Bimetallic Extruded Finned Tube with Aluminum Fins: The Ultimate Solution for Efficient Heat Transfer
DR Finned Tube

What It Is — A bimetallic finned tube consisting of an inner base tube (carbon steel, stainless steel, copper, etc.) and an outer aluminum fin layer formed through high‑pressure cold extrusion, creating a seamless metallurgical bond.

Why It Matters — Delivers superior thermal efficiency (up to 20% better than wrapped fins), outstanding corrosion resistance, and exceptional mechanical durability for demanding industrial environments.

Ideal For — Air‑cooled heat exchangers, power plant condensers, petrochemical processing, HVAC systems, oil & gas platforms, and any application requiring reliable long‑term heat exchange in harsh conditions.

Why Choose Us — As a direct manufacturer with an in‑house technical team, we offer fully customized designs, rigorous quality control, factory‑direct pricing, and responsive engineering support from initial consultation to after‑sales service.

What Is a Bimetallic Extruded Finned Tube?

A bimetallic extruded finned tube is a high‑performance heat exchanger component that combines two distinct metals through a precision cold extrusion process. An inner base tube—typically carbon steel, stainless steel, copper, or other alloys—is fitted with an outer aluminum sleeve (also called a muff tube). Under high pressure of approximately 1200 psi, three rotating tooling rolls extrude the aluminum outward, forming seamless spiral fins that are metallurgically bonded to the base tube.

Unlike conventional finned tubes where fins are simply wrapped or embedded, the extrusion process creates an integral structure with no mechanical joint between the fin and the tube. The aluminum outer layer fully encapsulates the base tube (except at the bare ends), providing complete corrosion protection while delivering exceptional thermal transfer efficiency.

How It Works — The Cold Extrusion Process

The manufacturing process begins with the insertion of the base tube into a thick‑walled aluminum muff tube. The composite assembly is then fed through a specialized extrusion machine equipped with multiple rotating arbors and forming discs. These tooling components apply controlled pressure to the aluminum surface, forcing the material upward into a spiral fin pattern through cold plastic deformation.

This cold working method offers several critical advantages:

• 100% metallurgical bond between the aluminum fin and the base tube eliminates contact thermal resistance, which can be as low as < 0.0001 m²K/W

• Enhanced mechanical strength of the fins due to work hardening during extrusion
• No thermal stress degradation because there is no dissimilar‑material interface to separate under thermal cycling

The extrusion is performed on a continuous fin extruder, ensuring consistent fin geometry, uniform fin pitch, and repeatable quality across entire production batches.

Key Advantages Over Other Fin Tube Types

When selecting fin tubes for industrial heat exchangers, engineers must choose among several types. Here is how extruded fins compare:

vs. Wrapped (L‑Fin / LL‑Fin) Tubes

Wrapped fins are formed by spirally winding a metal strip around the base tube under tension. While economical, they have significant limitations:

• Lower thermal efficiency — extruded fins deliver up to 20% better performance, particularly under high thermal cycling conditions

Limited temperature range — wrapped fins typically operate below 130°C, whereas extruded fins handle up to 300°C (and up to 325°C for specialized designs)

• Fin loosening risk — wrapped fins can loosen over time due to thermal expansion and vibration; extruded fins remain secure throughout the service life

vs. Embedded (G‑Fin) Tubes

Embedded fins are inserted into machined grooves in the base tube wall. Although suitable for higher temperatures (up to 400°C), they involve more complex manufacturing and are generally more expensive than extruded options.

Extruded fins offer superior corrosion protection because the aluminum sleeve fully covers the base tube, preventing moisture ingress at the fin root—a common failure point for embedded fins in corrosive environments.

vs. Welded Fins

High‑frequency welded fins provide strong bonds for extreme high‑temperature applications, but they are substantially more expensive and require more specialized manufacturing. For the vast majority of medium‑temperature (≤300°C) industrial applications, extruded fins deliver the optimal balance of performance, durability, and cost‑effectiveness.

Material Flexibility and Customization

The bimetallic design allows independent selection of base tube and fin materials to suit specific application requirements:

Base Tube Materials

• Carbon steel (ASTM A179, A192, SA210) — general industrial applications
• Stainless steel (304, 316, 321, 347) — corrosive or high‑purity environments
• Copper alloys — superior thermal conductivity for refrigeration and HVAC
• Other alloys available upon request

Fin Material

• Aluminum (1060, 1100, 6063) — optimal balance of thermal conductivity, corrosion resistance, and weight

Customizable Dimensions

• Tube outer diameter: 8mm to 150mm
• Fin height: 5mm to 50mm
• Fin thickness: 0.3mm to 1.5mm
• Fin density: 3 to 30 fins per inch (FPI)
• Tube length: up to 18 meters (custom lengths available)

This flexibility allows our engineering team to design finned tubes that match your exact heat load requirements, space constraints, and environmental conditions.

Wide‑Ranging Industrial Applications

Bimetallic extruded finned tubes are essential components across numerous industries where efficient thermal management is critical:

Power Generation — Air‑cooled condensers, heat recovery steam generators (HRSGs), economizers, and steam surface condensers in thermal, nuclear, and geothermal power plants

Oil & Gas — Offshore platform heat exchangers requiring salt‑spray corrosion resistance, refinery preheaters and condensers, gas dehydration units

Petrochemical & Chemical Processing — Reactors, condensers, evaporators, and reboilers handling aggressive chemicals such as ammonia, chlorine, and acids

HVAC & Refrigeration — Chillers, air‑handling units, air‑cooled condensers, and dehumidification systems for commercial buildings and data centers

Additional Applications — Industrial dryers, food processing plants, steel mills, incinerators, gas compression facilities, and charge air coolers

Why Choose Our Factory?

Direct Manufacturer Advantage

We are a dedicated manufacturer of bimetallic extruded finned tubes with years of industry experience. By dealing directly with the factory, you eliminate middle‑man markups and gain transparent pricing, shorter lead times, and direct communication with the people who actually make your products.

In‑House Technical Engineering Team

Our technical support team consists of experienced engineers with deep expertise in finned tube technology. They have worked on a wide range of projects across different industries, giving them the capability to handle any technical challenge—from fin geometry optimization to material selection for extreme environments.

Whether you need assistance with fin pitch calculation, thermal performance modeling, or custom tube bending for complex heat exchanger layouts, our engineers provide responsive, solution‑oriented support throughout your project.

Rigorous Quality Control

Quality is non‑negotiable in heat exchanger components. Our factory implements comprehensive quality control measures at every production stage:

• Raw material certification and incoming inspection for all base tubes and aluminum sleeves
• Dimensional verification of tube OD, wall thickness, fin height, fin thickness, and fin spacing

• Visual and ultrasonic inspection of bonds and welds
• Pressure testing to verify structural integrity

ISO and CE Certification — Our products meet international standards, giving you confidence in performance and safety.

Full Customization Capability

Every industrial heat exchange application has unique requirements. We support:

• OEM and ODM production based on customer drawings or samples
• Custom fin geometries (smooth, serrated, or specialized patterns)
• Tailored fin densities for specific airflow and heat load conditions
• Base tube materials selected to match internal fluid chemistry

Factory‑Direct Pricing and Lead Times

By manufacturing in‑house, we maintain efficient production processes that translate into competitive pricing. Stock items can ship within days; custom orders are typically completed within 15‑25 business days, depending on complexity and quantity.

The Value We Deliver to Your Business

For Engineering Managers — You gain a reliable technical partner who understands thermal system design. Our engineering team collaborates with you to optimize fin geometry, material selection, and dimensional specifications for your specific heat exchanger configuration. We provide thermal performance data and application engineering support to ensure your system achieves target efficiency.

For Procurement Professionals — You secure a direct, dependable supply chain with transparent pricing, consistent quality, and predictable lead times. Our quality control systems reduce the risk of field failures and warranty claims, while factory‑direct pricing improves your cost position.

For Plant Operations — You receive finned tubes built for longevity. The seamless aluminum‑to‑tube bond eliminates contact resistance degradation over time. The robust fins withstand high‑pressure water jet cleaning (up to 4.0 MPa) without deformation, reducing downtime and extending service intervals.

Corrosion protection means fewer replacements and lower lifecycle costs.

Service Commitment — From Inquiry to Installation

We stand behind every product with responsive, professional support:

• Technical consultation — Discuss your application requirements, thermal loads, and operating conditions
• Custom design — Our engineers develop fin geometry, material selection, and dimensional specifications
• Production — Rigorous quality control at each manufacturing stage
• Inspection and testing — Comprehensive dimensional verification and pressure testing
• Packaging and shipping — Secure export packaging to prevent damage during transit
• After‑sales support — Ongoing technical assistance for installation, maintenance, and future orders

FAQ

Q: What is the maximum operating temperature for extruded finned tubes?
A: Standard extruded finned tubes operate reliably up to 300°C (572°F). Specialized designs can reach up to 325°C.

Q: Can extruded fins be cleaned with high‑pressure water jets?
A: Yes. The cold extrusion process work‑hardens the aluminum fins, giving them exceptional mechanical strength. They withstand 4.0MPa water pressure cleaning without deformation, unlike wrapped or embedded fins.

Q: What base tube materials are available?
A: We offer carbon steel (ASTM A179, A192, SA210), stainless steel (304, 316, 321, 347), copper, copper‑nickel alloys, and other custom materials upon request.

Q: How do extruded fins compare to wrapped fins in corrosive environments?
A: Extruded fins provide superior corrosion protection because the aluminum sleeve completely encapsulates the base tube, leaving no exposed gaps at the fin root. This makes them the preferred choice for marine, coastal, and chemically aggressive environments.

Q: Do you offer custom fin geometries beyond standard smooth fins?
A: Yes. Our manufacturing capabilities include serrated fins (with 12 or 24 teeth per inch) that create turbulent flow for enhanced thermal efficiency, as well as other specialized patterns to meet specific application requirements.

Q: What certifications do your products carry?
A: We maintain ISO and CE certifications, with full compliance to ASTM and ASME standards where applicable. All products undergo rigorous inspection before shipment.

Contact Us

Ready to optimize your heat exchanger performance with premium bimetallic extruded finned tubes? Contact our engineering team today to discuss your project requirements. We look forward to providing you with high‑quality finned tubes, technical expertise, and responsive service that keeps your operations running efficiently.