Stainless Steel Coil Tube (Coiltube) — Low-Temperature Air-Cooled Chilled Water Circulation System
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubular product designed for demanding thermal management applications, particularly in low-temperature air-cooled chilled water circulation systems. This product leverages segmented control technology to optimize heat exchange efficiency under varying ambient conditions, making it suitable for industrial process cooling, HVAC (Heating, Ventilation, and Air Conditioning) systems, and specialized refrigeration environments where reliable low-temperature performance is critical.
The coil tube configuration provides a high surface-area-to-volume ratio, enabling superior thermal transfer characteristics compared to straight-tube alternatives. The segmented control approach allows operators to modulate coolant flow and temperature across discrete zones, achieving precise temperature regulation even in low-ambient-temperature scenarios.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its outstanding combination of corrosion resistance, thermal conductivity, and mechanical integrity across a wide operating temperature range.
- Base Material: Austenitic stainless steel conforming to ASTM A213 / ASME SA-213 or EN 10216-5 specifications (typical grades: 304, 304L, 316, 316L)
- Corrosion Resistance: Excellent resistance to oxidation, pitting, and stress corrosion cracking due to high chromium (Cr ≥ 18%) and nickel (Ni ≥ 8%) content; 316/316L grades additionally contain molybdenum (Mo 2–3%) for enhanced chloride resistance
- Mechanical Properties: Tensile strength (UTS, Ultimate Tensile Strength) of 515–750 MPa; Yield strength of ≥ 205 MPa; Elongation ≥ 40%
- Thermal Conductivity: 14–16 W/(m·K) at 20 °C, maintaining adequate heat transfer at low operating temperatures (down to −40 °C)
- Cryogenic Performance: Retains ductility and impact toughness at sub-zero temperatures without brittle fracture
- Hygienic Surface: Interior surface finish achievable to Ra ≤ 0.5 μm for sanitary and food-grade applications
Specifications
| Parameter | Specification / Range | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 – 50.8 mm (¼" – 2") | ASTM A213 / EN 10216-5 |
| Wall Thickness | 0.5 – 3.0 mm | Per customer requirement |
| Coil Diameter | 500 – 2,000 mm | Custom configuration |
| Coil Length (per coil) | 50 – 200 m | — |
| Material Grade | 304, 304L, 316, 316L, 321, 347 | ASTM A270 / EN 10217-7 |
| Surface Finish | Mill finish, Pickled & Passivated (P&P), Electropolished | Ra ≤ 0.5 μm (electropolished) |
| Operating Temperature Range | −40 °C to +450 °C | — |
| Maximum Operating Pressure | Up to 2.5 MPa (design-dependent) | ASME B31.3 |
| Welding Process | Orbital TIG (Tungsten Inert Gas) / Push-pull TIG | ISO 15614-1 |
| Heat Treatment | Solution annealed (1050–1150 °C, water quench) | ASTM A213 |
| Coating / Passivation | Chromic acid or citric acid passivation | ASTM A967 / AMS 2700 |
| Segmented Control Zones | 2 – 8 independent control sections per coil assembly | Custom engineering design |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorously controlled, multi-stage manufacturing workflow to ensure dimensional accuracy, metallurgical integrity, and functional reliability:
- Raw Material Procurement: Cold-rolled stainless steel strip or seamless pipe stock sourced from certified mills, verified by mill test certificates (MTC, Mill Test Certificate) and chemical composition analysis (via optical emission spectrometry, OES, or XRF — X-ray Fluorescence).
- Forming & Welding: Precision roll-forming to achieve the target OD and wall thickness, followed by high-purity argon-shielded orbital TIG welding for circumferential seam integrity. Push-pull TIG technique ensures a clean, uniform weld bead on both the interior and exterior surfaces.
- Coiling: The formed tube is coiled to the specified diameter using CNC-controlled winding equipment to maintain consistent bend radius without inducing material deformation or residual stress.
- Solution Annealing: Heat treatment at 1050–1150 °C followed by rapid water quench to dissolve carbides, restore full austenitic microstructure, and relieve internal stresses introduced during forming and welding.
- Pickling & Passivation: Acid pickling removes mill scale and oxidation; subsequent passivation treatment (per ASTM A967) forms a stable chromium oxide layer for maximum corrosion resistance.
- Quality Inspection: Includes hydrostatic pressure testing, dimensional measurement, visual inspection, and optional non-destructive testing (NDT) such as eddy current testing (ECT) or ultrasonic testing (UT) for weld integrity verification.
- Segmented Control Integration: The coil tube assembly is designed to accommodate segmented flow control valves and temperature sensors at discrete intervals, enabling zone-by-zone modulation of coolant flow in low-temperature air-cooled systems.
Applications
The segmented-control stainless steel coil tube finds application in a broad spectrum of industrial and commercial systems requiring precise low-temperature thermal management:
- Low-Temperature Air-Cooled Chilled Water Circulation: Segmented control enables optimized performance in air-cooled chillers operating under low ambient temperatures, preventing coil freezing while maintaining desired supply water temperatures.
- Industrial Process Cooling: Precision temperature control for chemical reactors, pharmaceutical manufacturing, electronics cooling, and food processing.
- HVAC Systems: Chiller coils and heat exchangers in commercial and industrial building climate control.
- Cryogenic Applications: Liquefied natural gas (LNG) pre-cooling, industrial refrigeration, and cryogenic storage systems.
- Food & Beverage Industry: Hygienic-grade coil assemblies for pasteurization, brewing, and dairy processing (316L grade recommended).
- Marine & Offshore: Seawater cooling coils and heat exchangers benefiting from 316L's superior chloride resistance.
- Power Generation: Condenser tubes and cooling loops in thermal power plants.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework to ensure product reliability and international compliance:
- ISO 9001:2015 — Quality Management System certification
- ISO 3834-2 — Requirements for quality documentation for fusion welding
- EN 10204 3.1 — Inspection certificates (third-party verified material and product testing)
- ASTM / ASME Compliance — Conformance to ASTM A213, ASME SA-213, and related standards for stainless steel tubes
- CE Marking — European conformity for pressure equipment (PED 2014/68/EU) where applicable
- Third-Party Inspection — Available upon request through accredited agencies (e.g., SGS, Bureau Veritas, TÜV)
- Mill Test Certificates (MTC) — Provided with every shipment, including chemical composition, mechanical properties, and heat treatment records
Unique Selling Points
The segmented-control coil tube design represents a significant advancement in low-temperature thermal management. By dividing the coil assembly into independently controllable zones, the system achieves:
- Enhanced Energy Efficiency: Zone-by-zone flow modulation reduces unnecessary cooling capacity, lowering energy consumption by up to 20–30% compared to conventional single-control coil systems.
- Superior Low-Temperature Performance: Segmented control prevents localized freezing in air-cooled environments, extending operational range to ambient temperatures as low as −15 °C without antifreeze additives.
- Extended Service Life: Reduced thermal cycling stress on individual segments minimizes fatigue cracking, extending coil tube lifespan significantly.
- Scalability & Flexibility: Modular design allows easy expansion or reconfiguration of the number of control zones to match evolving process requirements.
- Material Excellence: Full austenitic stainless steel construction ensures decades of corrosion-free service in aggressive chemical and marine environments.
- Custom Engineering Capability: Wenzhou Jixing Metal Materials Co., Ltd offers tailored coil configurations, including custom OD, wall thickness, coil diameter, and segmented control zone layouts to meet specific project specifications.