304 Stainless Steel Coil Tube (Coiltube) — Technical Specification
Product Designation: 304 SS Coil Tube / Spiral Coil Tube (盘管)
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd
Grade Reference: AISI 304 / ASTM A213 TP304 / EN 1.4301 / GB/T 12771
1. Product Overview
The 304 Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product formed into a continuous helical or spiral coil configuration. Unlike conventional straight-length tubes, coil tubes are manufactured in a pre-coiled geometry, offering significant advantages in heat exchange efficiency, space utilization, and mechanical flexibility. The helical geometry induces secondary flow patterns — including Dean vortices — which enhance turbulent mixing and mass transfer within the tube, a phenomenon extensively validated through computational fluid dynamics (CFD) simulations using software such as ANSYS Fluent.
Based on numerical simulation studies of coil-type separators, the 304 SS Coil Tube demonstrates superior performance in phase separation, heat recovery, and fluid distribution applications. The coiled configuration increases the effective residence time of fluids within a compact footprint, making it ideal for compact separation and processing systems.
Key Unique Selling Points (USPs):
- Enhanced Heat Transfer Coefficient: The helical geometry generates Dean vortices, increasing the turbulent heat transfer coefficient by 30–80% compared to straight tubes of equivalent diameter.
- Compact Footprint: Achieves high surface-area-to-volume ratios, reducing overall equipment dimensions by up to 40%.
- Corrosion Resistance: 304 grade provides excellent resistance to atmospheric, mild acidic, and alkaline environments.
- Low-Maintenance Operation: Seamless or welded construction minimizes leakage risk and extends service life.
- Customizable Geometry: Coil diameter, pitch, tube OD/ID, and length are tailored to specific process requirements.
2. Material Composition & Properties
2.1 Chemical Composition (AISI 304 / ASTM A213 TP304)
| Element | Specification (% by mass) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Manganese (Mn) | ≤ 2.00 |
| Silicon (Si) | ≤ 1.00 |
| Chromium (Cr) | 18.00 – 20.00 |
| Nickel (Ni) | 8.00 – 10.50 |
| Nitrogen (N) | ≤ 0.10 |
| Sulfur (S) | ≤ 0.030 |
| Phosphorus (P) | ≤ 0.045 |
| Iron (Fe) | Balance |
2.2 Mechanical Properties (Annealed Condition)
| Property | Specification |
|---|---|
| Tensile Strength (UTS) | ≥ 515 MPa (75 ksi) |
| Yield Strength (0.2% Proof) | ≥ 205 MPa (30 ksi) |
| Elongation (in 50 mm) | ≥ 40% |
| Hardness (HB) | ≤ 217 |
| Density | 7.93 g/cm³ |
| Thermal Conductivity (at 100°C) | 16.3 W/(m·K) |
| Specific Heat Capacity | 500 J/(kg·K) |
| Maximum Service Temperature | 870°C (1600°F) — continuous |
| Cryogenic Service Temperature | Down to −196°C (−320°F) |
2.3 Corrosion Resistance
- Excellent resistance to atmospheric corrosion, mild organic and inorganic acids
- Good resistance to dilute sulfuric acid, acetic acid, and phosphoric acid
- Resistant to pitting and crevice corrosion in non-chloride environments
- Not recommended for high-chloride environments (e.g., seawater); 316 grade recommended for such applications
3. Geometric & Dimensional Specifications
| Parameter | Specification / Range |
|---|---|
| Tube Outer Diameter (OD) | 6 mm – 108 mm (⅛" – 4") |
| Tube Wall Thickness | 0.5 mm – 6.0 mm |
| Coil Inner Diameter (CID) | 100 mm – 2000 mm (customizable) |
| Coil Pitch (Center-to-Center Spacing) | 5 mm – 50 mm (adjustable) |
| Total Coil Length | 5 m – 500 m (per coil assembly) |
| Number of Turns | 10 – 5000+ (dependent on coil length and CID) |
| End Condition | Plain, threaded (NPT/BSP), flanged (ANSI/ASME), or custom fittings |
| Surface Finish | Mill finish, brushed, polished (Ra ≤ 0.4 μm available on request) |
| Dimensional Tolerance (OD) | ± 0.05 mm – ± 0.2 mm (per ASTM A213) |
| Dimensional Tolerance (Wall) | ± 10% of nominal thickness |
4. Manufacturing Process
The production of 304 Stainless Steel Coil Tubes follows a rigorous, multi-stage manufacturing workflow to ensure dimensional accuracy, metallurgical integrity, and surface quality:
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Raw Material Procurement:
Virgin 304 stainless steel strip or seamless/welded tube blanks are sourced from certified mills. Each lot is verified via mill test certificates (MTC) for chemical composition and mechanical properties.
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Coiling / Helical Forming:
The straight tube is precisely coiled onto a mandrel using CNC-controlled coiling machinery. The forming process maintains controlled bending radii to prevent ovalization, wall thinning, or stress-induced cracking. The coil diameter and pitch are maintained within tight tolerances throughout the forming operation.
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Heat Treatment (Solution Annealing):
Coiled tubes are solution-annealed at 1050–1150°C followed by rapid water quenching to dissolve carbides and restore full austenitic microstructure. This process relieves residual stresses from coiling and maximizes corrosion resistance and ductility.
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Pickling and Passivation:
Post-annealing, the coil is subjected to acid pickling (nitric/hydrofluoric acid blend) to remove oxide scale, followed by passivation to form a protective chromium oxide layer. This ensures optimal corrosion resistance and a clean surface finish.
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Mechanical Testing and Inspection:
Each batch undergoes hydrostatic pressure testing (per ASTM A213), dimensional verification using calibrated gauges, and visual inspection for surface defects. Spectroscopic analysis (OES) confirms chemical composition compliance.
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End Preparation and Assembly:
Tube ends are cut, deburred, and fitted with threaded couplings, flanges, or other specified end connections. Final assembly is performed in a controlled environment to prevent contamination.
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Final Quality Assurance and Packaging:
Completed coil tubes are inspected, tagged with traceability documentation, and packaged in protective wooden crates or steel containers for shipment.
5. Applications
The 304 SS Coil Tube is employed across a wide spectrum of industrial and commercial applications where compact geometry, corrosion resistance, and thermal performance are critical:
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Chemical Processing & Separation:
Used in coil-type separators (validated via CFD/Fluent numerical simulation) for gas-liquid separation, oil-water separation, and multiphase flow management in petrochemical and refining operations. The helical geometry enhances centrifugal separation efficiency.
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Heat Exchangers & Thermal Management:
Coil tubes serve as efficient heat exchange elements in shell-and-coil heat exchangers, air-cooled condensers, and process cooling systems. The Dean vortex effect significantly enhances convective heat transfer coefficients.
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Pharmaceutical & Biotechnology:
Employed in CIP (Clean-in-Place) systems, reactor cooling jackets, and fluid distribution networks where sanitary-grade surface finish and corrosion resistance are mandatory.
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Food & Beverage Industry:
Used in pasteurization systems, sterilization loops, and hygienic fluid transfer lines. Complies with FDA and EHEDG standards for food-contact materials.
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Power Generation:
Applied in boiler economizers, condenser tube bundles, and steam generation systems where thermal cycling resistance and long-term durability are required.
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Automotive & Aerospace:
Used in fuel lines, hydraulic circuits, and turbocharger coolant loops where compact routing and high-temperature resistance are essential.
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Oil & Gas:
Deployed in upstream separation skids, downstream fuel handling systems, and process instrumentation lines.
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Refrigeration & HVAC:
Serves as evaporator and condenser coils in industrial refrigeration systems and large-scale HVAC installations.
6. Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent product quality and process control |
| ISO 14001:2015 | Environmental Management System certification for sustainable manufacturing practices |
| ISO 45001:2018 | Occupational Health and Safety Management System certification |
| ASTM A213 / A269 | Compliant with ASTM standards for austenitic stainless steel welded and seamless tube specifications |
| EN 10217-7 | European standard for austenitic stainless steel tubes for pressure purposes |
| GB/T 12771 | Chinese national standard for welded stainless steel seamless tubes |
| ASME B31.3 / B31.5 | Compliant with ASME codes for process piping and fluid power piping systems |
| NACE MR0175 / ISO 15156 | Material requirements for equipment in H₂S-containing environments (where applicable) |
| Mill Test Certificate (MTC) | EN 10204 Type 3.1 certificate provided with each shipment, documenting chemical analysis and mechanical test results |
7. Summary
The 304 Stainless Steel Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd represents a high-performance, versatile tubular solution engineered for demanding industrial applications. Backed by rigorous manufacturing processes, comprehensive quality certifications, and validated performance through CFD numerical simulation (including Fluent-based coil-type separator analysis), this product delivers exceptional thermal efficiency, corrosion resistance, and mechanical reliability in compact coil configurations. The combination of precision coiling technology, solution-annealed 304 austenitic stainless steel, and customizable geometric parameters makes it a preferred choice for engineers and designers across the chemical, pharmaceutical, energy, and food processing industries.
Note: For applications involving high-chloride environments (e.g., seawater, concentrated HCl), customers are advised to consider 316L (AISI 316L / ASTM A213 TP316L) grade coil tubes as an alternative. Custom specifications, special alloys (321, 347, 310S), and non-standard geometries are available upon request. Please consult the manufacturer's engineering team for application-specific