Stainless Steel Intermediate Cooler Coil Tube (盘管 / Coiltube) — Technical Specification
1. Product Overview
The Stainless Steel Intermediate Cooler Coil Tube (also referred to as 中冷盘管, Intermediate Cooler Coil) is a precision-engineered tubular heat exchange component manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is designed primarily for use in industrial refrigeration, air conditioning systems, and process cooling applications where efficient heat dissipation and energy conservation are critical requirements.
The coil tube serves as an intermediate cooling medium, facilitating thermal energy transfer between process streams. Its coiled geometry maximizes the heat exchange surface area within a compact footprint, thereby enhancing thermal efficiency and reducing overall energy consumption in the system. This product line represents a significant advancement in energy-saving heat exchange technology, as demonstrated by the company's comprehensive study on the energy-saving functions of intermediate cooler coil tubes (《中冷盘管的节能作用》).
1.1 Unique Selling Points
- Energy Efficiency: The optimized coil geometry achieves superior heat transfer coefficients, reducing compressor energy consumption by up to 20–30% compared to conventional straight-tube designs.
- Corrosion Resistance: Fabricated from high-grade austenitic stainless steel, providing exceptional resistance to oxidation, pitting, and intergranular corrosion in aggressive environments.
- Compact Design: The coiled configuration offers maximum heat exchange area per unit volume, enabling space-efficient installation in constrained industrial settings.
- Thermal Stability: Maintains consistent heat transfer performance across a wide temperature range (−40°C to +400°C), ensuring reliable operation under varying process conditions.
- Customization Capability: Available in multiple diameters, wall thicknesses, and coil configurations to meet specific application requirements.
2. Material & Properties
2.1 Base Material
The coil tube is manufactured from austenitic stainless steel conforming to international material standards. The primary grades offered include:
- SUS304 / AISI 304 / EN 1.4301: General-purpose austenitic stainless steel with excellent formability and corrosion resistance.
- SUS316L / AISI 316L / EN 1.4404: Low-carbon, molybdenum-bearing grade offering superior resistance to chloride-induced pitting and crevice corrosion.
- SUS321 / AISI 321 / EN 1.4541: Titanium-stabilized grade suitable for elevated temperature applications with enhanced resistance to intergranular corrosion.
2.2 Mechanical Properties
| Property | Specification | Test Method |
|---|---|---|
| Tensile Strength (抗拉强度) | ≥ 520 MPa | ASTM A380 / EN 10216-5 |
| Yield Strength (屈服强度) | ≥ 205 MPa | ASTM A380 / EN 10216-5 |
| Elongation (延伸率) | ≥ 40% | ASTM A380 / EN 10216-5 |
| Hardness (硬度) | ≤ 220 HV | ASTM A955 / ISO 6507 |
| Impact Strength (冲击强度) | ≥ 30 J at −40°C | ASTM A255 / ISO 148 |
2.3 Thermal Properties
| Property | Value (SUS304) | Value (SUS316L) |
|---|---|---|
| Thermal Conductivity (热导率) at 20°C | 16.3 W/(m·K) | 14.6 W/(m·K) |
| Specific Heat Capacity (比热容) at 20°C | 500 J/(kg·K) | 500 J/(kg·K) |
| Thermal Expansion Coefficient (热膨胀系数) 100–400°C | 17.3 × 10⁻⁶ /K | 16.0 × 10⁻⁶ /K |
| Operating Temperature Range | −196°C to +870°C | −196°C to +870°C |
2.4 Chemical Composition (Typical)
| Element | SUS304 (wt%) | SUS316L (wt%) |
|---|---|---|
| C (Carbon 碳) | ≤ 0.08 | ≤ 0.03 |
| Si (Silicon 硅) | ≤ 0.75 | ≤ 0.75 |
| Mn (Manganese 锰) | ≤ 2.00 | ≤ 2.00 |
| Cr (Chromium 铬) | 18.0–20.0 | 16.0–18.0 |
| Ni (Nickel 镍) | 8.0–10.5 | 10.0–14.0 |
| Mo (Molybdenum 钼) | — | 2.0–3.0 |
| N (Nitrogen 氮) | ≤ 0.10 | ≤ 0.10 |
3. Specifications
3.1 Dimensional Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outer Diameter (外径, OD) | 6 mm – 32.5 mm | ASTM A554 / EN 10217-7 |
| Wall Thickness (壁厚, WT) | 0.5 mm – 2.5 mm | ASTM A554 / EN 10217-7 |
| Coil Diameter (盘管直径, CD) | 50 mm – 500 mm (customizable) | Company Standard |
| Coil Length / Development Length (展开长度) | 1 m – 100 m (per coil unit) | Company Standard |
| Tolerance on OD (外径公差) | ±0.05 mm (precision grade) | ASTM A554 |
| Tolerance on WT (壁厚公差) | ±10% of nominal | ASTM A554 |
| End Preparation (端部处理) | Plain, Beveled, or Flanged | Customer Specification |
| Surface Finish (表面光洁度) | Ra ≤ 0.8 μm (polished); Ra ≤ 3.2 μm (standard) | ISO 1302 |
3.2 Pressure & Temperature Ratings
| Parameter | Specification |
|---|---|
| Design Pressure (设计压力) | Up to 16.0 MPa (depending on dimensions) |
| Test Pressure (试验压力) | 1.5 × Design Pressure |
| Maximum Operating Temperature (最高工作温度) | +400°C (continuous) |
| Minimum Operating Temperature (最低工作温度) | −196°C (cryogenic capable) |
3.3 Common Size Configurations
| Model Designation | OD × WT (mm) | Coil Diameter (mm) | Typical Application |
|---|---|---|---|
| JX-CT-06-05 | 6.0 × 0.5 | 100 | Refrigeration evaporator coils |
| JX-CT-09-08 | 9.0 × 0.8 | 150 | A/C intermediate coolers |
| JX-CT-12-10 | 12.0 × 1.0 | 200 | Process cooling systems |
| JX-CT-16-12 | 16.0 × 1.2 | 250 | Industrial heat exchangers |
| JX-CT-19-15 | 19.0 × 1.5 | 300 | High-pressure cooling loops |
| JX-CT-25-20 | 25.4 × 2.0 | 400 | Heavy-duty process applications |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Inspection (原材料检验): Incoming stainless steel strip/coil is verified for chemical composition (spectrometric analysis), mechanical properties, and surface quality per ASTM A480 / EN 10204 Type 3.1 certificates.
- Slitting & Leveling (分条与矫平): The parent coil is slit to the required width and leveled to eliminate coil set, ensuring uniform flatness for subsequent forming operations.
- Forming / Pipe Making (制管成型): Precision roll-forming or spiral welding converts the flat strip into a seamless or welded tube with tight dimensional tolerances. For seamless tubes, cold-drawing is employed.
- Coil Winding (盘绕成型): The formed tube is wound into the specified coil geometry using CNC-controlled winding equipment to maintain uniform pitch, concentricity, and mechanical integrity without work hardening.
- Welding & Joining (焊接与连接): Where continuous length is required, coil ends are joined by orbital TIG welding (GTAW) or resistance welding, followed by internal and external grinding to restore bore diameter.
- Precision Annealing (精密退火): The coiled tube undergoes solution annealing (1050–1100°C for SUS304; 1050–1150°C for SUS316L) followed by rapid quenching to achieve full austenitic structure, eliminate residual stresses, and restore maximum ductility.
- Pickling & Passivation (酸洗钝化): Acid pickling (HNO₃/HF mixture) removes oxide scale, followed by passivation treatment to establish a protective chromium oxide layer on the surface.
- Surface Finishing (表面处理): Optional mechanical polishing (Ra ≤ 0.8 μm) or electropolishing for sanitary applications.
- Quality Inspection & Testing (质量检测): Comprehensive dimensional measurement, hydrostatic pressure testing, dye penetrant testing (PT), eddy current testing (ECT), and radiographic testing (RT) as applicable.
- Packaging & Dispatch (包装与发货): Protected packaging with moisture barriers, labeling with material certificates, and traceability documentation.
4.2 Key Process Controls
- Dimensional Accuracy: CNC-controlled forming and winding ensure OD tolerance within ±0.05 mm and coil pitch consistency within ±0.5 mm.
- Microstructural Integrity: Annealing cycles are monitored via thermocouple-controlled furnaces with documented heat treatment records.
- Weld Quality: Orbital TIG welds are inspected by 100% visual examination and spot RT/PT per ASME Section IX requirements.
- Traceability: Each coil tube batch carries a unique heat number traceable to mill certificates and in-house test records.
5. Applications
5.1 Primary Application Domains
- Intermediate Cooling Systems (中冷系统): The primary application domain — coil tubes function as intermediate coolers in multi-stage compression systems, reducing discharge temperature between compression stages to improve overall thermodynamic efficiency and reduce energy consumption.
- Industrial Refrigeration (工业制冷): Evaporator and condenser coils in ammonia, fluorocarbon, and CO₂ refrigeration systems for food processing, cold storage, and chemical manufacturing.
- Air Conditioning Systems (空调系统): Intermediate coolers and economizer coils in commercial and industrial HVAC systems for enhanced energy efficiency.
- Process Cooling (工艺冷却): Precision temperature control in pharmaceutical manufacturing, chemical synthesis, and polymer processing applications.
- Cryogenic Applications (低温应用): Intermediate heat exchange in liquefied natural gas (LNG) processing, cryogenic storage, and low-temperature separation processes.
- Food & Beverage Industry (食品饮料行业): Sanitary-grade coil tubes for pasteurization, CIP (Clean-in-Place) compatible heat exchange systems in dairy, brewing, and beverage production.
- Power Generation (发电): Intermediate coolers in gas turbine combined cycle plants for improved thermal efficiency.
- Marine & Offshore (海洋与海上): Corrosion-resistant coil tubes for shipboard cooling systems and offshore platform process cooling.
5.2 Energy-Saving Performance
Based on the company's study on the energy-saving function of intermediate cooler coil tubes (《中冷盘管的节能作用》), the deployment of optimized stainless steel coil tube intermediate coolers in multi-stage compression systems has demonstrated the following energy-saving effects:
- Reduced Discharge Temperature: Intermediate cooling between compression stages reduces the discharge temperature of the second-stage compressor by