Stainless Steel Floating Coil Tube (Coil Tube) — Model No. 1308
Product Overview
The Stainless Steel Floating Coil Tube (also referred to as a helical coil heat transfer element or serpentine coil) is a precision-engineered tubular component designed primarily for use in floating coil heat exchangers (Floating Coil Type Heat Exchangers, FCHEs). Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this coil tube product represents a state-of-the-art solution for high-efficiency thermal exchange systems where compact design, corrosion resistance, and superior heat transfer performance are paramount.
Unlike conventional shell-and-tube heat exchangers, the floating coil tube design eliminates the need for tube sheets and allows the coil to be inserted and removed through a single port, significantly reducing maintenance downtime and facilitating easy cleaning of both the tube interior and the annular space. This product is particularly suited for applications involving viscous fluids, high-pressure differentials, and environments requiring strict hygienic or corrosion-resistant standards.
Material and Properties
The coil tube is fabricated from high-grade austenitic stainless steel, ensuring exceptional mechanical strength, thermal conductivity, and resistance to a wide range of corrosive media. The primary material grades include:
- SUS304 / AISI 304 (UNS S30400) — General-purpose austenitic stainless steel with excellent formability and corrosion resistance in oxidizing environments. Composition: 18–20% Cr, 8–10.5% Ni, ≤0.08% C.
- SUS316 / AISI 316 (UNS S31600) — Enhanced corrosion resistance due to 2–3% Mo addition, suitable for chloride-containing environments and chemical processing.
- SUS316L / AISI 316L (UNS S31603) — Low-carbon variant of 316, providing superior weldability and resistance to intergranular corrosion after welding operations.
- SUS321 / AISI 321 (UNS S32100) — Titanium-stabilized grade offering excellent resistance to intergranular corrosion at elevated temperatures (up to 870°C).
- SUS304L (UNS S30403) — Low-carbon version of 304 for improved weld zone corrosion resistance.
Key Material Properties (Typical for SUS304):
- Density: 8.0 g/cm³
- Thermal conductivity at 20°C: 16.3 W/(m·K)
- Thermal conductivity at 500°C: 21.5 W/(m·K)
- Specific heat capacity: 0.50 J/(g·K)
- Linear thermal expansion coefficient (20–100°C): 17.3 × 10⁻⁶ /K
- Young's modulus: 193 GPa
- Maximum service temperature: 870°C (continuous)
Specifications
| Parameter | Specification / Range |
|---|---|
| Product Model | 1308 (Coil Tube Series) |
| Tube Outer Diameter (OD) | Φ6 mm – Φ25 mm (customizable) |
| Tube Wall Thickness | 0.5 mm – 2.0 mm |
| Coil Pitch (Center-to-Center Distance) | 10 mm – 50 mm |
| Coil Height (Active Length) | 200 mm – 3,000 mm |
| Coil Outer Diameter | Φ50 mm – Φ500 mm |
| Number of Turns | 10 – 200+ turns |
| Surface Finish | No.4 Brushed / 2B / Polished (Ra ≤ 0.4 μm available) |
| Maximum Working Pressure | Up to 4.0 MPa (design-dependent) |
| Maximum Operating Temperature | −196°C to +450°C (grade-dependent) |
| Minimum Bend Radius | ≥ 3 × Tube OD (to prevent wrinkling) |
| End Connection Types | Butt Weld / Threaded / Flanged / Socket Weld |
| Standard Compliance | ASTM A213 / ASTM A269 / GB/T 12771 / EN 10216-5 |
| Customization | Available upon request (dimensions, material, finish) |
Manufacturing Process
The production of high-precision floating coil tubes involves a multi-stage manufacturing sequence designed to ensure dimensional accuracy, mechanical integrity, and surface quality:
- Raw Material Selection and Verification — Certified stainless steel seamless tubes or welded tubes are selected based on the target grade and specification. Incoming material undergoes 100% chemical composition analysis (via Optical Emission Spectroscopy, OES) and mechanical property verification.
- Cut-to-Length Preparation — Tubes are precisely cut to the required developed length using cold-saw or plasma cutting equipment, with end faces ground flush to ensure proper welding compatibility.
- Coil Forming (Helical Bending) — A CNC-controlled helical coiling machine wraps the straight tube into the specified spiral geometry. The process parameters — including coil pitch, outer diameter, and number of turns — are controlled to within ±0.5 mm tolerance. The bending process is performed at room temperature to preserve the metallurgical properties of the austenitic stainless steel.
- Welding of Coil Ends — The inlet and outlet tube ends are welded to header plates or connection fittings using TIG (Tungsten Inert Gas) welding or orbital welding techniques. Internal purge gas (Argon, Ar) is employed during welding to prevent oxidation of the weld zone.
- Heat Treatment (if required) — Solution annealing at 1050–1100°C followed by rapid water quenching may be applied to restore full austenitic structure and maximize corrosion resistance, particularly for welded assemblies.
- Surface Finishing — The coil surface is finished to the specified grade via mechanical polishing, electrolytic polishing, or passivation treatment (using nitric acid or citric acid solutions) to remove surface contaminants and enhance the passive chromium oxide layer.
- Pressure Testing and Inspection — Each finished coil tube assembly undergoes 100% pneumatic or hydraulic pressure testing at 1.5× the maximum working pressure to verify leak-tightness. Dimensional inspection is performed using calibrated measuring instruments.
Applications
The floating coil tube heat exchanger technology, utilizing the Model 1308 coil tube, finds extensive application across multiple industrial sectors:
- Food and Beverage Industry — Milk pasteurization, juice processing, beer brewing, and dairy product heating/cooling. The hygienic surface finish and ease of CIP (Clean-In-Place) and SIP (Sterilize-In-Place) make this design ideal for FDA/3-A compliant processing.
- Pharmaceutical Manufacturing — Process fluid heating and cooling where GMP (Good Manufacturing Practice) compliance and sanitary design are mandatory.
- Chemical Processing — Handling of corrosive fluids, acids, and solvents where the superior corrosion resistance of SUS316L provides long service life.
- Petrochemical and Oil Refining — Preheating of viscous crude oils, product cooling, and heat recovery systems where high heat flux and fouling resistance are critical.
- Power Generation — Condenser applications, feedwater preheating, and waste heat recovery systems.
- HVAC and Refrigeration — Chilled water distribution, heat pump systems, and industrial cooling circuits.
- Textile and Paper Industries — Dye liquor heating, pulp processing, and thermal recovery in continuous production lines.
Quality Certifications and Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and product certifications to assure customers of consistent product quality:
- ISO 9001:2015 — Quality Management System certification ensuring systematic quality control throughout the manufacturing process.
- ISO 14001 — Environmental Management System certification.
- ISO 45001 — Occupational Health and Safety Management System.
- CE Marking (EU) — Compliance with European directives for pressure equipment and mechanical safety.
- ASME Stamp (U Stamp) — For pressure vessel components where applicable.
- Third-Party Inspection — Available upon request through SGS, TÜV, or Bureau Veritas for critical applications.
- MTR (Material Test Report) — Provided with each shipment, documenting chemical composition, mechanical properties, and traceability to mill heat numbers.
- NDT (Non-Destructive Testing) — Hydrostatic testing, eddy current testing, and visual inspection performed on all coil assemblies.
Unique Selling Points
1. Superior Heat Transfer Efficiency: The helical coil geometry promotes turbulent flow even at low Reynolds numbers (Re > 2,300), achieving heat transfer coefficients 2–4× higher than straight tube designs. The high surface-area-to-volume ratio maximizes thermal exchange within a compact footprint.
2. Easy Maintenance and Cleaning: The floating coil design allows complete withdrawal of the coil through a single access port without disassembling the shell. This eliminates the need for tube-side rodding and significantly reduces maintenance costs and downtime.
3. Fouling Resistance: The inherent turbulence generated by the helical geometry provides self-cleaning action, minimizing fouling buildup and extending cleaning intervals compared to conventional heat exchangers.
4. Pressure Independence: Unlike plate heat exchangers, floating coil heat exchangers are not limited by gasket materials, enabling operation at higher pressures and wider temperature differentials between the two process streams.
5. Versatile Material Selection: Full range of stainless steel grades available, including duplex stainless steels and nickel alloys for extreme corrosion environments, without compromising the coil forming process.
6. Custom Engineering: All dimensions — coil diameter, pitch, tube OD, wall thickness, and number of turns — are customizable to meet specific thermal duty requirements, ensuring optimal performance for each application.
Conclusion
The Model 1308 Stainless Steel Floating Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. represents a premium-grade thermal exchange component that combines engineering excellence with manufacturing precision. Its application in floating coil heat exchangers delivers unmatched thermal performance, operational flexibility, and lifecycle cost advantages across a broad spectrum of industrial applications. The company's commitment to quality, supported by international certifications and advanced manufacturing capabilities, positions this product as a reliable solution for demanding thermal management challenges.