Product Description Content
API 661 Air Cooled Finned Tube Bundles & Pressure Vessel Replacement Cores
Yuhong Group Co., Ltd. is a direct manufacturer of high-efficiency air cooled heat exchanger cores, process vessels, and precision piping components. We design and fabricate custom finned tube bundle modules, heavy-duty heat exchanger tubesheet plates, threaded plug header boxes, and auxiliary components for forced and induced draft air coolers across the oil & gas, refining, and petrochemical industries.
Operating dedicated direct seamless tube mills and heavy fabrication shops, Yuhong Group maintains control over material chemistry, wall thickness tolerances, and NDE testing standards. Beyond specialized air cooler cores, our thermal product line includes standard shell and tube heat exchanger vessels, u tube bundle replacement sets, and high-pressure shell & tube heat exchanger cores engineered in strict accordance with API 661, ASME Section VIII Division 1, and ISO 13706 specifications.
Finned Tube Bundle Classifications & Structural Formats
We manufacture finned tube bundle replacement assemblies tailored to process operating temperatures, atmospheric corrosion severity, and fluid viscosity:
Extruded Fin Tubes (Type KL / Aluminum Sleeve): Formed by roll-extruding an outer aluminum collar over a base tube bundle core. Provides a continuous metallic contact zone that resists corrosion and seals the base tube wall at continuous operating temperatures up to 300°C.
Embedded Fin Tubes (Type G / High-Tension Embedded): Helically wound aluminum fin strip anchored under tension into a CNC-machined groove on the base tube outer diameter. Suitable for thermal duties up to 400°C in high-temperature refinery streams.
L-Foot / Double L-Foot Fin Tubes (Type L / LL): Helically wrapped L-shaped aluminum tape under high mechanical tension. Provides cost-effective surface area expansion for clean ambient air cooling loops up to 130°C.
Plug Type Header Box Bundles (API 661 Standard): Rectangular welded header box fitted with threaded shoulder plugs directly opposite each tube end, enabling mechanical cleaning, tube inspection, and selective plugged repair without box disassembly.
Removable Bonnet & Cover Plate Headers: Engineered for low-pressure applications containing heavy hydrocarbon fouling, allowing full cover plate removal for high-pressure hydro-blasting.
Air Cooler Header & Bundle Components Specifications
| Component | Engineering Standards & Material Options | Technical Function in Air Cooler Units |
| Heat Exchanger Tubesheet / Header Plate | Heavy Forged SA516 Gr 70, SA240 316L, Duplex 2205; CNC Precision Drilled with Double Serrations | Forms the main internal pressure wall between process media and atmosphere while retaining tube end connections. |
| Finned Heat Transfer Tube | Seamless Carbon Steel, Stainless Steel (304L/316L/2205), or Alloy Base Tube with Extruded/Embedded Fins | Functions as the primary heat dissipation element; extended aluminum fins increase air-side thermal conductivity. |
| Plug Box Header | Welded Structural Forged Plate Assembly with Submerged Arc Welded (SAW) Seams | Acts as the process fluid distribution header; contains threaded service ports aligned with every tube end. |
| Threaded Plugs & Soft Gaskets | Carbon Steel / Alloy Threaded Plugs with Soft Iron, Monel, or SS316 Gasket Rings | Provides a pressure-tight seal on inspection ports; designed for high-pressure cycling up to 35 MPa without weeping. |
| Side Frames & Spacer Saddles | Heavy Structural Steel C-Channels with Vibration-Damping Structural Supports | Supports the entire core weight, prevents long-span tube sag (up to 12m), and minimizes wind-induced vibration. |
Technical Highlights & Quality Assurance Protocols
Precision CNC Drilling & Serration: Tubesheet hole pattern tolerances are held to strict API 661 standards. Double serrated grooves cut into every heat exchanger tubesheet hole ensure high pull-out strength during hydraulic tube expansion.
Torque-Controlled Expansion: Automated expansion units bond the extended base tube ends to the inner tubesheet wall, creating pressure-tight joints rated for operating pressures exceeding 20 MPa.
Full-Penetration Header Welding: Header box longitudinal and circumferential seams undergo 100% Non-Destructive Examination (NDE), including Radiographic Testing (RT) and Ultrasonic Testing (UT).
Rigorous Factory Acceptance Testing (FAT): Every finned tube bundle assembly undergoes Hydrostatic Pressure Testing at 1.5x design pressure, Air-Under-Water Leak Testing for header plugs, and Positive Material Identification (PMI) on all wet components.
Engineering Guidelines: Thermal Core Selection & Maintenance
Calculating Air-Side Pressure Drop: Selecting fin density (e.g., 10 fins per inch vs. 11 fins per inch) directly impacts air-side pressure drop and fan power consumption. Higher fin density improves heat transfer area but requires careful fan static pressure calculation to prevent airflow starvation.
Preventing Galvanic Corrosion in Marine Environments: In coastal or offshore environments, salt spray can induce galvanic corrosion between aluminum fins and carbon steel base tubes. Specifying extruded fin tubes (Type KL) seals the underlying base tube from environmental exposure, preserving structural integrity.
Header Plug Maintenance & Torque Sequencing: When re-installing threaded shoulder plugs after cleaning, old soft-metal gaskets must be replaced. Plugs must be tightened in a cross-pattern torque sequence to standard API specifications to avoid galling header box threads.
Target Industries & Primary Applications
Oil & Gas Processing: Gas compression intercoolers/aftercoolers, natural gas liquid (NGL) fractionators, and offshore platform gas coolers.
Petroleum Refining: Crude Distillation Unit (CDU) overhead condensers, hydrotreater effluent coolers, and fluid catalytic cracking (FCC) slurry air coolers.
Petrochemical Plants: Ethylene glycol process coolers, condensate return coolers, and aromatic solvent cooling loops.
Power & Energy: Steam turbine surface condensers, turbine lube oil air coolers, and closed-loop cooling water heat exchangers.
Contact Yuhong Group Engineering Team
Contact our technical sales team for engineering quotes or custom specification requests regarding finned tube bundle modules, replacement tube bundle assemblies, complete shell and tube heat exchanger units, or precision heat exchanger tubesheet fabrications:
Company: Yuhong Group Co., Ltd.
Website: www.tema-heatexchanger.com
Direct Email: jimmy@steelseamlesspipe.com
Design Standards: API 661, ISO 13706, ASME Section VIII Div 1, TEMA Class R/B/C, PED 2014/68/EU
