Longitudinal Fin Tube
Straight fins welded along the tube axis for viscous fluids and low velocity gas
What Longitudinal Fin Tube Is
Longitudinal fins run straight along the tube axis instead of spiralling around it, so the fluid outside the tube flows between parallel channels rather than across a helix.
That geometry suits viscous liquids and low velocity gas, where a helical fin would either foul or cost more pressure drop than the extra surface is worth.
Fanbang welds 1U to 36U fins on base tubes from 12 mm up to 273 mm on two longitudinal fin production lines.
Why Engineers Specify It
Low pressure drop on the outside
Parallel channels along the tube cost far less pressure drop than cross flow over a spiral fin.
Handles viscous and fouling fluids
Straight channels drain and clean in the flow direction rather than trapping deposits.
Very large base tubes
Up to 273 mm outside diameter, so a single finned tube can serve as a tank heating element.
Fin count matched to duty
1U to 36U fins per tube lets surface area be tuned without changing the tube size.
Where It Is Used
- Chemical, petrochemical, oil and power industry
- Heat exchangers
- Fired heaters
- Gas coolers and heaters
- Tank heaters
Buyers Who Come to Us for This Tube
Tank farm and terminal operators
Heating heavy oil or bitumen in storage without a separate exchanger.
Fired heater fabricators
Convection sections where gas side pressure drop is the constraint.
Double pipe exchanger builders
The classic application for longitudinal finned inner tubes.
What Goes Wrong Without It
Viscous fluid fouling a spiral bank
Straight fins let the fluid flow along the channel instead of across it.
Pressure drop budget already spent
Longitudinal geometry adds surface without the cross flow penalty.
Heating a large storage tank
Base tubes to 273 mm let a finned element be built at tank scale.
Longitudinal Fin Tube Dimensions
These are the ranges our production lines run. Sizes outside them are quoted case by case rather than assumed.
| Item | Specification |
|---|---|
| Base tube diameter | 12 mm - 273 mm |
| Base tube wall thickness | 2.11 mm - 25.4 mm |
| Fin quantity | 1U - 36U |
| Fin thickness | 1.0 mm - 1.5 mm |
| Fin height | 5.0 mm - 25.0 mm |
Materials
| Component | Materials available |
|---|---|
| Base tube | Stainless steel, carbon steel, alloy steel, nickel |
| Fin strip | Carbon steel, stainless steel, alloy steel |
How It Is Made
Longitudinal Fin Tube on the Shop Floor
Inspection and Certification
Every tube passes eddy current and hydrostatic testing, with tensile, flattening, flaring, hardness and chemical analysis carried out on our own equipment. Fin pitch, fin height and finned length are verified as dimensional items in their own right.
The company holds ISO 9001:2015, CE certificate, Production licence for pressure pipe.
What Can Be Changed
- Base tube material and wall thickness within the range above
- Fin material, fin pitch and fin height to the bundle design
- Finned length and bare end length for the tubesheet joint
- Marking, packing and certificate scope for the destination market
Compared With the Alternatives
Compared with spiral or H type fins, longitudinal fins give lower outside pressure drop and handle viscous service better, but they add less surface area per metre for a given envelope. They are also the only fin type here available on base tubes up to 273 mm.
Use Guide
- Give the outside fluid viscosity and flow direction; a longitudinal fin only pays off in axial flow.
- Fin count (U number) is the main variable - fix duty first, then choose U count, then check pressure drop.
- For double pipe exchangers, state the shell bore so fin height leaves the annulus clearance you need.
Longitudinal Fin Tube FAQ
What does 1U to 36U mean?
It is the number of longitudinal fins welded around the tube. 36U is the maximum fin count we produce.
What is the largest base tube you can fin?
273 mm outside diameter, with wall thickness up to 25.4 mm.
Are the fins welded on both sides?
Yes, each fin is welded along the tube length at the fin root.
Is this the right tube for heavy fuel oil tank heating?
It is the usual choice, because the straight channels drain and clean in the flow direction and the outside pressure drop stays low.
Often Compared With
Spiral Fin Tube
Continuously welded helical fin for boiler, economizer and flue gas duty
Base tube diameter: 15 mm - 70 mm · Base tube wall thickness: 2.0 mm - 15.0 mm
H/HH Fin Tube
Split square fins welded in pairs, leaving a straight ash lane along the tube
Base tube diameter: 25 mm - 73 mm · Base tube wall thickness: 3.0 mm - 6.0 mm
Stud Fin Tube
Individually welded studs for the dirtiest furnace and process heater duty
Base tube diameter: 38 mm - 273 mm · Base tube wall thickness: 3.5 mm - 10.0 mmIndustries using this tube
Related reading
Quote Longitudinal Fin Tube From Your Drawing
Send base tube size, wall thickness, fin geometry, material and length. You get a quotation against the drawing, not a catalogue page.
[email protected] · Tel 0086 512 58392615 · Monday to Saturday, 08:30 - 17:30 China Standard Time (GMT+8)