Stainless Steel Spiral Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Spiral Coil Tube is a precision-engineered tubular component manufactured by Wenzhou Jixing Metal Materials Co., Ltd., designed primarily for thermal exchange applications. This product is formed by cold-winding straight stainless steel tubing into a continuous helical (spiral) configuration, creating a high surface-area-to-volume ratio geometry that significantly enhances convective heat transfer performance compared to conventional straight-tube heat exchangers.
Based on extensive research into the heat transfer characteristics of spiral coil tubes, this product leverages the secondary flow effects induced by curvature — including centrifugal force-driven Dean vortices — to promote turbulent mixing within the tube. This results in a marked increase in the Nusselt number (Nu) and overall heat transfer coefficient (U), making the coil tube particularly effective in compact heat exchanger designs where space efficiency and thermal performance are critical.
The spiral geometry also promotes uniform flow distribution, reduces fouling tendencies, and minimizes pressure drop relative to equivalent straight-tube assemblies of the same total heat transfer area.
2. Material & Properties
The coil tube is fabricated from austenitic stainless steel grades that offer an optimal combination of corrosion resistance, thermal conductivity, mechanical strength, and formability. The primary material grades and their key properties are summarized below:
- Grade 304 (UNS S30408 / 1.4301): General-purpose austenitic stainless steel with excellent corrosion resistance in oxidizing environments. Contains approximately 18% Chromium (Cr) and 8% Nickel (Ni). Suitable for food-grade, chemical, and pharmaceutical applications.
- Grade 316 (UNS S31603 / 1.4401): Enhanced corrosion resistance due to the addition of 2–3% Molybdenum (Mo), providing superior resistance to pitting and crevice corrosion in chlorinated environments.
- Grade 321 (UNS S32103 / 1.4541): Stabilized with Titanium (Ti), offering improved resistance to intergranular corrosion at elevated temperatures (up to 870°C).
- Grade 316L (UNS S31603 / 1.4404): Low-carbon variant of 316 (C ≤ 0.03%), optimized for welding applications where sensitization must be avoided.
| Property | Grade 304 | Grade 316 |
|---|---|---|
| Density (g/cm³) | 8.00 | 8.03 |
| Thermal Conductivity at 20°C (W/m·K) | 16.3 | 14.6 |
| Thermal Conductivity at 100°C (W/m·K) | 21.5 | 18.6 |
| Specific Heat at 20°C (J/kg·K) | 500 | 500 |
| Tensile Strength (MPa, min) | 520 | 515 |
| Yield Strength (MPa, min) | 205 | 205 |
| Elongation (% min) | 40 | 40 |
| Maximum Service Temperature (°C) | 870 | 870 |
| Corrosion Resistance | Excellent (general) | Superior (chloride/pitting) |
3. Specifications
The following table outlines the standard dimensional and geometric parameters available for the Stainless Steel Spiral Coil Tube product line:
| Parameter | Specification Range | Unit |
|---|---|---|
| Outer Diameter (OD) | 6.0 – 50.8 | mm |
| Wall Thickness (WT) | 0.5 – 3.0 | mm |
| Coil Diameter (Mean) | 100 – 2000 | mm |
| Coil Pitch | 10 – 100 | mm |
| Number of Turns | 10 – 500 | — |
| Total Tube Length | 5 – 500 | m |
| Surface Finish | Ra 0.4 – Ra 1.6 (Polished); Ra 3.2 – Ra 6.3 (Pickled) | — |
| End Condition | Plain, Beveled, Threaded, or Flanged | — |
| Dimensional Tolerance (OD) | ±0.05 mm (Precision); ±0.10 mm (Standard) | mm |
| Dimensional Tolerance (WT) | ±0.02 mm (Precision); ±0.05 mm (Standard) | mm |
| Helix Angle Tolerance | ±1° | degrees |
4. Manufacturing Process
The production of stainless steel spiral coil tubes follows a rigorous multi-stage manufacturing sequence to ensure geometric accuracy, mechanical integrity, and surface quality:
- Material Selection & Incoming Inspection: Raw seamless or welded stainless steel tubing is procured from certified mills and subjected to spectroscopic analysis (PMI), dimensional verification, and visual inspection to confirm conformance with ASTM A213, ASTM A269, or EN 10216 standards.
- End Preparation: Tube ends are deburred, chamfered, or pre-formed to the required configuration (threaded, beveled, or prepared for flange welding) to facilitate subsequent assembly.
- Cold Coiling (Helical Winding): A computerized coiling machine (CNC-guided) winds the straight tube into a precise helical geometry. The machine controls coil diameter, pitch, number of turns, and helix angle with high repeatability. The cold-forming process introduces beneficial work hardening, increasing the yield strength of the coil tube by approximately 15–30% compared to the straight tube.
- Stress Relief Annealing (Optional): For applications requiring reduced residual stress, the coil tube may be subjected to a controlled annealing cycle at 850–1050°C followed by air cooling, restoring ductility and eliminating coiling-induced residual stresses.
- Surface Treatment: Depending on the application, the coil tube may undergo pickling and passivation (acid bath treatment to remove scale and form a protective chromium oxide layer) or mechanical polishing (brushed or mirror finish, Ra ≤ 0.4 μm) for sanitary or aesthetic requirements.
- Quality Control & Testing: Final inspection includes dimensional measurement (laser scanning or CMM), hydrostatic pressure testing (typically 2–3× working pressure), leak testing (helium or bubble test for hermetic applications), and visual/magnetic particle inspection (MPI) for weld integrity where applicable.
- Packaging & Dispatch: Finished coil tubes are packaged with protective end caps, desiccant materials, and appropriate labeling in export-grade containers or wooden crates.
5. Applications
The Stainless Steel Spiral Coil Tube finds extensive use across multiple industrial sectors where enhanced heat transfer, corrosion resistance, and compact design are required:
- Chemical & Petrochemical Industry: Reactor cooling, heat exchanger bundles, distillation column internals, and process heating/cooling circuits where aggressive media (acids, chlorides, hydrocarbons) demand high corrosion resistance.
- Food & Beverage Processing: Pasteurization systems, milk coolers, juice heat exchangers, and CIP (Clean-in-Place) compatible thermal processing equipment (FDA/3-A compliant grades).
- Pharmaceutical Manufacturing: Sterile fluid heating, reactor temperature control, and heat recovery systems requiring hygienic-grade surface finishes (Ra ≤ 0.5 μm).
- Oil & Gas / Subsea Applications: Subsea heat exchangers, wellhead temperature control, and offshore platform thermal management systems (Grade 316L/321 for chloride resistance).
- Power Generation: Condensers, feedwater heaters, and waste heat recovery systems in both conventional and renewable energy installations.
- Automotive & Aerospace: Compact heat exchangers for engine cooling, hydraulic system temperature regulation, and thermal management in high-performance applications.
- Heat Pump & Refrigeration: Evaporator and condenser coils for air-source and water-source heat pumps, leveraging the enhanced heat transfer characteristics of spiral geometry.
- Marine & Shipbuilding: Seawater coolers, ballast water thermal systems, and marine engine cooling circuits.
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and the following certifications to assure product conformity and reliability:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and continuous improvement.
- ISO 14001:2015 — Environmental Management System certification demonstrating environmental responsibility in manufacturing operations.
- ISO 45001:2018 — Occupational Health and Safety Management System.
- EN 10204 3.1 / 3.2 — Material test certificates (Mill Test Reports) issued by authorized inspection personnel, providing traceable documentation of chemical composition, mechanical properties, and dimensional conformity.
- Product Standards: Manufactured in compliance with ASTM A213 (Austenitic Stainless Steel Tubing for High-Temperature Service), ASTM A269 (Austenitic Stainless Steel Tubing for Chemical and Allied Industries), EN 10216-5, and GB/T 12771 (Chinese National Standard for Seamless Stainless Steel Tubing).
- CE Marking — Conformity with European directives for products used in pressure equipment (PED 2014/68/EU) where applicable.
- NSF / FDA Compliance — Available for food-contact applications with certified sanitary-grade surface finishes and material compositions.
7. Unique Selling Points
- Enhanced Heat Transfer Performance: The spiral coil geometry induces Dean vortices and secondary flows that increase the Nusselt number by 20–40% over equivalent straight-tube configurations, reducing overall heat exchanger footprint.
- Superior Corrosion Resistance: Austenitic stainless steel grades provide exceptional resistance to oxidation, acid attack, and pitting corrosion, extending service life and reducing maintenance frequency.
- Precision Manufacturing: CNC-controlled coiling ensures repeatable geometry with tight tolerances (±0.05 mm on OD), guaranteeing consistent thermal performance across production batches.
- Customizability: Flexible design parameters (OD, wall thickness, coil diameter, pitch, number of turns) allow tailored solutions for specific thermal and mechanical requirements.
- Compact Design: High heat transfer area per unit volume enables space-constrained installations without sacrificing thermal capacity.
- Full Traceability: Complete documentation chain from raw material mill certificates through final inspection reports ensures compliance with international regulatory and quality standards.
Note: All specifications listed herein represent standard offerings. Custom configurations, alternative material grades, and non-standard surface finishes are available upon request. Technical consultation and thermal performance simulation services are provided to support project-specific design optimization.