Alloy Steel Flanges

Can your flanges maintain seal integrity under high heat and pressure cycles? Our ASTM A182 F11 and F22 Alloy Steel Flanges perform reliably across refineries, boilers, and power systems operating above 500°C.

Standard Specification

ASTM A182 (F11/F22), ASME B16.5, NACE MR0175/ISO 15156

Pressure Rating

Class 150 to 2500 (PN10 to PN420) [Higher temp rating than carbon steel]

Material

F11 (1¼Cr-½Mo), F22 (2¼Cr-1Mo) [Grade variations: F11 CL2, F22 CL3]

Nominal Size

½” to 48″ (DN15 to DN1200) [Limited by forging press capacity]

Flange Type

WN, SO, BL [No threaded types per NACE]

Product Description

Carbon steel often softens or scales at elevated service conditions. We offer alloy flanges with added chromium and molybdenum that retain hardness, resist oxidation, and allow longer run-times between shutdowns.

Facing Type

RF, RTJ [Special serrations for high-temp service]

Dimensions

ASME B16.5 + PWHT allowances [Thickness +10% vs carbon steel]

Bolt Circle Diameter

Matches standard flanges [±0.03″ tolerance for RTJ]

Number & Size of Bolt Holes

ASTM A193 B7/B16 bolts [Lubricated threads for high-temp]

Surface Finish

125-250 μin Ra (RF), 63-125 μin Ra (RTJ) [No grinding on sealing faces]

Corrosion Resistance

Oxidation-resistant up to 593°C [Not for sour service without PWHT]

Temperature Rating

-29°C to +593°C (F11), +621°C (F22) [Impact tested below -18°C]

Material Certification

EN 10204 3.1, NACE MR0175 (with PWHT), PED 2014/68/EU

Gasket Compatibility

Spiral Wound (SS316+Graphite), RTJ Oval [Metal jacketed for >400°C]

Coating/Plating

Temp-resistant paints (400°C+), No galvanizing [Prevents liquid metal embrittlement]

Manufacturing Method

Forged + Normalized/Tempered [PWHT at 675-760°C per ASTM A961]

Technical Advantages

Alloy steel flanges must resist oxidation, retain strength at temperature, and meet thermal treatment standards. Our F11 and F22 variants undergo full normalization and tempering, followed by optional PWHT to control grain structure. 
Each flanges maintains tensile integrity above 540°C and matches sealing dimensions with ASME B16.5 carbon steel types. We apply serrated face finish for high friction and use B7/B16 bolting with anti-seize coating to avoid thread seizing. 

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Need reliable Flanges for your next project? Get in touch with us today, and we’ll help you find exactly what you need!

Industry Applications

Thermal Power Plants

Connects headers and valves in high-temperature steam loops without joint failures. 

Petrochemical Reactors

Performs in heavy hydrogen and hydrocarbon service with low creep under thermal load. 

Boiler Pressure Parts

Seals safely at elevated pressures, ensuring no gasket extrusion or blowout. 

Heat Exchanger Units

Sustains joint strength under cycling thermal expansion and contraction. 

High-Temperature Pipelines

Handles thermal shock with stable bolt load across long pipe runs. 

Hydrogen Reformers

Delivers consistent flange hardness after post-weld heat treatment per NACE specs. 

Sealing for Critical Heat-Based Systems

High-pressure heat systems require flange materials that won’t soften or deform during service. Our alloy steel flanges retain shape through extended heat exposure and mechanical loading. 
Material traceability, mill test certificates, and documented heat treatment cycles come standard with every shipment. These flanges reduce downtime risks for buyers needing uninterrupted sealing at elevated temperatures. 

Having Doubts? Our FAQ

Check all our Frequently Asked Question

Can F11 and F22 flanges handle fluctuating pressure and temperature cycles?

Yes, both grades maintain mechanical strength under cyclic thermal stress due to their chromium-molybdenum content. Post-weld heat treatment stabilizes the microstructure and reduces creep deformation. This ensures consistent sealing without flange face distortion.

How do F11 and F22 flanges compare with carbon steel in elevated temperature applications?

Alloy steel flanges retain tensile strength beyond 540°C while carbon steel loses hardness above 400°C. F22 flanges operate safely up to 621°C in continuous service. This gives more thermal margin and longer service life.

What bolt compatibility should we follow for these flanges in high-temperature joints?

Use ASTM A193 B7 or B16 bolts with anti-seize lubrication to prevent galling. These bolts match the thermal expansion of F11 and F22 flanges. This prevents loss of preload during temperature cycling.

Will we receive dimensional tolerance control across large diameters?

Yes, we hold ±0.03″ tolerance on RTJ bolt circles even in flanges up to 48 inches. Forging and finish machining follow ASME B16.5 with extra allowance for heat-treated faces. You get uniformity in fit-up without on-site rework.

Can we request flange face serration suitable for high-temperature sealing?

Yes, we provide controlled serration profiles on RF and RTJ faces for elevated temperature gaskets. The grooves meet ASME finish range and prevent gasket creep under thermal load. This helps retain sealing pressure in long-term service.

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LOCATIONS

Global Sales Office

818, Preakness lane, Coppell, Texas, USA – 75019

Registered Office

10-A, First Floor, V.V Complex, Prakash Nagar, Thiruverumbur, Trichy-620013, Tamil Nadu, India.

Operations Office

9/1, Poonthottam Nagar, Ramanandha Nagar, Saravanampatti, Coimbatore-641035, Tamil Nadu, India. ㅤ

Other Locations

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Alloy Steel Flanges

Alloy Steel Flanges

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Alloy Steel Flanges

Alloy Steel Flanges

Need reliable Machining for your next project? Get in touch with us today, and we’ll help you find exactly what you need!

Get Latest Price

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