Yuhong Group: Complete Heat Exchanger Components – From Tubes to Flanges
Yuhong Group Co., Ltd. designs and manufactures a comprehensive range of thermal equipment for global industries. Our core offerings include shell and tube heat exchangers, pressure vessels, air coolers, and a complete supply of critical components: finned tube bundles, U-tube bundles, heat exchanger tubesheets, and all related parts – including forged flanges and covers for pressure-containing connections. Our full-service approach ensures you get exactly what you need for new projects or maintenance.
Shown in the attached photographs is one of our ASME SA336 F11 CL2 channel cover flanges – a forged chrome-moly alloy component precision-machined for high-temperature heat exchanger service.
Product Focus: Channel Cover Flange – The Access Point for Tube-Side Maintenance
The channel cover flange (also called a bonnet cover or end cover flange) is a critical pressure-retaining component that closes the end of a heat exchanger channel. It provides access to the tube side for inspection, cleaning, and maintenance, while maintaining a leak-tight seal under operating pressure and temperature.
Based on the images, this flange exhibits:
Material: ASME SA336 F11 CL2 (chrome-moly alloy steel, 1.25Cr-0.5Mo, Class 2)
Type: Channel cover flange (管箱盖法兰)
Dimensions: OD 630mm × ID 431.6mm × THK 100mm (as stamped on the part)
Manufacturing method: Forged (dense grain structure, no internal porosity)
Machining: Precision-machined face with bolt holes for stud bolts and gasket seating
Marking: Full traceability with material grade, dimensions, heat number, and project number
Why SA336 F11 CL2 Chrome-Moly for Channel Cover Flanges?
| Property | Benefit for Channel Cover Flange Application |
|---|---|
| 1.25Cr-0.5Mo alloy | Provides excellent high-temperature strength and creep resistance up to ~550°C. |
| Class 2 temper | Offers higher strength than Class 1 – suitable for elevated pressure services. |
| Forged construction | Uniform grain structure; no internal voids or laminations – critical for pressure-retaining components. |
| ASME compliance | Fully traceable to ASME Section II material specifications. |
| Hydrogen service capability | Chrome-moly alloys are widely used in hydrogen-rich environments (refining, petrochemical). |
| Heat number traceability | Each flange is stamped with heat number for full traceability. |
Key Components That Interface with This Channel Cover Flange
| Component | Material (Typical) | How It Interfaces with the Flange |
|---|---|---|
| Heat Exchanger Channel | Carbon steel or chrome-moly | Bolted to the flange; the channel cover flange closes the channel end. |
| Gasket | Spiral-wound, metal-jacketed, or RTJ | Seals between the channel cover flange and the channel body. |
| Stud Bolts & Nuts | SA193 B16 / SA194 4 or B7/2H | Pass through bolt holes; clamp the cover to the channel. |
| Heat Exchanger Tube | Carbon steel or alloy | Not directly connected – accessible when cover is removed. |
| Heat Exchanger Tubesheet | Carbon steel or alloy | Located inside the channel; the flange allows access to the tubesheet face. |
| U-Tube Bundle | Carbon steel or alloy | Accessible through the flanged opening when cover is removed. |
Technical Highlights of Our F11 Channel Cover Flange
Forged, not cast: Forging eliminates internal porosity and provides superior mechanical properties – essential for high-pressure containment.
Precision machining: The sealing face is machined to the required surface finish (typically 125-250 RMS for spiral-wound gaskets, or smoother for RTJ).
Bolt hole accuracy: Bolt holes are drilled on exact pitch circle – ensures proper bolt alignment during assembly.
Full traceability: Each flange is stamped with material grade, dimensions, heat number, and project number (as shown in your photographs).
High-temperature capability: Suitable for continuous service up to approximately 550°C (depending on pressure).
Hydrogen service: F11 is widely specified for hydrogen-containing streams in refineries and petrochemical plants.
Knowledge Module: Channel Cover Flange vs. Tube Side Flange – Understanding the Difference
| Flange Type | Location | Function | Access Provided |
|---|---|---|---|
| Channel Cover Flange (shown here) | End of the channel / bonnet | Closes the channel end; allows access to the tube side | Full access to tube ends and tubesheet face |
| Tube Side Flange | Between channel and shell/tubesheet | Connects the channel to the shell; allows tube-side fluid to enter/exit | Access to the channel interior when cover is removed |
| Shell Flange | On the shell body | Connects shell sections; provides shell-side access | Access to shell-side internals |
| Nozzle Flange | On inlet/outlet nozzles | Connects process piping to the heat exchanger | No internal access – piping connection only |
The flange shown in your photograph is a channel cover flange – it closes the end of the channel and is typically removed when tube-side inspection or maintenance is required.
Knowledge Module: F11 CL2 Material Properties & Applications
| Parameter | Value / Description |
|---|---|
| UNS number | K11572 |
| Nominal composition | 1.25% Cr, 0.5% Mo |
| Tensile strength (min) | ~515 MPa (Class 2) |
| Yield strength (min) | ~310 MPa (Class 2) |
| Max continuous service temp | ~550°C |
| Typical applications | Refinery exchangers, hydrogen coolers, high-pressure steam generators, reactor effluent coolers |
| ASME code | ASME Section II, Part A – SA-336/SA-336M |
When to specify F11 CL2 for channel cover flanges:
Operating temperature >400°C
Operating pressure >50 bar
Service involves hydrogen, steam, or high-temperature hydrocarbons
ASME Code compliance required
Carbon steel is inadequate due to creep or hydrogen attack concerns
Advantages of Ordering Channel Cover Flanges from Yuhong Group
Exactly to your drawing: We machine forged blanks to your specification – OD, ID, thickness, bolt circle, and facing type.
Fast turnaround: Forged blanks in common sizes are available; machining typically 1-3 weeks.
Any material: Chrome-moly (F11, F22, F5, F91), carbon steel (SA105, SA350 LF2), stainless steel (F304, F316L), nickel alloys.
Component-only or complete assembly: We supply just the flange – or the complete shell and tube heat exchanger with all associated components.
Full documentation: Material test certificate (MTC) per EN 10204 3.1, dimensional report, PMI test report (optional).
Knowledge Module: Flange Facing Types – Matching the Gasket to the Service
The sealing face of a flange must match the gasket type and service conditions:
| Facing Type | Abbreviation | Gasket Type | Best For |
|---|---|---|---|
| Raised Face | RF | Spiral-wound, sheet, or flat gasket | Most common – general service, moderate pressures |
| Ring-Type Joint | RTJ | Metal octagonal or oval ring | High-pressure, high-temperature services |
| Flat Face | FF | Soft sheet gasket | Low-pressure, large-diameter applications |
| Tongue & Groove | T&G | Compressed fiber or metal-jacketed | Critical services requiring positive gasket retention |
The flange shown in your photograph (machined face with bolt holes) is typically an RF (Raised Face) design – the most common facing type for heat exchanger channel covers.
Component-Only Supply – We Also Provide
If you need just parts (not a full exchanger), we supply:
Heat exchanger tubes – chrome-moly (F11/F22), stainless steel, carbon steel – cut to length, end-prepared for rolling or welding
Finned tube bundles – for air cooler retrofits and gas-cooling applications
U-tube bundles – complete with tubesheet, baffles, and tie rods
Heat exchanger tubesheet – drilled and grooved per your pattern
Baffles, tie rods, spacers – machined to your dimensions
Flanges & covers – SA105, SA350 LF2, F11, F22, F304, F316L – any facing type
Typical Applications for F11 Channel Cover Flanges
| Industry | Application | Why F11 CL2 |
|---|---|---|
| Petrochemical refineries | Hydrogen coolers, reactor effluent exchangers | High-temperature hydrogen service; resists H₂ attack. |
| Power generation | High-pressure steam heaters | Chrome-moly retains strength at 400-550°C. |
| Chemical processing | High-temperature acid / solvent heaters | Withstands thermal cycling and corrosive environments. |
| Oil & gas | Gas processing at elevated temperatures | Reliable in high-pressure, high-temperature gas service. |
Quality Assurance & Documentation
Every F11 channel cover flange we ship includes:
Mill Test Certificate (MTC) per EN 10204 3.1 – chemical analysis and mechanical properties
Dimensional inspection report – OD, ID, thickness, bolt circle, facing dimensions
Heat number stamping – as shown on the part for full traceability
PMI (Positive Material Identification) – available on request
NDE – UT, MT, or PT as required
Third-party inspection (SGS, BV, TÜV) – at buyer's request
Get a Quotation for Your F11 Channel Cover Flange
To quote a channel cover flange like the one in your photographs, send the following to jimmy@steelseamlesspipe.com:
Drawing (PDF, scan, or hand sketch with key dimensions: OD, ID, thickness, bolt circle, bolt hole size and quantity, facing type)
Or: send us your old flange for reverse engineering (return shipping arranged)
Material grade: F11 CL2 (as shown) or other
Facing type: RF, RTJ, FF, or T&G
Quantity required (single piece or production run)
We will respond with a dimensional drawing for approval, price, and delivery schedule – typically within 48 hours.
