A fin tube is a tube that has small fins around the outside surface.
These fins act as a filter and a mechanism to transfer heat from the material inside the tube to the outside space or vice versa. Fin tubes are used in applications that require a transfer of heat from a hot fluid to a colder fluid through the tube's wall.
Sunny Steel provide a wide range of fin tubes are used in heat exchangers (air, water and chemically cooled)
for various industries such as petroleum, petrochemical, steel, power generation and many more.
The advantages of finned tubes
Transferring heat from a hot fluid into a colder fluid through a tube wall is the reason many of us use finned tubes. But you may ask, what is the major advantage of using a finned tube? Why can’t you just use a regular tube to make this transfer? Well you can but the rate will be much slower.
Fin tube reference
Carbon steel fins are available on carbon, stainless steel, or copper tube. Please call for a specific size if not listed
| Type | Description | Base tube O.D. (mm) | Fin specification (mm) | ||
|---|---|---|---|---|---|
| Fin pitch | Fin height | Fin thick | |||
| Embedded | G-type fin tueb | 16-63 | 2.1-5 | <17 | ~0.4 |
| Extruded | Single metal combined metal | 8-51 | 1.6-10 | <17 | 0.2-0.4 |
| Low fin tube t-type fin tube | 10-38 | 0.6-2 | <1.6 | ~0.3 | |
| Bamboo tube corrugated tube | 16-51 | 8-30 | <2.5 | / | |
| Wound | l/kl/ll type fin tube | 16-63 | 2.1-5 | <17 | ~0.4 |
| String | String fin tube | 25-38 | 2.1-3.5 | <20 | 0.2-0.5 |
| U-type | U-type tube | 16-38 | / | / | / |
| Welding | HF-welding fin tube | 16-219 | 3-25 | 5-30 | 0.8-3 |
| H/HH type fin tube | 25-63 | 8-30 | <200 | 1.5-3.5 | |
| Studed fin tube | 25-219 | 8-30 | 5-35 | φ5-20 | |
According to user needs, we can produce all kinds of steel strip winding finned tube and steel aluminum composite finned tube.
Materials
Carbon steel fins are available on carbon, stainless steel, or copper tube. Please call for a specific size if not listed
Extruded tubes can be either from one piece or from 2 different materials (bimetallic).
- Base tube: Carbon steel, Stainless steel, Copper, Cupro Nickel, Aluminium, Alloy Steel
- Fin: Carbon steel, Stainless steel, Copper, Aluminium
- Rings: Carbon steel, Aluminium, Hot dip galvanizing
What kinds of finned tubes are used in air cooled heat exchanger?
The fin tubes can be of virtually any material available, such as carbon steel, stainless steel, Admiralty brass, or more exotic alloys.
The minimum preferred outside diameter is one inch. Some manufacturers sometimes use smaller tubes, but most of the process coolers have tubes which are 1.0", 1.25", or 1.5" OD. The minimum tube wall thicknesses vary with the material. In some cases the design pressure and design temperature of the ex-changer govern the minimum thickness.
The fins are almost always of aluminum material. The most common type of fin is the helically wrapped, L-footed type. These are used where the process temperatures are below about 350 deg. F. The API specification calls for cast zinc bands at the ends of the tubes to prevent the fins from unwrapping. Some of the better manufacturers also use cast zinc bands at the tube supports. For higher process temperatures, most customers prefer either embedded or extruded fins. The embedded fins have the highest temperature capabilities. They are made by a process which cuts a helical groove in the OD of the tube, wraps the fin into the groove, then rolls the upset metal from the tube back against the fin to lock it into place. The tube wall must be thicker with embedded fins because of the groove.
In some applications customers often prefer extruded fins. Extruded fins are made by putting an aluminum sleeve (sometimes called a muff) over the tube, then passing the tube through a machine which has rollers which squish the aluminum out to form fins. The process is similar to a thread-rolling machine. The end result is a fin which has extremely good contact with the tube, and no crevices to allow corrosion to start on the tube OD. Extruded fins are often used in coastal locations or on offshore platforms for this reason.
Inspections and Tests G-fin; L-fin; LL-fin; KL-fin; Extruded-fin Finned Tubes
Generally speaking, Tension wound finned tubes, embedded finned tubes and extruded finned tubes are main devices for air coolers and the common application fields are:
A. Heat exchangers for power plants (electric, nuclear, thermal and geothermal power plants)
B. Steam condensate systems
C. Chemical and petrochemical industry
D.Food processing plants and refrigeration technology
E. Industrial (steel mills, incinerators, gas compression facilities)
For the inspection and tests on G-fin, L-fin, LL-fin, KL-fin and extruded-fin finned tubes, we usually do the following tests:
- Chemical composition
- Mechanical properties
- Hydrostatic test
- Pneumatic test
- Boroscopic inspection
- Eddy current test
Tensile Test (only for extruded finned tube)
The material certificate including all the tests can be provided, and also with EN10204 3.1standard.
Welcome to contact with us for any kind of information and request.
Specific classification of finned tubes
Specific classification of finned tubes, there are lot of types of finned tubes, meanwhile also lot of new species comes up.
According to the classification process
- rolling forming finned tubes (extruded fin tube);
- welded finned tubes ( high frequency welded finned tubessubmerged arc welded finned tubes,
- roll forming finned tube
- set forming finned tube
- casting finned tube
- the tension wound finned tubes
- inserts the tube .
According to the fin shape classification
- square fin tube (Square finned tube);
- round finned tube
- spiral finned tube (spiral finned tube);
- the vertical fin tube (Longitudinal Finned Tube)
- corrugated fin tube
- serrated spiral finned tubes (Helical Serrated Finned Tubes);
- the needle finned tube
- the overall plate- fin tube ( plate-fin,
- the finned tube (inner finned tube).
Depending on whether the finned tubes finned tube material and the same material can be divided into groups :
- a single metal finned tube
- bi-metal composite finned tube
A single metal finned tube Material Classification
- copper finned tubes
- aluminum finned tube
- carbon steel finned tube
- stainless steel finned tube
- iron ( steel, finned tube etc. .
By use classification
- air conditioning with finned tubes
- air-cooled with finned tubes
- the boiler : finned water wall economizerair preheater tubes were used
- industrial waste heat recovery with finned tubes
- other special purpose finned tube etc.
The material certificate including all the tests can be provided, and also with EN10204 3.1standard.
Welcome to contact with us for any kind of information and request.
Why Use Aluminum Fins?
According to the heat exchange application and operation, there are various materials.
The common ones are Aluminum, Alloy, Copper, Brass, Nickel, Titanium, Stainless Steel, Carbon Steel, etc, among which the aluminum and alloy are mostly used.
The basic performance for fin tube heat exchange should be with good solder ability and form ability, higher mechanical strength, good corrosion resistance and thermal conductivity. In spite of these, aluminum and alloy are also featured in extension and higher tensile strength increases under lower temperature. Around all world, especially for low temperature and compact heat exchange, they are widely applied.
Let’s see the feature of aluminum
1. Low Density
By alloying and heat treatment, it can reach the structural of construction steel. Suitable for various transportation, especially for small vehicle, reducing weight and consumption.
2. Good Corrosion Resistance
When under harsh conditions, the materials oxide from aluminum is non-toxic. With aluminum heat exchange, no worries that air or liquid inside will be destructed by oxide after long time.
3. Good Thermal Conductivity
Especially suitable for radiating fin, heat transfer evaporator and condenser.
4. High Yielding and resistance to die cutting.
It is easy for processing and forming.
As a professional finned tube manufacturer, our leading product is aluminum finned tube. Should you have any interest, please contact us for more.
Fin Tube Ration Affected by Fin Height, Fin Thickness and Fin Pitch
Fin tube ration affected by fin heightWhen the fins are root-grounded on the base bare tube, in the case of heat from inside to outside, the heat will be transferred from fin root along fin height. It is also continuously transmitted to the surrounding fluid by convective heat transfer. As a result, the fin temperature gradually decreases along the altitude. This also illustrates that difference between fin temperature and ambient fluid temperature is reducing gradually and the heat change per unit is shrinking. Therefore, the effect of fin surface area on enhanced heat transfer is decreasing. The higher the fin, the contribution of the increased area to heat exchange is smaller.
Fin Height
Generally speaking, as for the high frequency welded fin tube applied in engineering project, when fin height is 15mm, the fin efficiency is about 0.8; when fin height is 20mm, the fin efficiency is decreased to 0.7. Based on this, 15mm is the best height. If fins height above 20mm, the fin efficiency will be very bad, so generally not adopted. However, for the aluminum fin on air cooler, height at 22-25mm are always adopted due to much better heat conductivity coefficient of aluminum than carbon steel.
How will fin pitch affect fin ratio?
Usually smaller pitch can effectively increase fin ratio. While considering the flow gas property and ash deposit , we should pay attention to following factors.
A. Serious heavy ash deposit
Such as electric furnace and converter in steel works and exhaust of industrial cellar furnace, the ash content is heavy. If fin tubes are used for heat exchange, larger fin pitch will be suggested. For example, if pitch above 10mm, it is necessary to add a air discharge and choose an air blower.
B. Occasion with small ash deposit but should also be cared.
Take exhaust on plant boiler and industrial boiler as example, 8mm fin pitch is suitable, but should be designed with self-blowing ability.
C. Occasion with no dust or light dust.
Such as exhaust on burning natural gas equipment or air cooler, fin pitch at 4-6mm is OK. For aluminum air cooler, 3mm as fin pitch is also chosen.
Fin Thickness
The choice on fin thickness depends on corrosion and abrasion of fluid gas. Usually thicker fin is used on site with heavy corrosion.
Extruded Aluminum Finned Tubes Product Range
Extruded Aluminum Finned Tubes, also known as “Integral Finned Tubes”. Integral finned tubes are manufactured by rolling process on tubes. During finning operation, the inside diameter of the tubes is reduced and helical fins are rolled on the tube wall.
Integral Low Finned Tubes
- These have fin height less than or equal to fin pitch.
- Tube Length: Up to 32 meter.
- Outside Diameter OD: Between 9.52 mm and 38.10 mm.
- Tube Wall Thickness WT: 0.58 mm (min) and above.
- Fins per Inch: 11, 16, 19, 23, 26, 30, 40 and 52 FPI.
- Available in ferrous and nonferrous materials Copper Alloys, Copper-Nickel alloy, Admiralty Brass Alloy C44300, Aluminum Brass Alloy C68700, Carbon Steel.
Integral Medium High Finned Tubes
- Fin height more than fin pitch.
- Tube Length: Up to 32 meter.
- Outside Diameter: Between 19.05 mm and 31.75 mm.
- Tube wall thickness: 2.1 mm (min) and above.
- Fins per Inch: 11, 16 and 19 FPI.
- Available in ferrous and nonferrous materials.
Low Finned U Bend Tubes
- Manufactured on in-house finned tube bending facility.
- Easy to install in the equipment maintaining the circulation ratio.
- Absorb thermal shocks in heat exchanger.
- Available in Copper Alloys, Copper-Nickel alloy, Admiralty Brass Alloy C44300, Aluminum Brass Alloy C68700, Carbon Steel, 304 and 304L Stainless Steel ranging from 30R to 710R.
Low finned tubes with internal rib
- Externally enhanced surface area with integrally helical ribs on the inner side.
- Improved inside heat transfer coefficient.
- Available in Copper, Copper Nickel Alloy, Carbon Steel with externally 19, 26 fins per inch and internally 8, 10 Ribs.
Low Finned Tubes Coils
- Manufactured by coiling the integral finned tube.
- Improved heat transfer area therefore compact size of heat exchangers.
- Available in Copper, in coil diameters as per user’s requirement (Min Coil ID 50 mm).
High Finned Tubes
- High Finned Tubes have extruded fin heights up to 0.625″ (16mm). Single metal and bi-metallic finned tubes are available. Bi-metal finned tubes have a separate alloy liner tube inside the extruded fins. The mono-metal finned tubes have no liner tube with the fins integral with the tube.
Corrugated Tubes
- Manufactured by corrugation process of indenting plain tube with smooth and uniform spiral projections, which generate turbulence in both outside and inside media.
- Higher turbulence ensures uniform temperature distribution.
- No thinning of tube wall during process of corrugation.
Extruded Aluminum Finned Tubes Characteristics
- Heat transfer per meter of tube on the outside is equal to the heat transfer per meter on the inside.
- The intermediate un-finned section and un-finned sections at both ends help to slip the integral finned tubes in to the tube-sheets of shell and tube heat exchanger in a manner similar to plain tubes.
Extruded Aluminum Finned Tubes Benefits
- Combination of lower fin height and more fins per meter maintains the general ratio of 1:1 fin height to fin spacing.
- Doesn’t require higher tube pitch therefore, doesn’t require shell size higher than shell of bare tube heat exchanger.
- Improved heat transfer coefficient and rate of heat transfer as compared to conventional finned tube designs.
- Compact design of heat exchanger having lesser weight and size.
- Improved tube life.
Extruded Aluminum Finned Tubes Quality Assurance
- Compliance with quality standards, ASME SB111, SB-359, SA-213, SA-450 and all codes as per ASME /EN/ JS.
- Customer / Third Party Inspection TPI.
- Fin dimensions checking by IMTEs and Profile checking on profile projector.
- Stress Relief Annealing of non-ferrous fin tube on in-house electric conveyor belt furnace.
- Stress relief annealing of ferrous fin tubes as per specifications provided if required by client at additional cost.
- 100% tubes tested for leakages by Hydrostatic Test as per standard and customers requirements.
- Third Party Inspection can be offered from Lloyd’s, BV, TUV, BHEL, NTPC, Intertek, SGS, EIL, IBR etc. as per customer requirement.
Extruded Aluminum Finned Tubes Applications
- HVAC & Boiler
- Power Plants
- Heat Recovery Steam Generators
- Petrochemical Industries
- Marine Applications
- Refrigeration Applications
- Economizers
- Oil and Gas Coolers
- Plumbing and Air Conditioning
- Condensers and Evaporators
- Shell and Tube Heat Exchanger
- Other various Heat exchanger applications
Why boiler use Finned Tubes?
Finned tubes are used in applications involving the transfer of heat from a hot fluid to a colder fluid through a tube wall.
The rate at which such heat transfer can occur depends on three factors:
- the temperature difference between the two fluids;
- the heat transfer coefficient between each of the fluids and the tube wall;
- and the surface area to which each fluid is exposed.
In the case of a bare (un-finned) tubes, where the outside surface area is not significantly greater than the inside surface area, the fluid with the lowest heat transfer coefficient will dictate the overall heat transfer rate. When the heat transfer coefficient of the fluid inside the tube is several times larger than that of fluid outside the tube (for example steam inside and oil outside), the overall heat transfer rate can be greatly improved by increasing the outside surface of the tube. In mathematical terms, the product of heat transfer coefficient for the outside fluid multiplied by the outside surface area is made to more closely match the product of the inside fluid heat transfer coefficient multiplied by the inside surface area.
“The whole concept of finned tubes is to increase the outside surface area of the tube.”
So the whole concept of finned tubes is to increase the outside surface area of the tube. As an example, a finned tube configuration of 2” (nominal, 2.375” actual) pipe with a ¾” high welded helical solid fin of 12 gauge thickness with 6 fins per inch has an outside surface area of 8.23 sq. ft. per linear foot; whereas the same bare pipe has an outside surface area of only .62 sq. ft. per linear foot. That is a 13X increase in outside surface area. See Design Information for extensive tables of surface areas and fin weights.
By increasing the outside surface area of the tube, the overall heat transfer rate is increased, thereby reducing the total number of tubes required for a given application. This reduces the overall equipment size and the cost of the project. In many cases, one finned tube replaces six or more bare tubes at less than 1/3 the cost and ¼ the volume.
A finned tube heat exchangers is a kind of heat exchanger design with the intention of uses plates and finned chambers to transfer heat between fluids. It is repeatedly categorized as a compact heat exchanger to emphasize its relatively high heat transfer surface area to volume ratio.
Advantages :
- High heat transfer efficiency especially in gas treatment
- Larger heat transfer area
- Approximately 5 times lighter in weight than that of shell and tube heat exchanger.
- Able to withstand high pressure
Fins can have a variety of shapes. For example, they can be pin fins protruding from a surface (as just described), or annular fins around a tube used to enhance heat flow into or out of the fluid flowing through the tube. The figure below illustrates such a fin.
If fins are attached to a wall with a metallurgical or adhesive joint, a significant thermal contact resistance may exist at the interface. This can be accounted for by a fin correction factor, discussed in a later section on the overall heat transfer coefficient.
Next, we will analyze the parallel flow heat exchanger for steady state flow. Steady state flow is a valid assumption for steady operating conditions and temperatures.
Production Technique & Applications
We offer multiple fin styles, all with different specs and operative requirements.
"G" fin
Max. operating temp. 450ºC
“Crimped” Fin
"KL" fin
“LL” Fin
"L" fin
“Extruded” Fin
Fin tube FAQs:
We are a pretty proactive bunch. So, while we do charge a small fee per design to cover our costs, we absorb these costs when it is for a regular customer or where we are working jointly on a project. We also refund the fees in case it is followed by an order.
Can you assist with the design for my application?
Absolutely, we can.
Applied Fin Tube
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.
| Fin material | N° fins per meter | Strip thickness | Production capacity |
|---|---|---|---|
| All type of material | From 50 to 500 | From 0,4mm. to 0,5mm. | More than 500 meters per day |
| Tube material | Tube thickness | O.D. tube | Lenght available |
| All type of material | 1,00mm. minimum | From 10,00mm. to 200,00mm. | All lenghts up to 8 Meters |
Why do Pin fin tubes weigh less than L type fin tubes?
Pin Fin tubes are made from wire. Being cylindrical, wire has a larger area per unit of weight than the strip used in L type fin tubes. Also, due to the looped nature of the wire, less material is put on the tube than in the case of L fins. Consequently, the surface area of fins per meter of tubes is also less. However due to the superior turbulence created by the looped wire the actual heat transfer per meter of tube is significantly higher than in the case of L Type Fin Tubes. All of this together contributes to the weight differential between wire wound fin tubes and L Type Fin Tubes. In the case of similar metals, it is weighing half and in the case of Aluminium L fin vs. Steel wire fin they weigh about the same. The higher performance S5 pin fin tubes have an airside heat transfer performance per meter of tube that is 250% of the L type fin tubes.
Can Sunny Steel supply my fin tubes?
Yes.
A lot of our customer choose to supply their own pipes or tubes, however, a lot of customers ask us to supply them and we are happy to accommodate! We stock various sizes and if we don’t have what you need we can bring it in from one of our many suppliers.
If you would like us to include the pipe or tube material in your order, please indicate that when you request a QUOTE.
High Frequency Resistance Welding
A continuous helical fin is attached to the base tube by high frequency electric resistance welding in order to give an efficient and thermally reliable bond. Fins can be either solid or serrated (segmented). The weld produced in this process is a true forge, blacksmith weld. This type of weld is comprised of a fusion between two portions of parent metal without the introduction of a filler material. The weld is simply produced by heating the interfaces to be joined to a plastic state and applying pressure.
Used in boilers, furnaces and fired heaters for efficient heat recovery.
Uses of finned tubes
The main uses for high frequency welded finned tubes are in the heat recovery associated with boilers for power generation and in furnace applications for the petrochemical industry.
Tube bending:
Our finning machines are equipped with online single or duplex cold bending equipment that can manipulate both ends of tubes in a single operation, thus ensuring exact alignment of the ends.
Do we stock fin tubes?
We do not. Our market lends itself to customer designed products, each special in itself. The number of combinations of diameter, overall length, materials and fin specs are too vast. Sunny Steel builds each finned product to each customers needs.
What are finned tubes used for?
Finned tubes are the main components of heat exchangers. They are a series of tubes where fins have been added on the outside to increase the contact area with the outside fluid, to exchange heat and between the fluid inside the tube and the fluid outside the tube. Finned tubes are elongated aluminium cladded carbon steel flat tubes with brazed aluminium fins.
The rate at which such heat transfer can occur depends on three factors:
(1) the temperature difference between the two fluids;
(2) the heat transfer coefficient between each of the fluids and the tube wall; and
(3) the surface area to which each fluid is exposed. In the case of a bare (unfinned) tubes, where the outside surface area is not significantly greater than the inside surface area, the fluid with the lowest heat transfer coefficient will dictate the overall heat transfer rate. When the heat transfer coefficient of the fluid inside the tube is several times larger than that of fluid outside the tube (for example steam inside and oil outside), the overall heat transfer rate can be greatly improved by increasing the outside surface of the tube. In mathematical terms, the product of heat transfer coefficient for the outside fluid multiplied by the outside surface area is made to more closely match the product of the inside fluid heat transfer coefficient multiplied by the inside surface arear.
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