Stainless Steel Spiral Coil Tube (Coiltube) — Product Technical Specification
1. Product Overview
The Stainless Steel Spiral Coil Tube (Coiltube) is a precision-engineered continuous tube product formed by cold-drawing and coiling wire or thin-walled tubing into a compact, spiral-arranged coil configuration. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product is designed for demanding thermal exchange and heat dissipation applications where space efficiency, corrosion resistance, and thermal conductivity are critical performance parameters.
The coil tube architecture provides a significantly larger heat transfer surface area per unit volume compared to straight-tube designs, making it ideal for applications such as slag coolers, heat exchangers, condensers, and boilers. The continuous spiral geometry promotes turbulent flow within the tube, thereby enhancing convective heat transfer coefficients and improving overall thermal performance.
Key Insight from Industry Practice: In built-in spiral coil type slag cooler systems, cavitation (汽蚀) can occur due to localized pressure drops at bends and coil transitions. Proper coil tube geometry, wall thickness selection, and material grade are critical to mitigating cavitation-induced damage and extending service life.
2. Material & Properties
2.1 Available Material Grades
- 304 (UNS S30408) — Austenitic stainless steel; excellent general corrosion resistance, weldability, and formability.
- 304L (UNS S30403) — Low-carbon variant of 304; superior resistance to intergranular corrosion in welding applications.
- 316 (UNS S31608) — Molybdenum-enhanced austenitic grade; superior resistance to pitting and crevice corrosion in chloride environments.
- 316L (UNS S31603) — Low-carbon variant of 316; enhanced weldability and resistance to sensitization.
- 321 (UNS S32108) — Titanium-stabilized grade; excellent resistance to intergranular corrosion at elevated temperatures (up to 870°C).
- 310S (UNS S31008) — High-temperature austenitic grade; outstanding oxidation resistance and thermal stability up to 1150°C.
- 347 (UNS S34700) — Niobium-stabilized grade; suitable for high-temperature structural and thermal applications.
2.2 Mechanical Properties (Typical — Annealed Condition)
| Property | 304 / 304L | 316 / 316L | 310S |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 515 | ≥ 515 | ≥ 515 |
| Yield Strength (0.2% Proof, MPa) | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 40 |
| Density (g/cm³) | 7.93 | 8.00 | 8.00 |
| Thermal Conductivity (W/m·K @ 100°C) | 16.3 | 14.6 | 20.9 |
| Maximum Service Temperature (°C) | 870 | 870 | 1150 |
2.3 Corrosion Resistance
- Resistance to atmospheric corrosion, dilute mineral acids, and organic acids.
- 316/316L grades offer superior resistance to chloride-induced pitting corrosion and crevice corrosion.
- Passive chromium oxide film provides self-healing protective barrier under normal operating conditions.
- Resistance to cavitation erosion is enhanced through proper material selection and coil geometry optimization.
3. Specifications
| Parameter | Specification / Range |
|---|---|
| Product Name | Stainless Steel Spiral Coil Tube (Coiltube) |
| Product Code / Reference | 989 |
| Outer Diameter (OD) | Φ 3 mm – Φ 50 mm (customizable) |
| Wall Thickness | 0.2 mm – 3.0 mm (customizable) |
| Coil Diameter | Φ 100 mm – Φ 2000 mm |
| Coil Length (per coil) | 50 m – 500 m (configurable) |
| Coil Pitch / Spacing | 1.0 mm – 20.0 mm (adjustable) |
| Surface Finish | Pickled & Passivated (P&P), Bright Annealed (BA), or Polished |
| Forming Method | Cold-drawn spiral coiling |
| End Treatment | Plain cut, Beveled, or Threaded |
| Packaging | Wooden pallet / steel drum with moisture-proof wrapping |
| Applicable Standards | ASTM A213, ASTM A269, EN 10217-7, GB/T 12771, JIS G3459 |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Selection & Inspection: Stainless steel wire or seamless tubing is procured from certified mills. Incoming materials undergo chemical composition analysis (spectrometry), mechanical testing, and dimensional verification.
- Pretreatment: Surface de-oxidation, acid pickling, and passivation treatment to remove scale, oxide films, and contaminants, ensuring a clean substrate for coiling.
- Cold Drawing (if applicable): Wire or tube is cold-drawn through precision dies to achieve target outer diameter and wall thickness with tight dimensional tolerances.
- Spiral Coiling: The formed tube is wound onto a mandrel or guide roll using CNC-controlled coiling equipment. The coiling process maintains consistent pitch, tension, and curvature to prevent kinking, wrinkling, or wall thinning.
- Welding (if required):strong> Butt joints or orbital TIG welding (GTAW) are employed to join coil segments, with full radiographic or dye-penetrant inspection of welds.
- Post-Coil Heat Treatment (if specified): Solution annealing at 1050°C – 1150°C followed by controlled cooling to restore full solution-annealed microstructure and mechanical properties.
- Final Surface Treatment: Pickling and passivation (or bright annealing in protective atmosphere) to achieve the required surface finish and corrosion resistance.
- Quality Inspection & Testing: Dimensional measurement, hydrostatic pressure testing, eddy current testing, and visual inspection.
- Packaging & Dispatch: Coils are secured on wooden pallets or steel drums with moisture barriers and shipping documentation.
4.2 Process Controls for Cavitation Mitigation
Based on industry lessons learned from built-in spiral coil type slag cooler applications, the following process controls are implemented to minimize cavitation risk:
- Uniform coil geometry: CNC-controlled coiling ensures consistent bend radius and pitch, eliminating stress concentration points that could trigger cavitation.
- Wall thickness optimization: Minimum wall thickness is calculated based on operating pressure, flow velocity, and fluid properties to prevent localized thinning and cavitation erosion.
- Material hardness control: Annealed condition provides adequate ductility and resistance to cavitation damage; work-hardened sections are avoided at coil transitions.
- Smooth internal surface: Internal surface roughness (Ra) is controlled below 1.6 μm to reduce turbulent eddy formation and pressure drop fluctuations.
5. Applications
- Slag Coolers (冷渣器): Built-in spiral coil configurations for waste heat recovery in cement kilns, steel mills, and power plants. The coil tube efficiently transfers heat from molten or semi-molten slag to circulating water or air.
- Heat Exchangers: Compact coil-type heat exchangers for industrial process heating and cooling where high surface-area-to-volume ratio is required.
- Boilers & Furnaces: Tube bundles for water-tube boilers, fired heaters, and industrial furnaces operating at elevated temperatures.
- Condensers & Evaporators: Refrigeration and HVAC systems, chemical processing condensers, and evaporator coils.
- Automotive & Aerospace: Compact heat management coils for engine cooling, hydraulic systems, and thermal control units.
- Food & Pharmaceutical Industry: Sanitary-grade coil heat exchangers for pasteurization, sterilization, and process temperature control.
- Marine & Offshore: Corrosion-resistant coil systems for shipboard cooling, ballast water treatment, and offshore platform thermal management.
6. Quality Certifications & Compliance
6.1 Manufacturing Certifications
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health & Safety Management System
- ISO 3834 — Quality requirements for welding of metallic products
6.2 Product Standards & Testing Compliance
| Standard | Description | Scope |
|---|---|---|
| ASTM A213 | Standard Specification for Seamless and Welded Austenitic Chromium- Chromium-Nickel Stainless Steel Tubing | Tube material |
| ASTM A269 | Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for Chemical and Similar Severe Service | Tube material |
| EN 10217-7 | Heat-Exchanger and Heat-Sink Tubing — Part 7: Austenitic Steels | European compliance |
| GB/T 12771 | Seamless Stainless Steel Tubing for Fluid Transport (Chinese National Standard) | Chinese market |
| JIS G3459 | Seamless Stainless Steel Tubing for General Use (Japanese Industrial Standard) | Japanese market |
| ASME BPVC Section I | Boiler and Pressure Vessel Code | Pressure equipment |
6.3 Testing & Inspection Protocols
- Chemical Analysis: Spark-OES or wet chemical analysis per ASTM E415 / ASTM E1019.
- Mechanical Testing: Tensile testing per ASTM E8/E8M; hardness testing per ASTM E92.
- Hydrostatic Testing: Pressure testing per ASTM A213 Section 8; hold time ≥ 10 seconds at test pressure.
- Dimensional Inspection: OD, wall thickness, coil pitch, and coil diameter verified with calibrated instruments (tolerance ± 0.05 mm).
- Surface Inspection: Visual and dye-penetrant testing (ASTM E709) for surface defects and weld integrity.
- Corrosion Testing: Salt spray testing (ASTM B117) for 316/316L grades; intergranular corrosion testing (ASTM A262 Practice E) for stabilization verification.
- Material Traceability: Full heat-number traceability from mill certificate through final product documentation.
7. Unique Selling Points
- Engineered for Cavitation Resistance: Drawing from extensive industry experience in spiral coil slag cooler applications, coil geometry and material selection are optimized to minimize cavitation-induced damage, extending operational life significantly.
- Superior Surface Integrity: Controlled coiling process ensures uniform wall thickness and smooth internal surfaces (Ra < 1.6 μm), reducing flow turbulence and pressure drop.
- Wide Material & Dimensional Flexibility: Multiple austenitic grades available across a broad range of OD, wall thickness, and coil configurations, enabling tailored solutions for diverse applications.
- Full Traceability & Documentation: Every coil batch is accompanied by mill test certificates (MTC), chemical analysis reports, and mechanical test data ensuring complete supply chain transparency.
- Integrated Quality Management: ISO 9001:2015 certified manufacturing with rigorous incoming, in-process, and outgoing inspection protocols.
- Custom Engineering Support: Wenzhou Jixing Metal Materials Co., Ltd.