Stainless Steel Coiltube for Ice Storage Tank Systems — Model 1412
Product Overview
The Stainless Steel Coiltube (Model 1412) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered continuous coil tubing designed specifically for ice storage tank systems and thermal energy storage applications. This product represents a critical component in the architecture of ice-based thermal energy storage (TES) systems, where it serves as the primary heat exchange medium during both the freezing and melting cycles. The coiltube is formed into a continuous spiral or helical configuration that maximizes the heat transfer surface area within a confined volumetric envelope, thereby enabling efficient thermal exchange between the refrigerant circulating within the tube and the surrounding ice slurry or water medium.
Based on extensive theoretical research into the melting process of ice in coiled pipe ice tanks — as documented in the study "Theoretical Study on the Melting Process of Ice Storage in Coiled Pipe Ice Tanks" — this product has been optimized to address the inherent challenges of phase-change heat transfer, including non-uniform ice melting patterns, buoyancy-driven natural convection effects, and the formation of thermal boundary layers that can impede heat flux during the discharge (melting) phase.
Material & Properties
The Coiltube is fabricated from high-grade austenitic stainless steel, selected for its superior corrosion resistance, thermal conductivity, and mechanical integrity under cyclic thermal loading conditions.
- Base Material: Austenitic Stainless Steel (SAE 304 / SAE 316L), conforming to ASTM A269 / ASTM A213 standards
- Corrosion Resistance: Exceptional resistance to chloride-induced pitting and crevice corrosion, particularly in SAE 316L grade, making it suitable for glycol-water mixtures and brine solutions commonly used in ice storage systems
- Thermal Conductivity: Approximately 16.3 W/(m·K) at 20°C, providing adequate heat transfer capability while maintaining structural durability
- Cryogenic Performance: Maintains full ductility and toughness at temperatures as low as −196°C (liquid nitrogen temperature), with no risk of brittle fracture
- Hygienic Surface: Internal surface roughness (Ra) of ≤0.4 μm achievable, ensuring minimal flow resistance and resistance to biological fouling
- Non-magnetic: Inherently non-magnetic in the annealed condition, eliminating interference with adjacent instrumentation
Specifications
| Parameter | Specification |
|---|---|
| Product Model | 1412 Coiltube |
| Material Grade | SAE 304 / SAE 316L (ASTM A269) |
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (customizable) |
| Wall Thickness | 0.5 mm – 3.0 mm (configurable per application) |
| Coil Length | Continuous coil up to 200 m per spool (custom lengths available) |
| Coil Pitch | 5 mm – 25 mm (optimized for heat transfer efficiency) |
| Surface Finish | Electropolished (Ra ≤ 0.4 μm) / Brushed / Standard mill finish |
| Operating Temperature Range | −196°C to +450°C |
| Maximum Operating Pressure | Up to 2.5 MPa (design-dependent) |
| Tolerance on OD | ±0.05 mm |
| Tolerance on Wall Thickness | ±10% of nominal |
| Heat Treatment | Solution annealed at 1050°C, followed by rapid water quench |
| Welding Suitability | TIG (GTAW) welding with matching filler metal (ER308L / ER316L) |
| Standards Compliance | ASTM A269, ASME B31.3, EN 10216-5, GB/T 12771 |
Manufacturing Process
The production of the Coiltube Model 1412 follows a rigorous multi-stage manufacturing sequence designed to ensure dimensional accuracy, metallurgical integrity, and consistent performance characteristics:
- Raw Material Selection: Certified hot-rolled stainless steel strip or seamless tube stock is sourced from accredited mills, with full chemical composition and mechanical property verification via spectroscopic analysis and tensile testing.
- Forming & Coiling: The straight tube or strip is fed through a precision forming die system where it is continuously bent into the required helical or spiral geometry. The forming process is controlled to avoid excessive strain hardening and maintain the ductility necessary for downstream handling and installation.
- Heat Treatment (Solution Annealing): The formed coil is subjected to solution annealing at 1050°C in a controlled atmosphere furnace to relieve residual stresses, restore full austenitic microstructure, and enhance corrosion resistance by dissolving any carbide precipitates that may have formed during forming.
- Surface Treatment: Electropolishing is applied to the internal bore to achieve a smooth, hygienic surface with Ra ≤ 0.4 μm. This reduces frictional losses and prevents ice crystal adhesion during freezing cycles.
- Quality Inspection: Each coil undergoes 100% visual inspection, dimensional verification (OD, wall thickness, pitch), and hydrostatic pressure testing at 1.5× the maximum operating pressure. Random samples are subjected to X-ray or ultrasonic testing for internal defect detection.
- Packaging & Shipping: Coils are wound onto protective spools, wrapped in moisture-proof polyethylene film, and secured for transport to prevent deformation or surface damage.
Applications
The Coiltube Model 1412 is engineered for demanding thermal management applications, with its primary deployment in ice storage tank systems. Key application domains include:
- Ice-Based Thermal Energy Storage (TES) Systems: Serves as the primary heat exchange element in ice storage tanks, facilitating the controlled freezing and melting of ice for peak-load shifting in commercial HVAC systems. The coil design optimizes the heat transfer rate during the melting process, addressing the well-documented challenge of buoyancy-driven stratification and non-uniform ice melt.
- Chilled Water Production: Integrated into chiller systems where the coil transfers heat from the primary refrigerant circuit to the secondary water loop, producing chilled water at temperatures ranging from −5°C to +7°C.
- Cold Chain Logistics: Utilized in refrigerated containers and cold storage facilities where reliable, corrosion-resistant heat exchange is essential for maintaining product integrity.
- Industrial Process Cooling: Applied in pharmaceutical, food processing, and chemical industries requiring precise temperature control with high-purity heat exchange media.
- Renewable Energy Integration: Employed in solar-thermal and geothermal systems where thermal energy storage is used to buffer intermittent energy supply and provide stable thermal output.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework to ensure that every Coiltube product meets international standards and customer-specific requirements:
- ISO 9001:2015 — Quality Management System certification, ensuring consistent product quality and continuous improvement processes.
- ISO 14001:2015 — Environmental Management System certification, demonstrating commitment to environmentally responsible manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management System certification.
- CE Marking — Conformity with European Directive requirements for pressure equipment and mechanical components.
- NACE MR0175 / ISO 15156 — Compliance with requirements for materials resistant to sulfide stress cracking in sour service environments.
- Mill Test Certificates (MTC): Every batch is accompanied by EN 10204 Type 3.1 material certificates, providing full traceability of chemical composition, mechanical properties, and heat treatment records.
- Third-Party Inspection: Available upon request — SGS, Bureau Veritas, or TÜV Rheinland inspection services are supported for critical applications.
Unique Selling Points
1. Theoretically Optimized Geometry: The coil pitch and diameter ratios are derived from validated numerical models of the ice melting process in coiled pipe tanks, ensuring maximum heat transfer efficiency during both charging (freezing) and discharging (melting) phases. This addresses the critical issue of declining heat transfer rates as the ice layer thins and natural convection patterns change.
2. Superior Surface Finish: Electropolished internal surfaces minimize ice adhesion and reduce the thermal resistance of the boundary layer, directly enhancing the effective heat transfer coefficient (U-value) by up to 15–20% compared to standard mill-finish tubes.
3. Full Traceability: Each coil carries a unique identification marking with complete material pedigree documentation, enabling full supply chain traceability from raw steel mill to end installation.
4. Custom Engineering Capability: Wenzhou Jixing offers tailored coil geometries — including variable pitch profiles, multi-pass configurations, and custom end fittings — to match specific tank dimensions and thermal performance requirements.
5. Proven Durability: The austenitic stainless steel matrix, combined with controlled cold-working limits and proper solution annealing, ensures a service life exceeding 25 years in aggressive brine and glycol environments without significant degradation of mechanical or thermal properties.
Conclusion
The Stainless Steel Coiltube Model 1412 from Wenzhou Jixing Metal Materials Co., Ltd represents a state-of-the-art solution for ice storage tank systems and thermal energy storage applications. Grounded in rigorous theoretical analysis of phase-change heat transfer phenomena, this product delivers optimized thermal performance, exceptional corrosion resistance, and long-term reliability. Its adherence to international quality standards and comprehensive certification framework makes it a trusted component for critical infrastructure in commercial, industrial, and energy sectors worldwide.