Stainless Steel Dry Coil Tube — Clean Room HVAC Energy-Efficient Solution
Product Code: JX-CT-318 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd
1. Product Overview
The Stainless Steel Dry Coil Tube (JX-CT-318) is a precision-engineered coiled tubing product designed specifically for dry cooling systems in cleanroom environments. A dry coil operates as an indirect evaporative cooling element, utilizing a separate refrigerant circuit to cool air without direct moisture contact, thereby maintaining stringent indoor air quality (IAQ) parameters in pharmaceutical, semiconductor, and biotechnology facilities. This product series addresses the critical challenge of energy-efficient air handling in controlled environments where humidity control, microbial containment, and thermal performance must coexist.
Based on extensive research into dry coil selection criteria for cleanroom energy conservation, the JX-CT-318 series integrates optimized tube geometry, surface treatments, and material selection to maximize heat transfer efficiency while minimizing pressure drop and fouling risk. The coil tube serves as the primary heat exchange surface within the air handling unit (AHU), enabling superior thermal regulation under low-enthalpy conditions typical of cleanroom return air streams.
2. Material & Properties
2.1 Base Material
The coil tube is manufactured from high-purity austenitic stainless steel conforming to international standards. The primary grades offered include:
- AISI 304 (UNS S30400): The standard grade for general cleanroom applications, offering excellent corrosion resistance, formability, and a minimum yield strength of 205 MPa.
- AISI 316 (UNS S31600): Enhanced molybdenum content (2.0–3.0%) provides superior resistance to chlorides and chemical contaminants, ideal for pharmaceutical and semiconductor cleanrooms.
- AISI 316L (UNS S31603): Low-carbon variant (C ≤ 0.03%) suitable for post-welding applications without sensitization risk.
- AISI 321 (UNS S32100): Titanium-stabilized grade for applications requiring elevated temperature resistance up to 870°C in intermittent service.
2.2 Mechanical Properties
| Property | Grade 304 | Grade 316 | Grade 316L |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 520 | ≥ 515 | ≥ 515 |
| Yield Strength (MPa) | ≥ 205 | ≥ 205 | ≥ 170 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 45 |
| Thermal Conductivity (W/m·K @ 100°C) | 16.3 | 14.6 | 14.6 |
| Specific Heat (J/kg·K) | 500 | 500 | 500 |
| Corrosion Resistance (Pitting, mm) | — | ≥ 32 (ASTM G48) | ≥ 32 (ASTM G48) |
2.3 Surface Finish
- Standard: 2B finish with surface roughness Ra ≤ 0.8 μm
- Polished: Mirror finish with Ra ≤ 0.2 μm (for high-cleanliness pharmaceutical applications)
- Electropolished: Ra ≤ 0.1 μm with passivated surface layer (for GMP-compliant environments)
3. Technical Specifications
| Parameter | Specification | Standard / Reference | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tube Outer Diameter (OD) | 6.35 mm / 9.53 mm / 12.7 mm / 15.88 mm | ASME B36.19M | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Tube Wall Thickness | 0.5 mm – 1.5 mm | ASTM A269 / A270 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Coil Pitch (Tube Spacing) | 12.7 mm – 38.1 mm (configurable) | ASHRAE Handbook – HVAC Systems | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fin Material | Aluminum (standard) / Stainless Steel (special) | — | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fin Density | 10 FPI – 24 FPI (fins per inch) | — | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fin Thickness | 0.1 mm – 0.25 mm | — | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Coil Length (per panel) | 300 mm – 1500 mm | — | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Coil Width (per panel) | 300 mm – 1200 mm | — | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Design Operating Pressure | 0.6 MPa – 1.6 MPa (gauge) | ASME BPVC Section VIII | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Operating Temperature Range | −40°C to +150°C | — | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Refrigerant Compatibility | R-134a, R-407C, R-410A, R-32, Glycol Solutions | ASHRAE Standard 34 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Pressure Drop (face velocity 2.5 m/s) | ≤ 150 Pa (configurable) | ASHRAE Standard 62.1 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Heat Transfer Coefficient | ≥ 180 W/m²·K (air-side) |
| Property | Grade 304 | Grade 316 | Grade 316L |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 520 | ≥ 515 | ≥ 515 |
| Yield Strength (MPa) | ≥ 205 | ≥ 205 | ≥ 170 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 45 |
| Thermal Conductivity (W/m·K @ 100°C) | 16.3 | 14.6 | 14.6 |
| Specific Heat (J/kg·K) | 500 | 500 | 500 |
| Corrosion Resistance (Pitting, mm) | — | ≥ 32 (ASTM G48) | ≥ 32 (ASTM G48) |
2.3 Surface Finish
- Standard: 2B finish with surface roughness Ra ≤ 0.8 μm
- Polished: Mirror finish with Ra ≤ 0.2 μm (for high-cleanliness pharmaceutical applications)
- Electropolished: Ra ≤ 0.1 μm with passivated surface layer (for GMP-compliant environments)
3. Technical Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Tube Outer Diameter (OD) | 6.35 mm / 9.53 mm / 12.7 mm / 15.88 mm | ASME B36.19M |
| Tube Wall Thickness | 0.5 mm – 1.5 mm | ASTM A269 / A270 |
| Coil Pitch (Tube Spacing) | 12.7 mm – 38.1 mm (configurable) | ASHRAE Handbook – HVAC Systems |
| Fin Material | Aluminum (standard) / Stainless Steel (special) | — |
| Fin Density | 10 FPI – 24 FPI (fins per inch) | — |
| Fin Thickness | 0.1 mm – 0.25 mm | — |
| Coil Length (per panel) | 300 mm – 1500 mm | — |
| Coil Width (per panel) | 300 mm – 1200 mm | — |
| Design Operating Pressure | 0.6 MPa – 1.6 MPa (gauge) | ASME BPVC Section VIII |
| Operating Temperature Range | −40°C to +150°C | — |
| Refrigerant Compatibility | R-134a, R-407C, R-410A, R-32, Glycol Solutions | ASHRAE Standard 34 |
| Pressure Drop (face velocity 2.5 m/s) | ≤ 150 Pa (configurable) | ASHRAE Standard 62.1 |
| Heat Transfer Coefficient | ≥ 180 W/m²·K (air-side) | — |
4. Manufacturing Process
The production of the JX-CT-318 dry coil tube follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, surface integrity, and thermal performance:
- Material Verification: Incoming stainless steel strip undergoes spectroscopic analysis (OES) to confirm chemical composition compliance with ASTM specifications. Each heat lot is accompanied by a mill test certificate.
- Slitting & Leveling: Precision slitting to target width, followed by tension leveling to eliminate coil set and ensure flatness within ±0.1 mm/m.
- Tube Forming: Cold-rolled tube forming using high-precision roller dies. The forming process is performed at controlled temperatures (≤ 40°C) to prevent work hardening that would compromise mechanical properties.
- Welding: Continuous longitudinal weld formation via TIG (Tungsten Inert Gas) or laser welding. Weld quality is verified through helium leak testing at 10⁻⁹ Pa·m³/s sensitivity.
- Coiling: Precision coiling onto mandrels of the specified outer diameter, with controlled tension to prevent ovality exceeding 1% of nominal OD.
- Fin Attachment: Fins are mechanically bonded to tubes using a corrugation-and-clinching process, ensuring a thermal contact resistance of ≤ 0.001 m²·K/W.
- Surface Treatment: Optional electropolishing, passivation, or PVD (Physical Vapor Deposition) coating for enhanced corrosion resistance and biocompatibility.
- Final Inspection: Dimensional verification via coordinate measuring machine (CMM), pressure testing at 1.5× design pressure, and visual inspection for surface defects.