Stainless Steel Coil Tube — Low-Temperature Wind-Cooled Chilled Water Circulation System (Segmented Control)
Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered continuous-length tubing product manufactured by Wenzhou Jixing Metal Materials Co., Ltd., specifically designed for integration into low-temperature wind-cooled chilled water circulation systems. This product represents an advanced solution for segmented thermal management, enabling efficient heat exchange under extreme ambient conditions. The coil tube is formed through continuous cold-drawing and coiling processes, resulting in a uniform, defect-free profile suitable for demanding industrial and commercial refrigeration applications.
Unlike conventional straight-length piping solutions, the coiled configuration maximizes heat transfer surface area within a compact footprint, making it ideal for outdoor air-source heat pump systems, cold storage facilities, and process cooling applications where space efficiency and thermal performance are critical. The segmented control architecture allows independent modulation of individual coil sections, optimizing energy consumption and maintaining precise temperature regulation across varying load conditions.
Material & Properties
Base Material Composition
The coil tube is fabricated from high-grade austenitic stainless steel, primarily conforming to the following standard grades:
- AISI 304 (UNS S30408) — General-purpose grade offering excellent corrosion resistance in most atmospheric and industrial environments.
- AISI 316 (UNS S31608) — Enhanced grade with molybdenum addition for superior resistance to chlorides, acids, and marine atmospheres.
- AISI 321 (UNS S32108) — Stabilized grade suitable for elevated-temperature service and thermal cycling applications.
Key Material Properties
- Corrosion Resistance: Exceptional resistance to pitting, crevice corrosion, and intergranular corrosion due to the high chromium (18–20%) and nickel (8–12%) composition.
- Temperature Tolerance: Operational range from −196 °C (liquid nitrogen service) to +870 °C (intermittent), accommodating deep cooling cycles without embrittlement.
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20 °C, providing reliable heat transfer performance in chilled water circuits.
- Non-Magnetic Properties: Austenitic microstructure ensures non-magnetic behavior after cold working, critical for certain instrumentation environments.
- Hygienic Surface: Ra ≤ 0.5 μm surface finish available upon request, meeting sanitary standards for food and pharmaceutical applications.
Specifications
| Parameter | Specification |
|---|---|
| Product Type | Continuous Coil Tube (Coiltube) |
| Material Grade | AISI 304 / 316 / 321 (Custom grades available) |
| Outer Diameter (OD) | 6.0 mm – 32.0 mm (customizable) |
| Wall Thickness | 0.5 mm – 3.0 mm |
| Coil Diameter | Standard: 500 mm / 600 mm / 800 mm / 1000 mm |
| Coil Length | Up to 2000 m per coil (continuous production) |
| Operating Temperature | −60 °C to +150 °C (continuous); up to −196 °C (short-term) |
| Operating Pressure | Up to 2.5 MPa (design dependent on OD and wall thickness) |
| Surface Finish | 2B / No.1 / Electropolished (Ra ≤ 0.5 μm) / Brushed |
| Tolerance (OD) | ±0.05 mm (precision grade); ±0.1 mm (standard grade) |
| Tolerance (Wall Thickness) | ±0.03 mm (precision grade); ±0.05 mm (standard grade) |
| Applicable Standards | ASTM A269 / ASTM A270 / EN 10217 / GB/T 12771 |
| End Treatment | Plain cut / Beveled / Threaded / Flanged (upon request) |
| Packaging | Wooden reel / Steel drum with moisture-proof wrapping |
Manufacturing Process
1. Raw Material Selection and Incoming Inspection
Hot-rolled stainless steel strip is sourced from certified mills and subjected to rigorous incoming inspection, including spectroscopic chemical analysis (OES), mechanical property verification, and dimensional measurement. Material traceability is maintained through heat number tracking throughout the entire production chain.
2. Cold Drawing (Continuous)
The strip is fed through a multi-pass cold-drawing line, reducing the cross-sectional dimensions to the target OD and wall thickness. This process enhances mechanical strength (tensile strength typically 520–750 MPa) and achieves precise dimensional tolerances. Lubrication is applied to ensure uniform deformation and prevent surface defects.
3. Annealing and Pickling
The cold-worked tube is annealed in a protective atmosphere (nitrogen or vacuum) at temperatures between 1050 °C and 1150 °C to relieve residual stresses, restore full austenitic ductility, and eliminate work-hardening effects. Subsequent pickling in a mixed acid bath removes surface oxides, followed by passivation to establish a stable chromium oxide protective film.
4. Precision Coiling
The finished tube is coiled onto precision mandrels at controlled tension, ensuring uniform curvature without kinking, flattening, or ovality. The coiling process is computer-controlled to maintain consistent coil diameter and pitch. Each coil is inspected for dimensional accuracy and surface quality before packaging.
5. Final Quality Assurance
Every coil undergoes comprehensive testing including:
- Hydrostatic pressure testing (100% inspection) to verify wall integrity.
- Eddy current (ET) or ultrasonic (UT) flaw detection for internal and external defects.
- Dimensional verification of OD, wall thickness, and coil geometry.
- Surface quality assessment under standardized lighting conditions.
- Chemical composition re-verification via portable XRF or laboratory OES.
Applications
Primary Applications
- Low-Temperature Wind-Cooled Chilled Water Circulation: The coil tube serves as the primary heat exchange element in segmented-control systems, where individual coil sections are independently regulated to match varying cooling loads. This architecture achieves COP (Coefficient of Performance) improvements of 15–30% compared to single-zone systems.
- Air-Source Heat Pump Units: Evaporator and condenser coils in commercial and industrial heat pump systems operating in climates ranging from −30 °C to +50 °C.
- Cold Storage and Refrigeration: Heat exchangers in warehouse refrigeration, freezer units, and cold chain logistics equipment.
- Process Cooling: Industrial process water cooling loops in semiconductor manufacturing, chemical processing, and pharmaceutical production facilities.
Secondary Applications
- Automotive radiator and intercooler tubing.
- Medical and laboratory equipment requiring corrosion-resistant fluid handling.
- Food and beverage processing systems (dairy, beverage, brewing).
- Solar thermal collector loop piping.
- Fuel cell and hydrogen energy system heat management.
Quality Certifications and Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring product conformity to international standards:
- ISO 9001:2015 — Quality Management System certification covering design, manufacturing, and delivery.
- ISO 14001:2015 — Environmental Management System certification demonstrating sustainable manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management System.
- CE Marking — Compliance with European directives for pressure equipment and machinery safety.
- EN 10204 Type 3.1 — Third-party inspection certificates available for material and product verification.
- NADCAP — Special process certification (available for aerospace-grade tubing upon request).
All production batches are accompanied by a full quality documentation package including mill test certificates (MTC), dimensional inspection reports, pressure test records, and material traceability data, ensuring complete supply chain transparency.
Unique Selling Points
The segmented control architecture of this coil tube system represents a paradigm shift in thermal management efficiency. By enabling independent modulation of discrete coil sections, the system dynamically adapts to real-time load variations, significantly reducing energy waste during partial-load operation — the most common operating condition in commercial applications. Combined with the inherent corrosion resistance and long service life of austenitic stainless steel, this solution delivers a total cost of ownership (TCO) advantage over carbon steel alternatives by a factor of 3–5x over a 15-year operational horizon.
- Continuous Coiled Delivery: Eliminates field welding joints, reducing leak risk and installation labor by up to 40%.
- Ultra-Low Temperature Capability: Maintains full mechanical integrity at temperatures as low as −60 °C continuous, enabling reliable operation in harsh northern climates without supplemental heating of the coil structure.
- Customizable Geometry: Coil diameter, pitch, OD, and wall thickness can be tailored to specific system design requirements through the company's flexible manufacturing platform.
- Hygienic and Food-Safe: Available in electropolished finish meeting FDA and 3-A Sanitary Standards for direct food-contact applications.
- Full Traceability: Each coil is assigned a unique batch identifier linked to raw material heat numbers, processing parameters, and inspection data.
Technical Support and Customization
Wenzhou Jixing Metal Materials Co., Ltd. offers comprehensive engineering support including thermal performance simulation, system integration consultation, and custom specification development. Technical data sheets, 3D CAD models, and sample coils are available upon request to facilitate system design and procurement decisions.