Stainless Steel Coil Tube (Coiltube) — Cold Water Heat Exchange Product
Product Overview
The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd, is a precision-engineered coiled stainless steel tubing product specifically designed for cold water heat exchange applications. This product is engineered to optimize thermal transfer efficiency within cold water distribution systems, ensuring reliable cold water balance across a wide range of industrial and commercial environments. The coiltube integrates advanced metallurgical design with thermal dynamics principles to deliver superior performance in chilled water circulation, refrigeration coils, and hydronic cooling systems.
The product addresses the critical engineering challenge of maintaining thermal equilibrium in cold water systems by leveraging the enhanced surface-area-to-volume ratio inherent in coiled configurations. This geometric advantage maximizes heat dissipation and absorption rates, making it an indispensable component in modern HVAC (Heating, Ventilation, and Air Conditioning) infrastructure and process cooling applications.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of corrosion resistance, thermal conductivity, mechanical strength, and long-term structural integrity under cyclic thermal loading.
- Base Material: Austenitic Stainless Steel (e.g., AISI 304 / AISI 316L)
- Corrosion Resistance: Excellent resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC) in aqueous environments
- Thermal Conductivity: 14–16 W/(m·K) at ambient temperature, providing efficient heat transfer performance
- Mechanical Properties: High tensile strength (≥520 MPa) and elongation (≥40%), ensuring dimensional stability during coiling operations
- Temperature Range: Operable from cryogenic temperatures (−196°C) to elevated temperatures (up to 870°C in non-oxidizing atmospheres)
- Hygienic Surface Finish: Available in polished (Ra ≤ 0.4 μm) or passivated finish for sanitary and food-grade applications
- Non-magnetic: Inherently non-magnetic in the annealed condition, suitable for MRI environments and electromagnetic-sensitive installations
Specifications
| Parameter | Specification / Range | Unit |
|---|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) | — |
| Material Grade | AISI 304, AISI 304L, AISI 316, AISI 316L | — |
| Outer Diameter (OD) | 6 – 50 | mm |
| Wall Thickness (WT) | 0.3 – 3.0 | mm |
| Coil Diameter | 100 – 1200 | mm |
| Coil Length | Custom (typically 5 – 100) | m |
| Surface Finish | 2B, BA (Bright Annealed), Polished, Passivated | — |
| Operating Pressure | Up to 1.6 (standard), up to 4.0 (special) | MPa |
| Operating Temperature | −196 to +870 | °C |
| Heat Transfer Coefficient | Enhanced via coiled geometry (up to 35% improvement over straight tube) | — |
| Standards Compliance | ASTM A213/A269, EN 10217-7, GB/T 12771 | — |
| Manufacturing Standard | ISO 9001:2015 | — |
| Customization | Available upon request (dimensions, pitch, material grade) | — |
Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous, multi-stage manufacturing protocol designed to ensure metallurgical homogeneity, dimensional precision, and optimal thermal performance:
- Raw Material Selection & Verification: High-purity stainless steel wire rod is sourced from certified mills and subjected to spectroscopic analysis (OES/PMI) to confirm chemical composition compliance with the specified grade.
- Wire Drawing & Annealing: The wire rod undergoes cold drawing to achieve precise outer diameter and wall thickness tolerances, followed by solution annealing at 1050–1150°C to relieve residual stresses and restore full austenitic microstructure.
- Tube Forming (Seamless or Welded): Depending on the application requirement, tubes are produced via seamless piercing (for high-pressure applications) or precision welding (ERW/Orbital TIG) for cost-effective large-scale production.
- Coiling Operation: The formed tube is coiled using CNC-controlled coiling machines to achieve precise coil diameter, pitch, and turn uniformity. The coiling process is optimized to minimize residual bending stresses and prevent ovality.
- Post-Coil Annealing & Stress Relief: The coiled product undergoes a controlled heat treatment cycle to eliminate coiling-induced residual stresses, ensuring dimensional stability and preventing stress corrosion susceptibility.
- Surface Treatment & Passivation: The final product receives chemical passivation (nitric acid or citric acid pickling) to remove surface contamination and establish a robust chromium oxide passive film, enhancing long-term corrosion resistance.
- Quality Inspection & Testing: Each batch undergoes hydrostatic pressure testing, dimensional verification (OD, WT, coil diameter), and visual/surface inspection. Optional testing includes PMI verification, mechanical testing, and intergranular corrosion testing (ASTM A262 Practice E).
Applications
The Stainless Steel Coil Tube is engineered for demanding cold water heat exchange and distribution applications where reliability, hygiene, and thermal efficiency are paramount:
- Chilled Water Distribution Systems: Optimized for cold water balance in large-scale HVAC systems, providing uniform thermal distribution across multi-zone cooling networks.
- Refrigeration & Cryogenic Coils: Suitable for evaporator coils, condenser coils, and cryogenic heat exchangers operating at sub-zero temperatures.
- Process Cooling in Chemical & Petrochemical Industries: Corrosion-resistant coil configurations for cooling process fluids, acids, and solvents.
- Food & Beverage Industry: Hygienic-grade coil tubes for pasteurization, brewing, and dairy processing systems requiring sanitary compliance (FDA, 3-A standards).
- Pharmaceutical & Biotechnology: Clean-in-place (CIP) compatible coils for bioreactors, sterilization loops, and pharmaceutical fluid handling.
- Marine & Offshore Applications: AISI 316L grade coils for seawater cooling systems and marine HVAC installations with high chloride resistance.
- Geothermal & District Cooling Systems: Coiled heat exchangers for ground-source heat pumps and centralized cold water distribution networks.
- Electronics Cooling: Precision-coiled tubing for high-power electronics, data center cooling, and semiconductor manufacturing thermal management.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework to ensure every coil tube product meets international standards and customer specifications:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO 45001:2018 — Occupational Health & Safety Management System
- EN 10204 3.1 — Material Test Reports (MTR) provided with each shipment
- CE Marking — Compliance with European regulatory requirements
- Material Standards: ASTM A213/A269, EN 10217-7, GB/T 12771, JIS G3459
- Testing Protocols: Hydrostatic testing (ASTM A530), PMI verification, dimensional inspection per ISO 2852, intergranular corrosion testing (ASTM A262)
Unique Selling Points
Superior Thermal Performance: The coiled geometry provides up to 35% enhancement in heat transfer efficiency compared to equivalent-length straight tubing, directly addressing cold water balance challenges in distribution systems.
- Customization Capability: Full customization of coil diameter, pitch, tube dimensions, and material grade to match specific system design requirements.
- Metallurgical Excellence: Post-coil annealing ensures stress-free microstructure, eliminating the risk of stress corrosion cracking in chloride-containing environments.
- Traceability & Documentation: Every production batch is accompanied by complete material traceability records, chemical analysis reports, and mechanical test certificates.
- Engineering Support: Technical team provides thermal modeling and system integration consulting to optimize cold water system performance.
- Long Service Life: Expected operational lifespan exceeding 20 years under normal conditions, with minimal maintenance requirements.
- Environmental Sustainability: Stainless steel is 100% recyclable, and the manufacturing process adheres to ISO 14001 environmental standards.
Technical Note on Cold Water Balance Optimization
Based on advanced thermal-fluid dynamics analysis, the coiltube configuration demonstrates significant advantages in maintaining cold water balance within hydronic systems. The coiled geometry promotes secondary flow patterns (Dean vortices) within the tube, which enhance turbulent mixing and reduce thermal stratification. This results in more uniform temperature distribution across the system, minimizing energy waste and ensuring consistent cooling capacity delivery to all connected endpoints. The product's design philosophy directly addresses the engineering challenges outlined in thermal balance studies, offering a practical, manufacturable solution for cold water system optimization.