. Every lot with EN 10204 3.1/3.2 MTC. ISO 9001:2015, made in Mumbai, India — exported to 50+ countries.
ASTM A182 F11 Alloy Steel Flanges — In Stock at Our Mumbai Works
What is an ASTM A182 F11 Slip On Flange?
F11 = the first alloy step.ASTM A182 F11 is a 1¼Cr-½Mo alloy steel forging grade: the molybdenum holds creep strength at steam temperatures, the chromium stands up to hot hydrogen per the API RP 941 Nelson curves. As a slip-on, it installs with two fillet welds under chrome-moly discipline — preheat, B2 consumables, PWHT. It is the grade power plants and refineries reach for first when carbon steel runs out at ~425 °C.
Also searched as: F11 slip on flange, F11 Cl.2 slip on flange, 1.25Cr slip on flange, SA182 F11 slip on flange, 13CrMo4-5 slip on flange, 1.7335 slip on flange — all refer to the product on this page.
Creep-strength-enhanced — modern high-energy steam
Rule of thumb: power plants climb the ladder for creep strength (temperature), refineries climb it for corrosion (sulfur). F11 is the strength entry rung — and the first grade on the API RP 941 Nelson curves above carbon steel for hot hydrogen.
ASTM A182 F11 Cl.2 Chemical Composition
C
Mn
Si
P
S
Cr
Mo
0.10-0.20
0.30-0.80
0.50-1.00
0.040 max
0.040 max
1.00-1.50
0.44-0.65
Values in weight % per ASTM A182 for F11 Class 2 — the class normally supplied for flanges. The molybdenum is the creep-strength element; the chromium stabilises carbides against hot hydrogen and adds oxidation resistance. Class 1 (lower carbon) and Class 3 (higher strength) are forged where the specification calls them out.
ASTM A182 F11 Cl.2 Mechanical Properties
Tensile Strength, MPa (ksi)
Yield Strength, Min, MPa (ksi)
Elongation % min (2")
Reduction of Area % min
Hardness, HB
485 (70) min
275 (40) min
20
30
143-207
Room-temperature strength matches A105 carbon steel — the difference is what happens as temperature climbs: the ½Mo addition holds allowable stress deep into the creep range where carbon steel's collapses. Supplied heat treated per ASTM A182; values demonstrated per heat on the EN 10204 certificate.
A182 F11 Slip On Flange Specifications
ASTM A182 F11 Slip On Flanges are available in the following specifications:
Material
ASTM A182 F11 Class 2 (default) / ASME SA182 F11 Cl.2 (UNS K11572); Cl.1 & Cl.3 on request
Size
1/2"NB to 24"NB per ASME B16.5; larger patterns to order
Class
150#, 300#, 400#, 600#, 900#, 1500#, 2500#
Facing
Raised Face (SORF) — default; Flat Face or RTJ where the piping class specifies
Heat Treatment
Annealed or normalized & tempered per ASTM A182, thermal record retained
Service
Steam & hot hydrogen duty — rated to 649 °C in the ASME B16.5 tables, creep governing in the upper range
Installation
Two fillet welds (hub + bore), pipe set back 1/8"; preheat + E8018-B2 consumables + PWHT ~700-745 °C per B31.3
Finish
Bare (anti-rust oiled); other surface preparation on request
Certification
EN 10204 3.1 (standard) / 3.2 witnessed
Equivalent Grades of ASTM A182 F11
Standard
ASME
UNS (Cl.2)
Werkstoff Nr.
DIN / EN (working equivalent)
ASTM A182 F11
SA182 F11
K11572
1.7335
13CrMo4-5 (formerly 13CrMo44)
European grades are duty equivalents rather than chemistry-identical matches — certificates always state the actual grade and class forged. System partners: ASTM A335 P11 pipe and A234 WP11 fittings — the 1¼Cr trio specified together on steam and hydrogen lines.
Why A182 F11 Slip Ons Are Specified
The First Grade Past Carbon Steel
When design temperature crosses ~425 °C, F11 is the cheapest alloy that keeps working — creep strength from ½Mo without the price of the higher rungs.
Stands Higher on the Nelson Curves
Chromium-stabilised carbides resist high-temperature hydrogen attack — the entry grade for hydrotreater and reformer loops per API RP 941.
Room-Temp Strength of Carbon Steel, Hot Strength It Can't Match
Same 485/275 MPa minimums as A105 at ambient — but the allowable-stress curves separate decisively as steam temperatures climb.
Slip-On Fit-Up Economy
Where the piping class permits, the slip-on saves the weld-neck's bevel-matching and cut-length precision — welcome on alloy lines where every rework costs PWHT.
Know the Handoffs
Hotter creep or hydrogen duty: F22, then F91. Hot sulfidic streams: F5/F9. Critical RT-mandated lines: F11 weld necks.
How Our A182 F11 Slip On Flanges Are Manufactured
1
Forging — cut billet of certified A182 F11 heat is hot-forged into the flange blank, keeping full heat traceability from raw material to despatch.
2
Heat treatment — annealed or normalized & tempered per ASTM A182, with the thermal record retained per lot; the controlled temper delivers the 143-207 HB working condition.
3
Machining — hub, faces and bolt holes to ASME B16.5; the bore machined slightly over pipe OD per the slip-on tolerance.
4
Facing — SORF raised face with serrated stock finish; flat face or RTJ groove where the order specifies.
5
Testing & marking — mechanical, chemical and hardness verification against the heat, then permanent marking of grade, class, size, rating and heat number.
6
Certification & packing — EN 10204 3.1 MTC (3.2 witnessed on request), export-packed as pictured on this page.
Where A182 F11 Slip On Flanges Are Used
The lower creep range and hot hydrogen: main and auxiliary steam lines, boiler external piping, hot reheat and extraction steam, hydrotreater and reformer hydrogen loops per API RP 941, hot oil systems, and refinery services one alloy step past carbon steel. Our F11 production and stock below:
A182 F11 Flanges — In Production at Our WorksA182 F11 Flange — Machined & MarkedPolybag-Lined Export Crate — Seaworthy Packing
A182 F11 Slip On Flange Dimensions
F11 slip-on dimensions follow the ASME B16.5 slip-on tables — identical for every material. Full charts by class:
Example: “Slip On Flange, 6″ NB, ASME B16.5 Class 300, RF, ASTM A182 F11 Cl.2, EN 10204 3.1 — 20 pcs.” Quotations normally within 24 hours with price, unit weight and delivery.
ASTM A182 F11 Slip On Flanges — Frequently Asked Questions
What is an ASTM A182 F11 slip on flange?
It is a slip-on flange forged from ASTM A182 F11 — a 1¼% chromium, ½% molybdenum alloy steel — dimensioned to ASME B16.5. The flange slides over the pipe end and is secured with two fillet welds, and the chrome-moly chemistry is the entry grade of elevated-temperature piping: the first step power plants and refineries take when carbon steel runs out of temperature. It serves steam lines, boiler external piping and hot hydrogen services.
What is the chemical composition of ASTM A182 F11?
For F11 Class 2, the class normally supplied for flanges, per ASTM A182: carbon 0.10-0.20%, manganese 0.30-0.80%, silicon 0.50-1.00%, phosphorus 0.040% max, sulphur 0.040% max, chromium 1.00-1.50% and molybdenum 0.44-0.65%. The chromium stabilises the steel's carbides against hot hydrogen and adds oxidation resistance; the molybdenum is the creep-strength element that keeps the flange strong at steam temperatures.
What are the mechanical properties of A182 F11 slip on flanges?
For F11 Class 2 per ASTM A182: tensile strength 485 MPa (70 ksi) minimum, yield strength 275 MPa (40 ksi) minimum, elongation 20% minimum in 2", reduction of area 30% minimum, and hardness 143-207 HB. The grade is supplied heat treated (annealed or normalized and tempered), and the values — matching A105 carbon steel at room temperature but holding far better as temperature climbs — are demonstrated per heat on the EN 10204 certificate.
What is the difference between F11 Class 1, Class 2 and Class 3?
Carbon level and strength. Class 1 is the low-carbon, lower-strength version (415 MPa / 60 ksi minimum tensile); Class 2 is the standard flange class at 485 MPa (70 ksi) tensile and 275 MPa yield; Class 3 is the high-strength version at 515 MPa (75 ksi) tensile and 310 MPa yield. Chromium and molybdenum ranges are the same family throughout. Flange orders that say simply 'F11' are normally supplied as Class 2 — state the class explicitly where the piping specification requires it.
When is F11 chosen over carbon steel A105?
When temperature, creep or hydrogen retires the carbon steel. A105 is economical to about 425 °C, beyond which prolonged service risks graphitization and its allowable stresses collapse. F11's ½% molybdenum holds creep strength deep into steam territory and its chromium resists hot hydrogen attack per the API RP 941 Nelson curves. The moment a line's design temperature or hydrogen partial pressure crosses the carbon-steel limits, F11 is the first and cheapest alloy step.
When is F11 chosen over F22?
F11 covers the lower half of the creep range; F22 (2¼Cr-1Mo) takes over above it. Typical practice runs F11 in steam and hot hydrogen service up to roughly 550-560 °C metal temperature, beyond which F22's higher chromium and doubled molybdenum earn their premium — and modern high-energy plants jump to F91. Hydrogen partial pressure moves the boundary too: the Nelson curves push hotter, higher-pressure hydrogen duty up the ladder. The piping specification fixes the split; both grades come from the same forge here.
What temperature can A182 F11 slip on flanges handle?
ASME B16.5 rates the 1¼Cr material class to 649 °C, with creep governing the allowable stresses in the upper range. In working practice F11 is the grade of choice from where carbon steel stops (about 425 °C) up to roughly 550-560 °C, with F22 and F91 covering the hotter rungs. As with every flange, the pressure rating falls as temperature rises — check the B16.5 table for the class at design temperature.
Why is F11 used in hydrogen service?
Because of high-temperature hydrogen attack (HTHA). Above the carbon-steel limits of the API RP 941 Nelson curves, hydrogen diffuses into steel, reacts with carbides and leaves internal methane fissures — an insidious, inspection-resistant damage mechanism. Chromium and molybdenum stabilise the carbides: F11 stands considerably higher on the Nelson curves than carbon steel, making it the entry grade for hydrotreater and reformer loops, with F22 covering hotter, higher-pressure hydrogen.
How is an A182 F11 slip on flange welded to pipe?
With two fillet welds — hub outside, bore inside, pipe set back 1/8" (3 mm) from the face — under chrome-moly discipline: preheat (typically 120-180 °C), matching E8018-B2 / ER80S-B2 consumables, and post-weld heat treatment at about 700-745 °C per ASME B31.3 requirements. F11 is the mildest of the chrome-molys to weld, but it is still an air-hardening alloy — plan the preheat and PWHT into fabrication.
What is the equivalent of ASTM A182 F11 in other standards?
ASME SA182 F11 is the boiler-code twin, and UNS K11572 designates the standard Class 2. The European working equivalent is 13CrMo4-5 (Werkstoff 1.7335, formerly DIN 13CrMo44). System partners specified alongside it: ASTM A335 P11 pipe and A234 WP11 fittings — the 1¼Cr trio of steam and hydrogen lines. Certificates always state the actual grade and class forged.
Are slip on flanges allowed in high-temperature service?
Within limits. Slip-on flanges are permitted by ASME B31.3 and serve on lower-criticality hot lines, but many power and refinery piping classes restrict creep-range and cyclic services to weld neck flanges, whose full-penetration butt weld can be radiographed and resists thermal fatigue better than fillet welds. Follow the piping class: where it allows a slip-on, an F11 slip-on delivers the metallurgy at lower flange and fit-up cost.
Is A182 F11 a stainless steel?
No. With just 1-1.5% chromium, F11 is a low-alloy steel — nowhere near the roughly 10.5% chromium needed to passivate. It rusts in ambient wet service like any carbon steel and offers no answer to aqueous corrosion; its alloying is aimed at creep strength and hydrogen resistance at elevated temperature. For wet corrosion move to 300-series stainless; for hot sulfidic refinery streams, to the higher-chromium F5 and F9.
What sizes and classes are A182 F11 slip on flanges available in?
From ½" to 24" NB per ASME B16.5 in Classes 150 through 2500, with larger patterns forged to order. Chrome-moly material is project-specific rather than shelf stock, so flanges are typically forged against the order — standard sizes normally dispatch within a few weeks with EN 10204 3.1 certification. State the required delivery on the enquiry and we confirm the schedule with the quotation.
What details are needed to get an accurate A182 F11 slip on flange quotation?
Five elements plus commercial terms: (1) size and standard — e.g. 6" NB ASME B16.5; (2) pressure class — 150 through 2500; (3) facing — SORF (raised face) default, flat face or RTJ where specified; (4) grade and class — ASTM A182 F11 Cl.2 (default), Cl.1 or Cl.3 where the specification requires, with any supplementary requirements; (5) certification — EN 10204 3.1 or 3.2. No pipe schedule is needed for the slip-on bore. Add the quantity and destination and we return price, weight and delivery.
Who manufactures ASTM A182 F11 slip on flanges in India?
Tesco Steel & Engineering is an ISO 9001:2015 certified flange manufacturer based in Mumbai, India, forging ASTM A182 F11 slip on flanges from ½" to 24" NB per ASME B16.5 — alongside the full chrome-moly family F5, F9, F22 and F91 — with heat-treated supply, full heat traceability and EN 10204 3.1/3.2 certification on every lot. Flanges are marked with grade, size, class and heat number and export to more than 50 countries.
