Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
Product Overview
The Stainless Steel Coil Tube, also known as Coiltube or Coil Pipe, is a precision-engineered continuous stainless steel tubing formed into a helical coil configuration. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product represents a critical component in thermal exchange systems, HVAC (Heating, Ventilation, and Air Conditioning) applications, and industrial fluid transport networks. The coil geometry maximizes the surface-area-to-volume ratio, enabling superior heat transfer efficiency while minimizing the spatial footprint of the installation.
Coiltube products are supplied in standardized coil diameters and lengths, facilitating easy handling, transportation, and on-site installation. The continuous nature of the coil eliminates the need for field welding or joining, thereby reducing potential leak points and enhancing long-term system reliability. This product line is particularly suited for applications where hygienic performance, corrosion resistance, and thermal conductivity are paramount requirements.
Material & Properties
The Stainless Steel Coil Tube is fabricated from austenitic stainless steel grades conforming to international standards. The primary material options include:
- AISI 304 (UNS S30400) — The most widely used grade, offering excellent general corrosion resistance, good formability, and suitability for food-grade and pharmaceutical applications. Contains a minimum of 18% Chromium (Cr) and 8% Nickel (Ni).
- AISI 316 (UNS S31600) — Enhanced corrosion resistance due to the addition of 2–3% Molybdenum (Mo), making it ideal for aggressive chemical environments and marine applications.
- AISI 321 (UNS S32100) — Stabilized with Titanium (Ti) to resist intergranular corrosion during welding and high-temperature service up to 870°C.
- AISI 316L (UNS S31603) — Low-carbon variant of 316, designed for superior weldability and resistance to sensitization in high-temperature environments.
Key Material Properties:
- Non-magnetic in annealed condition (austenitic structure)
- Thermal conductivity: 14.6–16.3 W/(m·K) depending on grade
- Coefficient of thermal expansion: 17.3 × 10⁻⁶ /°C (AISI 304)
- Maximum service temperature: up to 870°C (oxidation resistance)
- Surface finish options: 2B (cold-rolled and annealed), No.4 (brushed), 8K (mirror), and BA (Bright Annealed)
Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (available in increments of 0.5 mm upon request) |
| Wall Thickness (WT) | 0.3 mm – 3.0 mm (tolerance: ±10% per ASTM A269) |
| Coil Diameter (CD) | 200 mm – 2,000 mm (customizable based on application requirements) |
| Coil Length | 50 m – 500 m per coil (standard); bulk quantities available |
| Material Grade | AISI 304, 304L, 316, 316L, 321, 321H |
| Surface Finish | 2B, BA, No.4 Brushed, 8K Mirror (Ra ≤ 0.05 μm) |
| End Condition | Plain cut, beveled, or custom-formed (U-bend, S-bend) |
| Applicable Standards | ASTM A269/A269M, ASTM A213/A213M, ASME B36.19M, EN 10216-5 |
| Pressure Rating | Up to 10 MPa (1,000 psi) depending on OD and wall thickness |
| Temperature Range | -196°C (cryogenic) to +870°C (continuous service) |
| Tolerance (OD) | ±0.05 mm (precision grade); ±0.10 mm (standard grade) |
| Coil Pitch | Customizable: 5 mm – 50 mm (helical pitch) |
Manufacturing Process
The production of Stainless Steel Coil Tube follows a rigorous multi-stage manufacturing process designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection — Cold-rolled stainless steel strip or seamless tubing stock is sourced from certified mills with full material traceability and chemical composition verification via Optical Emission Spectroscopy (OES).
- Forming & Rolling — Flat strip is formed into tubular cross-section using precision roll-forming machinery with synchronized die sets to achieve uniform wall thickness and consistent geometry.
- Welding (for welded coil tube) — Continuous TIG (Tungsten Inert Gas) welding is performed with internal and external gas shielding to produce a high-quality, consistent weld seam. Weld overlap is minimized to ≤0.1 mm.
- Coiling — The formed tube is wound onto a precision coiling mandrel at controlled tension to produce the final coil geometry. The coil is supported on custom-designed spools to prevent deformation.
- Heat Treatment (Annealing) — Where required, the coil tube undergoes solution annealing at 1050–1150°C followed by controlled cooling to restore full austenitic microstructure and relieve residual stresses.
- Pickling & Passivation — The surface is treated with a nitric acid/hydrofluoric acid pickling solution to remove scale and oxidation, followed by passivation to form a protective chromium oxide layer.
- Precision Machining & Cutting — Final coil dimensions are verified, and end preparation (beveling, threading, or custom forming) is performed to specification.
- Quality Inspection — 100% visual inspection, dimensional measurement, hydrostatic pressure testing, and non-destructive testing (NDT) including dye penetrant testing (DPT) and eddy current testing are conducted.
Applications
The Stainless Steel Coil Tube finds extensive application across multiple industries due to its unique combination of corrosion resistance, thermal performance, and hygienic properties:
- HVAC & Fan Coil Systems — The coil tube serves as the heat exchange element in fan coil units (FCUs), air handling units (AHUs), and chiller coils. The helical coil geometry, when combined with optimized flow-path design and fuzzy logic controllers for precise temperature regulation, enables high-efficiency thermal management in commercial and residential buildings. Research into fuzzy control algorithms for fan coil unit operation has demonstrated that the thermal mass and response characteristics of stainless steel coil tubes contribute significantly to system stability and energy efficiency.
- Food & Beverage Processing — Used in pasteurization systems, brewing equipment, milk processing lines, and hygienic fluid transfer where CIP (Clean-in-Place) and SIP (Sterilize-in-Place) compatibility is required. AISI 316L grade is preferred for acidic or chlorinated environments.
- Pharmaceutical & Biotechnology — Employed in bioreactor cooling jackets, heat exchangers, and process piping where GMP (Good Manufacturing Practice) compliance and smooth surface finish (Ra ≤ 0.4 μm) are mandatory.
- Chemical & Petrochemical Industry — Utilized in heat exchangers, reactor coils, and process piping for corrosive chemical transfer, acid storage, and high-temperature service.
- Automotive Industry — Used in engine cooling systems, turbocharger intercoolers, and exhaust heat recovery systems where lightweight, high-performance heat exchange is critical.
- Power Generation — Applied in condensers, economizers, and feedwater heaters in both conventional and renewable energy (solar thermal, geothermal) installations.
- Marine & Offshore — AISI 316 and 316L coil tubes are used in ballast water systems, desalination plants, and marine engine cooling circuits.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that all Stainless Steel Coil Tube products meet or exceed international standards:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and continuous improvement processes.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management System certification.
- ASTM A269/A269M Compliance — Full conformance to specifications for seamless and welded austenitic stainless steel tubing.
- EN 10216-5 Compliance — European standard for stainless steel tubes and pipes for general applications.
- ASME B36.19M Compliance — Welded stainless steel tube dimensions and tolerances.
- NACE MR0175/ISO 15156 — Resistance to sulfide stress cracking for oil and gas applications (applicable grades).
- 3-A (Sanitary Standards) — Compliance for food-grade applications including surface finish, weld quality, and material purity.
- CE Marking — European conformity marking for products used in pressure equipment and machinery.
Unique Selling Points
1. Superior Heat Transfer Efficiency: The helical coil geometry provides a surface-area-to-volume ratio up to 8× greater than equivalent straight piping, enabling compact, high-performance thermal exchange systems ideal for fan coil units and industrial heat exchangers.
2. Leak-Free Continuous Construction: The seamless coil configuration eliminates field joints and welds, significantly reducing the risk of system failures and maintenance requirements.
3. Customizable Coil Parameters: Coil diameter, pitch, length, and end-forming are fully customizable to match specific application requirements, from cryogenic service to high-temperature industrial processes.
4. Comprehensive Material Options: Multiple stainless steel grades (304, 316, 321, and low-carbon variants) provide solutions for diverse corrosive environments, from food-grade hygiene to aggressive chemical processing.
5. Precision Manufacturing: Tight dimensional tolerances (±0.05 mm on OD) and controlled surface finishes ensure compatibility with precision-machined heat exchanger headers and mounting systems.
6. Full Traceability: Every coil is accompanied by a Mill Test Certificate (MTC) with full chemical and mechanical property data, ensuring complete material traceability from raw material to finished product.
Conclusion
The Stainless Steel Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. represents a state-of-the-art solution for applications demanding high-performance thermal exchange, corrosion resistance, and hygienic integrity. The product's versatility across HVAC systems, food processing, pharmaceutical manufacturing, and industrial heat exchange—coupled with rigorous quality assurance and adherence to international standards—positions it as a premier choice for engineers and procurement specialists seeking reliable, long-lasting coil tube solutions.