A KL-type fin tube gets its grip from knurling. The base tube surface is cut with a fine pattern of grooves, then an aluminium or copper strip is wound on top and rolled down until it locks into that pattern. Usually the fin and the tube are the same metal. Change that, and put an aluminium fin on a carbon steel or stainless steel base tube instead, and you've got a bimetallic KL-type fin tube. It's a small change on paper, but it means you can pick the fin for how well it moves heat and pick the base tube for how well it holds pressure or resists corrosion, without either choice being a compromise for the other.
Amardeep Steel Centre builds the same knurled, mechanically locked KL construction on ourKL Fin Tubes page. What this page covers specifically is the bimetallic version of it, where the fin metal and the base tube metal are chosen separately rather than matched. We have exported stainless steel and specialty tube products since 1982.
Technical Data
Specifications of Bimetallic KL-Type Fin Tubes
Parameter | Specification |
|---|---|
Fin Type | KL-Type, knurled and mechanically locked, bimetallic (fin and base tube materials differ) |
Fin Materials | Aluminium, Copper |
Base Tube Materials | Carbon Steel, Stainless Steel, Alloy Steel, Copper Alloys |
Base Tube Outer Diameter | 15.88 mm to 50.80 mm |
Fin Density | 7 to 11 fins per inch |
Fin to Tube Bond | Knurled and mechanically locked, higher grip than tension wound L or LL fin |
Maximum Operating Temperature | Up to 320 degrees Celsius, subject to fin material, base tube material, bond condition and application conditions |
Documentation | Mill Test Certificate supplied with every order |
Chemical Composition of Bimetallic KL-Type Finned Tubes
Material | Composition Note |
|---|---|
Aluminium Fin (1100 / 1050) | 99.0% minimum aluminium |
Copper Fin (C12200) | 99.9% minimum copper |
Carbon Steel Base Tube (A179) | 0.06% to 0.18% carbon |
Stainless Steel Base Tube (TP316) | 16.00% to 18.00% chromium, 10.00% to 14.00% nickel |
Mechanical Properties of Bimetallic KL-Type Fin Tubes
Material | Tensile Strength (Min) | Yield Strength (Min) | Elongation (Min) |
|---|---|---|---|
Aluminium Fin (1100) | 75 MPa | 20 MPa | 20% |
Copper Fin (C12200) | 220 MPa | 69 MPa | 35% |
Carbon Steel Base Tube (A179) | 325 MPa | 180 MPa | 35% |
Stainless Steel Base Tube (TP316) | 515 MPa | 205 MPa | 35% |
KL-Type Bimetallic Finned Tubes Dimension Chart
Bare Tube OD | Fin Height | FPI |
|---|---|---|
15.88 mm to 19.05 mm | 6.35 mm to 12.70 mm | 7 to 9 FPI |
25.40 mm to 31.75 mm | 12.70 mm to 19.05 mm | 8 to 10 FPI |
38.10 mm to 50.80 mm | 19.05 mm to 25.40 mm | 9 to 11 FPI |
Match your bare tube diameter against this chart for the standard fin height and density pairing.Share your drawing with our team if your project falls outside these ranges.
Applications of Bimetallic KL-Type Fin Tubes
- Higher Temperature Air Cooled Heat Exchangers: where the operating temperature exceeds what a tension wound L or LL fin can reliably hold.
- Process Cooling with Corrosive Fluids: the base tube handles the corrosion resistance while the fin handles the conductivity.
- High Mechanical Bond Applications: service where vibration or thermal cycling would loosen a wrap on fin over time.
- Chemical and Petrochemical Air Cooling: industrial process heat exchangers needing both durability and heat transfer efficiency.
Frequently Asked Questions
What is a bimetallic KL-type fin tube?
A Bimetallic KL-Type Fin Tube is a KL construction fin tube, knurled and mechanically locked, where the fin material is deliberately different from the base tube material, most often an aluminium or copper fin on a carbon steel, stainless steel, or copper alloy base tube.
What is the difference between a mono- and a bimetallic KL-type fin tube?
A mono KL-type fin tube uses the same metal for the fin and the base tube. A bimetallic KL-type fin tube uses two different metals, so the fin can be chosen for conductivity and the base tube for pressure and corrosion resistance independently.
Does KL construction use a machined groove like G-type?
No. KL construction uses a knurled surface pattern, a fine, repeated set of small grooves, not the single continuous machined groove used forG-Type fin tubes. The fin locks into the knurled pattern as it is wound and rolled down.
What is the maximum operating temperature for Bimetallic KL-Type Fin Tubes?
Bimetallic KL-type fin tubes can be supplied for temperatures up to 320 degrees Celsius, subject to the fin material, base tube material, bond condition, and applicable equipment design requirements. The final operating limit should be confirmed for the specified material combination and service conditions.
Which fin and base tube material combinations are available?
Amardeep Steel Centre supplies aluminium or copper fins on carbon steel, stainless steel, alloy steel, or copper alloy base tubes, matched to your process fluid and thermal requirements.
Does Amardeep provide Mill Test Certificates with Bimetallic KL-Type Fin Tubes?
Yes, every order ships with a mill test certificate covering the chemical and mechanical properties of both the fin and base tube materials used.
Why Choose Amardeep Steel Centre
Get in touch with our team with your project specification, or send an enquiry directly for a quote on Bimetallic KL-Type Fin Tubes built to your requirement.
Request a QuoteRelated Products
KL Fin Tubes, G Fin Tubes, Rectangular Finned Tubes, Bimetallic L-Type Fin Tubes and Finned Tubes
