Stainless Steel Coil Tube (Coiltube) — Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") is a precision-engineered continuous-loop stainless steel tubing product supplied by Wenzhou Jixing Metal Materials Co., Ltd. This product is designed for integration into ventilation, HVAC (Heating, Ventilation, and Air Conditioning), and mechanical engineering systems where flexible routing, thermal resistance, and long-term structural integrity are critical. The Coiltube is manufactured in a continuous coiled configuration, enabling efficient deployment in applications such as flexible hose assemblies, soft joint connections, fan coil unit (FCU) air duct interfaces, and supply air grille linkages within industrial ventilation installations.
Unlike conventional straight-length tubing, the coil configuration of this product offers superior installation flexibility, reduced labor time, and minimized material waste. The inherent spring-back characteristics of the coiled geometry allow the tube to be easily routed around obstacles and secured in complex geometries without the need for additional bending or forming operations on-site.
2. Material Composition and Properties
The Coiltube is fabricated from high-grade austenitic stainless steel, selected to deliver optimal combinations of corrosion resistance, mechanical strength, and thermal stability. The primary material grades utilized conform to international standards and include:
- Grade 304 (UNS S30408): The standard austenitic stainless steel grade offering excellent general-purpose corrosion resistance, suitable for most ambient and moderately aggressive environments.
- Grade 316 (UNS S31608): Enhanced with molybdenum (Mo) content of 2.0–3.0%, providing superior resistance to chlorides, acids, and marine atmospheric conditions.
- Grade 321 (UNS S32108): Stabilized with titanium (Ti) to resist intergranular corrosion at elevated temperatures (up to 870°C), making it suitable for high-temperature ventilation and exhaust applications.
Key material properties of the Coiltube are summarized as follows:
- Corrosion Resistance: Exceptional resistance to oxidation, rust formation, and chemical attack across a wide pH range.
- Mechanical Strength: High tensile strength and yield strength ensuring dimensional stability under pressure differentials and mechanical loads.
- Thermal Stability: Maintains structural integrity from cryogenic temperatures (down to −196°C) to elevated service temperatures (up to 870°C for Grade 321).
- Hygienic Surface: Low surface roughness (Ra ≤ 0.4 μm for polished finish) facilitating ease of cleaning and compliance with sanitary standards.
- Magnetic Properties: Essentially non-magnetic in the annealed condition, critical for applications involving electromagnetic interference (EMI) sensitivity.
- Weldability: Excellent weldability with standard TIG (Tungsten Inert Gas) and orbital welding methods, enabling on-site fabrication and modification.
3. Technical Specifications
| Parameter | Specification / Range |
|---|---|
| Product Designation | Stainless Steel Coil Tube (Coiltube) |
| Material Grade | SUS304 / SUS316 / SUS321 (per customer requirement) |
| Outer Diameter (OD) | φ3.0 mm – φ108.0 mm (customizable) |
| Wall Thickness | 0.3 mm – 3.0 mm (tolerance ±10%) |
| Coil Length (per coil) | 5 m – 50 m (standard); up to 100 m upon request |
| Surface Finish | Mirror polish (Ra ≤ 0.4 μm), electropolished, or 2B mill finish |
| Standard Reference | ASTM A213, ASTM A269, EN 10216-5, GB/T 14976 |
| Operating Temperature | −196°C to +870°C (grade-dependent) |
| Maximum Working Pressure | Dependent on OD, wall thickness, and grade; up to 16 bar for standard configurations |
| Minimum Bending Radius | ≥ 3 × OD (cold bending without cracking or collapse) |
| Packaging | Coiled on wooden spools or plastic-wrapped; palletized for bulk shipment |
4. Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous multi-stage manufacturing process designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: High-purity stainless steel strip or seamless tube blank material is sourced from certified mills and subjected to incoming chemical composition analysis (via Optical Emission Spectroscopy, OES) and mechanical property verification.
- Coil Winding / Forming: The tube is precisely wound into a continuous coil using CNC-controlled coil winding equipment. The winding process maintains uniform curvature and prevents surface scratches or deformation.
- Heat Treatment (Annealing): Where required, the coiled tube undergoes solution annealing at temperatures of 1050–1150°C followed by controlled cooling to restore full austenitic structure and relieve residual stresses introduced during forming.
- Surface Finishing: The tube surface is processed through mechanical polishing, chemical pickling, or electropolishing to achieve the specified surface finish (mirror, satin, or mill finish). Electropolishing removes micro-contaminants and enhances passive film formation.
- Quality Inspection: Each coil undergoes dimensional verification (OD, wall thickness via ultrasonic testing, UT), surface defect inspection (eddy current testing, ECT), hydrostatic pressure testing, and visual examination for surface imperfections.
- Packaging and Labeling: Inspected coils are protected with moisture-absorbent packaging, labeled with material certificates (Mill Test Certificate, MTC), and secured on wooden spools or pallets for export-ready shipping.
5. Applications
The Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. is engineered for a diverse range of industrial and commercial applications:
- Ventilation and HVAC Systems: Primary application domain. The Coiltube serves as a structural component in flexible hose assemblies, soft joints connecting fan coil units (FCU) to supply air grilles, and air distribution ductwork within commercial and industrial ventilation installations. Its flexibility and corrosion resistance make it ideal for damp or chemically aggressive ventilation environments.
- Industrial Exhaust Systems: Utilized in high-temperature exhaust routing for manufacturing facilities, laboratories, and process plants where thermal cycling and corrosive gas exposure are present.
- Food and Pharmaceutical Processing: Hygienic-grade Coiltube (electropolished, Grade 316L) is employed in CIP (Clean-in-Place) systems, steam piping, and sanitary air supply lines where product purity and ease of sanitization are paramount.
- Chemical Processing: Grade 316 Coiltube is deployed in chemical transfer lines, reactor vent systems, and scrubber installations requiring resistance to chlorides, sulfuric acids, and caustic solutions.
- Automotive and Aerospace: Precision Coiltube is used in exhaust system routing, fuel lines, and hydraulic hose cores where compact coiled storage and reliable performance under vibration are essential.
- Medical Gas Systems: Coiltube is integrated into medical gas supply networks, vacuum systems, and oxygen pipeline installations requiring high purity and leak-tight integrity.
6. Quality Certifications and Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that every production batch of the Stainless Steel Coil Tube meets or exceeds international standards:
- ISO 9001:2015 — Quality Management System certification demonstrating consistent capability to deliver products meeting customer and regulatory requirements.
- ISO 14001 — Environmental Management System certification, reflecting commitment to environmentally responsible manufacturing practices.
- EN 10204 3.1 Certificate — Each shipment is accompanied by a Mill Test Certificate (MTC) verifying chemical composition, mechanical properties, and conformity with the applicable product standard.
- Material Standards Compliance: Products are manufactured in accordance with ASTM A213 (Seamless and Welded Austenistic Stainless Steel Tubing for High-Temperature Service), ASTM A269 (Seamless and Welded Austenitic Stainless Steel Tubing for Chemical and Similar Severities), EN 10216-5 (Heat-Resistant, Hermetic and High-Purity Tubes), and GB/T 14976 (Chinese National Standard for Seamless Stainless Steel Tubes for Fluid Transport).
- Hygienic Compliance: Available in configurations meeting 3-A Sanitary Standards and FDA 21 CFR requirements for food-grade and pharmaceutical applications.
7. Unique Selling Points
Continuous Coil Configuration: Unlike discrete-length tubing, the continuous coiled format eliminates joint requirements during installation, reducing leak points and enhancing system reliability — a critical advantage in ventilation and HVAC applications where air-tightness is paramount.
- Installation Efficiency: The pre-formed coil geometry allows for rapid deployment and routing in complex spatial configurations, reducing on-site fabrication time by up to 40% compared to straight-length alternatives.
- Multi-Grade Flexibility: Availability across Grades 304, 316, and 321 enables tailored selection based on service environment, temperature, and corrosion exposure requirements.
- Surface Excellence: Mirror-polished and electropolished finishes not only enhance aesthetic quality but also improve corrosion resistance by eliminating surface imperfections that serve as initiation sites for pitting and crevice corrosion.
- Full Traceability: Each coil is traceable to its mill heat number and accompanied by a comprehensive Mill Test Certificate (MTC), ensuring full material provenance and quality documentation.
- Customization Capability: Wenzhou Jixing Metal Materials Co., Ltd. offers custom OD, wall thickness, coil length, and surface finish configurations to meet project-specific engineering requirements.
Wenzhou Jixing Metal Materials Co., Ltd. remains committed to delivering premium-grade stainless steel coil tube solutions that meet the demanding performance, durability, and compliance requirements of modern engineering applications worldwide.