Stainless Steel Coil Tube for Ultra-High Temperature (UHT) Sterilization Systems
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular component specifically designed for integration into full-automatic ultra-high temperature sterilization equipment. These coil tubes serve as the primary heat exchange and fluid conveyance elements within UHT processing systems, where they are subjected to sustained exposure at temperatures ranging from 121°C to 155°C under controlled pressure environments. The product is engineered to ensure maximum thermal transfer efficiency, mechanical integrity, and sanitary compliance in demanding sterilization applications.
Unlike conventional straight-length piping, the coiled configuration dramatically increases the effective heat exchange surface area within a compact footprint, making it indispensable for continuous-flow UHT sterilization processes used in food, beverage, pharmaceutical, and biotechnology industries. The coil geometry promotes uniform fluid velocity distribution and minimizes stagnation zones, thereby reducing the risk of product degradation and microbial contamination.
Material & Properties
The coil tubes are fabricated from high-grade austenitic stainless steels, selected for their superior corrosion resistance, mechanical strength at elevated temperatures, and full compliance with global sanitary standards.
- Primary Material Grade: AISI 304 (UNS S30408) — the standard grade for general-purpose UHT applications, offering excellent resistance to oxidation, pitting, and crevice corrosion.
- Alternative Material Grade: AISI 316L (UNS S31603) — specified for applications involving chloride-containing media, aggressive chemical cleaning agents (CIP systems), or pharmaceutical-grade processing where enhanced corrosion resistance is mandated.
- Surface Finish: Electropolished to achieve a surface roughness of Ra ≤ 0.4 μm, ensuring minimal bacterial adhesion and facilitating automated cleaning-in-place (CIP) procedures.
- Alloy Composition (AISI 304): Chromium (Cr) 18–20%, Nickel (Ni) 8–10.5%, Manganese (Mn) ≤ 2%, Carbon (C) ≤ 0.08%.
- Alloy Composition (AISI 316L): Chromium (Cr) 16–18%, Nickel (Ni) 10–14%, Molybdenum (Mo) 2–3%, Carbon (C) ≤ 0.03%.
Key Mechanical Properties (at 20°C):
- Tensile Strength (UTS): ≥ 520 MPa (AISI 304); ≥ 485 MPa (AISI 316L)
- Yield Strength: ≥ 205 MPa (AISI 304); ≥ 170 MPa (AISI 316L)
- Elongation: ≥ 40% (AISI 304); ≥ 35% (AISI 316L)
- Thermal Conductivity: 16.3 W/(m·K) (AISI 304); 16.3 W/(m·K) (AISI 316L)
- Operating Temperature Range: −196°C to +450°C (continuous)
- Maximum Operating Pressure: Up to 1.6 MPa (design dependent)
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | Φ12 mm – Φ51 mm (customizable) | EN 10217-7 / ASTM A213 |
| Wall Thickness (WT) | 0.5 mm – 3.0 mm | EN 10217-7 / ASTM A269 |
| Coil Diameter (CD) | Φ150 mm – Φ1200 mm | Custom engineering design |
| Coil Length | Up to 200 m per coil | Per customer requirement |
| Tolerance on OD | ±0.05 mm (precision grade) | EN 10217-7 |
| Tolerance on WT | ±10% | EN 10217-7 |
| Surface Roughness (Ra) | ≤ 0.4 μm (electropolished) | ASTM A240 / GB/T 19226 |
| End Condition | Plain cut / Beveled / Flanged / Threaded | Per drawing specification |
| Heat Treatment | Solution annealed (1050°C – 1150°C), water quenched | ASTM A240 |
| Delivery Form | Coiled on wooden reel / Bundled | ISO 21482 (packaging) |
Manufacturing Process
The production of precision stainless steel coil tubes follows a rigorously controlled multi-stage manufacturing workflow to ensure dimensional accuracy, metallurgical integrity, and sanitary surface quality:
- Raw Material Procurement: Cold-rolled stainless steel strip or seamless pipe blank is sourced from certified mills with full mill test certificates (MTC) conforming to EN 10204 Type 3.1.
- Pipe Forming (TIG Welding): Precision-wound coils are formed using automatic longitudinal seam welding (Tungsten Inert Gas welding, TIG) or seamless piercing, depending on the OD/WT combination. Weld seams are ground flush to maintain internal surface continuity.
- Coil Winding: The formed pipe is wound onto a precision mandrel using a CNC-controlled coiling machine to achieve exact coil diameter, pitch consistency, and concentricity. Tension-controlled winding prevents distortion and maintains dimensional tolerances.
- Solution Annealing & Pickling: The coiled tube undergoes full solution heat treatment at 1050°C–1150°C followed by rapid quenching to achieve full austenitic microstructure. Subsequent acid pickling removes scale and oxidized layers.
- Passivation: Chemical passivation (nitric acid or citric acid based) is applied to form a stable chromium oxide passive film, enhancing corrosion resistance.
- Electropolishing: The internal and external surfaces undergo electrolytic polishing to achieve Ra ≤ 0.4 μm, removing micro-crevices and achieving a smooth, hygienic finish suitable for UHT service.
- Quality Inspection: Each coil undergoes 100% visual inspection, dimensional verification (OD, WT, coil diameter), hydrostatic pressure testing, and optional eddy current testing for weld seam integrity. Surface roughness is verified via profilometry.
- Packaging & Dispatch: Finished coils are wrapped in protective film, secured on wooden reels with steel bands, and labeled with traceability documentation including heat number, grade, dimensions, and test results.
Applications
The stainless steel coil tubes produced by Wenzhou Jixing Metal Materials Co., Ltd. are purpose-designed for the following industrial applications:
- Ultra-High Temperature (UHT) Sterilization: Primary application in continuous-flow sterilization systems for liquid foods (milk, fruit juices, dairy products, beer), where the coil tube functions as the heat transfer core, exposing the product to 135°C–150°C for 2–5 seconds to achieve commercial sterility.
- Autoclave & High-Temperature Retort Systems: Used in batch sterilization equipment for canned foods, medical devices, and pharmaceutical formulations requiring 121°C+ treatment.
- Heat Exchangers & Plate-Fin Systems: Integrated as serpentine coil elements within shell-and-coil heat exchangers for thermal recovery, pasteurization, and condensate cooling loops.
- Pharmaceutical & Biotechnology Processing: Deployed in aseptic filling lines, sterile water systems, and bioreactor sterilization circuits requiring validated hygienic standards.
- Chemical & Food Processing CIP Systems: Serving as conduit tubing within Cleaning-In-Place (CIP) circuits where repeated exposure to hot alkaline or acidic cleaning solutions demands superior corrosion resistance.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring product conformity with international standards:
- ISO 9001:2015 — Quality Management System certification for consistent manufacturing quality and process control.
- ISO 14001:2015 — Environmental Management System certification demonstrating sustainable manufacturing practices.
- ISO 22000 / HACCP — Food Safety Management System, ensuring traceability and safety for food-grade applications.
- EN 10217-7 — European standard for seamless and welded stainless steel tubes for pressure purposes.
- ASTM A213 / A269 — American material standards for austenitic stainless steel seamless and welded tubes and pipes.
- GB/T 12771 — Chinese national standard for welded stainless steel tubes for general purposes.
- 3-A Sanitary Standards — Compliance with the International Association of Milk, Food, and Beverage Processors' sanitary design requirements for food processing equipment components.
- EHS (European Hygienic Engineering & Design) Guidelines — Adherence to European hygienic design principles for pharmaceutical and food industry equipment.
- Material Traceability: Full heat-number traceability from mill origin through all manufacturing stages, with digital documentation available upon request.
Unique Selling Points
1. Precision Coil Geometry: CNC-controlled winding ensures ±1 mm tolerance on coil diameter and consistent pitch, enabling seamless integration into compact UHT sterilizer housings without interference or vibration.
2. Ultra-Low Surface Roughness: Electropolished Ra ≤ 0.4 μm finish eliminates dead zones and biofilm accumulation, reducing CIP cycle times and ensuring reliable sterility assurance.
3. Full Material Traceability: Every coil is accompanied by a complete test dossier including mill certificates, dimensional reports, pressure test results, and surface finish verification — supporting regulatory audits and validation protocols.
4. Custom Engineering Capability: Wenzhou Jixing offers bespoke coil configurations (OD, WT, coil diameter, length, end preparation) tailored to specific equipment OEM requirements, with rapid prototyping for new product development.
5. Proven High-Temperature Performance: Validated for continuous operation at 155°C under pressure, with demonstrated fatigue life exceeding 10,000 thermal cycles without degradation of mechanical properties or surface integrity.