Stainless Steel Coil Tube (Coiltube) — Partial Freezing Ice Coil Tube System
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered heat transfer component designed for advanced thermal management applications, particularly within partial freezing ice coil tube (Partial Freezing Ice Coil Tube, PF-ICT) systems. This product integrates high-grade austenitic stainless steel with optimized coil geometry to facilitate controlled ice formation, efficient latent heat storage, and reliable air-inflation de-icing operations. The coil tube serves as the core functional element in ice storage air conditioning (Ice Storage Air Conditioning, ISAC) systems, where it alternates between freezing and de-icing cycles to provide energy-efficient thermal regulation.
This product line represents a significant advancement in thermal energy storage technology, leveraging metallurgical expertise to deliver superior corrosion resistance, mechanical durability, and thermal conductivity under cryogenic operating conditions. The design accommodates the unique stresses associated with ice formation, expansion, and air-inflation de-icing, ensuring long-term structural integrity and operational reliability.
Material & Properties
The coil tube is fabricated from premium-grade austenitic stainless steel, selected for its exceptional combination of mechanical strength, corrosion resistance, and thermal performance in cryogenic environments.
- Base Material: Austenitic Stainless Steel (UNS S30408 / S31603)
- Grade Options: SUS304, SUS316L, SUS321 — selected based on application-specific corrosion and temperature requirements
- Carbon Equivalent (CE): ≤ 0.03% (low-carbon variant for enhanced weldability and reduced intergranular corrosion risk)
- Chromium (Cr) Content: 18–20% — provides passive oxide layer formation and general corrosion resistance
- Nickel (Ni) Content: 8–12% — stabilizes austenitic microstructure and enhances ductility at low temperatures
- Molybdenum (Mo) Content: 2–3% (SUS316L variant) — improves resistance to pitting and crevice corrosion in chloride-containing environments
- Titanium (Ti) Stabilization: Present in SUS321 grade — prevents chromium carbide precipitation during welding and high-temperature service
- Cryogenic Impact Toughness: Maintains full ductility down to −196°C (Liquid Nitrogen Temperature), with no transition from ductile to brittle fracture behavior
- Thermal Conductivity: 14–16 W/(m·K) at 25°C — optimized for efficient heat transfer during freezing and de-icing cycles
- Surface Finish: 2B (cold-rolled and annealed) or BA (Bright Annealed) — reduces hydraulic resistance and prevents biofilm accumulation
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) | — |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd | — |
| Product Code | 1104 | Internal Catalog |
| Material Grade | SUS304 / SUS316L / SUS321 | JIS G4305 / ASTM A270 / EN 10217 |
| Outer Diameter (OD) | Φ6.0 mm – Φ25.0 mm (customizable) | ±0.1 mm tolerance |
| Wall Thickness (WT) | 0.5 mm – 1.5 mm | ±0.05 mm tolerance |
| Coil Pitch (Center-to-Center) | 10 mm – 50 mm (application-dependent) | ±0.5 mm tolerance |
| Coil Length | 1.0 m – 12.0 m (spooled or straight) | Custom lengths available |
| Operating Temperature Range | −40°C to +120°C | Cryogenic to moderate thermal cycling |
| Maximum Operating Pressure | 1.6 MPa (standard); 4.0 MPa (reinforced variant) | Hydrostatic test at 1.5× working pressure |
| De-Icing Method | Air-Inflation (pneumatic) — compatible with partial freezing ice coil tube system | Refer to PF-ICT experimental protocol |
| Ice Adhesion Coefficient | ≤ 0.15 N/mm² (optimized surface treatment) | Reduced ice adhesion for efficient de-icing |
| Heat Transfer Coefficient | ≥ 1500 W/(m²·K) (freezing phase); ≥ 2000 W/(m²·K) (de-icing phase) | Measured under standard test conditions |
| Surface Treatment | Electropolishing / Passivation / Anti-ice coating (optional) | ASTM A967 / ASTM A380 |
| Welding Compatibility | TIG (GTAW) / Argon Arc Welding — fully compatible with austenitic filler metals | ISO 6947 / AWS D10.6 |
| Standards Compliance | GB/T 12771, ASTM A269, EN 10216-5, JIS G3459 | Multi-standard certification |
Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous, multi-stage manufacturing protocol designed to ensure dimensional accuracy, metallurgical homogeneity, and operational performance under cryogenic thermal cycling:
- Raw Material Selection & Verification: Cold-rolled stainless steel strip (coil) is sourced from certified mills and subjected to spectroscopic analysis (Optical Emission Spectrometry, OES) to verify chemical composition, including Cr, Ni, Mo, C, Si, and Mn content within specified tolerances.
- Slitting & Cutting: The master coil is slit to the required strip width using precision slitting lines with servo-controlled edge alignment, ensuring dimensional consistency to ±0.05 mm.
- Coil Forming (Cold Bending): The flat strip is cold-formed into the required coil geometry using multi-station progressive dies. Forming parameters (bend radius, bend angle, springback compensation) are calibrated to minimize residual stress and maintain uniform wall thickness throughout the coil.
- Stress Relief Annealing (Optional): For applications requiring reduced residual stress, the formed coil tube undergoes stress relief annealing at 600–850°C in a controlled atmosphere (inert gas or vacuum) to prevent stress corrosion cracking (Stress Corrosion Cracking, SCC).
- Welding & Joining: Where continuous coil tube sections are required, longitudinal seams are welded using Tungsten Inert Gas (TIG) welding with matched filler wire (e.g., ER308L for SUS304, ER316L for SUS316L). Weld parameters are controlled to minimize heat-affected zone (Heat-Affected Zone, HAZ) sensitization.
- Surface Treatment: Electropolishing removes surface oxides and micro-contaminants, producing a smooth, passive surface with Ra ≤ 0.4 μm. Optional anti-ice coatings (fluoropolymer-based) are applied to reduce ice adhesion strength by up to 60%.
- Quality Inspection & Testing: Each production batch undergoes comprehensive testing including hydrostatic pressure testing, dimensional verification (CMM or laser measurement), visual inspection (Video Borescopy), and chemical spot-checking. Cryogenic impact testing (Charpy V-Notch) is performed on representative samples.
- Packaging & Storage: Finished coil tubes are coiled onto protective spools, wrapped in moisture-barrier packaging, and labeled with traceability documentation (heat number, batch ID, inspection certificate).
Applications
The Stainless Steel Coil Tube is engineered for a diverse range of thermal management and cryogenic applications, with particular emphasis on partial freezing ice storage systems:
- Ice Storage Air Conditioning (ISAC) Systems: Serves as the primary heat exchanger element in partial freezing ice coil tube systems, where controlled ice formation on the tube surface enables off-peak energy storage and on-peak cooling delivery. The air-inflation de-icing method, validated through experimental research (referenced in Product Code 1104 documentation), enables rapid and reliable ice removal without mechanical damage to the tube.
- Cryogenic Heat Exchangers: Utilized in liquid nitrogen, liquid oxygen, and other cryogenic fluid handling systems where the austenitic stainless steel maintains ductility and corrosion resistance at temperatures as low as −196°C.
- Refrigeration & Cold Chain Logistics: Employed in industrial refrigeration units, cold storage facilities, and pharmaceutical cold chain equipment requiring reliable heat transfer at sub-zero temperatures.
- Marine & Offshore Systems: SUS316L-grade coil tubes provide superior resistance to chloride-induced pitting corrosion in seawater environments, suitable for shipboard refrigeration and offshore platform thermal management.
- Food & Beverage Processing: Hygienic-grade coil tubes (Ra ≤ 0.4 μm) are used in dairy, beverage, and pharmaceutical processing lines where product contact requires compliance with FDA and EHEDG standards.
- Geothermal & Heat Pump Systems: Coil tubes serve as ground loop heat exchangers in geothermal heating and cooling installations, leveraging stainless steel corrosion resistance in soil and groundwater environments.
Unique Selling Points
- Validated Air-Inflation De-Icing Compatibility: The coil tube geometry and material properties are specifically optimized for air-inflation de-icing protocols, as demonstrated through experimental research on partial freezing ice coil tube systems. This eliminates the need for chemical or thermal de-icing methods, reducing operational complexity and environmental impact.
- Superior Cryogenic Performance: Full austenitic microstructure ensures no ductile-to-brittle transition at cryogenic temperatures, providing fatigue resistance and structural reliability through millions of freeze-de-ice thermal cycles.
- Multi-Grade Material Flexibility: Availability in SUS304, SUS316L, and SUS321 grades allows precise material selection based on the specific corrosion environment, temperature range, and regulatory requirements of each application.
- Enhanced Heat Transfer Efficiency: Precision coil geometry and optimized surface finish (electropolished or anti-ice coated) maximize convective heat transfer coefficients during both freezing and de-icing phases, improving system COP (Coefficient of Performance) by up to 15%.
- Full Traceability & Quality Assurance: Each product batch is accompanied by mill test certificates, heat number traceability, and inspection reports conforming to international standards (ISO 9001, EN 10204 Type 3.1).
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains comprehensive quality management and product certification systems to ensure compliance with international standards:
- ISO 9001:2015 — Quality Management System certification covering design, manufacturing, and testing processes
- EN 10204 Type 3.1 — Third-party inspection certificate confirming material compliance with specified standards
- CE Marking — Conformity with European Union safety and performance directives
- GB/T 12771 — Chinese National Standard for welded stainless steel tubes
- ASTM A269 / A270 — American Society for Testing and Materials standards for austenitic stainless steel tube
- JIS G3459 / G4305 — Japanese Industrial Standards for stainless steel seamless and welded tubes
- EN 10216-5 / EN 10217 — European standards for stainless steel tube for pressure and general purposes
- NSF/ANSI 61 — Drinking water system component certification (for food-grade applications)
- Pressure Vessel Inspection (ASME BPV) — Available for coil tubes used in pressure vessel assemblies
Note: The technical specifications and performance data presented herein are derived from experimental research on partial freezing ice coil tube air-inflation de-icing systems (Product Code 1104). Actual product performance may vary based on specific application conditions, installation configuration, and operating parameters. Custom specifications and engineering consultations are available upon request.