Stainless Steel Coil Tube (Coiltube) — Steam Drying Heat Exchange Application
Product Overview
The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd, is a precision-engineered heat exchange component designed specifically for steam drying systems. This product represents a critical element in industrial thermal processing, where reliable heat transfer efficiency, dimensional accuracy, and long-term mechanical integrity are paramount. The coil tube is engineered to withstand continuous exposure to high-temperature steam environments while maintaining structural stability through advanced axial and radial positioning solutions.
Unlike conventional straight tubes, the coiltube form factor provides a significantly increased surface-area-to-volume ratio, enabling superior thermal exchange performance within compact installation envelopes. This makes it an ideal solution for space-constrained industrial drying operations where maximum heat transfer efficiency is required.
Material & Properties
The coil tubes are fabricated from high-grade austenitic stainless steel, ensuring excellent corrosion resistance, thermal stability, and mechanical durability under demanding process conditions.
Commonly Available Grades
- 304 Stainless Steel (AISI 304 / UNS S30400) — General-purpose grade offering outstanding corrosion resistance in oxidizing environments, suitable for food-grade and pharmaceutical applications.
- 316 Stainless Steel (AISI 316 / UNS S31600) — Enhanced molybdenum content (2–3%) providing superior resistance to chlorides, acids, and aggressive chemical environments.
- 321 Stainless Steel (AISI 321 / UNS S32100) — Titanium-stabilized grade offering improved resistance to intergranular corrosion at elevated temperatures (up to 870°C).
- 316L Stainless Steel (AISI 316L / UNS S31603) — Low-carbon variant with enhanced weldability and resistance to sensitization.
Key Mechanical & Thermal Properties (316L Reference)
- Tensile Strength: ≥ 515 MPa (74,700 psi)
- Yield Strength (0.2% Offset): ≥ 205 MPa (29,700 psi)
- Elongation (at Break): ≥ 40%
- Thermal Conductivity (at 100°C): 16.3 W/(m·K)
- Maximum Service Temperature: 870°C (1,598°F)
- Linear Expansion Coefficient (20–100°C): 17.3 × 10⁻⁶ /°C
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Material Grade | 304 / 316 / 316L / 321 (Customizable) |
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (¼" – 2") |
| Wall Thickness | 0.5 mm – 3.0 mm (0.020" – 0.118") |
| Coil Diameter | 100 mm – 1,500 mm (4" – 59") |
| Pitch (Center-to-Center Spacing) | 10 mm – 50 mm (0.39" – 1.97") |
| Tube Length (per Coil) | 5 m – 50 m (16.4 ft – 164 ft) |
| Surface Finish | No. 4 Brushed / Mirror (Ra ≤ 0.1 μm) / Pickled & Passivated |
| End Condition | Plain / Threaded / Flanged / Welded (as required) |
| Pressure Rating | Up to 4.0 MPa (580 psi) at 200°C |
| Tolerance on OD | ±0.05 mm (±0.002") |
| Tolerance on Wall Thickness | ±10% of nominal |
| Coil Roundness Tolerance | ±1% of nominal coil diameter |
| Standards | ASTM A213 / ASME SA-213 / EN 10216-5 / GB/T 14976 |
Manufacturing Process
The production of high-quality stainless steel coil tubes involves a rigorous multi-stage process ensuring dimensional precision, metallurgical integrity, and surface quality:
- Material Selection & Inspection: Raw material coils are sourced from certified mills and subjected to incoming quality control, including chemical composition analysis (OES spectroscopy) and mechanical property verification.
- Coil Forming (Cold Coiling): Straight stainless steel tubes are precisely coiled using CNC-controlled mandrel-based forming machines. This process maintains consistent coil diameter, pitch, and roundness without introducing plastic deformation or work hardening beyond acceptable limits.
- Heat Treatment (Solution Annealing): Where required, coils undergo solution annealing at 1,040–1,150°C followed by controlled water quenching to restore full austenitic microstructure and maximize corrosion resistance.
- Pickling & Passivation: The coil surface is cleaned via hydrofluoric/nitric acid pickling to remove oxide scale, followed by passivation treatment to establish a protective chromium oxide layer (Cr₂O₃) for enhanced corrosion resistance.
- End Preparation: Tube ends are cut, deburred, and prepared per customer specifications (threading, flanging, or welding preparation).
- Non-Destructive Testing (NDT): Helium leak testing, eddy current inspection, and dimensional verification are performed to ensure zero defects in tube wall integrity and geometric accuracy.
- Final Inspection & Packaging: Each coil undergoes final dimensional and visual inspection, is labeled with full traceability documentation, and packaged in protective wrapping with wooden pallets or crates for shipment.
Applications
The Stainless Steel Coil Tube is widely employed across multiple industrial sectors where reliable heat exchange, corrosion resistance, and mechanical robustness are essential:
- Steam Drying Systems: Primary application for axial and radial heat exchange in industrial drying processes, including paper drying, textile drying, and food dehydration.
- Pharmaceutical Equipment: Steam sterilization (SIP) coils in bioreactors, distillation columns, and CIP (Clean-In-Place) systems requiring sanitary-grade surfaces.
- Food & Beverage Processing: Pasteurization heat exchangers, milk processing equipment, and brewing systems where FDA-compliant materials are mandated.
- Chemical Processing: Reactor cooling coils, condensers, and evaporators handling aggressive chemical media.
- Petrochemical Industry: Refinery heat exchangers, steam tracing systems, and distillation column internals.
- Power Generation: Feedwater heaters, economizers, and auxiliary steam systems in thermal power plants.
- Marine & Offshore: Seawater cooling coils and condenser bundles where chloride resistance is critical.
Axial & Radial Positioning Considerations
Based on engineering experience with steam drying heat exchange coil tube installations, the axial and radial positioning of coiltubes within shell-and-coil assemblies is a critical design parameter. Proper positioning ensures:
- Uniform steam distribution across the coil bundle, preventing localized hot spots and thermal stress concentrations.
- Adequate clearance between adjacent coils for optimal convective airflow and condensate drainage.
- Mechanical stability under thermal cycling, preventing vibration-induced fatigue failure.
- Facilitated maintenance access for inspection and replacement operations.
Wenzhou Jixing Metal Materials Co., Ltd provides engineering consultation on coil tube layout optimization, including axial spacing calculations, radial support bracket design, and thermal expansion accommodation strategies.
Unique Selling Points
- Precision Coil Forming: CNC-controlled manufacturing ensures coil diameter consistency within ±1% tolerance, critical for proper fit within heat exchanger shells.
- Full Traceability: Every coil tube batch is traceable to mill certification, with complete chemical and mechanical test reports available upon request.
- Custom Engineering Support: Dedicated technical team provides axial/radial positioning design consultation tailored to specific application thermal loads and installation constraints.
- Multi-Grade Availability: Comprehensive material range from standard 304 to specialty 316L and 321 grades, accommodating diverse environmental and regulatory requirements.
- Surface Quality Excellence: Mirror-polished (Ra ≤ 0.1 μm) finish options available for hygienic and pharmaceutical applications requiring CIP/SIP compatibility.
- Cost-Effective Thermal Performance: The coiltube geometry delivers 30–50% higher heat transfer surface area per unit volume compared to equivalent straight tube bundles.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems and adheres to internationally recognized standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ASME SA-213 — Specification for Seamless Austenitic Chromium-Nickel Alloy Steel Tubing for High Temperature Service
- ASTM A213 / A269 — Standard Specifications for Seamless and Welded Austenitic Stainless Steel Tubes
- EN 10216-5 — European Standard for Non-ferrous Tubes for Heat Exchangers
- GB/T 14976 — Chinese National Standard for Seamless Stainless Steel Tubes for Fluids
- CE Marking — European Conformity for pressure equipment applications
- Material Test Reports (MTR): Third-party certified chemical analysis, mechanical testing, and NDT reports provided with each shipment
- Sanitary Compliance: Product available in sanitary-grade finish meeting 3-A (Three-A Sanitary Standards) and FDA 21 CFR requirements
Technical Support & Documentation
Customers receive comprehensive technical documentation including:
- Material Test Reports (MTR) with chemical composition and mechanical property data
- Dimensional inspection certificates
- NDT reports (leak testing, eddy current inspection)
- Heat exchanger layout drawings and positioning recommendations
- Installation and maintenance guidelines
- Warranty documentation (standard 24-month performance guarantee)
Contact & Ordering Information
For detailed quotations, custom specifications, or engineering consultation regarding stainless steel coil tube applications in steam drying and heat exchange systems, contact Wenzhou Jixing Metal Materials Co., Ltd. Custom coil diameters, pitches, lengths, and surface finishes are available upon request. Minimum order quantities and lead times are subject to material availability and specification complexity.