Low Fin Tube
Low Fin Tube - seamless steel tube
One-piece hot extruded integral spiral finned tube eliminates contact thermal resistance, delivers long service life under high temperature, ash-laden and corrosive flue gas working conditions.
Integral spiral finned tube (also known as integral rolled circular finned tube, integral finned tube) is a high-efficiency heat transfer component optimized for harsh industrial thermal conditions. It is not a regular welded fin tube; instead, it is milled from a single piece of thick-walled seamless steel tube via hot extrusion or hot rolling process, with continuous spiral fins formed as an integral part of the base tube — no welding, no brazing, no mechanical bonding between the fin and base tube. This eliminates the thermal resistance caused by gaps or inconsistent fusion in traditional assembled fin tubes, ensuring uninterrupted heat transfer from the innermost wall of the base tube to the outermost edge of the fins.
As a core heat exchange component, this monolithic finned tube solves typical drawbacks of conventional heat transfer tubes under high-temperature, high-pressure and corrosive flue gas, including low heat transfer efficiency, fin shedding, heavy ash fouling and short service lifespan. It becomes the preferred heat transfer element for thermal power, petrochemical and waste heat recovery large-scale energy projects due to balanced heat transfer efficiency, mechanical strength and stable long-term operation.
Integral spiral finned tube is a high-strength, high-efficiency heat exchange element manufactured through precision hot-working forming. Its core competitive advantage lies in the integrated monolithic structure: spiral fins and base tube are formed from identical seamless thick-wall steel without any welds or connection seams. This structural feature completely avoids hidden risks existing on welded fin tubes, such as fin detachment, incomplete fusion and gap electrochemical corrosion.
Integral forming expands effective heat exchange area significantly, without contact thermal resistance between fin and tube. φ32×3mm tube with 10mm fin height & 8.5mm pitch owns 4x heat transfer area vs smooth tube, 1.5x vs wrapped welded fin tube. Spiral fins disrupt flue gas laminar boundary layer, overall heat transfer coefficient over 100% higher than plain tubes, effectively cutting system fuel consumption.
Consistent metallurgical structure eliminates weak connection points; dune-shaped fin root optimizes flue gas flow field and lowers local ash scouring intensity. Spiral flow suppresses Karman vortex street which causes concentrated abrasion, uniform tube wall thickness maintained under long-term ash-laden flue gas operation, avoiding tube perforation failure.
High section inertia allows maximum support span up to 5.28m, nearly double smooth tube’s 2.71m limit. Rigidity attenuation is minimal even at working temperature up to 460°C, effectively preventing span bending and vibration fatigue fracture under high-temperature flue gas impact.
Rotational flue gas flow guided by spiral fins eliminates low-speed recirculation dead zone where ash accumulates. Burr-free smooth fin surface reduces ash adhesion, minor ash sediment can be cleaned by regular steam soot blowers, stable heat transfer efficiency without frequent shutdown cleaning.
No fin-tube gap corrosion or shedding risk, strong thermal & mechanical shock resistance. Service life reaches 7~8 years, 2-3 times longer than smooth tube or welded fin tube under identical harsh flue gas conditions, drastically cutting tube bundle replacement frequency and unplanned downtime loss.
Stable heat transfer without long-term efficiency attenuation, lower daily maintenance workload, wide load adaptation range. Though initial procurement cost is slightly higher, energy saving, maintenance reduction and long service cycle bring obvious overall lifecycle cost reduction for large industrial projects.
| Material Category | Standard Grades | Max Continuous Temp | Applicable Scenarios |
|---|---|---|---|
| Carbon Steel | ASTM A179, ASTM A210 Gr.C | ≤450°C | Medium-low temp boiler economizer, heating furnace waste heat recovery |
| Alloy Steel | SA213 T5, T9, T11 | ≤550°C | High-temperature boiler superheater, weak corrosive flue gas |
| Stainless Steel | TP304, TP316L | ≤550°C | Acidic sulfur-containing flue gas, chemical waste heat recovery |
| Parameter Item | Custom Range |
|---|---|
| Base Tube Outer Diameter | 15.88mm ~ 50.80mm (5/8" ~ 2") |
| Base Tube Wall Thickness | 2mm ~ 6mm, customized per pressure demand |
| Fin Height | 8mm ~ 16mm, adjusted for anti-wear & heat transfer |
| Fin Pitch | 5mm ~ 12mm, optimized for ash fouling resistance |
| Fin Thickness | 0.8mm ~ 2.0mm |
| Single Tube Length | Max 18 meters, custom length available |
All structural dimensions can be precisely adjusted according to flue gas ash content, operating temperature and customer heat exchanger drawing requirements.
All finished tubes supply EN 10204 3.1 factory test certificate; SGS/BV third-party inspection documents are available for EPC overseas projects.
Parameter matching must combine full project working condition data to achieve optimal cost-performance ratio, key judging factors as below:
It is recommended to provide full flue gas parameter, heat recovery demand and equipment drawing to manufacturer technical team for professional engineering calculation and customized solution.
Manufacturing system certified by ISO 9001 quality management system, product complies with ASTM, ASME BPVC, NB/T and GB national industrial standards. Additional CE (EU market) and EAC (Eurasian Union) certification documents available upon overseas customer demand; all inspection reports issued in official English version for international EPC project acceptance.
Integral spiral finned tube represents advanced mature heat exchange tube technology for harsh industrial thermal recovery systems. The integrated hot rolling one-piece structure fundamentally overcomes inherent defects of traditional welded fin tubes including fin shedding, performance attenuation and short service life. This product perfectly matches high-efficiency long-cycle operation demand of utility boilers, petrochemical process furnaces and multi-type waste heat recovery equipment.
If you need reliable high-performance heat exchange components to reduce long-term operating cost and improve energy utilization efficiency of your industrial heat exchange project, integral spiral finned tube is your optimal selection. Contact our professional technical sales team for customized technical solution based on your actual flue gas working conditions and heat recovery parameters.
Smooth Spiral Transition
Continuous Metallurgical Grain
Ultra-High Structural Rigidity
Understanding how extended surfaces enhance heat exchanger performance by reducing thermal resistance on the gas side.
A finned tube heat exchanger is built upon a plain round tube (base tube). The fundamental question is: how can we increase the heat transfer rate of a plain tube? One of the most effective methods is to add extended surfaces—fins—to the outer surface of the tube, typically on the flue gas side.
The overall heat transfer equation is:
Q = U × A × ΔTm
Where:
Q = Total heat transfer rate (W)
U = Overall heat transfer coefficient (W/m²·K), referenced to the base tube outer surface
A = Heat transfer area of the base tube outer surface (m²)
ΔTm = Logarithmic mean temperature difference (K)
When fins are attached to the outer surface, the effective heat transfer area (Aeff) increases to several times—or even dozens of times—the original plain tube area. Although the gas-side heat transfer coefficient (hout) itself remains unchanged, the apparent thermal resistance referred to the base tube area is significantly reduced, thereby enhancing the overall heat transfer process.
The total thermal resistance of a finned tube can be expressed as:
1/U = 1/hin + δ/λ + 1/(η × hout)
Where:
hin = Inside (tube-side) heat transfer coefficient (W/m²·K)
δ/λ = Wall conduction thermal resistance (m²·K/W)
η = Fin efficiency (0 < η ≤ 1)
hout = Outside (gas-side) heat transfer coefficient (W/m²·K)
In most industrial applications, the gas side (e.g., flue gas) has a much lower heat transfer coefficient than the liquid or steam side. This makes the gas side the controlling thermal resistance. By adding fins, we increase the effective area and reduce this controlling resistance without changing the fluid properties themselves.
While finned tubes offer significant advantages, several factors must be considered in actual engineering design:
| Design Factor | Impact on Performance |
|---|---|
| Fin Efficiency (η) | Higher fins increase area but reduce η due to temperature drop along fin height. Optimal fin height must be determined. |
| Fin Pitch | Closer pitch increases area but raises flow resistance and fouling risk. Wider pitch is preferred for dusty or fouling-prone environments. |
| Gas-Side Velocity | Higher velocity improves hout but increases pressure drop and fan power consumption. |
| Fouling & Ash Deposition | In boiler or flue gas applications, fin spacing must accommodate soot-blowing and periodic cleaning. |
| Material Selection | Fin and base tube materials must be compatible with gas chemistry, temperature and corrosion conditions. |
The core principle of finned tube heat transfer is: instead of increasing the heat transfer coefficient, we use extended surface area to overcome the thermal resistance on the low-coefficient side (typically the gas side).
This approach achieves three key objectives simultaneously:
In practice, successful finned tube design requires balancing fin efficiency, fin geometry, gas-side pressure drop, fouling behavior and material compatibility to ensure long-term, reliable performance.
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