Stainless Steel Coil Tube for Intermediate Cooler Applications
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 347) is a precision-engineered tubular component specifically designed for use in intermediate coolers within two-stage compression refrigeration systems. This product is engineered to maintain optimal outlet temperature control, thereby directly influencing the thermodynamic efficiency and overall performance of the refrigeration cycle. The coil tube serves as a critical heat exchange element that regulates the temperature of refrigerant gas between the first-stage and second-stage compressors, ensuring that the intermediate cooling process operates within the desired thermal envelope.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its superior combination of corrosion resistance, thermal conductivity, and mechanical integrity under cyclic thermal loading conditions.
- Material Grade: Austenitic Stainless Steel (304 / 316 / 316L conforming to ASTM A213 / ASME SA-213)
- Corrosion Resistance: Excellent resistance to chloride-induced pitting and crevice corrosion, critical for refrigeration environments where moisture and chemical contaminants are present
- Thermal Conductivity: Optimized for efficient heat transfer between the refrigerant medium and the cooling fluid in the intermediate cooler
- Mechanical Properties: Maintains structural integrity under repeated thermal expansion and contraction cycles inherent to two-stage compression operation
- Hygienic Surface Finish: Electropolished or mechanically polished inner and outer surfaces to minimize fouling and ensure maximum heat transfer efficiency
Technical Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Type | Coil Tube (盘管) | — |
| Product No. | 347 | Internal Catalog |
| Material Grade | Stainless Steel 304 / 316 / 316L | ASTM A213 / ASME SA-213 |
| Outer Diameter (OD) | 6.0 – 25.4 mm (customizable) | ISO 3505 |
| Wall Thickness | 0.5 – 1.5 mm | — |
| Coil Diameter | 100 – 600 mm (application-dependent) | — |
| Tube Length per Coil | 1.5 – 12.0 m | — |
| Surface Finish | Mirror polished / Electropolished (Ra ≤ 0.4 μm) | ASTM A269 |
| Operating Temperature Range | −60 °C to +200 °C | — |
| Maximum Operating Pressure | Up to 4.0 MPa (gauge) | ASME BPVC Section VIII |
| Heat Treatment | Solution annealed and water quenched | ASTM A270 |
| End Preparation | Beveled ends per ASME B1.20.1 | ASME B1.20.1 |
| Winding Tolerance | ±1.0 mm on coil diameter; ±0.5 mm on pitch | — |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing sequence to ensure dimensional accuracy, surface quality, and metallurgical integrity:
- Material Selection & Incoming Inspection: Stainless steel seamless tubes are sourced from certified mills and subjected to spectroscopic analysis (PMI), dimensional verification, and hydrostatic testing prior to acceptance.
- Cold Drawing / Precision Sizing: Tubes are cold-drawn to achieve the required outer diameter and wall thickness tolerances, ensuring uniform wall cross-section critical for consistent heat transfer performance.
- Surface Treatment: Inner and outer surfaces undergo mechanical polishing followed by electropolishing to achieve a mirror finish (Ra ≤ 0.4 μm), minimizing flow resistance and fouling potential.
- Solution Annealing: Tubes are heated to 1050–1100 °C and rapidly water-quenched to dissolve carbides, restore full austenitic microstructure, and maximize corrosion resistance.
- Coil Winding: Precision CNC-controlled winding machines form the tube into the specified coil geometry, maintaining uniform pitch, coil diameter, and spring-back compensation to prevent post-forming distortion.
- End Forming & Beveling: Tube ends are beveled per ASME B1.20.1 for welding compatibility with connecting fittings and headers.
- Final Quality Control: Each coil tube undergoes dimensional inspection, surface defect examination (visual and eddy current), hydrostatic pressure testing, and material certification verification.
Applications
The primary application of this coil tube is within the intermediate cooler (intercooler) of two-stage compression refrigeration systems. In such systems, refrigerant gas discharged from the first-stage (low-pressure) compressor is cooled before entering the second-stage (high-pressure) compressor. The outlet temperature of the intermediate cooler coil tube directly governs:
- Compression Work Reduction: Lower intermediate temperatures reduce the specific compression work of the second-stage compressor, improving the Coefficient of Performance (COP).
- Discharge Temperature Control: Effective intermediate cooling prevents excessive discharge temperatures that can degrade lubricant quality and accelerate component wear.
- System Reliability: Stable intermediate cooling minimizes thermal cycling stress on compressor components, extending service life.
- Refrigerant Capacity Optimization: Proper intermediate temperature management ensures maximum refrigerant mass flow rate and cooling capacity.
Additional applications include industrial process cooling, chemical processing heat exchangers, pharmaceutical manufacturing systems, food processing refrigeration, and HVAC (Heating, Ventilation, and Air Conditioning) equipment requiring high-purity stainless steel components.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and certifications to ensure product conformity with international standards:
- 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
- ASME / SA-213 — Compliance with American Society of Mechanical Engineers standards for stainless steel tubing
- ASTM A213 — Conformance with American Society for Testing and Materials specifications for austenitic stainless steel seamless tubes
- EN 10217-7 — European standard compliance for stainless steel cold-drawn tubes
- Material Traceability: Full mill certification (MTC) and heat number traceability provided for every batch, enabling complete supply chain accountability
Unique Selling Points
- Thermally Optimized Design: Coil geometry is engineered to maximize heat exchange surface area while minimizing pressure drop, directly improving intermediate cooler efficiency in two-stage compression systems.
- Superior Surface Quality: Mirror-polished interior (Ra ≤ 0.4 μm) reduces flow friction losses and prevents fouling, maintaining heat transfer performance over extended service life.
- Dimensional Precision: CNC-controlled winding ensures coil diameter and pitch accuracy within ±1.0 mm and ±0.5 mm respectively, guaranteeing seamless integration into intercooler housings.
- Full Material Traceability: Every coil tube is accompanied by complete material certification documentation, ensuring compliance with regulatory and audit requirements in demanding industries.
- Customization Capability: Flexible manufacturing capacity allows customization of coil diameter, tube dimensions, material grade, and surface finish to meet specific system design requirements.
- Proven Performance in Refrigeration Systems: Extensive application track record in two-stage compression refrigeration systems demonstrates reliable intermediate cooling performance and long-term durability under cyclic thermal loading.
Technical Note: The intermediate cooler coil tube outlet temperature is a critical process parameter in two-stage compression refrigeration systems. Research and operational experience indicate that each 1 °C reduction in intermediate cooler outlet temperature can yield approximately 1–3% improvement in system COP. Wenzhou Jixing Metal Materials Co., Ltd. coil tubes are engineered to support precise temperature control within the intermediate cooler, enabling system operators to optimize refrigeration performance and energy efficiency.