316L Sanitary Stainless Steel Heat Exchanger Coil Tube for Dairy Pasteurizers
Product Overview
The 316L Sanitary Heat Exchanger Coil Tube is a precision-engineered welded stainless steel coil tube specifically designed for use in dairy pasteurization systems. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product is purpose-built to withstand the demanding thermal and chemical conditions encountered during the pasteurization of milk and dairy products. Operating within the critical pasteurization window of 72–85°C for a minimum hold time of 15 seconds, this coil tube ensures reliable, efficient heat transfer while resisting the protein-based fouling and scaling that commonly degrade conventional heat exchanger surfaces.
Unlike standard industrial coil tubing, this product incorporates a turbulent flow internal geometry and an ultra-smooth sanitary surface finish to minimize the adhesion of denatured proteins, lactose crystallization, and mineral deposits — extending cleaning cycles, reducing downtime, and maintaining consistent heat transfer performance over extended operational periods.
Material & Properties
The coil tube is fabricated from ASTM A270 / EN 10216-5 Grade 316L austenitic stainless steel, selected for its superior resistance to pitting, crevice corrosion, and stress-corrosion cracking in the presence of dairy-derived chlorides, lactic acid, and cleaning agents (CIP chemicals such as nitric acid, caustic soda, and peracetic acid).
- Corrosion Resistance: The addition of 2.0–2.5% molybdenum provides enhanced resistance to chloride-induced pitting and stress-corrosion cracking compared to 304/304L grades, making it the preferred material for dairy processing environments.
- Low Carbon Content (≤0.03% C): Eliminates the risk of intergranular corrosion during welding and high-temperature operation, ensuring long-term structural integrity.
- Sanitary Surface Finish (Ra ≤ 0.8 μm): The internal and external surfaces are electropolished to a roughness average of 0.8 micrometers or below, meeting FDA 21 CFR 178.3010 and EHEDG standards for food-contact surfaces. This ultra-smooth finish prevents bacterial colonization and significantly reduces protein adhesion.
- Biocompatibility: Fully compliant with food-grade requirements; no lead, nickel leaching concerns beyond regulatory limits, and no toxic alloying elements.
Specifications
| Parameter | Specification |
|---|---|
| Material Grade | ASTM A270 / EN 10216-5 316L (UNS S31603) |
| Manufacturing Method | Sanitary welded coil tube (ERW / orbital TIG welded) |
| Surface Finish (Internal) | Electropolished, Ra ≤ 0.8 μm |
| Surface Finish (External) | Brushed or electropolished, Ra ≤ 0.8 μm |
| Operating Temperature | Up to 85°C (pasteurization range: 72–85°C) |
| Hold Time | ≥ 15 seconds at target pasteurization temperature |
| Flow Design | Turbulent flow internal geometry (enhanced heat transfer, anti-scaling) |
| Weld Type | Autogenous sanitary weld, internal ground and polished flush |
| Compliance | FDA 21 CFR 178.3010, EHEDG, 3-A Sanitary Standards, ISO 22000 |
| Available OD | 12.7 mm – 108 mm (customizable) |
| Wall Thickness | 0.8 mm – 3.0 mm (customizable) |
| Coil Diameter | Custom per OEM heat exchanger design |
| End Forming | Sanitary tri-clamp, weld-in, or custom end fittings |
Manufacturing Process
Each coil tube is produced through a tightly controlled multi-stage manufacturing process designed to ensure dimensional accuracy, surface integrity, and sanitary compliance:
- Coil Forming: High-precision CNC coil forming machines roll the 316L flat strip into the required coil geometry with tight tolerance on outer diameter, wall thickness, and coil pitch.
- Welding: Continuous longitudinal welds are produced using automated resistance welding (ERW) or high-speed orbital TIG welding. Weld parameters are optimized to minimize heat-affected zone (HAZ) width and prevent oxidation.
- Internal Weld Grinding: The internal weld seam is ground flush to eliminate crevices that could harbor bacteria or promote fouling.
- Electropolishing: Both internal and external surfaces undergo electrochemical polishing to achieve Ra ≤ 0.8 μm. This process passivates the surface, removes micro-contaminants, and creates a uniform chromium oxide layer that enhances corrosion resistance.
- Acid Pickling & Passivation: Post-welding acid pickling removes mill scale and heat tint; subsequent passivation restores full passive film integrity.
- Dimensional & Surface Inspection: Every coil tube undergoes 100% dimensional verification, surface roughness measurement (per ASTM A262 / ISO 10110), and visual inspection of weld quality.
- Hydrostatic Testing: Each coil is pressure-tested to 1.5× maximum operating pressure to confirm weld integrity and absence of leaks.
- Packaging: Tubes are wrapped in protective film, boxed, and shipped with full material traceability documentation.
Applications
This 316L sanitary heat exchanger coil tube is specifically engineered for the following dairy pasteurization applications:
- Plate Pasteurizers: Integrated as heating and cooling coils within multi-plate heat exchanger assemblies for batch and continuous pasteurization of whole milk, skim milk, and cream.
- Tubular Pasteurizers: Serves as the core heat transfer element in shell-and-coil tubular pasteurization systems for small to medium-capacity dairy processing lines.
- Hold-Tube Pasteurizers: Functions as the holding coil ensuring the minimum 15-second residence time at 72–85°C to achieve effective pathogen inactivation.
- Cooling Coils: Used in the post-pasteurization cooling section to rapidly reduce product temperature while preventing thermal shock.
- UHT Pre-Treatment Systems: Suitable for pre-heating stages in ultra-high temperature processing lines.
The turbulent flow design actively disrupts the boundary layer near the tube wall, promoting uniform temperature distribution and preventing the localized overheating that leads to protein denaturation and scaling. This is critical in dairy applications where even minor fouling can reduce heat transfer efficiency by 20–40% and create harborage points for Listeria and other spoilage organisms.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems to ensure every coil tube meets international standards for food-grade stainless steel products:
- ISO 9001:2015 — Quality Management System certification
- ISO 22000 / HACCP — Food Safety Management System
- 3-A Sanitary Standards — Meeting U.S. dairy industry sanitary design requirements
- EHEDG — European Hygienic Engineering Design Group compliance for surface finish and design
- FDA 21 CFR 178.3010 — U.S. Food and Drug Administration compliance for stainless steel food-contact surfaces
- CE Marking — European conformity for machinery and food-contact materials
- EN 10216-5 — European standard for austenitic stainless steel tubes for heat exchangers
- ASTM A270 — American standard for seamless and welded austenitic stainless steel tubing
Full material test reports (MTR), surface roughness certificates, and hydrostatic test records are provided with every shipment for complete traceability and regulatory audit readiness.
Unique Selling Points
- Anti-Scaling Turbulent Flow Design: Proprietary internal geometry ensures turbulent flow conditions even at low flow velocities, dramatically reducing protein fouling and extending cleaning intervals by up to 50%.
- Ultra-Smooth Ra ≤ 0.8 μm Surface: Superior to standard sanitary finishes (Ra ≤ 1.2 μm), providing maximum hygiene and minimum bacterial adhesion.
- 316L Grade Selection: Superior to 304L in chloride-rich dairy environments, offering longer service life and reduced maintenance.
- Full Traceability: Each coil tube is accompanied by complete material documentation, enabling seamless regulatory compliance for global dairy export markets.
- Custom Engineering: Coil dimensions, end fittings, and layout configurations are fully customizable to match OEM pasteurizer designs.