Stainless Steel Coil Tube for Freeze Dryer Cold Trap Applications
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd (序号 No. 1024)
1. Product Overview
The Stainless Steel Coil Tube (盘管 Coiltube) is a precision-engineered heat exchange component specifically designed for freeze dryer (lyophilizer) cold trap systems. This product serves as the critical heat transfer surface within the cold trap condenser, where water vapor sublimated from frozen pharmaceutical or biological products is captured and condensed back into solid ice. The coil tube geometry maximizes the surface-area-to-volume ratio, enabling efficient condensation of water vapor at ultra-low temperatures (typically −40°C to −80°C), thereby protecting the vacuum pump and maintaining system pressure integrity during the freeze drying process.
Based on extensive research into frost formation characteristics on coil tube surfaces (《冻干机冷阱盘管表面结霜特性的研究》), this product has been optimized for superior frost deposition uniformity, enhanced heat transfer efficiency, and reliable long-term performance under cyclic thermal loading conditions.
2. Material & Properties
2.1 Base Material
- Primary Alloy: Austenitic Stainless Steel — UNS S30408 / S31603 (AISI 304 / 316L)
- Alternative Grades: S32168 (321), S34700 (347) for elevated temperature applications
- Material Form: Seamless stainless steel tubing, cold-worked (annealed and pickled condition)
2.2 Mechanical Properties
- Tensile Strength (UTS): ≥ 520 MPa (AISI 304), ≥ 515 MPa (AISI 316L)
- Yield Strength (0.2% offset): ≥ 205 MPa (AISI 304), ≥ 170 MPa (AISI 316L)
- Elongation: ≥ 40% (AISI 304), ≥ 45% (AISI 316L)
- Impact Toughness (−40°C): ≥ 47 J (Charpy V-notch), ensuring resistance to brittle fracture at cryogenic operating temperatures
2.3 Physical & Thermal Properties
- Thermal Conductivity (25°C): 16.3 W/(m·K) (AISI 304), 14.6 W/(m·K) (AISI 316L)
- Thermal Conductivity (−40°C): ~13.5 W/(m·K) (AISI 304)
- Linear Thermal Expansion Coefficient (20–100°C): 17.3 × 10⁻⁶ /K (AISI 304)
- Density: 8.00 g/cm³ (AISI 304), 8.03 g/cm³ (AISI 316L)
- Specific Heat Capacity (25°C): 0.50 J/(g·K)
2.4 Corrosion Resistance
- Pitting Resistance (PREN): 18–20 (AISI 304), 24–26 (AISI 316L)
- Chloride Stress Corrosion Cracking (Cl-SCC) Resistance: Excellent (AISI 316L with Mo addition)
- Oxidation Resistance: Suitable for continuous service up to 870°C (1600°F) in non-cyclic oxidation
- Cryogenic Compatibility: Fully qualified for service down to −196°C (liquid nitrogen temperature)
3. Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Name | Stainless Steel Coil Tube (盘管 Coiltube) | — |
| Material Grade | AISI 304 / 316L (UNS S30408 / S31603) | ASTM A213 / A269 |
| Outer Diameter (OD) | Φ6 mm – Φ16 mm (standard range) | ASTM A269 |
| Wall Thickness | 0.5 mm – 1.5 mm | ASTM A269 |
| Coil Pitch (Spacing) | 3.0 mm – 8.0 mm (adjustable per design) | Customer-specific |
| Coil Diameter | Φ50 mm – Φ200 mm | Customer-specific |
| Coil Length / Turns | Up to 12,000 mm (customizable) | — |
| Surface Finish (Ra) | ≤ 0.8 μm (electropolished), ≤ 1.6 μm (passivated) | ASTM A967 |
| Operating Temperature Range | −80°C to +200°C | — |
| Maximum Operating Pressure | 1.5 MPa (15 bar) | ASME BPVC VIII |
| Surface Treatment | Acid pickling + Passivation + Optional Electropolishing | ASTM A967 / A380 |
| Connection Type | Welded (TIG/Orbital), Flared, or Threaded | ASME B31.3 |
| Applicable Standards | GB/T 12771, ASTM A213, EN 10216-5 | — |
| Traceability | Full material certification (EN 10204 3.1) | EN 10204 |
4. Manufacturing Process
4.1 Process Flow
- Material Selection & Incoming Inspection: Seamless stainless steel tubing sourced from certified mills, verified for chemical composition (spectrometric analysis), mechanical properties, and dimensional accuracy per ASTM A213/A269.
- Cutting & End Preparation: Precision saw cutting to specified lengths; end faces deburred and prepared for welding or flaring.
- Forming & Coiling: Cold coiling on CNC-controlled mandrel dies to achieve precise coil diameter, pitch, and geometry. The coiling process maintains dimensional tolerances within ±0.5 mm for coil diameter and ±0.3 mm for pitch.
- Solution Annealing (if required): For heavily cold-worked configurations, solution annealing at 1050–1150°C in a protective atmosphere (argon or vacuum) followed by controlled cooling to relieve residual stresses and restore full austenitic microstructure.
- Welding & Assembly: Orbital TIG (Tungsten Inert Gas) welding for end connections and support structures. Weld parameters controlled to minimize heat-affected zone (HAZ) sensitization. Helium leak testing (≤ 1 × 10⁻⁹ Pa·m³/s) verifies weld integrity.
- Surface Treatment: Acid pickling (HNO₃/HF blend) followed by passivation to remove scale and enrich the surface chromium oxide layer. Optional electropolishing achieves Ra ≤ 0.8 μm for pharmaceutical-grade cleanliness.
- Final Inspection & Testing: Dimensional verification (CMM), surface finish measurement, hydrostatic pressure testing (1.5× operating pressure), and cryogenic impact testing per ASTM A370.
4.2 Key Process Controls
- Dimensional Tolerance: Coil OD ±0.5 mm; Pitch ±0.3 mm; Tube OD ±0.1 mm
- Weld Quality: 100% visual inspection; radiographic testing (RT) for critical welds per ASME Section V
- Cleanliness: Particle count ≤ 100 particles ≥ 5 μm per 100 mL rinse (for pharmaceutical applications)
- Cryogenic Qualification: Proof-tested at −40°C for dimensional stability and absence of cracking
5. Applications
5.1 Primary Applications
- Pharmaceutical Freeze Dryers (Lyophilizers): Cold trap condenser coil for capturing sublimated water vapor, protecting the vacuum system (roots pump / screw pump) from moisture ingress.
- Biopharmaceutical Processing: Cold traps in bioreactor exhaust systems for sterile filtration and condensate recovery.
- Vacuum Pump Protection: General industrial vacuum systems requiring cold trap protection against volatile contaminants.
- Cryogenic Gas Processing: Condensers and cold traps in helium/nitrogen recovery systems.
5.2 Secondary Applications
- Food Industry Freeze Dryers: Coffee, fruits, and functional food lyophilization
- Electronics Manufacturing: Cold traps in vacuum deposition chambers
- Research & Laboratory: Ultra-high vacuum (UHV) systems, mass spectrometry, and electron microscopy
- Medical Device Manufacturing: Cold traps in spray-drying and solvent recovery systems
6. Quality Certifications & Compliance
6.1 Factory & System Certifications
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health & Safety Management System
- GMP (Good Manufacturing Practice) — For pharmaceutical-grade products
- ASME "U" Stamp — Pressure Vessel Code certification (where applicable)
6.2 Product Certifications
- Material Certification: EN 10204 Type 3.1 (Mill Test Certificate) with full chemical analysis and mechanical test results
- Weld Procedure Qualification (WPQ/WPS): Per ASME Section IX / EN ISO 15614
- Non-Destructive Testing (NDT): RT, PT, or Helium Leak Testing per ASME Section V
- Food Contact Compliance: FDA 21 CFR 178.3010 (where applicable)
- EU Compliance: EC No. 1935/2004 (Food Contact Materials Directive)
6.3 Testing & Inspection Protocols
- Hydrostatic Test: 1.5 × design pressure, held for minimum 10 minutes with zero pressure drop
- Leak Test: Helium mass spectrometer leak detection, sensitivity ≤ 1 × 10⁻⁹ Pa·m³/s
- Cryogenic Test: Thermal cycling between +25°C and −80°C (≥ 100 cycles) with post-test dimensional and NDE verification
- Frost Deposition Test: Validation of uniform frost formation characteristics per research protocols (冻干机冷阱盘管表面结霜特性的研究)
7. Unique Selling Points
- Optimized Frost Deposition Geometry: Coil pitch and surface finish engineered based on research into frost formation dynamics, ensuring uniform ice nucleation and growth patterns that maximize condensation efficiency and facilitate easy defrost cycles.
- Cryogenic-Grade Material Selection: Full austenitic stainless steel composition ensures exceptional toughness and dimensional stability at ultra-low temperatures (−80°C and below), eliminating risk of brittle fracture.
- Pharmaceutical-Grade Cleanliness: Electropolished surface with Ra ≤ 0.8 μm meets GMP requirements for pharmaceutical lyophilization, minimizing microbial contamination risk and facilitating CIP (Clean-In-Place) procedures.
- Full Traceability: Every coil tube is traceable from raw material mill to final delivery, with complete documentation chain supporting regulatory audits (FDA, EMA).
- Custom Engineering Capability: Flexible design parameters (coil diameter, pitch, tube size, length) allow optimization for specific freeze dryer models and process requirements.
- Research-Validated Performance: Product design informed by peer-reviewed studies on frost formation characteristics in freeze dryer cold traps, ensuring scientifically grounded performance optimization.
8. Technical Notes & Recommendations
Installation Guidance: Ensure proper thermal insulation (vacuum-jacketed or multi-layer insulation) around the coil assembly to minimize heat ingress and maintain cold trap performance. Support structures should accommodate thermal contraction (approximately 0.5% linear contraction from +25°C to −80°C).
Maintenance: Periodic defrost cycles (heated water or ambient air) are recommended to remove accumulated frost. The smooth electropolished surface facilitates easy frost release. Inspect for pitting or corrosion annually, particularly in chloride-containing environments.
Storage: Store in a dry, ventilated environment. Protect from mechanical damage and avoid contact with carbon steel to prevent galvanic contamination and iron pitting.
Manufacturer Contact: Wenzhou Jixing Metal Materials Co., Ltd (温州吉兴金属材料有限公司)
Product Reference No.: 1024
Classification: Literature Study / Technical Documentation (文献学习)