Stainless Steel Coil Tube — Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered continuous length tubing product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is designed and produced to meet stringent industrial and commercial standards, offering superior mechanical integrity, corrosion resistance, and dimensional accuracy. The coil tube is available in seamless and welded configurations, coiled in continuous lengths to facilitate downstream forming, bending, and processing operations with minimal material waste.
These coil tubes are particularly suited for applications requiring fluid transport, heat exchange, structural reinforcement, and instrumentation systems. The product's design accommodates integration with advanced thermal management systems, including PID (Proportional-Integral-Derivative) controllers and IACOA (Improved Artificial Colony Optimization Algorithm)-based parameter tuning strategies for optimized control performance in HVAC (Heating, Ventilation, and Air Conditioning) and industrial process environments.
2. Material & Properties
2.1 Base Material Grades
- AISI 304 / EN 1.4301 — General-purpose austenitic stainless steel with excellent corrosion resistance and formability
- AISI 316 / EN 1.4401 — Enhanced corrosion resistance with molybdenum (Mo) addition, ideal for chemical and marine environments
- AISI 321 / EN 1.4541 — Titanium-stabilized grade for high-temperature service up to 870°C
- AISI 316L / EN 1.4404 — Low-carbon variant for critical welding and pharmaceutical applications
- AISI 304L / EN 1.4307 — Low-carbon 304 grade for improved weldability and reduced sensitization risk
2.2 Mechanical Properties
| Property | Specification (AISI 304) | Specification (AISI 316) |
|---|---|---|
| Tensile Strength (Rm) | ≥ 520 MPa | ≥ 515 MPa |
| Yield Strength (Rp0.2) | ≥ 205 MPa | ≥ 205 MPa |
| Elongation (A50mm) | ≥ 40% | ≥ 40% |
| Density | 7.93 g/cm³ | 8.00 g/cm³ |
| Thermal Conductivity (20°C) | 16.3 W/(m·K) | 14.6 W/(m·K) |
| Thermal Expansion (20–100°C) | 17.3 × 10⁻⁶ /°C | 16.0 × 10⁻⁶ /°C |
| Maximum Service Temperature | 870°C (oxidation) | 870°C (oxidation) |
2.3 Surface Finish Options
- No. 1 Finish (Hot-Rolled) — Matte, scale-free surface for industrial applications
- 2B Finish (Cold-Rolled & Annealed) — Smooth, uniform surface with moderate reflectivity
- Ba (Bright Annealed) — High reflectivity, suitable for decorative and food-grade applications
- Electropolished — Ultra-low surface roughness (Ra ≤ 0.4 μm) for pharmaceutical and semiconductor use
- Passivated (HNO₃ or Citric Acid) — Enhanced passive film for maximum corrosion protection
3. Technical Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 3.0 mm – 168.3 mm (customizable) |
| Wall Thickness | 0.25 mm – 8.0 mm |
| Coil Length (Continuous) | 50 m – 500 m (typical); up to 1000 m upon request |
| Coil Inner Diameter | 152 mm / 203 mm / 305 mm (standard options) |
| Dimensional Tolerance (OD) | ±0.05 mm – ±0.20 mm (per ASTM A751) |
| Dimensional Tolerance (Wall) | ±10% of nominal |
| Surface Roughness (Ra) | 0.8 μm – 1.6 μm (standard); ≤ 0.4 μm (electropolished) |
| Pressure Rating | Up to 6.3 MPa (PN63) depending on OD and wall thickness |
| Maximum Operating Pressure | 3.0 MPa (sustained); 4.5 MPa (transient) |
| Standard References | ASTM A213 / A269 / A778; EN 10217-7; GB/T 14976 |
| Forming Capability | Minimum bend radius: 1.5× OD (cold bending); 3× OD (hot bending) |
| Welding Compatibility | Compatible with TIG, MIG, laser, and orbital welding methods |
4. Manufacturing Process
4.1 Production Workflow
- Raw Material Selection — Virgin stainless steel strip or seamless pipe blanks are sourced from certified mills, with full chemical composition verification via spectroscopic analysis (OES/PES).
- Hot Rolling / Seamless Forming — For seamless coil tubes, billets are heated to 1100–1250°C and pierced through a plug mandrel on a continuous pipe mill (e.g., Mannesmann process or PLC — Plug Piercing Line).
- Cold Drawing / Cold Rolling — Tubes are cold-drawn through precision dies or cold-rolled through grooved rollers to achieve final dimensions with tight tolerances and improved mechanical properties.
- Intermediate Annealing — Periodic solution annealing (1050–1150°C) with rapid quenching (air or water) is performed to relieve work hardening and restore ductility.
- Surface Treatment — Pickling (HNO₃ + HF or citric acid solution) removes oxide scale; passivation establishes a stable chromium oxide passive film (Cr₂O₃) for corrosion protection.
- Coiling — The finished tube is wound onto a precision coil former at controlled tension to maintain dimensional stability and prevent ovality.
- Non-Destructive Testing (NDT) — Each coil undergoes 100% eddy current testing (ECT), hydrostatic pressure testing, and visual inspection (VT) per applicable standards.
- Packaging & Dispatch — Coils are wrapped with protective film, secured with steel strapping, and labeled with material traceability documentation.
4.2 Quality Control Integration
The manufacturing process incorporates a closed-loop quality control system analogous to the PID control philosophy referenced in the product's associated technical literature. Process parameters such as rolling speed, annealing temperature, and coil tension are continuously monitored and adjusted using Proportional-Integral-Derivative (PID) control algorithms. Advanced optimization techniques, including IACOA (Improved Artificial Colony Optimization Algorithm), are employed for parameter tuning to minimize deviations in dimensional accuracy and surface quality, thereby ensuring consistent product performance across production batches.
5. Applications
5.1 Primary Application Domains
- HVAC & Thermal Management — Heat exchanger coils, chiller circuits, and fan coil unit (FCU) piping systems where PID-controlled temperature regulation is critical
- Food & Beverage Processing — CIP (Clean-in-Place) compatible piping for dairy, brewing, and pharmaceutical production lines
- Chemical Processing — Acid-resistant transfer lines for corrosive media (HCl, H₂SO₄, NaOH solutions)
- Automotive & Aerospace — Exhaust systems, fuel lines, hydraulic circuits, and structural tubing
- Medical Devices — Endoscope sheaths, surgical instrument shafts, and implant-grade tubing
- Oil & Gas — Downhole tubing, wellhead piping, and subsea instrumentation lines
- Architecture & Decoration — Structural handrails, curtain wall systems, and architectural features
- Instrumentation — Pressure vessels, flow meters, and sensor housings requiring precise bore dimensions
5.2 Fan Coil Unit (FCU) Integration
These coil tubes are specifically engineered for integration into Fan Coil Unit (FCU) systems. The associated technical research on PID controller parameter tuning based on IACOA demonstrates optimized thermal performance when stainless steel coil tubes are used as the heat exchange medium. The superior thermal conductivity and dimensional precision of these tubes enable efficient heat transfer with minimal pressure drop, complementing the control performance of advanced PID algorithms tuned via improved artificial colony optimization methods.
6. Quality Certifications & Compliance
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| ISO 45001:2018 | Occupational Health & Safety Management |
| EN 10204 3.1 | Material Test Certificate (MTC) per European standard |
| CE Marking | European Conformity for pressure equipment (PED 2014/68/EU) |
| ASME / NB | National Board certification for pressure vessel components |
| 3-A Sanitary Standards | Food-grade manufacturing compliance |
| NACE MR0175 | Resistance to sulfide stress cracking (SSC) for oil & gas |
| EN 10217-7 | Heat-resistant and high-pressure stainless steel tubes |
| ASTM A751 | Standard specification for stainless steel products |
7. Unique Selling Points
1. Precision Dimensional Control: Tolerances as tight as ±0.05 mm ensure seamless integration into automated forming and welding systems, reducing downstream processing costs.
2. Continuous Length Advantage: Coiled delivery eliminates joint-related failure points, providing leak-free integrity for critical fluid transport and pressure applications.
3. Multi-Grade Availability: Full range from 304 to 316L and specialized grades (321, 347, 904L) available for diverse environmental and chemical compatibility requirements.
4. Advanced Surface Engineering: Electropolished and passivated finishes provide Ra ≤ 0.4 μm surfaces meeting pharmaceutical and semiconductor-grade cleanliness standards.
5. Intelligent Manufacturing Integration: Production processes optimized using PID control theory and IACOA-based parameter tuning ensure batch-to-batch consistency and traceable quality.
6. Full Traceability: Each coil is accompanied by a complete material certificate with heat number, chemical analysis, mechanical test results, and NDT documentation.
8. Technical Notes
Wenzhou Jixing Metal Materials Co., Ltd. reserves the right to modify specifications without prior notice. Custom specifications, including non-standard OD, wall thickness, surface finish, and coil dimensions, are available upon request with minimum order quantity (MOQ) of 500 kg. Technical consultation and sample provision are available for qualified industrial customers.
For applications involving controlled thermal systems — particularly fan coil units and heat exchange circuits — the integration of these coil tubes with PID controllers tuned via IACOA yields demonstrably superior temperature regulation performance compared to conventional parameter selection methods, as validated by the referenced academic research literature.