Stainless Steel Coil Tube for Microalgae Cultivation Systems
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product designed for specialized applications in bioprocessing and microalgae cultivation systems. As a critical component of the New-Type Coil Tube Microalgae Cultivation Machine, this product combines the structural integrity of stainless steel with the geometric advantages of a continuous coiled configuration, enabling efficient heat exchange, fluid distribution, and nutrient delivery within closed-loop biological systems.
Unlike conventional straight pipe assemblies, coil tubes offer superior surface-area-to-volume ratios, enhanced fluid dynamics, and compact spatial footprint—making them ideal for bioreactor integration, photobioreactor (PBR) manifolds, and nutrient circulation loops in industrial-scale microalgae production.
Material Composition & Mechanical Properties
Base Material
- Grade: SUS304 / SUS316L (AISI 304 / 316L)
- Chemical Composition (SUS316L): Carbon ≤0.03%, Chromium 16.0–18.0%, Nickel 10.0–14.0%, Molybdenum 2.0–3.0%, Silicon ≤1.00%, Manganese ≤2.00%, Phosphorus ≤0.045%, Sulfur ≤0.030%
- Corrosion Resistance: Exceptional resistance to chlorinated nutrient media, acidic growth substrates, and prolonged exposure to biological fluids
Mechanical Properties
| Property | SUS304 (Annealed) | SUS316L (Annealed) |
|---|---|---|
| Tensile Strength (MPa) | ≥520 | ≥485 |
| Yield Strength (MPa, 0.2% offset) | ≥205 | ≥170 |
| Elongation at Break (%) | ≥40 | ≥40 |
| Density (g/cm³) | 7.93 | 8.00 |
| Thermal Conductivity (W/m·K, 20°C) | 16.3 | 14.6 |
| Operating Temperature Range | −196°C to +870°C | −196°C to +870°C |
Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6 mm – 32 mm (customizable) |
| Wall Thickness | 0.5 mm – 2.0 mm |
| Coil Diameter | 100 mm – 500 mm |
| Coil Length per Spool | 5 m – 200 m |
| Surface Finish | Mirror polished (Ra ≤0.4 μm) or Electropolished (Ra ≤0.2 μm) |
| Seam Type | Welded (TIG) or Seamless (cold-drawn) |
| Tolerance (OD) | ±0.05 mm |
| Tolerance (Wall Thickness) | ±0.03 mm |
| Maximum Working Pressure | 1.6 MPa (standard); 4.0 MPa (reinforced) |
| End Treatment | Beveled, threaded, flanged, or socket-welded |
| Applicable Standards | ASTM A269 / A213 / A249; GB/T 12771; EN 10217-7 |
Manufacturing Process
- Raw Material Selection: High-purity stainless steel strip or seamless tube billets sourced from certified mill suppliers, verified via spectroscopic analysis (OES) for chemical compliance.
- Forming & Coiling: Precision CNC-controlled coiling machines form straight tube stock into uniform helical geometries with controlled pitch, diameter, and curvature radius to ensure consistent hydraulic performance.
- Welding (if applicable): Pulsed TIG welding performed under argon shielding with internal purge gas to achieve penetration welds free of oxidation, porosity, or cold laps.
- Heat Treatment: Solution annealing at 1050–1100°C followed by controlled water quenching to restore full austenitic microstructure and maximize corrosion resistance.
- Surface Finishing: Multi-stage mechanical polishing followed by electrochemical polishing (electropolishing) to achieve biocompatible surface roughness, remove work-hardened layers, and passivate the surface.
- Dimensional Inspection: Laser diameter measurement, ultrasonic wall-thickness scanning, and coordinate measuring machine (CMM) verification of coil geometry.
- Hydrostatic & Leak Testing: Each coil subjected to 1.5× working pressure hydrostatic test for minimum 30 seconds with zero pressure drop tolerance.
Applications
Microalgae Cultivation Systems (Primary Application)
- Photobioreactor (PBR) Nutrient Delivery: Coil tubes serve as distribution manifolds for nutrient-rich culture media, ensuring uniform flow and minimizing dead zones that could lead to biofilm formation.
- Heat Exchange Coils: Integrated temperature control loops maintain optimal growth temperatures (20–30°C) for thermophilic and mesophilic microalgae species (e.g., Chlorella vulgaris, Spirulina platensis, Haematococcus pluvialis).
- Gas Sparging & CO₂ Delivery: Micro-perforated coil variants enable controlled CO₂ aeration for enhanced photosynthetic rates.
- Closed-Loop Circulation: Continuous coil configurations facilitate recirculation of culture media, reducing contamination risk and improving biomass yield.
Additional Applications
- Bioprocessing and pharmaceutical manufacturing
- Food and beverage processing (dairy, beverage dispensing systems)
- Medical device tubing and dialysis equipment
- Heat exchangers in HVAC and industrial cooling systems
- Chemical processing and semiconductor clean-room fluid systems
Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System
- CE Marking — Conformity with European health, safety, and environmental protection standards
- NSF/ANSI 61 — Drinking water system components (where applicable)
- 3-A Sanitary Standards — Dairy and food processing equipment compliance
- Mill Test Certificates (MTC): EN 10204 Type 3.1 certificates provided for each batch, documenting chemical composition and mechanical properties
- Full Traceability: Heat number tracking from raw material through final product for complete supply chain auditability
Unique Selling Points
The coil tube products from Wenzhou Jixing Metal Materials Co., Ltd. distinguish themselves through several key advantages:
- Biocompatible Surface Integrity: Electropolished surfaces with Ra ≤0.2 μm eliminate microbial adhesion sites, critical for long-term aseptic operation in microalgae bioreactors.
- Precision Geometric Consistency: CNC-coiled geometry ensures uniform hydraulic resistance and predictable pressure drop across the entire coil length—eliminating flow maldistribution common in hand-formed alternatives.
- Superior Corrosion Performance: SUS316L grade with controlled interstitial carbon content provides outstanding resistance to chloride-induced pitting in nutrient media containing ammonium salts and trace metal chelates.
- Compact System Integration: High surface-area-to-volume ratio enables space-efficient reactor designs, reducing capital expenditure for large-scale algae cultivation facilities.
- Customizable Configurations: Flexible ordering options for coil diameter, pitch, length, wall thickness, and end fittings to match specific bioreactor architectures.
- Full Documentation Package: Each shipment includes material certificates, dimensional inspection reports, and hydrostatic test records supporting regulatory submissions for food-grade and pharmaceutical applications.
Technical Notes
When integrating coil tubes into microalgae cultivation systems, engineers should account for the following design considerations:
- Minimum bend radius should not exceed 3× tube OD to prevent flow separation and turbulence-induced shear stress on algal cells.
- For photoautotrophic cultivation, coil placement must not obstruct light penetration paths in tubular PBRs; UV-transmissive jacketing may be required.
- Periodic CIP (Clean-In-Place) compatibility is ensured by the electropolished interior surface, which tolerates repeated alkaline peroxide and acid citric acid cleaning cycles without surface degradation.
- Thermal expansion coefficient (17.3 × 10⁻⁶ /°C for SUS304) should be accommodated in support structures to prevent mechanical fatigue under thermal cycling.