ASME SA336 F11 CL2 Channel Cover Flange | Forged Chrome-Moly Heat Exchanger Components
Heavy-Duty ASME SA336 F11 CL2 Forged Chrome-Moly Channel Cover Flanges
Are you designing a thermal system for severe hydrogen service, or replacing a leaked bonnet flange on a high-pressure steam generator? Ensuring long-term structural integrity at elevated temperatures requires advanced forged metallurgy.
Yuhong Group Co., Ltd. engineers and manufactures precision-machined ASME SA336 F11 Class 2 (SA336 F11 CL2) chrome-moly alloy forged flanges. As critical external pressure-retaining components for shell and tube heat exchangers, our heavy-wall channel cover flanges (bonnet flanges) provide reliable leak-tight sealing and easy access to tube bundles during routine maintenance turnarounds.
Technical Highlights: Why Specify Forged SA336 F11 Class 2?
In heavy processing industries operating between 400 degrees C and 550 degrees C, standard carbon steel suffers from strength degradation and creep. ASME SA336 F11 (1.25Cr-0.5Mo alloy) is the industry standard for these environments.
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Exceptional Creep and Hydrogen Resistance: The deliberate addition of Chromium and Molybdenum provides superior high-temperature tensile strength and guards against high-temperature hydrogen attack (HTHA) in refinery hydrotreating and hydrocracking loops.
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Class 2 Tempered Strength: Class 2 heat treatment provides higher mechanical properties than Class 1, with a minimum tensile strength of 515 MPa and minimum yield strength of 310 MPa, allowing for thinner yet safer pressure vessel wall profiles under high pressures (above 50 bar).
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Integrity of Forged Construction: Our heavy-duty blanks are hot-forged from solid billets to guarantee a dense, uniform grain structure. This process eliminates internal porosity and subsurface laminations, ensuring full compliance with ASME Section III and VIII requirements.
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CNC Flange Facing Precision: Sealing faces are machined to precise surface finishes, typically 125-250 RMS for spiral-wound gaskets, or high-gloss smooth finishes for Ring-Type Joint (RTJ) metal gaskets.
Technical Specifications & Engineering Limits
Every forged chrome-moly flange from Yuhong Group undergoes 100% testing and is hard-stamped with its unique heat number and material code for complete traceability.
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Material Standard: ASME SA336 Grade F11 Class 2 / ASTM A336 F11 CL2 (UNS K11572)
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Exchanger Design Standards: Fully compliant with TEMA Class R (Refinery), Class B, and Class C
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Standard Dimensions Shown: Outer Diameter (OD) 630mm, Inner Diameter (ID) 431.6mm, Finished Thickness 100mm
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Flange Facing Profiles: Raised Face (RF), Ring-Type Joint (RTJ), Tongue and Groove (T&G), Flat Face (FF)
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Quality Control & Testing: 100% Ultrasonic Testing (UT), Liquid Penetrant Testing (PT), Positive Material Identification (PMI), and Dimensional Inspection
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Documentation Provided: EN 10204 3.1 Mill Test Certificate (MTC), NDT Reports, Forging Diagrams
Selection Guidelines: Operating Limits for Carbon Steel vs. Chrome-Moly
| Operational Factor |
Carbon Steel Flanges (SA105) |
Chrome-Moly Flanges (SA336 F11 CL2) |
| Max Service Temperature |
Up to 400 degrees C (Risk of graphitization above this) |
Up to 550 degrees C (Excellent creep resistance) |
| Hydrogen Environment |
Limited (Susceptible to methane bubble cracking) |
Safe (Chromium traps carbon, preventing hydrogen attack) |
| Minimum Tensile Strength |
Around 485 MPa |
515 MPa (Class 2 offers higher pressure ratings) |
| Primary Industry Use |
Utility steam, clean hydrocarbons, low-pressure water |
Refinery hydroprocessing, high-pressure steam loops |
Critical Engineering Checklist: Specifying Your Replacement Flange Correctly
To prevent costly dimensional mismatches or installation delays during a plant shutdown, please cross-examine these technical parameters before finalizing your order:
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Gasket Seating Profile Match: Ensure the flange face matching pattern (RF serration vs. RTJ oval/octagonal groove) aligns with your existing channel body and gasket style.
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Bolt Circle Diameter (BCD) Accuracy: Double-check the total bolt hole count, hole diameters, and pitch circle diameter to guarantee perfect stud bolt alignment during torque tightening.
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Traceability Standards: For heavy chemical and refinery deployment, ensure your procurement requires hard-stamped material heat numbers and optional third-party inspections (SGS, BV, TUV).
Single-Source Supply for Pressure Vessel Components
Yuhong Group offers a flexible scope of supply, accommodating component-only spare parts or fully integrated heat exchanger systems:
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Matching Alloy Tubes: Seamless chrome-moly tubes (ASME SA213 T11 / T22), stainless steel seamless tubes, and nickel alloy tubes.
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Internal Hardware: Precision-drilled tubesheets, segmental baffle plates, tie rods, and carbon steel spacers.
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Fasteners & Seals: High-temperature stud bolts (SA193 B7 / B16), heavy hex nuts (SA194 2H), and custom spiral-wound gaskets.
Request a 48-Hour Technical Quote
Accelerate your maintenance turnaround schedule. Send your PDF engineering blueprints, CAD files, or dimensional datasheets directly to our global sales engineering division:
📧 Email: jimmy@steelseamlesspipe.com
Please include the following for a rapid quote:
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Flange Outer Diameter (OD), Inner Diameter (ID), and finished thickness.
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Bolt circle diameter (BCD), bolt hole size, and total hole count.
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Preferred facing type (RF or RTJ) and your target operating temperature/pressure.
Our technical sales team will deliver a comprehensive commercial proposal and technical sketch within 48 hours.
Por favor verifique seu email!
