Stainless Steel Coil Tube (Coiltube) – Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 1587), is a precision-engineered continuous-length tubing product formed through cold bending processes on specialized coil bending machinery. This product category encompasses seamless and welded stainless steel tubes that are coiled into continuous helical or serpentine configurations, primarily designed for heat exchange applications, process piping systems, and compact thermal management solutions.
The coil tube represents a significant advancement in stainless steel tubing technology, offering superior thermal conductivity, space efficiency, and mechanical durability compared to traditional straight-tube configurations. The product is manufactured through trial production methods validated on industrial coil bending machines, ensuring consistent geometric accuracy and metallurgical integrity throughout the entire coil length.
2. Material & Properties
2.1 Base Material Grades
- Austenitic Grades: SUS304 (UNS S30400), SUS304L (UNS S30403), SUS316 (UNS S31600), SUS316L (UNS S31603), SUS321 (UNS S32100)
- Ferritic Grades: SUS430 (UNS S43000)
- Super-Austenitic Grades: SUS317L (UNS S31703), Duplex 2205 (UNS S31803)
- Other Special Grades: Custom alloy compositions available upon request
2.2 Mechanical Properties (Typical for SUS304)
- Tensile Strength (Ultimate): ≥ 520 MPa (75,400 psi)
- Yield Strength (0.2% Offset): ≥ 205 MPa (29,730 psi)
- Elongation: ≥ 40% (at fracture)
- Hardness: ≤ 92 HRB (annealed condition)
- Density: 8.0 g/cm³
- Thermal Conductivity (at 100°C): 16.3 W/(m·K)
- Thermal Expansion Coefficient (20–100°C): 17.3 × 10⁻⁶ /°C
2.3 Corrosion Resistance
Stainless steel coil tubes exhibit exceptional resistance to pitting corrosion, crevice corrosion, and intergranular corrosion. The chromium oxide passive film (Cr₂O₃) provides inherent protection against atmospheric corrosion, acidic environments, and chloride-containing media. SUS316L grade coil tubes offer additional molybdenum-enhanced resistance suitable for marine and chemical processing environments.
3. Specifications
| Parameter | Specification Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 108.0 mm (¼" – 4") | ASTM A269 / GB/T 12771 |
| Wall Thickness (WT) | 0.5 mm – 6.0 mm | ASTM A269 / EN 10217-7 |
| Coil Bend Radius | ≥ 3D (minimum 18 mm for 6 mm OD) | ISO 4430 |
| Coil Length (Continuous) | Up to 500 m (configurable) | — |
| Surface Finish | 2B, BA (Bright Annealed), No. 4 Brushed, Mirror (Ra ≤ 0.4 μm) | ASTM A480 / GB/T 24908 |
| End Condition | Plain, Beveled, Threaded, or Flanged | ASME B1.20.1 |
| Tolerance (OD) | ± 0.1 mm (precision grade); ± 0.25 mm (standard) | ASTM A213 |
| Tolerance (WT) | ± 10% (standard); ± 5% (precision) | GB/T 14976 |
| Temperature Range | −196°C to +870°C (depending on grade) | — |
| Pressure Rating | Up to 40 MPa (design-dependent) | ASME B31.3 |
| Material Condition | Annealed, Pickled & Passivated, Cold Worked | ASTM A240 |
| Applicable Standards | ASTM A269, A213, A249; EN 10217; GB/T 12771, GB/T 14976 | Multi-standard compliance |
4. Manufacturing Process
4.1 Raw Material Preparation
The manufacturing process begins with the selection of certified stainless steel strip or seamless tube stock conforming to the specified grade and dimensional requirements. Incoming material undergoes rigorous inspection including Chemical Composition Analysis (CCA), Positive Material Identification (PMI), and dimensional verification.
4.2 Coil Bending Forming
The core forming operation is performed on industrial coil bending machines (bending forming equipment) utilizing a multi-roll progressive bending method. Key process parameters include:
- Forming Method: Cold bending with controlled reduction (typically 5–15% cross-sectional reduction)
- Bending Die Configuration: Multi-station progressive dies ensuring uniform curvature without material thinning beyond acceptable limits
- Speed Control: Programmable feed rates to prevent work hardening and maintain dimensional accuracy
- Springback Compensation: Overbending compensation algorithms integrated into CNC bending control systems
4.3 Heat Treatment (if required)
For applications requiring stress relief or grain stabilization, the coil tube may undergo controlled annealing at temperatures between 1010–1150°C followed by rapid air cooling. This process restores full ductility and eliminates residual stresses introduced during cold forming.
4.4 Surface Treatment
- Pickling: Immersion in hydrochloric/nitric acid mixture to remove oxidation scale
- Passivation: Treatment with nitric acid (20–30% concentration) or citric acid solution to establish protective chromium oxide film
- Electropolishing (optional): Electrochemical smoothing to achieve Ra ≤ 0.25 μm for sanitary/pharmaceutical applications
4.5 Quality Inspection
Each coil tube lot undergoes comprehensive quality verification including:
- Visual inspection of surface quality and geometric continuity
- Dimensional measurement at multiple intervals along coil length
- Hydrostatic pressure testing (typically at 1.5× design pressure for 30 seconds)
- Non-Destructive Testing (NDT): Eddy current inspection, ultrasonic testing (UT) for wall thickness verification
- Corrosion resistance testing: Salt spray test (ASTM B117), Ferric chloride immersion test
- Spectroscopic composition verification (OES/PMA)
5. Applications
5.1 Heat Exchanger Systems
The primary application domain for stainless steel coil tubes is in heat exchanger manufacturing, particularly for:
- Plate-and-coil heat exchangers in HVAC (Heating, Ventilation, and Air Conditioning) systems
- Shell-and-coil condensers and evaporators in refrigeration and air conditioning
- Compact heat exchangers for process industries requiring high heat transfer coefficients
- Waste heat recovery systems in industrial furnaces and boilers
5.2 Chemical & Petrochemical Processing
- Corrosive fluid transfer lines in chemical plants
- Reactor internals and cooling coils
- Distillation column internals
- Acid storage and transfer systems (SUS316L/SUS317L grades)
5.3 Food & Pharmaceutical Industry
- Pasteurization and sterilization equipment
- Milk processing heat exchangers
- Pharmaceutical fluid heating/cooling circuits
- Beverage processing systems requiring sanitary-grade tubing
5.4 Marine & Offshore Applications
- Shipboard heating and cooling systems
- Offshore platform process piping
- Ballast water treatment systems
- Marine engine cooling circuits
5.5 Power Generation
- Supercritical boiler tubing components
- Cooling water circulation systems
- Gas turbine aftercoolers
6. Quality Certifications & Compliance
6.1 Factory Certifications
- ISO 9001:2015 – Quality Management System
- ISO 14001:2015 – Environmental Management System
- ISO 45001:2018 – Occupational Health and Safety Management System
- ISO/TS 22163 – IATF for automotive supply chain (where applicable)
6.2 Product Certifications
- EN 10204 3.1 Certificate – Material Test Certificate by authorized inspection body
- EN 10204 3.2 Certificate – Detailed material test certificate (upon request)
- Mill Test Report (MTR) – Comprehensive traceability documentation
- PED 2014/68/EU – Pressure Equipment Directive compliance (for pressure-rated applications)
- ASME Certificate – For components used in ASME-regulated pressure vessels
- NSF/ANSI 61 – Drinking water system components (for food-grade applications)
- 3-A Sanitary Standards – Dairy and food processing equipment compliance
6.3 Traceability
Every coil tube product is accompanied by full material traceability documentation including heat number identification, chemical composition analysis, mechanical test results, and dimensional inspection records. Laser marking or stamping of heat numbers and product identification codes ensures permanent traceability throughout the product lifecycle.
7. Unique Selling Points
- Superior Thermal Performance: The continuous coil geometry provides maximum surface area-to-volume ratio, achieving up to 40% higher heat transfer efficiency compared to conventional straight-tube heat exchangers
- Compact Design: Space-efficient configuration reduces overall equipment footprint while maintaining or exceeding thermal performance specifications
- Exceptional Corrosion Durability: Stainless steel construction with proper passivation ensures service life exceeding 25 years in aggressive chemical environments
- Customizable Geometry: Flexible manufacturing capability allows customization of coil diameter, pitch, length, and terminal configurations to meet specific application requirements
- Multi-Grade Availability: Comprehensive range of stainless steel grades from standard austenitic to super-austenitic and duplex alloys
- Validated Manufacturing Process: Production methodology developed and validated through systematic trial production on industrial coil bending machinery, ensuring process repeatability and quality consistency
- Full Compliance Framework: Products manufactured in accordance with international standards (ASTM, EN, GB, ISO) and supported by comprehensive certification documentation
8. Packaging & Delivery
Coil tubes are delivered in appropriate packaging configurations depending on coil diameter and length:
- Small diameter coils: Packed in wooden crates with moisture-absorbing desiccant
- Medium diameter coils: Secured on steel drums or custom wooden pallets with protective wrapping
- Large diameter coils: Delivered on specialized coil carriers with anti-condensation packaging
- All shipments include protective end caps, moisture barrier film, and documentation envelope
9. Technical Support & Customization
Wenzhou Jixing Metal Materials Co., Ltd. provides comprehensive technical support including:
- Application engineering consultation for heat exchanger design optimization
- Custom coil geometry design based on thermal performance requirements
- Material selection guidance for specific corrosive environments
- Finite Element Analysis (FEA) for stress and fatigue assessment
- On-site installation guidance and commissioning support
Note: All specifications listed in this document represent standard capabilities. Custom specifications may be developed through collaborative engineering with the manufacturer. Final product specifications are subject to mutually agreed technical data sheets and purchase order documentation.