Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd, designed for continuous, uncut delivery in coil form to facilitate downstream processing and fabrication. This product is primarily utilized in HVAC (Heating, Ventilation, and Air Conditioning) systems, refrigeration circuits, heat exchangers, and industrial piping applications where corrosion resistance, thermal conductivity, and mechanical durability are critical performance parameters.
The coil tube is supplied in tightly wound, continuous lengths, eliminating the need for welding joints in many applications and thereby enhancing system integrity, reducing leak points, and improving overall thermal efficiency. The product is engineered to meet international standards including ASTM (American Society for Testing and Materials), EN (European Norms), and GB (Guo Biao — Chinese National Standards).
2. Material & Properties
The Coil Tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional resistance to oxidation, pitting, and general corrosion in both ambient and elevated-temperature environments.
2.1 Available Grades
- 304 / 304L (UNS S30400 / S30403): The most widely used austenitic stainless steel, offering excellent corrosion resistance, formability, and weldability. 304L provides lower carbon content for superior resistance to sensitization during welding.
- 316 / 316L (UNS S31600 / S31603): Enhanced molybdenum content (2.0–3.0%) provides superior resistance to pitting and crevice corrosion, particularly in chloride-rich environments.
- 321 (UNS S32100): Titanium-stabilized grade suitable for high-temperature service up to 870°C, resistant to intergranular corrosion.
- 310S (UNS S31008): High-temperature alloy with excellent resistance to scaling and oxidation, suitable for extreme thermal environments.
2.2 Mechanical Properties (Annealed Condition — Grade 304)
- Tensile Strength: ≥ 515 MPa (74,700 psi)
- Yield Strength (0.2% offset): ≥ 205 MPa (29,700 psi)
- Elongation: ≥ 40% (minimum)
- Hardness: ≤ 92 HRB (Rockwell B scale)
- Density: 8.0 g/cm³
- Thermal Conductivity (20°C): 16.3 W/(m·K)
- Thermal Expansion Coefficient (20–100°C): 17.3 × 10⁻⁶ /°C
3. Technical Specifications
| Parameter | Specification / Range |
|---|---|
| Outer Diameter (OD) | 3.0 mm – 108 mm (customizable upon request) |
| Wall Thickness | 0.3 mm – 6.0 mm |
| OD Tolerance | ±0.05 mm to ±0.15 mm (per ASTM A269 / EN 10216) |
| Wall Thickness Tolerance | ±10% of nominal (or ±0.05 mm, whichever is greater) |
| Coil Length (Continuous) | Up to 500 m per coil (custom lengths available) |
| Coil Inner Diameter | 500 mm – 1,500 mm |
| Surface Finish | 2B (Cold Rolled & Annealed), No.4 (Brushed), BA (Bright Annealed), Mirror (8K) |
| Manufacturing Process | Seamless (Seamless Tube) or Welded (ERW / TIG Welded) |
| Heat Treatment | Solution Annealing at 1050°C – 1150°C followed by rapid cooling |
| Coil Weight | Up to 3,000 kg per coil |
| Standard References | ASTM A269, ASTM A213, EN 10216-5, GB/T 14976, GB/T 12771 |
| End Condition | Plain, Beveled, or Threaded (upon request) |
4. Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous, multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: Virgin stainless steel billets or strips are sourced from certified suppliers with full mill test certificates (MTC) per EN 10204 Type 3.1.
- Hot Rolling / Billet Extrusion: Steel billets are heated to 1,200°C – 1,300°C and extruded through calibrated dies to produce seamless tube blanks with initial wall thickness.
- Piercing & Elongation: The extruded blanks undergo piercing to create hollow sections, followed by multi-stand elongation to reduce OD and wall thickness to target dimensions.
- Cold Drawing / Cold Rolling: Tubes are drawn through precision tungsten carbide dies to achieve tight dimensional tolerances (±0.05 mm), improved surface finish, and enhanced mechanical properties.
- Solution Annealing: Tubes are heated to 1,050°C – 1,150°C in a controlled atmosphere furnace to dissolve carbide precipitates, restore full austenitic microstructure, and achieve maximum corrosion resistance.
- Pickling & Passivation: Tubes are treated with nitric/hydrofluoric acid solution to remove oxide scales, followed by passivation to establish a protective chromium oxide film on the surface.
- Coiling: Continuous tube lengths are wound onto precision coilers with controlled tension to produce uniform, damage-free coils with consistent winding density.
- Quality Inspection: Each coil undergoes ultrasonic testing (UT) for internal defects, eddy current testing (ECT) for surface and near-surface flaws, dimensional verification, and chemical composition analysis via optical emission spectrometry (OES).
- Packaging: Coils are wrapped with moisture-resistant protective film, secured with steel strapping, and placed on wooden pallets or steel cradles for export-ready shipping.
5. Applications
The Stainless Steel Coil Tube finds extensive application across multiple industrial sectors:
- HVAC & Refrigeration Systems: Used in fan coil units, chiller circuits, condenser tubes, evaporator coils, and heat exchanger assemblies where high thermal conductivity and corrosion resistance are essential.
- Food & Beverage Processing: Sanitary-grade tubing for dairy, brewing, and pharmaceutical processing lines requiring compliance with FDA and 3-A Sanitary Standards.
- Chemical & Petrochemical Industry: Piping and heat exchanger tubes in aggressive chemical environments, particularly where chloride-induced corrosion is a concern (Grade 316L).
- Automotive Industry: Fuel lines, brake lines, exhaust system components, and turbocharger coolant circuits.
- Medical Equipment: Tubing for medical gas delivery systems, sterilization equipment, and diagnostic instruments.
- Marine & Offshore: Seawater cooling circuits, ballast water systems, and desalination plant heat exchangers.
- Architectural & Decorative: Handrails, balustrades, and structural elements in commercial and residential construction.
- Fiberglass-Reinforced Plastic (FRP) Fan Coil Air Conditioners: The coil tube serves as the core heat transfer element in FRP-based fan coil units, where its stainless steel construction ensures long-term resistance to condensation corrosion and microbial growth within the air-handling system.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system with the following certifications and standards compliance:
- ISO 9001:2015: Quality Management System certification ensuring consistent product quality and continuous improvement.
- ISO 14001:2015: Environmental Management System certification demonstrating commitment to environmental stewardship.
- CE Marking (EU Conformity): Compliance with European directives for pressure equipment and construction products.
- PED (Pressure Equipment Directive 2014/68/EU): Certification for products used in pressure-containing applications.
- NSF/ANSI 61: National Sanitation Foundation certification for potable water applications.
- Mill Test Certificates (MTC): Full chemical and mechanical test data provided per EN 10204 Type 3.1 for every production lot.
- NACE MR0175 / ISO 15156: Compliance for sour service applications in oil and gas industries.
7. Unique Selling Points
Continuous Coil Form Factor: Unlike cut-length tubes, the coil format eliminates longitudinal weld seams, significantly reducing leak risk and improving thermal transfer efficiency in heat exchanger and HVAC applications.
- Superior Dimensional Consistency: Cold-drawn manufacturing ensures ±0.05 mm OD tolerance, critical for precision assembly in fan coil units and heat exchanger tube bundles.
- Customizable Specifications: Full range of grades, dimensions, surface finishes, and coil configurations available to meet project-specific requirements.
- Full Traceability: Each coil is individually batch-traced with complete mill test data, enabling full supply chain accountability.
- Extended Service Life: Austenitic stainless steel construction provides 25–50 year service life in most applications, significantly outperforming carbon steel alternatives.
- Environmental Sustainability: Stainless steel is 100% recyclable with no degradation of material properties, supporting circular economy objectives.