Stainless Steel Coil Tube (Coiltube) — Ice Storage Chilled Water Application
Product Overview
The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered tubular product designed specifically for ice storage systems in regional centralized chilled water stations. This product is supplied in coil (continuous spiral) form, enabling seamless integration into thermal energy storage tanks and plate-and-fin coil assemblies used in district cooling infrastructure. The coil tube serves as the primary heat exchanger element within ice storage units, where it facilitates efficient thermal exchange between the circulating chilled water and the phase-change ice medium during both charging and discharging cycles.
Coil tubes in this category are distinguished from seamless straight tubes by their continuous helical geometry, which provides superior flexibility during installation, enhanced mechanical resilience under thermal cycling, and optimized surface-area-to-volume ratios critical for high-efficiency heat transfer in ice storage applications.
Material & Properties
The coil tube is fabricated from austenitic stainless steel grades conforming to international standards, selected for their exceptional corrosion resistance, cryogenic toughness, and long-term structural integrity in aqueous thermal environments.
- Primary Alloy Grades: SUS304 (ASTM A213 TP304), SUS316L (ASTM A213 TP316L)
- Corrosion Resistance: Superior resistance to chloride-induced pitting and general corrosion in chilled water and brine environments
- Cryogenic Performance: Maintains full ductility and mechanical strength at operating temperatures as low as −18°C to −40°C
- Hygienic Properties: Non-toxic, non-leaching, and resistant to biofilm formation
- Thermal Conductivity: 14–16 W/(m·K) for 304 grade; 13–15 W/(m·K) for 316L grade
- Maximum Service Temperature: 870°C (304); 815°C (316L)
- Minimum Ductile Temperature: −196°C (full range)
Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 38.1 mm (customizable) |
| Wall Thickness | 0.5 mm – 2.0 mm |
| Coil Length (per coil) | 20 m – 200 m (configurable) |
| Coil Winding Diameter | 300 mm – 1200 mm |
| Material Grade | SUS304 / SUS316L / SUS321 |
| Surface Finish | Bright Annealed (BA) / Electropolished (Ra ≤ 0.4 μm) |
| End Treatment | Plain cut / Beveled / Threaded / Flanged |
| Manufacturing Standard | ASTM A213 / GB/T 12771 / EN 10216-5 |
| Operating Pressure | Up to 1.6 MPa (design dependent) |
| Operating Temperature Range | −40°C to +150°C |
| Dimensional Tolerance | OD: ±0.05 mm; Wall: ±0.03 mm |
Manufacturing Process
The production of high-quality stainless steel coil tubes follows a rigorous multi-stage manufacturing protocol:
- Hot Rolling: Stainless steel slabs are hot-rolled into seamless pipe blanks with controlled microstructure and grain size.
- Pilot Milling: A pilot is inserted and the pipe is drawn through a mill to achieve precise intermediate dimensions.
- Piercing and Elongation: The tube blank is pierced and elongated to target OD and wall thickness specifications.
- Precision Drawing: Cold or warm drawing operations refine dimensional accuracy and surface finish.
- Heat Treatment (Solution Annealing): Tubes are solution-annealed at 1050°C – 1100°C followed by controlled cooling to achieve full austenitic structure and maximum corrosion resistance.
- Pickling and Passivation: Acid pickling removes oxide scale; passivation treatment establishes a stable chromium oxide passive film.
- Coiling (Spooling): The finished tube is wound onto a coil former at controlled tension to maintain geometric integrity and prevent springback deformation.
- Non-Destructive Testing (NDT): 100% eddy current testing and hydrostatic pressure testing ensure freedom from internal and external defects.
- Final Inspection: Dimensional verification, surface quality assessment, and chemical/spectral analysis confirm compliance with specified standards.
Applications
The coil tube is engineered for demanding thermal management applications, with primary use cases including:
- Ice Storage Chilled Water Systems: Serves as the heat exchange coil within thermal energy storage tanks in district cooling plants, enabling load shifting and peak shaving of refrigeration capacity.
- Regional Centralized Cooling Stations: Integrated into plate-fin and shell-and-coil heat exchangers for large-scale commercial and industrial cooling distribution.
- Cryogenic Systems: Suitable for liquid nitrogen and sub-zero refrigerant circuits requiring cryogenic-grade materials.
- Food and Beverage Processing: Utilized in hygienic heat exchange applications requiring non-toxic, easily cleanable surfaces.
- Pharmaceutical Manufacturing: Employed in process cooling and sterilization systems where material purity is critical.
- Building HVAC Systems: Used in chilled beam and radiant cooling coils for high-end commercial buildings.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality assurance systems ensuring product compliance with international standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO/TS 22163 — Railway Industry Quality Management (where applicable)
- CE Marking — Conformity with European directives
- Mill Test Certificates (MTC) — EN 10204 3.1 / 3.2 certification for each batch
- Third-Party Inspection: Available upon request (SGS, BV, TUV, DNV)
- Hydrostatic Test Report — 100% tested to specified pressure hold times
- Spectrochemical Analysis Report — Confirming alloy composition within specified limits
Unique Selling Points
- Continuous Coil Configuration: Eliminates field welding joints, reducing leak risk and maintenance requirements in ice storage systems.
- Cryogenic-Grade Performance: Full mechanical integrity at ice storage operating temperatures without embrittlement.
- Ultra-Precise Dimensions: Tight tolerances ensure proper fit within coil pack assemblies and heat exchanger housings.
- Extended Service Life: Superior corrosion resistance ensures 20+ year operational lifespan in aggressive aqueous environments.
- Customizable Geometry: Coil winding diameter, tube length, and end treatments tailored to specific project requirements.
- Full Traceability: Each coil batch carries complete production documentation from raw material mill certificate through final NDT results.
Note: For ice storage coil tube installations in regional centralized cooling stations, proper hoisting and installation procedures must follow engineering specifications to prevent mechanical damage to the coil geometry. Wenzhou Jixing Metal Materials Co., Ltd. provides technical support for coil handling, rigging, and installation guidance to ensure optimal field performance.