Stainless steel low finned tube

Stainless Low Fin (Integral) Tubing

Stainless low fin tubing is produced by cold forming shallow, closely spaced fins directly from the base tube wall. Unlike high fin tubes, the overall outside diameter after finning remains close to that of the original tube, which allows direct installation into standard shell and tube heat exchangers without modifying baffles or tube sheets.

During manufacturing, multiple rolling discs plastically deform the tube surface to raise fins outward while maintaining full continuity with the base material. This integral structure eliminates any interface resistance between fin and tube, providing excellent heat conduction and strong mechanical integrity. The process also improves surface hardness due to cold working, which can enhance wear and erosion resistance in certain applications.

From a performance standpoint, low fin tubes increase the external surface area significantly, typically by a factor of 2.5 to 3 compared to plain tubes. This enhancement is particularly effective when the shell side heat transfer coefficient is relatively low, such as in gas side applications.

Typical Technical Parameters

Tube outside diameter before finning: 12.7 mm to 31.75 mm
Wall thickness: 1.0 mm to 3.0 mm
Fin height: 0.8 mm to 1.8 mm
Fin pitch: 8 fins per inch to 26 fins per inch
Fin thickness: approximately 0.2 mm to 0.5 mm
Finning ratio (external surface area ratio): 2.0 to 3.5
Maximum operating temperature: up to 400°C depending on material
Maximum operating pressure: typically up to 10 MPa depending on design code
Tube length: up to 20 meters

Common materials include austenitic stainless steels such as 304, 304L, 316, and 316L, as well as duplex stainless steels and other corrosion resistant alloys when required.

Key Advantages

The increased surface area allows for higher heat transfer efficiency, which can reduce the total number of tubes required in a heat exchanger. This leads to smaller shell diameters, lower material consumption, and reduced capital cost.

Because the outer diameter remains nearly unchanged, low fin tubes are well suited for retrofitting existing exchangers. Performance can be improved without redesigning the shell, supports, or piping system.

The integral fin structure ensures excellent thermal conductivity and eliminates the risk of fin loosening during operation. In addition, the cold worked surface can provide better resistance to certain types of fouling and mechanical wear.

With proper material selection, these tubes offer strong resistance to corrosion. For example, using high alloy stainless steels or titanium in aggressive environments such as seawater service can significantly extend service life and reduce maintenance frequency.

Applications

Low fin tubes are commonly used in petrochemical plants, refineries, power generation facilities, HVAC systems, and various process industries. They are especially suitable for condensers, coolers, and heaters where air or gas flows on the shell side and liquid flows inside the tube.

They are also widely applied in situations such as air cooled heat exchangers, lube oil coolers, and systems requiring compact and lightweight designs, including offshore platforms and modular process units.

Typical Use Cases

They are preferred when the shell side heat transfer coefficient is the controlling resistance, when expensive materials are involved and efficiency improvements can offset material costs, when upgrading existing exchangers to increase capacity, and when space or weight limitations are critical to the overall system design.

FIN TUBE MEETS THE FOLLOWING QUALITY STANDARDS
ASTM A1012 Seamless and Welded Ferritic, Austenitic and Duplex Alloy Steel Condenser and Heat Exchanger Tubes with Integral Fins