316L Sanitary Coiled Tube for Dairy Pasteurizer Heat Exchangers
Product Overview
The 316L Sanitary Coiled Tube (Coiltube) is a precision-engineered heat exchange component specifically designed for use in dairy pasteurization systems. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this coiled tube is purpose-built to withstand the demanding thermal cycling and hygienic requirements of continuous-flow pasteurization processes, where milk is heated to temperatures between 72°C and 85°C (162°F–185°F) for a minimum of 15 seconds to ensure pathogen elimination while preserving nutritional and sensory qualities.
Unlike conventional heat exchanger tubes, this coiled tube incorporates a turbulent flow internal design that actively resists protein scaling and biofilm formation — one of the most persistent challenges in dairy processing equipment. The combination of high-grade 316L austenitic stainless steel, ultra-smooth interior surfaces, and hydrodynamic optimization makes this product an ideal solution for high-throughput dairy processing facilities.
Material & Properties
The coiled tube is fabricated from AISI 316L (UNS S31603) sanitary-grade austenitic stainless steel, selected for its exceptional corrosion resistance, hygienic performance, and long-term durability in food-grade environments.
- Corrosion Resistance: The addition of 2.0–3.0% molybdenum provides superior resistance to chloride pitting and crevice corrosion, essential for environments involving salted dairy products and aggressive cleaning agents (CIP chemicals).
- Low Carbon Content: The "L" (low carbon) designation ensures resistance to sensitization during welding, preventing intergranular corrosion and maintaining material integrity throughout the product's service life.
- Surface Finish: Interior surface roughness of Ra ≤ 0.8 μm (32 μin) minimizes bacterial adhesion and facilitates effective CIP (Clean-In-Place) operations, meeting the most stringent sanitary requirements of the dairy industry.
- Hygienic Compliance: All surfaces conform to FDA 21 CFR and EU 1935/2004 food contact material regulations.
Technical Specifications
| Parameter | Specification |
|---|---|
| Material Grade | AISI 316L / UNS S31603 |
| Tube Type | Sanitary welded coil tube (helical/coiled configuration) |
| Outside Diameter (OD) | 12.7 mm – 50.8 mm (1/2" – 2") |
| Wall Thickness | 0.8 mm – 2.0 mm (0.031" – 0.079") |
| Surface Roughness (Interior) | Ra ≤ 0.8 μm (≤ 32 μin) |
| Surface Roughness (Exterior) | Ra ≤ 1.6 μm (≤ 63 μin) |
| Weld Type | Continuous longitudinal welded seam, passivated |
| Coil Diameter | Custom (typical: 200 mm – 600 mm / 8" – 24") |
| Coil Pitch / Spacing | Custom, optimized for turbulent flow |
| Operating Temperature | −50°C to +400°C (−58°F to +752°F) |
| Operating Pressure | Up to 1.6 MPa (232 psi) continuous |
| Flow Design | Turbulent flow internal geometry (anti-scaling) |
| Standards Compliance | ASTM A269, ASTM A270, EN 10217-7 |
Manufacturing Process
The production of this sanitary coiled tube follows a rigorous, multi-stage manufacturing process to ensure dimensional accuracy, surface integrity, and hygienic performance:
- Coil Winding: Precision cold-forming of 316L stainless steel coil stock using CNC-controlled winding equipment to achieve exact coil diameter, pitch, and concentricity tolerances.
- Seam Welding: Continuous longitudinal seam welding performed using high-purity argon shielding to prevent oxidation and ensure weld integrity.
- Passivation & Pickling: Post-weld acid pickling and chemical passivation to remove heat-affected scale and restore the full corrosion resistance of the 316L alloy.
- Electropolishing: Interior electropolishing to achieve the specified Ra ≤ 0.8 μm surface finish, removing micro-roughness and creating a smooth, uniform surface that resists bacterial colonization.
- Turbulent Flow Integration: Internal helical rib structures or corrugations are incorporated during the forming process to promote turbulent flow patterns, increasing heat transfer coefficients and preventing protein deposit accumulation on tube walls.
- Quality Inspection: Each coil undergoes dimensional verification, surface roughness measurement, hydrostatic pressure testing, and visual/weld inspection prior to shipment.
Applications
Primary Application: Dairy Pasteurization Systems
This coiled tube is specifically engineered for integration into plate-and-frame and tubular pasteurizer systems used in dairy processing. During the pasteurization cycle, raw milk is circulated through the coiled tube where it is heated to a target temperature of 72–85°C (162°F–185°F) for a minimum holding time of 15 seconds. This thermal treatment effectively destroys pathogenic microorganisms (including Listeria, Salmonella, E. coli, and Campylobacter) while maintaining the nutritional profile, flavor, and shelf stability of the finished product.
Key Application Areas:
- Plate Heat Exchanger Coils: Used as serpentine or helical coils within pasteurizer heat exchange assemblies for milk, cream, and cheese whey processing.
- HTST Pasteurizers: High-Temperature Short-Time pasteurization systems requiring rapid heating and cooling with minimal product degradation.
- Regenerative Heat Exchangers: Preheating sections where warm pasteurized product transfers heat to incoming raw product, improving energy efficiency.
- UHT Processing Support: Auxiliary heating coils in ultra-high temperature processing lines for shelf-stable dairy products.
Additional Applications:
- Food and beverage pasteurization systems (juices, beverages)
- Pharmaceutical clean fluid heating circuits
- Beverage brewing and fermentation temperature control
- Chemical processing heat exchangers requiring high corrosion resistance
Unique Selling Points
Turbulent Flow Anti-Scaling Design: The proprietary internal flow geometry promotes turbulent conditions within the tube, significantly reducing protein fouling and scaling that commonly plagues dairy heat exchangers. This extends cleaning intervals, reduces downtime, and improves overall equipment effectiveness (OEE).
- Superior Surface Finish: Ra ≤ 0.8 μm interior finish exceeds standard sanitary requirements, ensuring minimal bacterial adhesion and optimal CIP performance.
- 316L Grade Advantage: Molybdenum-enhanced alloy provides unmatched resistance to chloride attack from cleaning chemicals and salt-containing dairy products.
- Energy Efficiency: Turbulent flow increases the heat transfer coefficient by up to 30–50% compared to smooth tubes, reducing energy consumption in pasteurization cycles.
- Custom Coil Geometry: Flexible manufacturing capability allows customization of coil diameter, pitch, and length to match specific pasteurizer designs and throughput requirements.
- Extended Service Life: The combination of 316L material, electropolished surfaces, and anti-scaling design results in significantly longer replacement intervals compared to standard coil tubes.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and holds the following certifications to ensure product reliability and regulatory compliance:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001 — Environmental Management System Certification
- ISO 22000 / HACCP — Food Safety Management System Certification
- NSF/ANSI 61 — Drinking Water System Components Certification
- 3-A Sanitary Standards — Sanitary Design Approval for Dairy Equipment Components
- CE Marking — European Conformity for Machinery Directive compliance
- ASTM A269 / A270 — Material and dimensional compliance for stainless steel tubing
All products are accompanied by full material test certificates (MTC), surface finish reports, and dimensional inspection documentation to facilitate customer quality audits and regulatory submissions.