Crimped Type Finned Tube

L/LL/KL Finned Tube Product Description:

LL Finned Tube(Overlapped Footed Fin)

The Overlapped Footed Fin (OLFF) is characterized as a double LL fin and is widely used throughout the world as an alternative to the extruded fin. This fin is considered an interference fit type of fin and is used in corrosive applications where protection of the base tube is required. The double LL coverage of the base tube represents a double strip thickness coverage of the base tube. Typically, this fin is produced out of aluminum or copper fin strip. This fin type is not suitable for carbon steel or stainless steel fin materials as the material is too hard for the formation of the characteristic LL foot. The foot of the fin is formed by pulling the strip through a two stage preform roller set. By preforming the foot of the fin into a “joggle” or a one thickness offset, it is possible to take advantage of the ability to place the heel of one fin on the toe of the adjacent fin. The preformers preform the foot to allow the fins to fit together on the surface of the tube, for continuous contact with the base tube and forms a seal to protect the base tube from atmospheric corrosion.

KL Finned Tube(Knurled Aluminum Tubing)

The Knurled Footed Fin is characterized as adding increased tube and fin surface area due to the knurled surface on the fin foot and tube. The fin is consider an interference fit type fin and because of the knurls some heat transfer specialist give the fin added performance ratings due to a mechanical type bond of the fin material to the tube wall surface. Typically, this fin is produced out of aluminum or copper fin strip. This fin type is not suitable for carbon steel or stainless steel fin materials as the material is too hard for the formation of the characteristic L or LL foot. Knurling depth in the tube wall is affected by the hardness of the tube material chosen. The fin, whether W/O or OLFF, is formed using standard fin height hardware.

L Finned Tube(Wrap-On Fin)

The Wrap-On (W/O) Fin or “L” footed fin is characterized as an L fin and is widely used throughout the world. This fin is considered an interference fit type fin and is limited to light duty. Typically this fin is produced out of aluminum or copper fin strip. This fin type is not suitable for carbon steel or stainless steel fin materials as the material is too hard for the formation of the characteristic L foot. The foot of the fin is formed by pulling the strip through a two stage preformer set. The first stage rolls the fin to a 45-degree foot and the second stage rolls it to a true 90-degree foot. The tooling controls the fin height as specified. As a result of this, each combination of FPI (pitch) and fin strip thickness requires a specific strip width.

L/LL/KL Finned Tube(Knurled Aluminum Tube) Manufacturing Process:

Applied Fin Tube is made with strip wrapped under tension around the base of the tube. Fins are welded to the base tube at the strip ends.

L/LL/KL Finned Tube(Aluminum Finned Tubes) Advantages:

L Finned Tube

Suitable for low-temperature application.

The finning type is the most cost effective method compared to the others.

The failed fins can be easily removed during production and bare tube can be used again for finning.

There is no need for make a helical grove over the core tube.

It is possible to place the fins on a very thin-walled tube with is particularly desirable when using expensive alloys as core tube.

The tube can withstand a temperature of up to 130°C without the risk of atmospheric corrosion or thermal stress.

LL Finned Tube

This type of finned tube is often used as an alternative to the more expensive extruded type fin in corrosive environments.

Maximum operating temperature 170ºC.

KL Finned Tube

Corrosion-resistant Tubes

Vibration resistance

It can withstand temperatures of up to 320°C (608°F).

High thermal performance and stress resistance combined with protection from air corrosion is a one-of-a-kind combo.

Any form of finned tube can be replaced with KL.

L/LL/KL Finned Tube Properties:

Atmospheric Corrosion Resistance: OK

Mechanical Resistance: Poor

Fin Contact: Interference Fit

Fin To Tube Bond :Moderate

Heat Transfer Efficiency :Moderate

L/LL/KL Finned Tube Applications：

. the petroleum, chemical and petrochemical process industries

. natural gas treatment

. the steel industry: blast furnace and converter systems

. power generation: steam turbine exhaust condensing

- contact condensing with cooling of circulating condensate

- fossil and nuclear power plants

. air conditioning (Freon, ammonia, propane)

. incineration of household refuse

. compressor coolers, etc.

L/LL/KL Finned Tube Specifications：