Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Catalog No.: 1228
Product Category: Formed Stainless Steel Tubular Products
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-formed tubular product manufactured from high-grade austenitic stainless steel wire, wound into a continuous helical coil configuration. This product is engineered to deliver superior thermal transfer performance, mechanical durability, and corrosion resistance in demanding industrial and commercial applications. The coil geometry provides a significantly increased surface-area-to-volume ratio compared to straight tube sections, making it particularly advantageous for heat exchange systems, thermal energy storage (TES) configurations, and fluid distribution networks.
Based on advanced research into thermal conductive coil tube heat transfer performance in ice storage tank systems, this product line has been optimized for efficient thermal energy exchange. Studies on the heat transfer characteristics of thermal conductive coil tubes in ice storage tanks have demonstrated that helical coil configurations achieve enhanced convective heat transfer coefficients due to the secondary flow patterns induced by centrifugal forces within the curved geometry. This fundamental advantage translates directly into improved system efficiency for thermal storage and recovery applications.
2. Material & Properties
2.1 Base Material
The coil tube is fabricated from seamless stainless steel wire conforming to international metallurgical standards. The primary material grades available include:
- AISI 304 (UNS S30400): General-purpose austenitic stainless steel with excellent formability and corrosion resistance. Suitable for most atmospheric, food-grade, and mild chemical environments.
- AISI 316L (UNS S31603): Low-carbon austenitic grade with added molybdenum (2.0–3.0%) providing superior resistance to pitting and crevice corrosion. Recommended for marine, chemical processing, and pharmaceutical applications.
- AISI 321 (UNS S32100): Titanium-stabilized austenitic grade offering enhanced resistance to intergranular corrosion at elevated temperatures (up to 870°C).
2.2 Mechanical Properties
| Property | Specification (AISI 304) | Specification (AISI 316L) | Test Standard |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 515 MPa | ≥ 485 MPa | ASTM A270 / ASTM E8 |
| Yield Strength (Rp0.2) | ≥ 205 MPa | ≥ 170 MPa | ASTM A270 / ASTM E8 |
| Elongation (A50) | ≥ 40% | ≥ 40% | ASTM A270 / ASTM E8 |
| Hardness (HV) | ≤ 210 HV | ≤ 210 HV | ASTM A270 |
| Thermal Conductivity | 16.3 W/(m·K) at 100°C | 14.6 W/(m·K) at 100°C | ASTM E1530 |
| Maximum Service Temperature | 870°C (continuous) | 870°C (continuous) | — |
2.3 Corrosion Resistance
The austenitic stainless steel composition ensures outstanding resistance to oxidation and corrosion across a wide range of environmental conditions. The passive chromium oxide film (Cr₂O₃) self-heals under oxidizing conditions, providing long-term protection. The addition of molybdenum in 316L grade further enhances resistance to chlorides and halogen-containing media, making it suitable for aggressive chemical environments.
3. Specifications
3.1 Dimensional Parameters
| Parameter | Range / Value | Tolerance |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 32.0 mm | ± 0.10 mm |
| Wall Thickness (WT) | 0.30 mm – 2.00 mm | ± 0.05 mm |
| Coil Diameter (Mean) | 150 mm – 1500 mm | ± 2.0% |
| Coil Height (Winding Length) | 50 mm – 3000 mm | ± 3.0% |
| Coil Pitch (Spacing) | 3.5 mm – 25.0 mm | ± 0.5 mm |
| Number of Turns | 5 – 5000 turns | ± 1% |
| Tube Length (Uncoiled) | 1 m – 500 m | ± 1% |
| End Treatment | Plain / Flared / Threaded / Fitted | Per drawing |
3.2 Surface Finish Options
| Finish Type | Ra Value (μm) | Application |
|---|---|---|
| Mill Finish (Standard) | 0.4 – 0.8 | General industrial use |
| Brushed Finish | 0.4 – 1.6 | Aesthetic / decorative applications |
| Electro-polished | 0.05 – 0.2 | Pharmaceutical / food processing |
| Mirror Polish | ≤ 0.05 | High-end decorative / sanitary |
4. Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing process designed to ensure dimensional accuracy, mechanical integrity, and surface quality:
- Raw Material Inspection: Incoming stainless steel wire is verified for chemical composition (via Optical Emission Spectroscopy, OES), mechanical properties, and surface quality in accordance with ASTM A576 / ASTM A580 wire rod specifications.
- Wire Drawing: The stainless steel wire is drawn through precision tungsten carbide dies to achieve the target outer diameter and wall thickness with tight dimensional tolerances. This cold working process also imparts beneficial work hardening and improves surface finish.
- Annealing (if required): Selected grades undergo solution annealing at 1050–1100°C followed by controlled cooling to restore ductility, relieve residual stresses, and ensure uniform microstructure for subsequent forming operations.
- Coil Winding: The precision-drawn tube is wound onto CNC-controlled coil winding machines. The winding parameters (pitch, tension, diameter) are programmatically controlled to ensure uniform geometry and consistent coil density. Tension control systems prevent tube deformation during the forming process.
- End Processing: Coil ends are trimmed, deburred, and optionally processed with threading, flaring, or fitting attachment depending on the application requirement. Seal welding is available for closed-loop configurations.
- Passivation & Cleaning: The finished coil tube undergoes chemical passivation treatment (nitric acid or citric acid based) to maximize the protective chromium oxide layer. Subsequent ultrasonic cleaning removes all contaminants.
- Final Quality Inspection: Each batch undergoes dimensional verification, visual inspection, hydrostatic pressure testing (where applicable), and non-destructive testing (NDT) including dye penetrant inspection (DPI) for surface defect detection.
5. Applications
The Stainless Steel Coil Tube is designed for versatile deployment across multiple industrial sectors:
- Thermal Energy Storage (TES) Systems: As demonstrated in research on heat transfer performance of thermal conductive coil tubes in ice storage tanks, helical coil configurations are highly effective for phase-change thermal energy storage. The enhanced heat transfer coefficients resulting from secondary Dean vortices within the curved tube geometry facilitate efficient ice formation and melting cycles.
- Heat Exchangers: Compact heat exchanger designs utilizing coil tube arrays for liquid-to-liquid and gas-to-liquid thermal exchange in HVAC systems, process cooling, and power generation.
- Refrigeration & Air Conditioning: Evaporator and condenser coils for commercial and industrial refrigeration systems, leveraging the high surface-area-to-volume ratio for enhanced heat transfer efficiency.
- Chemical Processing: Reactor internals, heat transfer coils, and fluid distribution systems in corrosive chemical environments where 316L grade provides essential corrosion protection.
- Food & Beverage Industry: Sanitary-grade fluid distribution coils, pasteurization equipment, and thermal processing systems requiring food-safe materials and easy-to-clean surfaces.
- Pharmaceutical Manufacturing: CIP (Clean-in-Place) compatible coil assemblies for pharmaceutical fluid processing, utilizing electro-polished finishes to minimize microbial adhesion.
- Automotive & Aerospace: Fuel line coils, hydraulic system tubing, and thermal management components requiring high temperature and pressure resistance.
- Oil & Gas: Subsea wellhead tubing, chemical injection coils, and thermal recovery systems in harsh offshore environments.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and product certifications to ensure compliance with international standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO 45001:2018 — Occupational Health and Safety Management System
- CE Marking — Conformity with European Health, Safety, and Environmental Protection standards
- ASME B&W Code — Compliance for pressure vessel and piping applications (where applicable)
- ASTM A576 / A580 — Compliance for seamless and welded austenitic stainless steel pipe and tube
- GB/T 12771 — Chinese National Standard for stainless steel seamless pipes
- JIS G3459 — Japanese Industrial Standard for austenitic stainless steel pipe (where applicable)
- EN 10216-5 — European Standard for seamless stainless steel tubes for pressure purposes
7. Unique Selling Points
Enhanced Thermal Performance: The helical coil geometry inherently generates secondary Dean flow patterns within the tube, increasing the Nusselt number (Nu) and overall heat transfer coefficient by 20–40% compared to equivalent straight tube configurations. This advantage is particularly pronounced in turbulent flow regimes (Re > 10,000).
- Customizable Geometry: Full parametric customization of coil diameter, pitch, turn count, and tube dimensions to meet specific application requirements and spatial constraints.
- Superior Corrosion Resistance: Austenitic stainless steel composition ensures decades of service life in aggressive environments without degradation of mechanical or thermal properties.
- Compact Design: High surface-area-to-volume ratio enables compact system footprints while maintaining or exceeding thermal performance of conventional straight-tube designs.
- Wide Temperature Range: Operational capability from cryogenic temperatures (-196°C) to elevated temperatures (870°C continuous) without loss of structural integrity.
- Sanitary-Grade Availability: Electro-polished and mirror-finished options meeting FDA and EHEDG requirements for food-grade and pharmaceutical applications.
- Integrated End Connections: Available with pre-fitted flanges, threaded connections, or sanitary fittings to reduce installation time and ensure leak-free assembly.
- Batch Traceability: Full material traceability from raw wire mill certificates through final product inspection, supporting regulatory compliance and quality assurance.
8. Technical Notes
Heat Transfer Enhancement: Research on thermal conductive coil tube heat transfer performance in ice storage tank systems has confirmed that the helical coil configuration promotes enhanced convective heat transfer through the generation of Dean vortices. These secondary flow structures disrupt the thermal boundary layer, increasing the effective heat transfer area and reducing thermal resistance. The dimensionless Dean number (De = Re·√(d/D)) serves as a critical parameter for characterizing the intensity of secondary flow, where Re is the Reynolds number, d is the tube inner diameter, and D is the coil mean diameter. Optimal coil design balances the heat transfer enhancement against the associated pressure drop penalty.
Installation Guidance: Coil tubes should be installed with adequate support brackets at intervals not exceeding 1.5× the coil mean diameter to prevent sagging and vibration-induced fatigue. Thermal expansion compensation must be incorporated for applications involving significant temperature differentials.
Storage & Handling: Store in a dry, ventilated environment away from direct sunlight and aggressive chemicals. Protect against mechanical damage during transport. Use appropriate lifting equipment for large coil assemblies to avoid deformation.
Document Reference: Product Catalog No. 1228 | Wenzhou Jixing Metal Materials Co., Ltd.
Revision Date: Current | Subject to technical updates without prior notice