Notched Fin Tubes are enhanced heat transfer tubes in which the fin edge is formed with a repeated notch pattern to alter fluid flow across the fin surface. The notches are impressed into the edge of an existing solid or helically wound fin without removing material, so the fin keeps most of its mechanical strength while gaining a groove structure that promotes turbulence. That turbulence disrupts the thermal boundary layer along the fin, helping heat transfer coefficients run 2 to 5 times higher than a bare tube.
The construction can be built on different base tube and fin materials according to the temperature, corrosion conditions and thermal requirements of the equipment. Notched Fin Tubes are used in heat exchangers, boiler equipment, waste heat recovery systems, air-cooled equipment and selected process applications.
Amardeep Steel Centre has manufactured and exported stainless steel and speciality tube products since 1982, shipping to more than 40 countries today. We supply finned tube products with attention to fin geometry, tube material, dimensional consistency and material documentation for industrial heat transfer applications.
Technical Data
Specifications of Notched Fin Tubes
| Parameter | Specification |
|---|---|
|
Fin Thickness |
0.3 mm to 1.5 mm |
|
Fin Construction |
Solid or helically wound base fin with a defined notch pattern |
|
Fin Materials |
Carbon steel, stainless steel or aluminium, subject to design |
|
Base Tube Materials |
Carbon steel A179, A192 and A210; stainless steel TP304 and TP316; alloy steel P11 and P22 |
|
Base Tube Outer Diameter |
19 mm to 76 mm |
|
Fin Height |
5 mm to 25 mm |
|
Fin Pitch |
3 to 8 fins per inch |
|
Notch Depth |
10% to 30% of total fin height, confirmed against thermal design |
|
Fin Configuration |
Spiral or other specified fin arrangement |
|
Tube Length |
According to customer drawing and project requirement |
|
Documentation |
Mill Test Certificate and inspection documents as specified |
Chemical Composition of Notched Finned Tubes
The chemical composition is determined by the selected base tube grade. The values below show selected elements for commonly specified grades. The complete chemical requirements should be confirmed against the applicable ASTM or ASME material specification.
| Grade | Carbon C | Manganese Mn | Chromium Cr | Molybdenum Mo |
|---|---|---|---|---|
|
ASTM A179 |
0.06% to 0.18% |
0.27% to 0.63% |
Not specified |
Not specified |
|
ASTM A213 T11 |
0.05% to 0.15% |
0.30% to 0.60% |
1.00% to 1.50% |
0.44% to 0.65% |
|
ASTM A213 T22 |
0.05% to 0.15% |
0.30% to 0.60% |
1.90% to 2.60% |
0.87% to 1.13% |
|
ASTM TP304 |
0.08% max |
2.00% max |
18.00% to 20.00% |
Not specified |
Notched Fin Tubes' Mechanical Properties
The mechanical properties below refer to the base tube material. The notching operation does not create a separate material grade. Final product suitability must be checked against the complete tube specification and operating conditions.
| Grade | Tensile Strength Minimum | Yield Strength Minimum | Elongation Minimum |
|---|---|---|---|
|
ASTM A179 |
325 MPa |
180 MPa |
35% |
|
ASTM A213 T11 |
415 MPa |
205 MPa |
30% |
|
ASTM A213 T22 |
415 MPa |
205 MPa |
30% |
|
ASTM TP304 |
515 MPa |
205 MPa |
35% |
Physical Properties of Notched Finned Tubes
| O.D. (mm) | Wall Thickness (mm) | Fin O.D. (mm) | Fin Wall Thickness (mm) | Minimum Wall Thickness (mm) | Ridge Height (mm) | Nominal Outside Surface Area (m²/m) | Actual Outside Surface Area (m²/m) | Nominal Inside Surface Area (m²/m) | Nominal Inside Surface Area (m²/m) | |
|---|---|---|---|---|---|---|---|---|---|---|
|
1 |
15.88 |
0.70 |
15.88 |
0.50 |
0.45 |
0.15 |
0.0498 |
0.0752 |
0.0454 |
0.0499 |
|
2 |
19.05 |
0.70 |
19.05 |
0.50 |
0.45 |
0.15 |
0.0598 |
0.0898 |
0.0554 |
0.0609 |
|
3 |
25.40 |
0.80 |
25.40 |
0.55 |
0.50 |
0.15 |
0.0797 |
0.1201 |
0.0753 |
0.0828 |
Dimension Chart for Notched Fin Tubes
| Base Tube OD | Fin Height | Fin Pitch |
|---|---|---|
|
19 mm to 38 mm |
12.7 mm to 19.05 mm |
5 to 8 FPI |
|
38 mm to 57 mm |
19.05 mm to 25.4 mm |
4 to 6 FPI |
|
57 mm to 76 mm |
19.05 mm to 25.4 mm |
3 to 5 FPI |
Applications of Notched Fin Tubes
Notched Fin Tubes are used where increased external surface area and modified fluid flow can support the required heat transfer duty.
- Petrochemical Heat Exchangers: Used in process equipment where controlled fin geometry can increase the available external heat transfer surface.
- Power Boilers: A Notched Fin Tube for Boilers can be considered for economizers and heat recovery equipment.
- Waste Heat Recovery: Used in selected systems recovering heat from process gases and combustion gases.
- Air Cooled Heat Exchangers: Suitable where fin geometry and airflow conditions support the required thermal performance.
- Boiler Economizers: Applied where heat recovery from flue gas is required.
- Chemical Processing Plants: Used for selected heating and cooling duties.
- Gas Processing Equipment: Considered for applications requiring increased external heat transfer area.
- Industrial HVAC: Used in selected compact heat transfer equipment where the fin structure suits the airflow conditions.
Frequently Asked Questions
What are Notched Fin Tubes?
Notched Fin Tubes have repeated notches impressed along the fin edge that promote fluid mixing and can improve heat transfer under suitable operating conditions.
What does a Notched Fin Tube manufacturer supply?
A Notched Fin Tube manufacturer can supply tubes with specified base tube grades, fin materials, fin height, fin density, notch geometry, dimensions and inspection documentation.
How does a Notched Fin Tube differ from a Serrated Fin Tube?
A notched fin has notches impressed into the edge of an existing solid or helically wound fin without removing material. A serrated fin is cut or slit along the strip edge before it is wound onto the tube. Because less material is disturbed, a notched fin generally retains more mechanical strength, while both constructions promote similar turbulence.
Are Notched Fin Tubes for boilers suitable for economizers?
Yes. Notched Fin Tubes for boilers are considered for economizers and heat recovery equipment where enhanced gas side heat transfer is required.
How much can Notched Fin Tubes improve heat transfer?
Published supplier literature reports improvements of up to 2 to 5 times the bare tube coefficient for specific designs. Actual performance depends on geometry and operating conditions.
What materials are available for Notched Fin Tubes?
Notched Fin Tubes can be supplied with carbon steel, stainless steel or alloy steel base tubes, with fin materials selected according to temperature and service requirements.
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