Extruded Finned Tubes

A: An extruded finned tube is made by mechanically deforming an outer metal layer — usually aluminum — into a continuous helical fin directly over the base tube, all without melting or adding filler metal. The big difference from high-frequency welded fin tubes is the absence of a weld seam. In an extruded fin tube, the fin root and the tube are either mechanically interlocked with extreme contact pressure (bimetallic type) or are a single continuous piece of metal (all-aluminum type). Wrapped fin tubes rely on tension alone and loosen over time. Welded fin tubes introduce a heat-affected zone. Extruded finned tubes avoid both problems, giving you a stronger fin root and far more stable thermal performance over years of thermal cycling.

A: In a bimetallic extruded finned tube, you have two distinct metals: a pressure-bearing base tube (carbon steel, stainless steel, copper-nickel, titanium, etc.) and an outer aluminum fin that’s extruded tightly onto it. The base tube handles the pressure and internal corrosion; the aluminum fin handles the heat dissipation. In an aluminum extruded fin tube, the base tube and fins are the same aluminum alloy — no interface, no second metal. That means zero galvanic corrosion risk and the lightest possible construction, but also lower pressure and temperature limits. If you’re dealing with steam, high pressure, or aggressive fluids, you need the bimetallic version. For low-pressure clean water or glycol loops, the all-aluminum extruded finned tube is a very cost-effective choice.

A: The temperature limit is determined primarily by the fin material. All our aluminum-fin extruded fin tubes — both monolithic and bimetallic — are rated for continuous operation up to 300°C (572°F). Above this temperature, aluminum begins to soften and lose mechanical strength, and the bond integrity can degrade over repeated thermal cycles.
For applications running above 300°C, we typically recommend our high frequency welded carbon steel or alloy steel fin tubes, which handle temperatures up to 650°C reliably. Our engineering team will always specify the right technology for your actual operating range.

A: The pressure rating comes entirely from the base tube — the fins play no role in containing pressure. A bimetallic extruded finned tube can be designed for very high pressures, often 30 MPa or more, simply by specifying the right base tube material and wall thickness. An aluminum extruded fin tube, on the other hand, is limited by the strength of the aluminum itself; you’re usually looking at a maximum of around 4 MPa. So when you’re asking about pressure, the real question is: what base tube do you need? That’s why in inquiries for bimetallic tubes, we always ask about tube-side pressure, temperature, and media first.

A: Absolutely — but only the bimetallic type, and only with the right base tube. Seawater will quickly corrode an aluminum extruded fin tube from the inside. For seawater service, we supply bimetallic extruded finned tubes with a copper-nickel (CuNi 90/10 or 70/30) or titanium base tube and aluminum fins. The CuNi or titanium handles the seawater corrosion, while the aluminum fins take care of the air-side heat rejection. This is a well-proven solution on offshore platforms and FPSOs, where weight savings and corrosion resistance both matter enormously.

A: For standard bimetallic extruded finned tubes with a carbon steel base and aluminum fins, and using common sizes, you can typically expect delivery in 50 days. If you need a special base tube alloy — titanium, nickel alloys, certain duplex stainless steels — that adds procurement time, and the lead may stretch to 60 days. Extruded serrated finned tubes add a small extra step but don’t significantly change the schedule. We always confirm the exact delivery date when quoting, based on current raw material availability.

A: Yes, build-to-print is the norm in the extruded fin tube industry. Just provide your drawings or technical specification sheet, indicating the base tube material, aluminum fin alloy, fin height, fin pitch, tube length, tube end details, and whether you want plain or serrated fins. We’ll review the design, produce a production proposal drawing for your approval, and then move into tooling and sample production. This back-and-forth ensures your bimetallic or aluminum extruded finned tubes match your heat exchanger exactly.

A: Choose serrated when you need an extra 10–20% heat transfer from the same tube envelope, or when your exchanger sees wet and dry cycling — think air-cooled condensers, evaporators, or outdoor heat pump coils. The notches on an extruded serrated finned tube break up the air boundary layer, raising the heat transfer coefficient, and they also provide drainage paths so condensate or defrost water doesn’t bridge the fins. The serrated version adds only a small cost premium over the plain extruded finned tube, but in space-constrained or efficiency-critical projects, it can make a meaningful difference.

A: You’ll find extruded finned tubes everywhere: power plant air-cooled condensers (ACC), refinery and petrochemical air coolers, large commercial HVAC chillers and heat pumps, data center dry coolers, cold storage evaporators, and even in automotive and electronics liquid-to-air heat exchangers. Bimetallic extruded finned tubes dominate where high pressure and corrosive media are present; aluminum extruded fin tubes are popular in lower-pressure, clean-fluid systems where weight and corrosion resistance matter more than raw strength.

A: We don’t enforce a strict minimum order quantity, but because the extrusion tooling needs a certain run to stabilize, orders of a few hundred meters per batch are more economical. As for length, custom lengths are a standard part of the business. An extruded fin tube can be produced from half a meter up to around 22 meters in a single piece, limited mainly by shipping constraints. Whatever your exchanger layout requires, just let us know the exact cut lengths and the plain-end details, and we’ll accommodate them.