What is an Oval Finned Tube?

The oval finned tube is a type of heat exchanger that consists of an oval base tube and outer rectangular fins. Examples include oval rectangular finned tubes, oval-oval finned tubes, oval circular finned tubes, spiral oval flat tubes, and oval H-shaped finned tubes. Oval finned tubes are gaining popularity due to their superior performance compared to round finned tubes and are widely used in industries such as ethylene production and oil refining.

These tubes are characterized by their unique oval shape and fins spirally wound around them, significantly enhancing heat transfer efficiency.

Types and Advantages of Oval Finned Tubes

Oval finned tubes serve as efficient heat exchange elements, offering several advantages:

Compact Layout: Reduces the overall volume and footprint of the heat exchanger.
Low Air Side Resistance: Enhances the heat transfer coefficient between fluids, increasing efficiency.
Larger Heat Transfer Area: Provides a larger heat transfer perimeter compared to circular tubes, improving efficiency.
High Strength and Durability: Rectangular steel fins offer strength and long service life, preventing freezing and cracking in winter.
Optimized Flow Resistance: Compact arrangement reduces outer flow resistance, effectively managing air flow.

The configurations of finned round and flat tube heat exchanger. (adopted from [99]). (a) In-line classic tube shape, (b) Staggered classic tube shape, (c) In-line flat tubeand (d) Staggered flat tube.

Benefits of Oval Fin Tubes

Enhanced Heat Transfer: The oval design and spiral fins significantly increase the surface area, resulting in better heat transfer performance.
Compact and Efficient: Allows for a larger heat exchange surface area within a smaller footprint, making the system more efficient and compact.
Reduced Pressure Loss: The design can lower the refrigerant pressure loss by more than 50%, making systems more energy-efficient.
Durability: Suitable for high-temperature and high-pressure applications, providing long-term reliability and performance.
Versatility: Applicable in a wide range of industries and customizable to meet specific operational needs.

Applications

Air-Cooled Heat Exchangers: Used in cooling applications where the ambient air is used for heat dissipation.
Condensers and Heaters: Common in the HVAC industry, improving efficiency in heating and cooling systems.
Oil Refinery and Petrochemical Industry: Utilized in various processes requiring efficient heat transfer.
Power Plants: Used in steam turbine flue gas condensation, condenser water contact cooling, and auxiliary heat exchange systems.
Steel Industry: Integral to blast furnace and converter systems.
Waste Incinerators and Compressor Coolers: Enhances the heat exchange process in these high-stress environments.

Variations in Finned Tubes

Finned tubes can vary based on the installation position and arrangement of fins:

Inner vs. Outer Finned Tubes: Outer finned tubes are more commonly used.
Longitudinal vs. Horizontal Finned Tubes: Fins can be arranged longitudinally or horizontally.
Shape of Base Tubes: Base tubes can be round, oval, or flat.

While round finned tube heat exchangers dominate the market, research shows that oval tubes are more effective at reducing air side flow resistance and energy consumption.

Material Composition: The base tube can be made from copper, aluminum, carbon steel, or stainless steel. Fins are typically made from high thermal conductivity materials like copper or aluminum and may be coated for corrosion resistance.
Design: The oval shape provides a larger surface area compared to round tubes, improving heat transfer rates. Spiral fins create turbulence in the fluid flowing through the tube, enhancing the heat transfer efficiency.
Heat Transfer Efficiency: The design increases the surface area, resulting in higher heat transfer rates. Spiral fins help improve airflow and heat transfer by creating turbulence.
Durability: High corrosion resistance and long service life, especially when made from or coated with suitable materials.
Temperature and Pressure: Suitable for high-temperature and high-pressure applications. Applied Temperature: Up to 850°C (1593°F).

All Kind of oval fin tubes material can be applied for this type of fins.

Fin spec can be changed follow with client requirement.

Applied Temperature: 850C(1593 F)

This is for Air Cooled Oil Cooled Heat Exchanger, Condenser, Heater in field of Oil Refinery, Petrochemical Industry Offshore and Power plants.

Finned Tube Materials

Typical combinations of fin, base tube and ring materials

We offer a broad portfolio of fin and base tube materials, customizable to meet specific requirements for thermal conductivity, mechanical strength, and corrosion or erosion resistance.

Material Compatibility by Manufacturing Process

L-Foot / Embedded Aluminum Fin Tubes

Fin material: Aluminum (typically 1100-O)
Base tube: Carbon steel, stainless steel, copper, brass (other weldable or bondable materials on request)

High-Frequency Welded (HFW) Helical Fin Tubes

Any fin and tube combination compatible with high-frequency resistance welding
Suitable for carbon steel, alloy steel, stainless steel, nickel alloys and specialty alloys

Typical Material Combinations

Component	Common Materials
Base Tube	Carbon steel, Alloy steel, Stainless steel, Copper, Cupro-Nickel, Titanium, Aluminium
Fin	Carbon steel, Stainless steels (304, 310, 316, 321, 409, 410), Nickel 200, Inconel, Copper, Aluminium
Support Rings	Carbon steel, Aluminium, Hot-dip galvanized steel

Material Selection Criteria

Service Temperature: Determines allowable alloy system
Corrosive Environment: Gaseous, aqueous or soil-side corrosion

Erosive Conditions: Particle-laden flows or high velocities
Thermal Conductivity: Required heat transfer performance

Common Base Tube Specifications

Material Group	Typical Grades & Standards
Carbon Steel	A179, A192, SA210 Gr A1 / C, A106 Gr B, A333 Gr 3 / 6 / 8, DIN 17175 St35.8 / St45.8, EN 10216 P195 / P235 / P265, GB/T 3087 10 / 20, GB/T 5310 20G / 20MnG
Alloy Steel	A209 T1 / T1a, A213 T2 / T5 / T9 / T11 / T12 / T22 / T91, A335 P2 / P5 / P9 / P11 / P12 / P22 / P91, EN 10216-2 13CrMo4-5, 10CrMo9-10, 15NiCuMoNb5-6-4
Stainless Steel	TP304 / 304L, TP316 / 316L, TP310 / 310S, TP347 / 347H
Copper & Copper-Nickel	UNS C12200 / C14200 / C70600, CuNi 90-10, CuNi 70-30
Titanium	ASTM B338 Grade 2

Note: Carbon steel fins are compatible with carbon steel, stainless steel and copper base tubes. For sizes or material combinations not listed, please contact our technical team for feasibility verification and thermal-mechanical assessment.

Technology

It is fabricated with a batch of single fins that were processed by the punch press and then manually or mechanically, with a certain distance (wingspan) on the base tube.

This is the earliest fin tube fabrication with low cost and simple production process/ technology, easy to maintain. Divides into manual set and mechanical set. Manual set uses a tool that relies on the power of man to press the fins one by one. This method is limited by the pressure of the fin, so it is easy to get loose. The machine – set fin is carried on the wing piece machine. Due to the mechanical impact or liquid pressure, the pressure of the fin is high, so it can be used in a larger volume. The bonding strength between fin and tube is high and not easy to loosen. Mechanical transmission has high productivity, but the noise is large, the safety is poor, and the working conditions of the workers are not good. Although the hydraulic transmission does not have the above problem, but the equipment price is more expensive, the technical requirement to use maintenance personnel is higher, its productivity is also lower.

Currently HF Fin Tube is one of the most widely used helical fin tubes, you can see it as waste heat recovery in power, metallurgy, concrete, oil and gas, petrochemical, etc. When winding the steel strip around steel tube, the use of high frequency current skin effect and proximity effect on steel strip and steel pipe surface heating, until the plastic state or melt, the coil steel belt must be under pressure to complete welding. Comparing with embedded type and spot welding spiral crimped type, it is more advanced either on fin tube quality or production efficiency or automation degree.

The extruded fin is formed from an outer aluminum tube with a large wall thickness (muff), which is aligned over an inner base tube. The two tubes are pushed through three arbors with rotating discs that literally squeeze or extrude the aluminum fins up and out of the muff material in a spiral shape in one operation. Comparing with welding fin tube, dr extruded fin has higher production efficiency with low cost on material and high heat transfer. At present, it divides into copper or aluminum single metal fin tube and bi-metal composited fin tube.

Fin tube manufacturers produce a wide range of fin tubes. They are used in heat exchangers (air, water and chemically cooled) for various industries such as petroleum, petrochemical, steel, power generation and many more.

Corrosion protection processes are performed during fin tube manufacturing and the material used is corrosion resistant. Some fin tube types are:

Helical high fins

Helical high finned tubes are used to repair air-cooled heat exchangers and are available in 5 variations

Type	Manufacturing Feature	Typical Properties
KL Fin	Fin foot is knurled into a matching knurl on the base tube, enhancing mechanical bonding and thermal contact.	Max Temp: 260 °C (500 °F) Corrosion Resistance: Fair Mechanical Strength: Fair Fin Material: Aluminium, Copper
G Fin	Fin strip is wound into a pre-grooved tube and locked by cold-flow of the base tube material, ensuring a secure joint at elevated temperatures.	Max Temp: 400 °C (750 °F) Corrosion Resistance: Poor Mechanical Strength: Fair Fin Material: Aluminium, Copper, Carbon Steel
LL Fin	Similar to L fin, but with the fin foot overlapped to fully encapsulate the base tube, improving corrosion protection in aggressive atmospheres.	Max Temp: 180 °C (355 °F) Corrosion Resistance: Fair Mechanical Strength: Poor Fin Material: Aluminium, Copper
L Fin	Fin strip is tension-wound onto the base tube, providing uniform contact pressure and basic corrosion protection for the underlying tube.	Max Temp: 150 °C (300 °F) Corrosion Resistance: Fair Mechanical Strength: Poor Fin Material: Aluminium, Copper
Extruded Fin	Formed from bi-metallic tube by extruding aluminium outer layer into integral fins, providing excellent bond strength and full encapsulation of the base tube.	Max Temp: 285 °C (545 °F) Corrosion Resistance: Excellent Mechanical Strength: Excellent Fin Material: Aluminium

Uncovered tube area between the fins

Fin foot is pre-formed into an LL shape (overlapped LL) and applied to base tube under tension.
However, foot is pre-shaped to give overlap of one foot onto another, thereby improving base tube protection and thermal contact area Fin materials: Aluminum Base tube materials: Any metallic material.
The smooth flat fins perpendicular to the tube surface give rise to very low resistance to air /gas flow and ensure that fouling is kept to a minimum. The foot of the fin is in contact with base tube and provides a complete sheathing over the finned length.

The Overlapped "L" fin design has interlocking fins that are wound together to prevent movement and separation. The fin protects the entire tubes, so the designation works well for the applications where corrosion is a factor.This type of finned tube is often used as an alternative to the more expensive extruded type fin in corrosive environments.

Common Applications: Steam Coils, Air Pre-heaters.
Max. Working Temperature: 180 °C
Atmospheric Corrosion Resistance: OK
Mechanical Resistance: Poor
Fin Material: Copper, Aluminum
Base Tube materials: Any material available, such as Carbon steel Tube, A179, A192, A210, stainless tube A269/A213 T5 T11 T22 304 316

What are fin tubes?

Fin tubes are a type of heat exchanger that is used in many different industries. These tubes have a finned surface, which increases their surface area and allows them to transfer heat more efficiently. This makes them ideal for applications where high heat transfer rates are required, such as in power plants and refrigeration systems.

Fin tubes are made from a variety of materials, including copper, aluminum, and stainless steel. They are available in a range of sizes and shapes and can be customized to meet the specific needs of each application.

One of the key benefits of fin tubes is their ability to operate efficiently at high temperatures and pressures. This makes them suitable for use in a wide range of applications, including air conditioning, heat exchangers, and radiators.

In addition to their high thermal performance, fin tubes are also durable and long-lasting. They are resistant to corrosion and can withstand the harsh environments often found in industrial settings. This makes them a cost-effective solution for many different industries.