Stainless Steel Coil Tube (Coil Tube) — Ultra-High Temperature Sterilization Application

Product Overview

The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered tubular component designed for use in Ultra-High Temperature (UHT) sterilization systems. Unlike conventional shell-and-tube heat exchangers, coil tube configurations offer a continuous, helical geometry that maximizes heat transfer efficiency while minimizing fluid turbulence and product degradation. This product is particularly suited for the food, pharmaceutical, and biotechnology industries where thermal processing integrity and sanitary compliance are paramount.

Coil tubes are formed by winding seamless or welded stainless steel tubing into a helical or spiral shape, creating a compact heat exchange surface that facilitates rapid and uniform heat transfer. The continuous curvature eliminates dead zones and stagnant regions, ensuring thorough sterilization with minimal residence time variation.

Material & Properties

Coil tubes are typically fabricated from austenitic stainless steel grades selected for their superior corrosion resistance, high-temperature strength, and hygienic surface finish. The following materials are commonly employed:

• AISI 304 (UNS S30408) — General-purpose grade with excellent corrosion resistance and formability; suitable for most UHT applications involving food-grade fluids.
• AISI 316L (UNS S31603) — Enhanced molybdenum content (2.0–3.0%) provides superior resistance to chloride-induced pitting and crevice corrosion; preferred for aggressive chemical environments.
• AISI 321 (UNS S32100) — Titanium-stabilized grade offering improved resistance to intergranular corrosion at elevated temperatures above 600 °C.
• AISI 316Ti (UNS S31635) — Combines molybdenum and titanium stabilization for maximum resistance in high-temperature, chloride-rich environments.

Key Material Properties (Typical for AISI 316L):

• Chromium (Cr): 16.0–18.0%
• Nickel (Ni): 10.0–14.0%
• Molybdenum (Mo): 2.0–3.0%
• Carbon (C): ≤ 0.030% (L-grade)
• Tensile Strength: ≥ 485 MPa
• Yield Strength (0.2% offset): ≥ 205 MPa
• Elongation: ≥ 40%
• Operating Temperature Range: −196 °C to 870 °C (reducing atmosphere)

Specifications

Parameter	Specification / Range
Product Name	Stainless Steel Coil Tube (Coiltube)
Product Code	No. 549
Material Grade	AISI 304, 316L, 321, 316Ti
Outer Diameter (OD)	Φ6 mm – Φ51 mm (customizable)
Wall Thickness	0.5 mm – 3.0 mm
Coil Diameter	Φ50 mm – Φ2000 mm
Coil Length	Up to 3000 m (continuous coil)
Surface Finish	Electro-polished Ra ≤ 0.25 μm; Passivated
End Treatment	Plain, Threaded, Flanged, or Weld-prepped
Maximum Operating Pressure	Up to 4.0 MPa (design-dependent)
Maximum Operating Temperature	145 °C (UHT process standard); up to 870 °C (material limit)
Tolerance (OD)	±0.05 mm (precision drawn)
Tolerance (Wall Thickness)	±0.02 mm
Applicable Standards	ASTM A269, ASTM A270, EN 10217-7, GB/T 12771
Hygienic Standards	3-A Sanitary Standards, EHEDG, FDA 21 CFR

Manufacturing Process

The production of stainless steel coil tubes involves a multi-stage manufacturing sequence designed to ensure dimensional precision, metallurgical integrity, and surface quality:

1. Raw Material Selection — High-purity stainless steel seamless tubes or precision-welded tubes are sourced from certified mills. Incoming material undergoes spectroscopic analysis (OES) and mechanical property verification.
2. Cold Drawing / Cold Forming — Tubes are cold-drawn through precision dies to achieve exact OD and wall thickness tolerances. Cold working enhances mechanical strength and surface smoothness.
3. Coil Winding — The formed tube is wound onto a precision mandrel using CNC-controlled coiling equipment. The winding process maintains consistent pitch, diameter, and spring-back compensation to achieve the target helical geometry.
4. Welding (if applicable) — For multi-pass coil assemblies, butt welding or orbital TIG welding is performed at designated connection points. Welds are ground flush and inspected for continuity.
5. Stress Relief Annealing — Where required, the coil tube assembly undergoes controlled heat treatment to relieve residual stresses introduced during cold forming, typically at 1050–1100 °C followed by controlled cooling.
6. Surface Finishing — Electro-polishing removes surface imperfections and achieves a mirror finish (Ra ≤ 0.25 μm). Subsequent passivation treatment (nitric acid or citric acid) removes free iron and enhances passive film formation.
7. Quality Inspection — Each coil tube undergoes dimensional verification, hydrostatic pressure testing, visual inspection, and Non-Destructive Testing (NDT) including dye penetrant testing (DPT) or magnetic particle inspection (MPI) for surface discontinuities.

Applications

Stainless steel coil tubes find extensive application across multiple industries, with UHT sterilization being a primary use case:

• Ultra-High Temperature (UHT) Sterilization Systems — Coil tubes serve as the heat transfer element in UHT processing equipment for liquid foods (milk, juice, soups, sauces). The helical geometry provides high heat transfer coefficients (typically 2000–4000 W/m²·K) with minimal fouling.
• Food Processing — Pasteurization, sterilization, and thermal concentration of dairy, beverage, and condiment products.
• Pharmaceutical Manufacturing — Sterilization of injectable solutions, biological reagents, and clean-in-place (CIP) systems.
• Biotechnology — Heat exchange in fermentation systems, bioreactor cooling, and downstream processing.
• Chemical Processing — Heat exchange in corrosive environments where alloy resistance is required.
• Condensing Systems — Steam condensation in vacuum systems and evaporative concentration equipment.

Advantages of Coil Tube vs. Shell-and-Tube Configuration in UHT Systems

Based on comparative analysis of shell-and-tube and coil tube ultra-high temperature sterilization equipment, the coil tube configuration demonstrates several distinct technical advantages:

• Higher specific heat transfer area per unit volume (up to 40% greater surface density)
• Reduced fluid residence time with more uniform flow distribution
• Lower tendency for product degradation due to shorter, more consistent heating paths
• Reduced fouling accumulation due to turbulent flow in curved geometry
• Compact footprint enabling space-efficient equipment design
• Easier cleaning and sanitization due to continuous, accessible geometry

Quality Certifications & Standards Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and holds the following certifications to ensure product conformity and traceability:

• ISO 9001:2015 — Quality Management System certification ensuring consistent production quality and process control.
• ISO 14001:2015 — Environmental Management System certification demonstrating sustainable manufacturing practices.
• ISO 45001:2018 — Occupational Health and Safety Management System.
• 3-A Sanitary Standards — Compliance with dairy and food industry hygienic design requirements.
• EHEDG (European Hygienic Engineering & Design Group) — Compliance with European hygienic design guidelines.
• FDA 21 CFR — Food and Drug Administration compliance for food-contact materials.
• CE Marking — Conformity with European health, safety, and environmental protection standards.
• Mill Test Certificates (MTC) — EN 10204 Type 3.1 certificates provided with each shipment for full material traceability.

Unique Selling Points

• Precision Engineering — CNC-controlled coiling ensures dimensional accuracy of ±0.5 mm on coil diameter, guaranteeing seamless integration into sterilization equipment assemblies.
• Superior Surface Quality — Electro-polished surfaces with Ra ≤ 0.25 μm minimize microbial adhesion and facilitate automated cleaning protocols (CIP/COP).
• Customization Capability — Full range of OD, wall thickness, coil diameter, and material grades available to meet specific application requirements and equipment design constraints.
• UHT-Optimized Design — Coil geometry specifically engineered for UHT thermal processing, delivering superior heat transfer performance with minimal product quality loss.
• Full Traceability — Complete material and process documentation from raw material to finished product, ensuring regulatory compliance in food and pharmaceutical sectors.