L-Type Fin Tube – Aluminum L-Foot Tension Wound Finned Tubes for Heat Exchanger

Material Overview

Aluminum L-foot tension wound finned tubes are bi-metallic or multi-metallic heat transfer elements in which a thin aluminum strip is helically wound around a base tube under controlled tension. An “L”-shaped foot is first formed on one edge of the fin strip; this foot bears directly on the outer surface of the tube and mechanically locks the fin to the tube along its full length.

The base tube can be carbon steel, low-alloy steel, stainless steel or non-ferrous materials such as copper and brass, while the fin is typically made from high-thermal-conductivity aluminum alloys (e.g. 1050, 1060, 3003, 5052, 1100). This design combines the mechanical strength and pressure rating of the base tube with the excellent thermal conductivity and corrosion resistance of aluminum fins.

L-type fin tubes are widely used in air-cooled heat exchangers, industrial radiators and process gas coolers, especially where operating temperatures are in the low to medium range and additional protection of the tube wall is required.

Specifications

These values represent common manufacturing capabilities for aluminum L-foot tension wound finned tubes. Actual dimensions and tolerances are finalized to customer drawings and applicable codes.

• Base tube materials

  • Carbon steel: e.g. SA-179, SA-210, SA-214

  • Stainless steel: e.g. TP304/304L, TP316/316L

  • Alloy steels or non-ferrous (copper, brass, Cu-Ni) on request

• Fin material

  • Aluminum alloys: AA1050/1050A, 1060, 1100, 3003, 5052 (others on request)

  • Temper typically H14 / H16 for fin stock

• Tube outside diameter (OD)

  • Approx. 12.7–50.8 mm (1/2"–2") commonly supplied

  • Other OD ranges possible depending on material and wall thickness

• Tube wall thickness

  • Usually 1.5–6.0 mm depending on design pressure and code; heavier walls available for high-pressure service

• Fin height

  • Approx. 6–16 mm (1/4"–5/8"), with higher fins possible for special designs

• Fin thickness

  • Typically 0.2–0.4 mm (≈0.008"–0.016")

• Fin pitch (fin density)

  • 5–13 fins per inch (≈4–16 mm fin pitch) according to thermal design

• Maximum tube length

  • Up to approx. 15–18 m (≈50–60 ft), depending on material and transport limits

• Recommended operating temperature

  • Typically up to about 200 °C (≈400 °F) continuous service

  • Short-term peaks up to ≈230+ °C (450 °F) may be acceptable depending on base tube material, fin alloy and environment

  • For higher metal temperatures, extruded or embedded fin types are generally preferred

Main Features

• High heat transfer efficiency

  • Aluminum fins offer very high thermal conductivity and a large external surface area, significantly increasing overall heat-transfer coefficients in air-side-controlled services.

• Secure mechanical fin–tube bond

  • The L-foot is tension-wound so that each fin turn bears firmly against the tube, providing uniform fin spacing and preventing fin movement or separation under thermal cycling and vibration.

• Improved corrosion protection of base tube

  • The foot of the fin covers the tube surface, shielding the steel from direct exposure to the atmosphere and reducing under-fin corrosion risk in many environments.

• Optimized for air-cooled service

  • L-type fin tubes are widely used in air-cooled heat exchangers and fin-fan coolers where moderate temperatures, pressure and vibration levels are expected.

• Flexible combination of materials

  • Any suitable tube material can be combined with high-conductivity aluminum fins, balancing cost, corrosion resistance and pressure rating for each project.

• Cost-effective solution

  • Compared with extruded fin tubes, tension-wound aluminum L-foot finning generally offers lower material and manufacturing cost while still providing reliable fin adhesion and good service life in appropriate conditions.

Our Advantages – Answering Typical Customer Questions

1. “Will the fins loosen or rattle under vibration and thermal cycling?”

• The L-foot profile and controlled tension winding produce a mechanical interlock between fin and tube that resists fin lifting and movement in the typical operating range up to about 400–450 °F.

• Uniform fin spacing and tight root contact help prevent fretting and noise, improving long-term stability in fin-fan coolers and air coolers.

2. “How is base-tube corrosion controlled, especially outdoors or in coastal plants?”

• The aluminum L-foot covers the tube surface, providing an additional barrier between the environment and the steel or alloy tube.

• Matching of fin alloy (e.g. 3003 or 5052 for improved corrosion resistance) and tube alloy (e.g. stainless steel or Cu-Ni) is selected to minimize galvanic effects in marine or chemically aggressive atmospheres.

3. “Can you meet my code and standard requirements?”

• Base tubes and aluminum fin materials are sourced and manufactured in accordance with major international standards: ASTM (B209, B221, B234/B241/B429), EN (EN 573-3, EN 755-1/2), GOST 4784, JIS H 4000/H 4040 and GB/T 3190, GB/T 4437.1, among others.

• Chemical composition and mechanical properties of aluminum fin alloys are controlled to the relevant alloy designations (1050, 1060, 3003, 5052, 6063, etc.), ensuring traceable and repeatable performance.

4. “Can you match my existing bundle design (OD, fin height, FPI, length)?”

• We support typical tube ODs from 1/2" to 2", fin heights from about 1/4" to 5/8", fin pitches from 5 to 13 FPI and tube lengths up to ~15–18 m, which covers most common refinery, petrochemical and power applications.

• Customized geometries and fin densities can be engineered to match existing thermal designs or retrofit requirements.

5. “What about maintenance, cleaning and replacement?”

• The smooth aluminum fin surface is compatible with standard air-blow or low-pressure water wash cleaning procedures commonly used on fin-fan units.

• Consistent adherence to standard alloy designations and dimensional ranges facilitates the supply of replacement tubes that are fully interchangeable with original bundles.

Chemical Composition – Typical Aluminum Fin Alloys

Mechanical Properties – Typical Aluminum Fin Alloys

Applicable Standards

Depending on material selection and customer specification, L-type aluminum L-foot finned tubes can be manufactured in accordance with the following (or equivalent) standards:

• ASTM (USA)

  • ASTM B209 – Aluminum and Aluminum-Alloy Sheet and Plate (aluminum fin strip)

  • ASTM B221 / B221M – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes (aluminum tubes and sections)

  • ASTM B234 / B241 – Aluminum and Aluminum-Alloy Drawn Seamless Tubes / Seamless Pipe and Tube for condensers and heat exchangers

• EN (Europe)

  • EN 573-3 – Aluminium and aluminium alloys – Chemical composition and form of wrought products (alloy designation and composition)

  • EN 755-1 / EN 755-2 – Aluminium and aluminium alloys – Extruded rod/bar, tube and profiles – Technical conditions for delivery and mechanical properties

• GOST (Russia/CIS)

  • GOST 4784 – Aluminium and wrought aluminium alloys – Grades and chemical composition

• JIS (Japan)

  • JIS H 4000 – Aluminium and aluminium alloy sheets, strips and plates (fin strip)

  • JIS H 4040 – Aluminium and aluminium alloy bars, rods and wires (related to extruded products and tubes)

• GB / T (China)

  • GB/T 3190 – Chemical composition of wrought aluminium and aluminium alloys (alloy limits)

  • GB/T 4437.1 – Aluminium and aluminium alloy hot-extruded tubes – Part 1: Seamless tubes (aluminum base tubes)

Steel, stainless steel and other base tube materials are matched to project-specific codes such as ASME, EN, GB or GOST pressure-piping and boiler standards as required.

Application Fields

General application areas

Aluminum L-foot tension wound finned tubes are suitable for a wide range of thermal equipment where air-side resistance dominates and enhanced external surface is required:

• Air-cooled heat exchangers and fin-fan coolers in refineries and petrochemical plants

• Gas coolers and intercoolers for compressors and gas turbine systems

• Industrial radiators for engines, turbines and large rotating equipment

• Waste-heat recovery units and economizers (within temperature limits)

• Process gas, air heater and dryer coils

• HVAC and refrigeration condensers/evaporators where metallic fin-and-tube designs are preferred

Typical use within each sector

• Oil & Gas / Petrochemical

  • Air-cooled process gas coolers, condenser bundles, stabilizer overhead coolers and fin-fan coolers in pipe rack installations.

• Power generation

  • Generator and motor air-coolers, turbine lube-oil coolers, hydrogen coolers (where aluminum fins are acceptable), and auxiliary system air coolers.

• Chemical and fertilizer plants

  • Air coolers for process streams (NH₃, synthesis gas, air, nitrogen), product coolers, and solvent recovery systems, where moderate temperature and corrosivity match aluminum fin capability.

• Metallurgy, paper, food and drying equipment

  • Hot-air heaters and dryers, oven coils and process air heaters that benefit from high fin area and relatively low fin weight.

• HVAC / refrigeration

  • Custom coils and industrial air heaters where robust metallic fins and heavy-wall tubes are preferred over light commercial coils, within suitable temperature and corrosion envelopes.

Q: Are you trading company or manufacturer ?

A: manufacturer,also can do trading.

Q: How long is your delivery time?

A: Generally speaking,it is 10-15 days if the goods are in stock,or it is 30-40 days if the goods are not in stock,

it is according to quantity.

Q: Do you provide samples? is it free or extra ?

A: Yes, we could offer the sample for free charge but need pay the cost of freight.

Q: What is your terms of payment ?

A: Payment<=2000USD, 100% in advance. Payment>=2000USD, 30% T/T in advance ,balance before shippment.

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