Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Code: 350
Category: Literature Learning / Technical Reference
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product manufactured in continuous coil form, designed primarily for use in heat exchanger assemblies, fan coil units (FCU), and HVAC (Heating, Ventilation, and Air Conditioning) systems. As a critical component in thermal-fluid exchange applications, the coil tube delivers superior heat transfer efficiency, mechanical durability, and corrosion resistance under demanding operational environments.
This product specification draws upon advanced research findings, including numerical and experimental studies on flow field optimization of fan coil units, to ensure that the coil tube geometry and material selection align with best-in-class aerodynamic and thermodynamic performance. The coil tube is supplied in standardized coil configurations, enabling efficient downstream forming, cutting, and assembly operations.
2. Material & Properties
2.1 Material Grades
- Austenitic Stainless Steels: AISI 304 (UNS S30400), AISI 316 (UNS S31600), AISI 321 (UNS S32100)
- Alternative Grades: AISI 304L, AISI 316L, AISI 310S, AISI 410, AISI 430
- Custom Alloy Options: Available upon request for specialized corrosion or temperature resistance requirements
2.2 Mechanical Properties (Typical — AISI 304 Annealed)
| Property | Value | Unit |
|---|---|---|
| Tensile Strength (UTS) | ≥ 515 | MPa |
| Yield Strength (0.2% Offset) | ≥ 205 | MPa |
| Elongation at Break | ≥ 40 | % |
| Hardness (Brinell) | ≤ 201 | HB |
| Density | 7.93 | g/cm³ |
| Thermal Conductivity (at 100 °C) | 16.3 | W/(m·K) |
| Thermal Expansion Coefficient (20–100 °C) | 17.2 | × 10⁻⁶ /K |
2.3 Chemical Composition (AISI 304 — Typical)
| Element | C | Si | Mn | P | S | Cr | Ni | N |
|---|---|---|---|---|---|---|---|---|
| Specification (%) | ≤ 0.08 | ≤ 1.00 | ≤ 2.00 | ≤ 0.045 | ≤ 0.030 | 18.00–20.00 | 8.00–10.50 | ≤ 0.10 |
2.4 Key Material Advantages
- Exceptional Corrosion Resistance: The high chromium (Cr) and nickel (Ni) content forms a self-healing passive oxide film, providing outstanding resistance to atmospheric corrosion, water, and a wide range of chemical media.
- High Temperature Performance: Suitable for sustained operation at temperatures up to 870 °C (AISI 304) and 870 °C (AISI 316), with oxidation resistance maintained through proper alloying.
- Low Temperature Toughness: Retains excellent ductility and impact resistance down to cryogenic temperatures (−196 °C), making it ideal for refrigeration and cryogenic coil tube applications.
- Hygienic Surface Finish: Available in polished, electropolished, or passivated finishes suitable for food-grade and pharmaceutical applications.
3. Specifications
3.1 Dimensional Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 50.8 mm (1/8" – 2") | ASTM A213 / GB/T 12771 |
| Wall Thickness (WT) | 0.3 mm – 3.0 mm | ASTM A213 / GB/T 12771 |
| Coil Inner Diameter (ID) | 150 mm – 600 mm | Manufacturer Standard |
| Coil Length (Continuous) | Up to 5,000 m (custom lengths available) | — |
| OD Tolerance | ± 0.05 mm (precision grade) | ASTM A213 |
| Wall Thickness Tolerance | ± 10% of nominal | ASTM A213 |
| Straightness | ≤ 1.5 mm/m | ISO 1128 |
3.2 Surface Finish Options
| Finish Type | Roughness (Ra) | Application |
|---|---|---|
| Bright Annealed (BA) | 0.4 – 0.8 μm | General industrial, heat exchangers |
| Mirror Polished | 0.05 – 0.1 μm | Food processing, pharmaceutical |
| Electropolished | 0.03 – 0.1 μm | Sterile processing, biotech |
| Passivated | As polished | Enhanced corrosion resistance |
| Matte / Satin | 0.2 – 0.4 μm | Architectural, decorative |
3.3 Heat Exchanger / FCU-Specific Coil Tube Configurations
| Configuration | Description | Typical Application |
|---|---|---|
| Straight Coil Tube | Continuous coil of seamless or welded stainless steel tube | Plate & fin heat exchangers, FCU coils |
| U-Tube Configuration | Coil formed into U-bends for compact heat exchange | Shell & tube heat exchangers |
| Serpentine Coil | S-shaped continuous coil for maximum surface area | Air-to-water heat exchangers, FCU |
| Finned Coil Tube | Coil tube with mechanically bonded or brazed fins | HVAC coils, refrigeration condensers/evaporators |
4. Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing process to ensure dimensional accuracy, metallurgical integrity, and surface quality.
4.1 Process Flow
- Raw Material Selection: Premium-grade stainless steel strip or bar stock sourced from certified suppliers (e.g., POSCO, Outokumpu, Baowu) with full mill test certificates (MTC).
- Coil Slitting & Leveling: Full-width stainless steel coils are slit to the required strip width and leveled to eliminate residual stress and ensure flatness.
- Tube Forming & Welding: The leveled strip is formed into tube cross-sections via a roll-forming or rotary-drawing process. For welded tubes, the seam is joined using TIG (Tungsten Inert Gas) welding or laser welding under inert gas shielding (argon or helium) to prevent oxidation.
- Seam Grinding & Inspection: The weld seam is ground flush and inspected via eddy current testing (ECT) and visual examination (VT) to ensure weld integrity.
- Pipe Drawing & Sizing: Tubes are drawn through precision dies to achieve the final outer diameter and wall thickness tolerances.
- Heat Treatment (Annealing): Solution annealing is performed at 1050–1150 °C followed by rapid quenching to restore full austenitic structure, relieve residual stresses, and achieve maximum ductility. Bright annealing (BA) is conducted in a controlled atmosphere furnace (dew point ≤ −60 °C) to maintain a clean, oxide-free surface.
- Peeled & Coiled: The finished tube is peeling-coiled onto the required coil diameter using a hydraulic coiling head with controlled tension to prevent deformation or kinking.
- Surface Treatment: Optional passivation, pickling, or polishing treatments are applied per customer specification.
- Final Quality Control: Dimensional verification (OD, WT, straightness), chemical composition analysis (spectrometry), mechanical testing (tensile, hardness), and surface quality inspection.
- Packaging & Shipping: Coils are wrapped in protective film, sleeved, and packaged on wooden pallets or steel drums for secure transport.
4.2 Quality Control Milestones
- Incoming material inspection (chemical composition, mechanical properties)
- In-process dimensional monitoring at forming, welding, and drawing stages
- Non-Destructive Testing (NDT): Eddy current, ultrasonic testing (UT) for weld seam integrity
- Destructive Testing (DT): Tensile testing, impact testing (Charpy V-notch), and hardness testing on representative samples
- Final product audit with full traceability documentation
5. Applications
The stainless steel coil tube is a versatile product with applications spanning multiple industries. Its performance characteristics are particularly well-suited for thermal-fluid exchange systems, as validated by numerical and experimental research on flow field optimization in fan coil units.
5.1 HVAC & Refrigeration
- Fan Coil Units (FCU): The coil tube serves as the primary heat exchange element in FCU assemblies, transferring thermal energy between circulating fluid (water or refrigerant) and ambient air. Flow field optimization studies have demonstrated that properly designed coil tube geometries improve air distribution uniformity and reduce pressure drop by up to 15–25%.
- Chillers & Heat Pumps: Used in evaporator and condenser coils for commercial and industrial refrigeration systems.
- Air Handling Units (AHU): Coil tubes are integrated into cooling and heating coils within large-scale air handling systems.
5.2 Heat Exchanger Manufacturing
- Plate & Fin Heat Exchangers: Coil tubes are cut and formed into serpentine or U-bend configurations for compact, high-efficiency heat exchange.
- Shell & Tube Heat Exchangers: Seamless or welded coil tubes are used as tube bundles in process heat exchangers.
- Double-Pipe Heat Exchangers: Coil tubes of varying diameters are used for jacketed heat exchange applications.
5.3 Industrial & Process Applications
- Chemical Processing: Corrosion-resistant coil tubes for transporting aggressive chemical fluids in reactors, heat exchangers, and piping systems.
- Food & Beverage Industry: Hygienic-grade coil tubes for pasteurization, sterilization, and thermal processing equipment (e.g., UHT systems, CIP loops).
- Pharmaceutical & Biotechnology: Electropolished coil tubes for sterile fluid transfer, bioreactor cooling systems, and clean-in-place (CIP) applications.
- Petrochemical: High-temperature and high-pressure coil tubes for distillation columns, heat recovery systems, and process piping.
5.4 Other Applications
- Automotive: Coil tubes for exhaust heat exchangers, turbocharger cooling loops, and fuel cell thermal management.
- Solar Thermal: Coil tubes for evacuated tube solar collectors and flat plate solar water heating systems.
- Marine: Seawater-cooled heat exchanger coils for shipboard HVAC and propulsion cooling systems.
6. Quality Certifications & Compliance
| Certification / Standard | Description |
|---|