Stainless Steel Coil Tube for High-Performance Wall-Mounted Terminal Air Conditioning Systems
Product Overview
The Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically designed for application in large-scale data center high-energy wall-mounted coil tube terminal air conditioning systems. The Coiltube serves as the core heat exchange element within terminal units, facilitating efficient thermal transfer between refrigerant and ambient air to maintain precise environmental conditions in critical infrastructure facilities.
As data centers continue to grow in scale and computational density, the demand for high-efficiency, reliable, and compact thermal management solutions has intensified. The Coiltube product line addresses these demands by combining superior material properties with advanced manufacturing techniques to deliver exceptional thermal performance, mechanical integrity, and long-term service life.
Material & Properties
The Coiltube is fabricated from high-grade stainless steel, selected for its outstanding combination of corrosion resistance, thermal conductivity, mechanical strength, and hygienic properties.
Material Composition
- Base Alloy: Austenitic stainless steel conforming to ASTM A269 / A270 or equivalent standards
- Grade Options: SUS304 (18/8), SUS316L (low-carbon, molybdenum-enhanced)
- Carbon Content: ≤ 0.08% (SUS304); ≤ 0.03% (SUS316L)
- Chromium Content: 18–20% (SUS304); 16–18% (SUS316L)
- Nickel Content: 8–10% (SUS304); 10–14% (SUS316L)
- Molybdenum Content: 0% (SUS304); 2–3% (SUS316L)
Key Physical Properties
- Thermal Conductivity: 16.3 W/(m·K) at 20°C (SUS304); 16.3 W/(m·K) at 20°C (SUS316L)
- Specific Heat Capacity: 500 J/(kg·K)
- Density: 8.0 g/cm³
- Thermal Expansion Coefficient: 17.3 × 10⁻⁶ /K (20–100°C)
- Operating Temperature Range: −196°C to +870°C
Mechanical Properties
- Tensile Strength (Annealed): ≥ 515 MPa (SUS304); ≥ 515 MPa (SUS316L)
- Yield Strength (0.2% Offset): ≥ 205 MPa
- Elongation at Break: ≥ 40%
- Hardness: ≤ 92 HRB (annealed condition)
Corrosion Resistance
- Excellent resistance to atmospheric corrosion and general chemical environments
- SUS316L variant provides enhanced resistance to pitting and crevice corrosion in chloride-containing environments
- Resistance to intergranular corrosion (IGC) confirmed via ASTM A262 Practice E testing
- Passive film stability maintained in pH range 4–10
Specifications
| Parameter | Specification | Tolerance / Standard |
|---|---|---|
| Outer Diameter (OD) | 6.35 mm / 8.00 mm / 9.53 mm / 10.00 mm / 12.70 mm / Custom | ±0.10 mm |
| Wall Thickness | 0.50 mm / 0.65 mm / 0.80 mm / 1.00 mm / Custom | ±0.05 mm |
| Coil Length | 3 m / 5 m / 10 m / 15 m / Custom (up to 30 m continuous) | ±0.05 m |
| Coil Inner Diameter (Winding) | 50 mm / 75 mm / 100 mm / 150 mm / Custom | ±2 mm |
| Surface Finish | Bright Annealed (BA) / Electropolished (Ra ≤ 0.4 μm) / Passivated | ASTM A967 |
| End Treatment | Plain cut / Flanged / Threaded (M14×1.5, 1/4" NPT, 3/8" NPT) / Weld fitting ready | Per customer drawing |
| Hydrostatic Test Pressure | 1.5 × Maximum Working Pressure | ASTM A269 |
| Maximum Working Pressure | Up to 4.0 MPa (depending on OD and wall thickness) | Calculated per ASME B31.5 |
| Refrigerant Compatibility | R-134a / R-410A / R-32 / R-1234yf / R-407C / Ammonia (NH₃) | ASHRAE 34 |
| Operating Temperature Range | −40°C to +80°C (system level) | Per system design |
| Heat Transfer Coefficient | ≥ 2500 W/(m²·K) (refrigerant-side, turbulent flow) | Measured per ISO 5151 |
| Standards Compliance | ASTM A269 / A270, ASME B31.5, EN 10217, GB/T 12771 | — |
Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous, multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and surface quality.
Process Flow
- Raw Material Selection and Incoming Inspection: Mill-certified stainless steel strip or tube blanks are sourced from certified suppliers. Each batch undergoes chemical composition verification (OES/ICP), mechanical property testing, and visual inspection for surface defects.
- Tube Forming: Precision cold-rolled or seamless tubes are produced to specified OD and wall thickness. For seamless tubes, hot-rolling followed by cold-drawing is employed to achieve dimensional tolerances within ±0.10 mm.
- Cutting and Deburring: Tubes are cut to required lengths using automated laser or guillotine cutting systems. All burrs are removed to prevent flow obstruction and fatigue initiation sites.
- Coil Winding (Coiling): Straight tubes are wound into precise spiral configurations using CNC-controlled coil winding machines. The winding process maintains uniform pitch, consistent bend radius, and controlled spring-back to achieve target coil geometry.
- Welding (if required): End joints and connections are fabricated using orbital TIG (Tungsten Inert Gas) welding or resistance welding. Weld seams are inspected via dye penetrant testing (PT) or eddy current testing (ECT) to confirm full penetration and absence of defects.
- Heat Treatment / Stress Relief: Where required, the coiled assembly undergoes solution annealing at 1050–1150°C followed by controlled cooling to relieve residual stresses introduced during forming and winding.
- Surface Treatment: Tubes receive pickling and passivation per ASTM A967 to remove scale and establish a stable chromium oxide passive film. Electropolishing is available for applications requiring ultra-low surface roughness.
- Hydrostatic Pressure Testing: Each coil assembly is subjected to hydrostatic pressure testing at 1.5× the maximum working pressure for a minimum dwell time of 30 seconds to verify leak-tightness and structural integrity.
- Final Inspection and Quality Control: Dimensional verification (OD, wall thickness, coil diameter, pitch), visual inspection, and non-destructive testing (NDT) are performed. All results are documented and traceable.
- Packaging and Dispatch: Products are wrapped in protective film, secured with strapping, and labeled with batch identification, material certification, and test documentation prior to shipment.
Applications
Primary Application: Large Data Center High-Energy Wall-Mounted Terminal Air Conditioning
The Coiltube is the principal heat exchange component in wall-mounted terminal units deployed in high-density data center environments. These systems are engineered to manage heat loads exceeding 20 kW per rack in modern hyperscale data centers.
Key Application Scenarios
- Hyperscale Data Centers: Precision temperature and humidity control for server racks with heat dissipation requirements up to 30–50 kW per unit area
- Cloud Computing Infrastructure: Reliable thermal management for cloud service providers requiring 99.999% (five nines) uptime
- Edge Computing Nodes: Compact, wall-mounted cooling solutions for distributed edge data centers with limited floor space
- Telecommunications Equipment Rooms: Environmental conditioning for high-density telecom switching and routing equipment
- Financial Trading Floor Server Rooms: Critical cooling for latency-sensitive computing infrastructure
- AI/ML Training Facilities: Thermal management for GPU-accelerated computing clusters generating extreme heat loads
System Integration Context
In a typical high-energy wall-mounted terminal air conditioning system, the Coiltube serves as the evaporator or condenser coil within the terminal unit. Refrigerant flows through the coiled tubing while air is circulated across the coil by axial or centrifugal fans. The compact spiral geometry maximizes heat transfer surface area within minimal installation footprint, making it ideal for wall-mounted configurations in space-constrained data center environments.
Quality Certifications
Product Certifications
- ISO 9001:2015 — Quality Management System certification for manufacturing processes
- ISO 14001:2015 — Environmental Management System certification
- CE Marking — Conformity with European Machinery Directive and Pressure Equipment Directive (PED 2014/68/EU)
- RoHS Compliance — Restriction of Hazardous Substances directive
- REACH Compliance — Registration, Evaluation, Authorisation and Restriction of Chemicals
Material and Testing Certifications
- EN 10204 3.1 — Material test certificates with independent inspection
- Mill Test Reports (MTR) — Full chemical and mechanical property documentation per ASTM E1 / E415
- Hydrostatic Test Reports — Batch-level pressure test documentation
- NDT Reports — Eddy current and/or dye penetrant testing results for weld integrity
- Intergranular Corrosion Test — ASTM A262 Practice E (Acetic Acid Test) or Practice A (CuSO₄ Test)
- Pitting Corrosion Test — ASTM G48 Practice A (Ferric Chloride Test) for SUS316L grades
Compliance with Industry Standards
- ASTM A269 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for Chemical and Similar Severe Service
- ASTM A270 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Pipe
- ASME B31.5 — Pressure Piping, Process Plants
- EN 10217 — Stainless Steel Tubes for General Purposes
- GB/T 12771 — Stainless Steel Seamless Tubes for General Purposes (Chinese National Standard)
- UL Listed components for electrical safety where applicable
Unique Selling Points
- Optimized for High-Density Cooling: Coil geometry engineered specifically for terminal units handling heat loads of 20–50 kW, addressing the unique thermal challenges of modern hyperscale data centers
- Superior Corrosion Resistance: Premium stainless steel grades ensure decades of reliable service in humid, chemically active data center environments without degradation of heat transfer performance
- Compact Installation Footprint: Wall-mounted design maximizes floor space utilization in data center halls where every square meter of rack space is revenue-generating
- Full Traceability: Every coil tube carries complete material, manufacturing, and test documentation enabling lifecycle quality assurance and compliance with ITIL/ISO 20000 service management requirements
- Customizability: Flexible manufacturing capability supports custom OD, wall thickness, coil geometry, end fittings, and refrigerant compatibility to match specific system design requirements
- Energy Efficiency: High heat transfer coefficient and low pressure drop characteristics contribute to lower compressor energy consumption and improved system COP (Coefficient of Performance)
- Environmental Sustainability: Compatible with next-generation low-GWP refrigerants (R-1234yf, R-32), supporting data center operators' carbon reduction targets and compliance with F-Gas regulations
Technical Notes
Note 1: All dimensional specifications are subject to ±0.10 mm manufacturing tolerance unless otherwise stated. Custom tolerances may be available upon request with additional lead time.
Note 2: The Coiltube is designed for use in closed-loop refrigeration systems. It is not intended for direct potable water contact or open-loop hydronic applications without appropriate additional treatment.
Note 3: For data center applications operating above 25°C ambient temperature or with high humidity (>80% RH), SUS316L grade is recommended to ensure long-term corrosion resistance of the coil tube surface.
Note 4: System-level performance (cooling capacity, COP, refrigerant charge) depends on