Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. (温州吉兴金属材料有限公司)
Product Catalog No.: 854
Classification: Literature-Based Technical Reference — Coil Tube Engineering Applications
1. Product Overview
The Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") is a precision-formed tubular product manufactured from austenitic or duplex stainless steel wire or strip. Unlike straight seamless or welded tubes, the Coiltube is produced in a continuous spiral-wound or helical-coiled configuration, offering superior flexibility, compact storage, and efficient heat transfer characteristics. This product line is engineered for demanding applications in HVAC (Heating, Ventilation, and Air Conditioning), air purification systems, heat exchangers, and chemical processing where corrosion resistance, mechanical integrity, and long-term reliability are paramount.
Wenzhou Jixing Metal Materials Co., Ltd. specializes in the manufacturing of high-grade stainless steel coil tubes that meet or exceed international standards including ASTM (American Society for Testing and Materials), EN (European Norms), and JIS (Japanese Industrial Standards). The Coiltube product is distinguished by its uniform wall thickness, excellent surface finish, and dimensional accuracy achieved through advanced cold-forming and precision winding technologies.
2. Material Composition & Mechanical Properties
2.1 Commonly Available Grades
- 304 (UNS S30400): The most widely used austenitic stainless steel grade, offering excellent general corrosion resistance, formability, and weldability. Suitable for food-grade, pharmaceutical, and general industrial applications.
- 316 (UNS S31600): Enhanced corrosion resistance due to 2–3% molybdenum (Mo) content, providing superior performance in chlorinated environments, marine applications, and chemical processing.
- 316L (UNS S31603): Low-carbon variant of 316, minimizing sensitization risk during welding. Preferred for high-purity and medical applications.
- 321 (UNS S32100): Titanium-stabilized grade offering excellent resistance to intergranular corrosion at elevated temperatures (up to 870°C / 1600°F).
- 304L (UNS S30403): Low-carbon version of 304, ideal for heavy welding applications requiring post-weld corrosion resistance.
- 904L (UNS N08904): High-alloy austenitic grade with exceptional resistance to non-oxidizing acids, including sulfuric acid and mixed acid environments.
2.2 Typical Mechanical Properties (Annealed Condition)
| Property | 304 / 304L | 316 / 316L | 321 |
|---|---|---|---|
| Tensile Strength (UTS) — MPa | ≥ 515 | ≥ 515 | ≥ 515 |
| Yield Strength (0.2% offset) — MPa | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (A₅₀) — % | ≥ 40 | ≥ 40 | ≥ 40 |
| Density — g/cm³ | 7.93 | 8.00 | 7.93 |
| Thermal Conductivity (20°C) — W/(m·K) | 16.3 | 14.6 | 16.3 |
| Maximum Service Temperature — °C | 870 | 870 | 900 |
2.3 Chemical Composition (Typical, wt%)
| Element | 304 | 316 | 321 |
|---|---|---|---|
| Carbon (C) | ≤ 0.08 | ≤ 0.08 | ≤ 0.08 |
| Chromium (Cr) | 18.0–20.0 | 16.0–18.0 | 17.0–19.0 |
| Nickel (Ni) | 8.0–10.5 | 10.0–14.0 | 9.0–12.0 |
| Molybdenum (Mo) | — | 2.0–3.0 | — |
| Titanium (Ti) | — | — | 5×(C−0.02) to 0.70 |
| Sulfur (S) | ≤ 0.03 | ≤ 0.03 | ≤ 0.03 |
| Phosphorus (P) | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 |
3. Product Specifications
3.1 Dimensional Parameters
| Parameter | Range / Value | Tolerance |
|---|---|---|
| Outer Diameter (OD) — mm | 3.0 – 50.8 | ±0.10 mm |
| Wall Thickness (WT) — mm | 0.30 – 3.00 | ±10% |
| Coil Length per Spool — m | 5 – 200 (customizable) | ±1% |
| Winding Diameter — mm | 100 – 600 | ±2% |
| Straight Length (if applicable) — mm | 500 – 6000 | ±3 mm |
| End Form | Plain, Beveled, Threaded, Flanged | Per drawing |
3.2 Surface Finish Options
- BA (Bright Annealed): Mirror-like finish with Ra ≤ 0.4 μm; ideal for food processing and pharmaceutical applications.
- No. 4 Brushed: Unidirectional matte finish with Ra 0.4–0.8 μm; suitable for architectural and general industrial use.
- 2B Cold Rolled: Standard industrial finish with Ra 0.6–1.6 μm.
- Electropolished: Ultra-smooth surface with Ra ≤ 0.2 μm; used in semiconductor and biotechnology applications.
- Pickled & Passivated: Chemically cleaned and passivated to enhance corrosion resistance.
3.3 Applicable Standards
- ASTM A269 / A269M: Seamless, Austenitic Stainless Steel Tubing for Chemical and Similar Severe Service Applications
- ASTM A312 / A312M: Seamless and Welded Austenitic Stainless Steel Tubes for High-Pressure and High-Temperature Boilers
- ASTM B730: Seamless and Welded Ferritic and Austenitic Stainless Steel Tubes for Chemical Process Plant and Heat Exchanger Service
- EN 10216-5: Heat Exchangers and Radiators — Stainless Steel Tubes
- GB/T 12771: Chinese National Standard for Stainless Steel Seamless Tubes for Fluid Transport
- GB/T 14976: Chinese National Standard for Cold-Drawn Stainless Steel Tubes for Fluid Transport
4. Manufacturing Process
4.1 Process Flowchart
- Raw Material Inspection: Incoming stainless steel wire or strip undergoes spectroscopic analysis (OES — Optical Emission Spectroscopy) to verify chemical composition compliance.
- Cold Drawing / Cold Forming: The raw material is cold-drawn or cold-formed through precision dies to achieve the target outer diameter and wall thickness with tight dimensional tolerances.
- Intermediate Annealing: Periodic annealing at 1050–1150°C followed by controlled cooling relieves accumulated cold-work stresses and restores ductility.
- Precision Winding / Coiling: The formed tube is wound onto a precision-driven coil former at controlled tension to produce uniform spiral or helical coil geometry. Automated tension control systems ensure consistent coil pitch and winding diameter.
- Final Annealing & Passivation: The coiled product undergoes final solution annealing and acid pickling (typically using nitric-hydrofluoric acid mixture or citric acid) followed by passivation to remove scale and form a protective chromium oxide layer.
- Non-Destructive Testing (NDT): 100% electromagnetic testing (ET) and/or eddy current inspection to detect surface and near-surface defects. Hydrostatic pressure testing at 2–3× working pressure to verify weld integrity for welded tubes.
- Final Dimensional Inspection: Coordinate Measuring Machine (CMM) and optical gauging to verify OD, wall thickness, straightness, and coil geometry.
- Packaging & Dispatch: Products are packaged in moisture-proof wrapping with protective end caps, palletized, and labeled with full traceability documentation.
4.2 Key Manufacturing Technologies
- Computer Numerical Control (CNC) Winding: Ensures repeatable coil geometry with pitch accuracy of ±0.5 mm.
- Continuous Annealing Furnace: Enables uniform heat treatment across the entire coil length without localized overheating.
- In-Line Eddy Current Inspection: Real-time defect detection at production speeds up to 60 m/min.
- Custom Bending & Forming: Capabilities for U-bends, hairpin bends, and custom coil configurations tailored to specific heat exchanger designs.
5. Applications
5.1 HVAC & Air Purification Systems
Stainless steel coil tubes serve as the core heat transfer elements in Fan Coil Units (FCUs), air handling units, and air purification systems. Research on formaldehyde (HCHO) purification using fan coil tube configurations has demonstrated that the large surface-area-to-volume ratio of coiled stainless steel tubing enhances contact time between air and catalytic or adsorbent media, improving pollutant removal efficiency. The corrosion-resistant properties of 316L-grade coil tubes ensure long-term performance stability in humid indoor environments where conventional carbon steel components would degrade.
5.2 Heat Exchangers
- Shell-and-tube heat exchangers for chemical processing
- Plate-fin heat exchangers for cryogenic applications
- Air-cooled heat exchangers for power generation
- Refrigeration evaporators and condensers
5.3 Food & Pharmaceutical Industry
- Pasteurization and sterilization equipment heat exchangers
- Wash-in-place (WIP) and Clean-in-place (CIP) systems
- Beverage processing and dairy equipment
- Pharmaceutical fluid transfer and purification systems
5.4 Marine & Offshore
- Seawater cooling systems and heat exchangers
- Ballast water treatment systems
- Desalination plant heat recovery units
5.5 Chemical & Petrochemical Processing
- Reactor coil heating/cooling elements
- Process fluid heat exchange in corrosive environments
- Distillation column internals
5.6 Medical & Biotechnology
- Medical gas delivery systems
- Bioreactor temperature control coils
- Hospital HVAC filtration and purification
6. Quality Certifications & Compliance
6.1 Factory & Management Certifications
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health and Safety Management System
- ISO/TS 22163 — Technical Specification for Automotive Production Parts (where applicable)
6.2 Product & Industry Certifications
- NSF/ANSI 61 — Drinking Water System Components (where applicable)
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