Stainless Steel Coil Tube — Product Technical Specification
Product Overview
The Stainless Steel Coil Tube (Product Code: 1113) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered, continuously coiled tubular product designed for demanding thermal exchange and fluid transport applications. The coil tube is formed through a seamless cold-drawing or cold-rolling process, producing a uniform, kink-free geometry that ensures consistent hydraulic performance and thermal efficiency throughout its operational lifespan. This product falls under the category of literature-based technical development, integrating validated test methodologies — specifically the Dry-Wet Condition Equivalence Method — to ensure performance reliability under variable environmental and operational conditions.
Material & Properties
The coil tube is fabricated from austenitic stainless steel grades selected for superior corrosion resistance, mechanical strength, and thermal stability. The following material properties characterize the product:
- Base Material: Austenitic stainless steel (AISI 304 / 316 / 321), conforming to ASTM A213 / ASME SA-213 standards
- Chemical Composition: Carbon (C) ≤ 0.08%, Chromium (Cr) 18.0–20.0%, Nickel (Ni) 8.0–10.5%, Molybdenum (Mo) ≤ 2.0% (for 316 grade)
- Tensile Strength: ≥ 515 MPa (75 ksi)
- Yield Strength (0.2% offset): ≥ 205 MPa (30 ksi)
- Elongation: ≥ 40% (at break)
- Corrosion Resistance: Excellent resistance to atmospheric, acidic, and chloride-induced corrosion; suitable for both wet and dry operational environments
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C
- Operating Temperature Range: −196°C to +870°C (depending on grade)
Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Product Code | 1113 | Internal Classification |
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (¼" – 2") | ASTM A213 / ASME SA-213 |
| Wall Thickness | 0.5 mm – 3.0 mm (0.020" – 0.118") | ASTM A213 |
| Coil Diameter | 300 mm – 1,200 mm | Manufacturer Specification |
| Coil Length | Up to 100 meters (continuous coil) | Manufacturer Specification |
| Surface Finish | 2B / BA (Bright Annealed) / Polished (Ra ≤ 0.4 μm) | ASTM A478 |
| End Condition | Plain end / Beveled end / Welded cap | Customer Requirement |
| Pressure Rating | Up to 4.0 MPa (580 psi) at 20°C | ASME B31.3 |
| Dimensional Tolerance | ±0.05 mm (OD), ±0.03 mm (wall thickness) | ASTM A213 |
| Heat Treatment | Solution Annealed (1050°C – 1150°C, water quench) | ASTM A213 |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorously controlled multi-stage manufacturing sequence:
- Material Selection & Verification: Ingot or slab stock is procured from certified mills with full chemical composition analysis (spectrometric testing) and mechanical property certification.
- Hot Rolling & Annealing: The base steel is hot-rolled into semi-finished tube blanks and subjected to solution annealing to achieve a fully austenitic microstructure free of carbide precipitation.
- Cold Drawing / Cold Rolling: Semi-finished tubes are cold-worked to final dimensions using precision dies and mandrels, ensuring tight dimensional tolerances and enhanced mechanical properties through strain hardening.
- Intermediate Annealing: Tubes are annealed at intermediate stages to relieve residual stresses accumulated during cold working and to maintain ductility for continued forming.
- Coiling: The finished tube is wound into a continuous coil using a controlled coiling head that maintains uniform tension and prevents surface damage or deformation.
- Surface Finishing: Optional pickling, passivation, and polishing treatments are applied to achieve the specified surface finish and enhance corrosion resistance.
- Quality Inspection: Each coil undergoes non-destructive testing (NDT) including eddy current testing (ECT), hydrostatic pressure testing, and dimensional verification.
Applications
The stainless steel coil tube is engineered for a diverse range of industrial applications where corrosion resistance, thermal efficiency, and dimensional precision are critical:
- HVAC & Thermal Exchange Systems: Used in fan coil units (FCU), air handling units, and heat exchangers where the Dry-Wet Condition Equivalence Test Method validates performance under both dry-bulb and wet-bulb (condensing) operational scenarios.
- Refrigeration & Cryogenics: Suitable for evaporator and condenser coils operating in low-temperature environments.
- Food & Beverage Processing: Hygienic-grade surface finishes (BA/Polished) meet FDA and 3-A sanitary standards for fluid transport of potable water, dairy, and beverage products.
- Chemical & Petrochemical Industry: Resistant to aggressive media, acids, and chlorides; suitable for process piping, heat exchangers, and condensate collection systems.
- Pharmaceutical Manufacturing: Compliant with GMP requirements for clean-in-place (CIP) and steam-in-place (SIP) processing.
- Automotive & Aerospace: Lightweight, high-strength tubing for fuel lines, brake lines, and hydraulic systems.
Quality Certifications & Testing Methodology
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality assurance programs aligned with international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- ASME Section IX — Welding qualification (for welded coil tube variants)
- CE Marking — Compliance with European Machinery Directive
- EN 10204 3.1 — Material test certificates per lot
Dry-Wet Condition Equivalence Test Method
The product's thermal performance is validated using the Dry-Wet Condition Equivalence Method (干湿工况等价法), a standardized approach for testing fan coil units and heat exchange coil assemblies. This methodology establishes an equivalence between dry-condition and wet-condition (condensing) operating states, enabling accurate determination of cooling capacity, sensible heat ratio, and airflow characteristics under realistic service conditions. Key parameters measured include:
- Dry-bulb air inlet and outlet temperatures
- Wet-bulb air inlet and outlet temperatures
- Condensate collection rate
- Refrigerant-side inlet and outlet temperatures
- Airflow velocity and volume
This test methodology ensures that the coil tube's thermal performance is reliably characterized regardless of ambient humidity conditions, providing end-users with predictable and consistent system performance.
Unique Selling Points
- Dimensional Precision: Ultra-tight tolerances (±0.05 mm OD, ±0.03 mm wall) ensure seamless integration into precision heat exchanger and piping assemblies.
- Continuous Coil Format: Eliminates butt welds and reduces installation time by up to 40% compared to cut-length tubing.
- Validated Thermal Performance: Performance data derived from the Dry-Wet Condition Equivalence Method provides engineering-grade confidence in heat exchange efficiency.
- Grade Versatility: Available in multiple stainless steel grades (304, 316, 321) to match specific corrosion and temperature requirements.
- Full Traceability: Each coil is accompanied by a mill test certificate (MTC) with heat number, chemical analysis, and mechanical property data.