Stainless Steel Spiral Coil Tube — Coiltube (Product No. 517)
Product Overview
The Stainless Steel Spiral Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. represents a precision-engineered tubular product formed through advanced spiral coiling technology. This product is designed to deliver superior mechanical integrity, corrosion resistance, and dimensional accuracy for a wide range of industrial applications. The coil tube is produced using state-of-the-art Spiral Coil Tube Manufacturing Apparatus (螺旋盘管制作装置), which ensures consistent geometry, uniform wall thickness, and minimal residual stress throughout the coiled configuration.
Unlike conventional straight-length pipes that require additional bending and forming operations downstream, the spiral coil tube is delivered in a pre-formed helical configuration, offering significant advantages in terms of installation efficiency, space utilization, and hydraulic performance. The continuous coil form eliminates the need for numerous butt-weld joints, thereby reducing potential failure points and enhancing the overall reliability of the system.
Material & Properties
Base Material Grades
- Austenitic Stainless Steel — 304 (UNS S30400): General-purpose grade with excellent corrosion resistance, formability, and weldability. Suitable for non-aggressive chemical environments.
- Austenitic Stainless Steel — 316 (UNS S31600): Enhanced molybdenum content provides superior resistance to pitting and crevice corrosion, particularly in chloride-containing environments.
- Super Austenitic Stainless Steel — 316L (UNS S31603): Low-carbon variant offering improved weldability and resistance to intergranular corrosion.
- Custom Alloy Grades: Available upon request, including 321, 347, 904L, and duplex 2205 configurations for specialized service conditions.
Key Mechanical Properties
- Tensile Strength: ≥ 520 MPa (304 grade), ≥ 570 MPa (316 grade)
- Yield Strength: ≥ 205 MPa (minimum)
- Elongation at Break: ≥ 40% (as-rolled condition)
- Hardenability: Non-magnetic in annealed condition; minimal work hardening during forming
- Corrosion Resistance: Excellent resistance to atmospheric, aqueous, and mild chemical environments
- Temperature Range: −196°C to +870°C (304 grade); −196°C to +870°C (316 grade)
Surface Finish Options
- 2B Finish: Standard cold-rolled and annealed surface with matte appearance
- No. 4 Brushed Finish: Fine linear grain pattern suitable for architectural and decorative applications
- Mirror (8K) Finish: High-polish reflective surface for hygienic and aesthetic requirements
- Pickled & Passivated (P&P): Chemical cleaning to remove scale and form protective chromium oxide layer
Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 219.1 mm (¼" – 8") | ASTM A554 / EN 10217 |
| Wall Thickness | 0.3 mm – 6.0 mm | ASTM A554 / GB/T 12771 |
| Coil Pitch (Helix Pitch) | 50 mm – 500 mm (customizable) | Project-specific |
| Coil Diameter (Mean) | 200 mm – 3,000 mm | Project-specific |
| Number of Turns | 1 – 500+ turns (continuous) | Project-specific |
| OD Tolerance | ±0.1 mm (≤ 12.7 mm OD); ±1% (> 12.7 mm OD) | ASTM A554 |
| Wall Thickness Tolerance | ±10% | ASTM A554 |
| Coil Pitch Tolerance | ±2 mm | Internal Specification |
| Helix Diameter Tolerance | ±3 mm | Internal Specification |
| Material Grade | 304, 304L, 316, 316L, 321, 347, 904L, 2205 | ASTM A270 / A554 |
| Forming Method | Spiral Coiling Apparatus (Cold Forming) | Proprietary Technology |
| End Condition | Plain end, Beveled end, Threaded, or Custom | Customer specification |
| Maximum Coil Length | Up to 200 meters (continuous) | Internal Specification |
| Operating Pressure Rating | Up to 40 MPa (depending on configuration) | ASME B31.3 |
| Standards Compliance | ASTM A554, ASME SA-554, EN 10217-7, GB/T 12771 | Multi-standard |
Manufacturing Process
1. Raw Material Selection & Incoming Inspection
High-purity stainless steel wire rod or seamless tube stock is sourced from certified mills and subjected to rigorous incoming inspection. Materials undergo Positive Material Identification (PMI) testing via X-ray fluorescence (XRF) spectroscopy to verify alloy composition. Mechanical property verification is performed through tensile testing and hardness measurement in accordance with ASTM E10 and ASTM E8 standards.
2. Straightening & Pre-Treatment
Raw material is fed through precision straightening rollers to achieve a true, straight configuration with minimal residual curvature. The material surface is cleaned and degreased to remove mill scale, oils, and contaminants that could compromise the coiling process or final product quality.
3. Spiral Coiling Formation (Core Process)
The heart of the manufacturing process utilizes the Spiral Coil Tube Manufacturing Apparatus (螺旋盘管制作装置), a proprietary system that combines the following sub-processes:
- Material Feeding: The straightened tube stock is fed at controlled speed into the forming station via hydraulic drive systems.
- Rotary Forming: Precision-guided rollers progressively bend the tube stock around a rotating mandrel or through a forming die, creating the helical geometry. The forming angle and feed rate are precisely controlled to maintain uniform curvature without wall thinning or ovalization.
- Pitch Control: Servo-controlled feed mechanisms ensure accurate and consistent helix pitch throughout the entire coil length. Real-time monitoring systems track pitch deviation and automatically compensate.
- Springback Compensation: The apparatus incorporates pre-calculated springback compensation algorithms based on material grade, wall thickness, and target dimensions, ensuring final product geometry meets tolerance requirements.
4. Heat Treatment (If Required)
For applications requiring enhanced mechanical properties or elimination of forming-induced residual stresses, the coil tube may undergo solution annealing at temperatures between 1010°C and 1150°C followed by rapid quenching. This process restores full austenitic microstructure and maximizes corrosion resistance.
5. Surface Treatment & Finishing
The formed coil tube undergoes surface treatment including:
- Pickling: Immersion in mixed acid solution (nitric + hydrofluoric acid) to remove oxide scale
- Passivation: Treatment with citric or nitric acid to establish a stable chromium oxide passive layer
- Polishing/Brushing: Mechanical finishing to achieve specified surface roughness (Ra ≤ 0.4 μm for sanitary grades)
6. Final Quality Inspection
Every production batch undergoes comprehensive quality verification including:
- Dimensional Inspection: Laser scanning or CMM (Coordinate Measuring Machine) verification of OD, wall thickness, pitch, and coil diameter
- Visual Inspection: Surface examination for defects, scratches, or geometric irregularities
- Non-Destructive Testing (NDT): Eddy current testing for wall thickness verification and defect detection; helium leak testing for pressure integrity
- Chemical Analysis: Spectrographic verification of alloy composition
- Hydrostatic Testing: Pressure testing at 1.5× working pressure to verify structural integrity
7. Packaging & Delivery
Completed coil tubes are carefully packaged with protective wrapping, anti-corrosion coatings, and appropriate labeling. Large coils are secured on wooden or steel pallets with anti-slip fixtures. Each shipment includes a Mill Test Certificate (MTC) conforming to EN 10204 3.1 requirements, documenting material grade, heat number, dimensions, and test results.
Applications
Heat Exchanger & Thermal Management
Spiral coil tubes are extensively used in shell-and-coil heat exchangers, air coolers, and condensers where the helical geometry maximizes heat transfer surface area within a compact envelope. The continuous coil form eliminates the need for U-bends or return channels, simplifying manufacturing and improving thermal efficiency.
Refrigeration & HVAC Systems
In refrigeration systems, stainless steel coil tubes serve as evaporator coils, condenser coils, and intermediate heat exchangers. The corrosion resistance of austenitic stainless steel is particularly advantageous in systems using ammonia, glycol-based refrigerants, or in marine environments.
Chemical Processing & Petrochemical Industry
Coil tubes are deployed in reactor internals, distillation column feed preheaters, heat recovery units, and process cooling systems. Grades such as 316L and 904L provide resistance to aggressive chemical media including sulfuric acid, hydrochloric acid, and chlorinated solvents.
Food & Beverage Processing
In hygienic processing environments, mirror-finish 316L coil tubes are used in pasteurizers, sterilizers, heat exchangers, and product transfer lines. The smooth surface finish minimizes product retention and facilitates CIP (Clean-In-Place) operations.
Power Generation
Spiral coil tubes find application in steam generators, turbine cooling systems, boiler economizers, and waste heat recovery systems in both conventional and renewable energy power plants.
Automotive & Aerospace
In automotive applications, coil tubes are used for exhaust heat recovery, fuel cooling systems, and hydraulic line assemblies. In aerospace, they serve in environmental control systems and fuel manifold assemblies where weight optimization and corrosion resistance are critical.
Oil & Gas Industry
Coil tubes are utilized in subsea production systems, flow assurance systems, wellhead assemblies, and separator internals where resistance to H₂S and CO₂ corrosion is essential.
Quality Certifications
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System — Certified for consistent product quality and process control |
| ISO 14001:2015 | Environmental Management System — Demonstrating environmental responsibility in manufacturing |
| EN 10204 3.1 | Material Test Certificate — Independent verification of material compliance |
| ASTM A554 | Standard Specification for Seamless and Wrought Stainless Steel Pipe, Tubing, and Hollow Shapes |
| ASME SA-554 | Boiler and Pressure Vessel Code — Material qualification for pressure-containing applications |
| GB/T 12771 | Chinese National Standard for Stainless Steel Seamless Tubes for Fluid Transport |
| EN 10217-7 | European Standard for Tubes and Pipes for Mechanical and Thermal Uses |
| PED 2014/68/EU | Pressure Equipment Directive Compliance — For pressure-containing applications in EU market |
| NSF/ANSI 61 | Drinking Water System Components — Health Effects Certification (for food/water applications) |
| 3-A Sanitary Standards | International Dairy, Food, and Beverage Equipment Standards (for hygienic applications) |