Stainless Steel Coil Tube — Precision Engineered for HVAC and Industrial Applications
Product Overview
The Stainless Steel Coil Tube (SSCT) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. represents a high-performance tubular product engineered through cold-drawn and coiling processes to deliver superior dimensional accuracy, mechanical strength, and corrosion resistance. This product is specifically designed for applications in Fan Coil Units (FCUs), heat exchangers, refrigeration systems, and industrial fluid transport, where reliable thermal transfer and long-term durability are critical.
Building upon the research findings presented in the study "Research and Application of Adaptive Energy-Saving Control Strategy for Fan Coil Units", the SSCT product line is optimized to support adaptive control architectures that dynamically regulate airflow and thermal output. The tube's consistent wall thickness and low thermal resistance characteristics enable precise modulation of heat exchange efficiency, directly contributing to energy savings of 15%–30% in HVAC (Heating, Ventilation, and Air Conditioning) systems when integrated with intelligent control algorithms.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, conforming to internationally recognized metallurgical standards. The following material grades are available depending on application requirements:
- SUS304 / AISI 304 (UNS S30400) — General-purpose corrosion resistance; ideal for HVAC and domestic water systems.
- SUS316 / AISI 316 (UNS S31600) — Enhanced chloride resistance; recommended for coastal and chemical environments.
- SUS316L (UNS S31603) — Low-carbon variant for welding-intensive applications requiring reduced intergranular corrosion risk.
- SUS321 (UNS S32100) — Titanium-stabilized grade for high-temperature service up to 870°C.
Key mechanical and physical properties include:
- Tensile Strength (UTS): 520–720 MPa
- Yield Strength (0.2% Proof Stress): ≥ 205 MPa
- Elongation at Break: ≥ 40%
- Thermal Conductivity (25°C): 14.5–16.5 W/(m·K)
- Corrosion Resistance: Passivation via chromium oxide layer (Cr ≥ 18%); pitting resistance equivalent number (PREN) ≥ 19 for 316 series
- Operating Temperature Range: −196°C to +870°C
Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | Φ 3.0 mm – Φ 12.7 mm | ASTM A269 / GB/T 14976 |
| Wall Thickness | 0.3 mm – 1.2 mm | ISO 13978 |
| Coil Diameter | Φ 150 mm – Φ 600 mm | Manufacturer Specification |
| Coil Length | 50 m – 500 m (customizable) | — |
| Diameter Tolerance | ±0.05 mm | ASTM A269 |
| Wall Thickness Tolerance | ±10% | ISO 13978 |
| Surface Finish | Bright Annealed (BA) / No.4 Brushed / Mirror Polish (Ra ≤ 0.2 μm) | ASTM A473 |
| End Condition | Plain / Beveled / Crimped | Customer-Specified |
| Heat Treatment | Solution Annealed at 1050°C – 1100°C, followed by water quench | ASTM A240 |
| Winding Direction | Clockwise (CW) / Counter-Clockwise (CCW) | Application-Specific |
Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous multi-stage manufacturing protocol designed to ensure metallurgical integrity and dimensional precision:
- Raw Material Procurement: Hot-rolled stainless steel strips are sourced from certified mills and subjected to incoming inspection for chemical composition (via Optical Emission Spectrometry, OES) and mechanical properties.
- Slitting and Leveling: The strip is slit to the required width and cold-rolled to achieve the target wall thickness with tight tolerance control.
- Forming and Welding: The leveled strip is formed into a tubular shape via roll-forming dies and seam-welded using Transverse Pulse TIG (Tungsten Inert Gas) welding or laser welding technology to produce a continuous, leak-free seam.
- Heat Treatment (Solution Annealing): The welded tube undergoes solution annealing at 1050°C–1100°C in a protective atmosphere furnace (nitrogen or argon), followed by rapid water quenching. This process dissolves carbide precipitates, restores full austenitic structure, and eliminates residual welding stresses.
- Pickling and Passivation: The annealed tube is immersed in a mixed acid bath (nitric acid + hydrofluoric acid) to remove scale and oxide deposits, followed by passivation treatment to re-establish the protective chromium oxide film.
- Precision Drawing: The tube passes through calibrated drawing dies to achieve final dimensional tolerances (±0.05 mm OD) and surface finish requirements.
- Coiling: The finished tube is wound onto precision steel coils using a controlled tension winding system to prevent kinking, deformation, or inter-coil contact damage.
- Quality Inspection and Packaging: Each coil undergoes 100% visual inspection, dimensional verification, and pressure testing. Samples are subjected to hydrostatic testing (at 2.5× working pressure) and, where required, eddy current testing for seam integrity.
Applications
HVAC Systems and Fan Coil Units (FCUs)
The primary application domain for this coil tube is in the construction of heat exchangers within Fan Coil Units. Research on adaptive energy-saving control strategies for FCUs has demonstrated that coil tubes with uniform wall thickness and high thermal conductivity enable more accurate temperature sensing and responsive modulation of cooling/heating capacity. When integrated with adaptive algorithms that adjust fan speed and valve position based on real-time thermal load, the system achieves significant energy reduction while maintaining occupant comfort.
Additional Application Domains
- Refrigeration and Air Conditioning: Condenser and evaporator coils for commercial and industrial refrigeration systems.
- Medical Equipment: Sterilizable tubing for medical gas delivery and dialysis machines (SUS316L grade).
- Food and Beverage Processing: Sanitary-grade tubing for CIP (Clean-in-Place) systems and dairy processing lines.
- Chemical Processing: Corrosion-resistant tubing for chemical dosing, mixing, and transfer systems.
- Automotive Industry: Fuel lines, brake lines, and HVAC components for passenger and commercial vehicles.
- Construction and Architecture: Structural tubing for decorative railings, handrails, and architectural features.
- Water Treatment: Ultrafiltration membrane housings and RO (Reverse Osmosis) system tubing.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring product conformance to international standards:
- ISO 9001:2015 — Quality Management System certification covering all manufacturing and supply chain processes.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management System.
- CE Marking (EU) — Conformity with European directives for pressure equipment and construction products.
- EN 10204 3.1 — Full third-party inspection certificates provided upon request, including chemical analysis, mechanical test reports, and dimensional verification.
- Mill Test Certificates (MTC) — Issued in accordance with EN 10204 / ASTM standards for each production lot.
- NSF/ANSI 61 — Available for potable water contact applications (SUS304 and SUS316 grades).
- 3-A Sanitary Standards — Compliant for food and pharmaceutical industry applications.
Unique Selling Points
The SSCT product line from Wenzhou Jixing Metal Materials Co., Ltd. distinguishes itself through the following competitive advantages:
- Adaptive Energy-Efficiency Compatibility: The tube's precise dimensional tolerances and uniform thermal properties make it inherently compatible with adaptive control strategies for Fan Coil Units, enabling real-time energy optimization without hardware modification.
- Superior Dimensional Consistency: Cold-drawing processes achieve OD tolerances of ±0.05 mm, ensuring seamless integration into automated heat exchanger manufacturing lines and minimizing assembly waste.
- Extended Service Life: Solution-annealed austenitic microstructure provides fatigue resistance exceeding 10⁷ cycles, translating to a design life of 20+ years in HVAC applications.
- Customization Flexibility: Full customization of coil diameter, tube dimensions, surface finish, and end conditions to meet specific OEM (Original Equipment Manufacturer) requirements.
- Traceability and Documentation: Complete batch traceability from raw material mill certificate through final inspection, supporting compliance audits and warranty claims.
Conclusion
The Stainless Steel Coil Tube product from Wenzhou Jixing Metal Materials Co., Ltd. represents the convergence of precision metallurgy, advanced manufacturing, and intelligent systems integration. By delivering a substrate material that supports adaptive energy-saving control architectures in Fan Coil Units and other thermal management systems, this product contributes to the broader goals of energy efficiency, sustainability, and operational excellence in modern HVAC and industrial applications.