July 06, 2025

Finned Tubes and their applications

Wrought Steel vs Cast Steel

Finned tubes are widely used in applications where heat needs to be transferred from a hot fluid to a cooler one across the tube wall. The efficiency of this heat transfer depends on several factors, including the temperature difference between the two fluids, the heat transfer coefficient between the fluids and the tube wall, and the surface area available for heat exchange.

Table of contents

  • What is finned tube?
  • Different types of finned tubes
  • Why Finned Tubes are made of Aluminum?
  • Finned tube heat exchanger working principle
  • Low fin tubes dimension
  • Uses Of Helical solid finned tubes
  • Advantages of Using Fin and tube heat exchangers
  • G Type Finned Tube Features
  • Quality Control for Stainless steel finned tube
  • Size Range Of G Type Fin Tube
  • Classification of Finned tubes based on process and fin shape
  • High fin tubes Vs Low fin tubes
  • What can Cause Leakages in Low Fin Tubes?
  • What Affects the Heat Transfer in a Low Fin Tube?

What is finned tube?

Finned tubes are long tubes with small fins attached to their outer surfaces, acting as heat exchangers. These fins enhance the heat transfer process by increasing the surface area. They are essential components in heat exchangers and are used to transfer heat efficiently between thermally conductive fluids.

View different types of fin tubes for heat exchangers

The table below provides an overview of the various types of finned tubes used in heat exchangers. It will help you choose the most suitable type for your specific application, ensuring optimal performance and functionality.

Different types of finned tubes

Fin Type Icon Tube Material Fin Material Fin Height Fin Thickness Tube Diameter
Plain Finned Plain Finned Tube Carbon steel, stainless steel, copper, aluminum Aluminum, copper, stainless steel 6-25 mm 0.2-0.6 mm 12.7 mm (1/2") to 63.5 mm (2.5")
L-Finned L-Finned Tube Carbon steel, stainless steel, copper Aluminum, copper, stainless steel 6-19 mm 0.3-0.5 mm 15.9 mm (5/8") to 38.1 mm (1.5")
G-Finned G-Finned Tube Carbon steel, stainless steel, alloy steel Aluminum, copper 6-15 mm 0.3-0.5 mm 15.9 mm (5/8") to 50.8 mm (2")
Extruded Finned Extruded Finned Tube Aluminum, copper Aluminum 8-16 mm 0.4-1.2 mm 12.7 mm (1/2") to 31.8 mm (1.25")
U-Tube Finned U-Tube Finned Tube Carbon steel, stainless steel, alloy steel Aluminum, copper, stainless steel 6-25 mm 0.3-0.5 mm 15.9 mm (5/8") to 38.1 mm (1.5")
Studded Finned Studded Finned Tube Carbon steel, stainless steel, alloy steel Carbon steel, alloy steel 10-50 mm 6-12 mm 25.4 mm (1") to 114.3 mm (4.5")
Helical Finned Helical Finned Tube Carbon steel, stainless steel, copper, aluminum Aluminum, copper, stainless steel 8-16 mm 0.3-0.5 mm 12.7 mm (1/2") to 76.2 mm (3")

Refer sizes and uses of finned aluminum tubing

Finned aluminum tubing is commonly used in refrigeration systems, air conditioning units, and industrial processes that involve heating and cooling. Its high heat transfer capacity and durability make it a preferred choice over other types of heat exchangers.

Why Finned Tubes are made of Aluminum?

Aluminum finned tubes have a size range of 3/8″ to 1 1/2″.

Aluminum is widely used for manufacturing finned tubes due to its properties:

  • High thermal conductivity
  • Lightweight
  • Corrosion resistance
  • Good ductility and malleability
  • Cost-effective

Finned tube heat exchanger working principle

Wrought Steel vs Cast Steel

Finned tube heat exchangers are primarily used to transfer heat from one fluid to another through the tubes, with the fins enhancing the heat transfer efficiency.

Low fin tube has a fin of about 1/16th in height

A low fin tube is a standard tube with a small fin, typically around 1/16th of an inch in height. The fin is embedded within the tube wall and is commonly used in applications such as coolers, chillers, and condensers where liquid-to-liquid or liquid-to-gas heat transfer is required.

Low fin tubes dimension

Description Size dimension
Tube Outside Diameter Min. 12.7mm / Max. 31.75mm
Tube thickness (plain section) Min. 1.245mm / Max. 3.404mm
Fin pitch 19 – 26 – 27 – 28 – 30 – 36 fins per inch
Fin height Max. 1,40mm
Tube length Max. 25000mm
Welded Helical solid finned tubes widely used in petrochemical industry

These tubes are designed to withstand harsh conditions, including corrosion, high pressure, and elevated temperatures. They are commonly used in the petrochemical industry and industrial boilers, where such environments are typical. They are also used for heating, cooling, or recovering heat from industrial exhaust systems.

Uses Of Helical solid finned tubes

  • Petrochemical industries
  • Natural gas processing
  • Blast furnace and converter system
  • Power generation
  • Waste incinerators
  • Air conditioning
  • Compressor coolers

Advantages of Using Fin and tube heat exchangers

  • Increases heat transfer rate
  • Improves heat transfer coefficient
  • Reduces equipment size
  • Helps in cost-efficient projects
  • Increases the outside surface area

G Type Finned Tube Features

  • High fin stability
  • Superior heat transfer efficiency
  • High operating temperature capability
  • Excellent temperature resistance
  • Exceptional thermal shock resistance

Quality Control for Stainless steel finned tube

  • Chemical composition analysis
  • Dimensional inspection
  • Flatten test
  • Non-destructive testing
  • Hydrostatic test
  • Mechanical property testing
  • Expansion test
  • Surface quality check

Size Range Of G Type Fin Tube

Base Tube Specification Fin Specification
Outside Diameter (mm) Wall Thickness (mm) Height (mm) Thickness (mm) Pitch (mm)
15.88-50.8 1.0-3.0 6.35-25.4 0.4 2.1-6.0
Material Material Length
SS, CS, Alloy Steel, Copper CS, Aluminum, Copper ≤ 15m

Classification of Finned tubes based on process and fin shape

Tube Outside Diameter Fin Thickness Fin Height Fins per Pitch
5/8 .015 / .016/ .020 3/8,1/2 6, 7, 8, 9, 10, 11, 12
3/4 5/8,1/2
1 5/8,1/2
1 1/4 5/8,1/2
1 1/2 5/8,1/2
Finned tubes generally use air to cool or heat fluids such as water

Finned tubes significantly increase the surface area of the tube, allowing for more effective heat transfer with air. Using air for heating or cooling is beneficial because it is readily available, economical, and eliminates the need for complex heating equipment, making it a practical and efficient solution.

High fin tubes Vs Low fin tubes

Features High Fin Tubes Low Fin Tubes
Fin Density Higher fin density Lower fin density
Heat Transfer Efficiency Higher efficiency due to more fins Lower efficiency compared to high fin tubes
Surface Area-to-Volume Ratio Higher ratio due to dense fins Lower ratio due to sparse fins
Maintenance and Cleaning Requires more maintenance due to closely spaced fins Requires less maintenance due to wider spacing
Cost Considerations More expensive due to complex manufacturing More cost-effective

What can Cause Leakages in Low Fin Tubes?

  • Scale buildup: Can narrow the inner diameter, leading to pressure build-up and eventual leakage.
  • Thermal shock: Sudden temperature changes can cause cracks or ruptures.
  • Improper installation: Proper installation and regular maintenance can prevent leaks.
  • Tube corrosion: Corrosion increases the risk of leakage.

What Affects the Heat Transfer in a Low Fin Tube?

Several factors influence the effectiveness and efficiency of heat transfer in low fin tubes:

  • Fluid properties
  • Fin arrangement
  • Number of fins
  • Dimensions of the fins
  • Surface finish

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