Tesco Steel & Engineering manufactures ASTM A182 F11 alloy steel flanges — the 1.25% chromium, 0.5% molybdenum (1.25Cr-0.5Mo) chrome-moly forging grade. The chromium and molybdenum give good creep strength, elevated-temperature strength and resistance to high-temperature hydrogen attack, making F11 a standard material for boiler, steam and moderate high-temperature refinery piping. As a hardenable alloy steel it normally needs preheat and post-weld heat treatment. Supplied in Class 1, 2 or 3. Available in weld neck, slip-on, blind, socket-weld, threaded, lap-joint, spectacle and orifice types to ASTM A182 / ASME B16.5. Class 150 to 2500, NPS 1/2″ to 24″, PN6 to PN400. ISO 9001:2015 certified. Made in India.
ASTM A182 F11 (1.25Cr-0.5Mo) Alloy Steel Flanges
A182 F11 Weld Neck & Blind Flanges
Tesco Steel & Engineering manufactures A182 F11 flanges in all types from weld neck to orifice, Class 150 to 2500 — supplied normalized-and-tempered with EN 10204 3.1 / 3.2 certification, hardness results and third-party inspection on request. Explore the wider alloy steel flange range, the higher-chrome A182 F22 flanges, A182 F5 flanges and A182 F9 flanges, and the flange dimension charts.
| ASTM A182 F11 flanges are available in the following specifications: | |
|---|---|
| Material Grade | ASTM A182 / A182M Grade F11, Class 1 / 2 / 3 (1.25Cr-0.5Mo chromium-molybdenum alloy steel) |
| Alloy Type | Chromium-molybdenum (chrome-moly) hardenable alloy steel |
| Heat Condition | Annealed or normalized and tempered |
| Size | 1/2″ NB to 24″ NB (DN 15 to DN 600); larger to ASME B16.47 |
| Class / Rating | 150#, 300#, 600#, 900#, 1500#, 2500# · 3000#, 6000#, 9000# (socket-weld / threaded) |
| Pressure Ratings | PN 6 – PN 400 (PN6, 10, 16, 25, 40, 64, 100, 160, 250, 320, 400) |
| Related Specs | Pipe ASTM A335 P11; casting ASTM A217 WC6; fittings ASTM A234 WP11; plate A387 Gr11 |
| Dimensional Standards | ASME B16.5, ASME B16.47 (Series A & B), MSS SP-44, DIN EN 1092-1 |
| Flange Types | Weld Neck (WNRF), Slip-On (SORF), Blind, Socket Weld (SWRF), Lap Joint, Threaded / Screwed, Spectacle Blind, Long Weld Neck, Orifice, Plate |
| Flange Faces | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Tongue & Groove (T&G) |
| Weld Filler | E8018-B2 / ER80S-B2 (matching 1.25Cr-0.5Mo), with preheat & PWHT |
| Testing | Hardness, hydrostatic, UT, MT/PT per spec; EN 10204 3.1 / 3.2 |
F11 is the 1.25Cr-0.5Mo member of the A182 chrome-moly family — the lowest-chromium of the common grades. The chromium and molybdenum give creep strength and hydrogen resistance for moderate high-temperature service.
| Element | ASTM A182 F11 |
|---|---|
| Carbon (C) | 0.05 – 0.15% |
| Manganese (Mn) | 0.30 – 0.80% |
| Silicon (Si) | 0.50 – 1.00% |
| Chromium (Cr) | 1.00 – 1.50% |
| Molybdenum (Mo) | 0.44 – 0.65% |
| Phosphorus (P) | 0.030% max |
| Sulphur (S) | 0.030% max |
| Mechanical Property (Class 2) | ASTM A182 F11 |
|---|---|
| Tensile Strength (min) | 70 ksi (485 MPa) |
| Yield Strength (min) | 40 ksi (275 MPa) |
| Elongation (min) | ~20% |
| Hardness | ≤ 197 HBW (typical) |
| Classes | Class 1 (~60 ksi) · Class 2 (~70 ksi) · Class 3 (~75 ksi) |
| Service Temperature | Sustained high temperature, ~550–600°C |
| Product Form | 1.25Cr-0.5Mo Designation |
|---|---|
| Forgings / Flanges | ASTM A182 F11 |
| Seamless Pipe | ASTM A335 P11 |
| Castings | ASTM A217 WC6 |
| Fittings | ASTM A234 WP11 |
| Plate | ASTM A387 Gr 11 |
| Common name | 1.25Cr-0.5Mo Chrome-Moly Alloy Steel |
F11 Weld Neck Flange (WNRF)
F11 Slip-On Flange (SORF)
F11 Blind Flange
| Flange Type | Description & F11-Specific Use |
|---|---|
| Weld Neck (WNRF) | Tapered hub butt-welded to pipe for high-integrity boiler and steam piping; weld with E8018-B2 filler, preheat & PWHT. |
| Slip-On (SORF) | Fillet-welded over the pipe; used in chrome-moly piping at moderate pressure. |
| Blind | Seals pipe ends and vessel nozzles in high-temperature steam and hydrocarbon systems. |
| Socket Weld (SWRF) | Small-bore (1/2″–2″) instrument and branch connections in hot service. |
| Lap Joint (LJRF) | Used with an F11 stub end where frequent dismantling is required. |
| Threaded (TRFF) | Internal NPT/BSP threads for non-welded connections. |
| Spectacle Blind / Long Weld Neck | Isolation spades and nozzle/long-neck flanges in A182 F11 for high-temperature duty. |
| Property | F11 | F22 | F5 | F9 |
|---|---|---|---|---|
| Nominal type | 1.25Cr-0.5Mo | 2.25Cr-1Mo | 5Cr-0.5Mo | 9Cr-1Mo |
| Chromium | ~1.25% | ~2.25% | ~5% | ~9% |
| Temperature capability | Moderate | High | High | Highest |
| Sulphidic / hydrogen resistance | Moderate | Good | High | Highest |
| Relative cost | Lowest | Low | Higher | Highest |
| Typical role | Boiler / steam / moderate temp | Hydrogen / high-temp | Hot refinery sulphur | Hottest, highest-Cr |
Chromium-molybdenum chemistry gives good creep and elevated-temperature strength for boiler/steam service to ~550–600°C.
Resists high-temperature hydrogen attack per the Nelson curves at moderate temperature/pressure.
The lowest-chromium of the common chrome-moly grades — cost-effective where higher chrome is not required.
A long-established power and refinery material with matching pipe (A335 P11), fittings and castings.
| Industry | Typical Application |
|---|---|
| Power Generation | Boiler, superheater, reheater and steam-line flanges |
| Oil Refining | Moderate high-temperature and hydrogen-service process flanges |
| Petrochemical | Elevated-temperature hydrocarbon process flanged connections |
| Hydrogen / Hydroprocessing | Moderate-temperature hydrogen-service flanges per API 941 |
| Heaters & Furnaces | Fired-heater and steam-line flanged connections |
| Process Plant | General elevated-temperature piping flanges |
Made from certified 1.25Cr-0.5Mo with PMI verification of chromium and molybdenum — chemistry, class and heat-treatment on the MTC.
Supplied in the specified class, annealed or normalized-and-tempered, with hardness within spec for weldability and service.
WNRF, SORF, blind, socket-weld, threaded, lap-joint, spectacle, LWN, orifice and plate — in RF, FF, RTJ and T&G.
EN 10204 3.1 / 3.2 MTC with hardness results, heat/lot traceability, hydrostatic and third-party inspection on request.
A182 F11 flange prices reflect the chrome-moly alloy content plus forging and heat treatment — it is the most economical chrome-moly grade for boiler, steam and moderate high-temperature service. Tesco Steel & Engineering offers competitive ex-works pricing from Mumbai with full export documentation and material traceability. Click Ask for Quote or message us on WhatsApp at +91 92233 66922 with flange type, size (NB), pressure class, quantity and documentation requirements.
Q1. What is an ASTM A182 F11 flange?
An ASTM A182 F11 flange is a forged chromium-molybdenum (chrome-moly) alloy steel flange with about 1.25% chromium and 0.5% molybdenum (1.25Cr-0.5Mo). The chromium and molybdenum give good creep strength, elevated-temperature strength and resistance to high-temperature hydrogen attack, making F11 a standard material for boiler, steam and moderate high-temperature refinery piping. Flanges are made to ASTM A182 and machined to ASME B16.5 / B16.47 dimensions.
Q2. What is the chemical composition of ASTM A182 F11?
ASTM A182 F11 nominal composition: carbon 0.05–0.15%, manganese 0.30–0.80%, silicon 0.50–1.00%, chromium 1.00–1.50%, molybdenum 0.44–0.65%, phosphorus 0.030% max, sulphur 0.030% max. The ~1.25% chromium with ~0.5% molybdenum is the defining 1.25Cr-0.5Mo chrome-moly composition.
Q3. What are the classes of A182 F11?
ASTM A182 F11 is supplied in Class 1, Class 2 and Class 3, which share the same chemistry but differ in tempering and resulting strength. Class 1 has the lowest strength (tensile ~60 ksi min), Class 2 is the common general grade (tensile ~70 ksi min, yield ~40 ksi min), and Class 3 has the highest strength (tensile ~75 ksi min). The project specification states which class is required; Class 2 is the most widely used.
Q4. What is the difference between A182 F11, F22, F5 and F9?
These are chrome-moly alloy steels with increasing chromium for higher temperature and corrosion resistance: F11 is 1.25Cr-0.5Mo, F22 is 2.25Cr-1Mo, F5 is 5Cr-0.5Mo, and F9 is 9Cr-1Mo. F11 is the lowest-chromium of the group, used for boiler/steam and moderate high-temperature service, while F22, F5 and F9 step up for higher temperatures and more aggressive high-temperature sulphur/hydrogen environments.
Q5. Do A182 F11 flanges need post-weld heat treatment?
Usually yes. As a hardenable chrome-moly steel, F11 generally requires preheat (typically around 150–250 degrees C) before welding and post-weld heat treatment (PWHT, a temper around 690–730 degrees C) to relieve stress, temper the heat-affected zone and restore toughness, depending on thickness and code. Matching low-hydrogen consumables (e.g. E8018-B2 / ER80S-B2) are used.
Q6. What standards apply to A182 F11 flanges?
A182 F11 flanges are forged to ASTM A182/A182M (Grade F11, Class 1/2/3) and machined to ASME B16.5 (1/2 inch to 24 inch) or ASME B16.47 / MSS SP-44 for larger sizes, with EN 1092-1 for PN-rated flanges. Material is supplied annealed or normalized-and-tempered with EN 10204 3.1 / 3.2 certification. Matching pipe is ASTM A335 P11, casting ASTM A217 WC6, fittings ASTM A234 WP11.
Q7. What are the mechanical properties of A182 F11 Class 2?
Typical ASTM A182 F11 Class 2 properties: tensile strength 70 ksi (485 MPa) minimum, yield strength 40 ksi (275 MPa) minimum, elongation about 20% minimum, hardness generally below 197 HBW. It is supplied in the normalized-and-tempered (or annealed) condition with good elevated-temperature and creep properties.
Q8. What temperature can A182 F11 flanges handle?
A182 F11 is used for sustained elevated-temperature service, commonly up to about 550–600 degrees C, with good creep strength and resistance to high-temperature hydrogen attack. The exact allowable temperature and pressure follow the applicable code (e.g. ASME B16.5 / B31.1 / B31.3) ratings for the grade.
Q9. What industries use A182 F11 flanges?
ASTM A182 F11 flanges are used in power generation (boiler, superheater and steam piping), oil refining and petrochemical (moderate high-temperature and hydrogen service), and general high-temperature process plant where chrome-moly creep strength is required at a lower cost than the higher-chromium grades.
Q10. Are A182 F11 flanges supplied with material test certificates?
Yes. Every A182 F11 flange is supplied with EN 10204 3.1 (or 3.2) mill test certificates confirming chemistry, mechanical properties, class, heat-treatment condition and heat/lot traceability, with hardness, hydrostatic testing and third-party inspection on request. Tesco Steel & Engineering is an ISO 9001:2015 certified manufacturer and exporter from Mumbai, India.