Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered continuous-length tubular product formed into a compact coil configuration. This product is specifically designed for applications requiring high thermal conductivity, corrosion resistance, and structural integrity in fluid transport and heat exchange systems. The coil tube architecture enables efficient space utilization, reduced connection points, and enhanced hydraulic performance in compact assemblies such as fan coil units (FCUs), heat exchangers, and refrigeration circuits.
The design philosophy of this coil tube is informed by computational fluid dynamics (CFD) simulation and performance analysis methodologies, ensuring that dimensional tolerances, wall thickness uniformity, and coil geometry are optimized for maximum thermal-hydraulic efficiency. The integration of simulation-driven design principles into the manufacturing process distinguishes this product from conventional coil tubes in terms of predictable performance and consistency.
2. Material & Properties
2.1 Base Material Grades
- AISI 304 (UNS S30400) — Austenitic stainless steel with superior corrosion resistance, formability, and weldability; suitable for general-purpose HVAC and food-grade applications.
- AISI 316 (UNS S31600) — Molybdenum-enhanced austenitic grade offering exceptional resistance to pitting and crevice corrosion; ideal for marine, chemical, and pharmaceutical environments.
- AISI 321 (UNS S32100) — Titanium-stabilized austenitic grade providing elevated temperature resistance and reduced sensitization risk.
- AISI 304L (UNS S30403) — Low-carbon variant of 304 with enhanced weldability and reduced intergranular corrosion susceptibility.
2.2 Key Physical and Mechanical Properties
| Property | AISI 304 | AISI 316 |
|---|---|---|
| Tensile Strength (MPa) | ≥ 520 | ≥ 515 |
| Yield Strength (0.2% Offset, MPa) | ≥ 205 | ≥ 205 |
| Elongation (%) | ≥ 40 | ≥ 40 |
| 16.3 | 16.3 | |
| Density (g/cm³) | 8.00 | 8.03 |
| Maximum Service Temperature (°C) | 870 | 870 |
| Chromium Content (%) | 18.0–20.0 | 16.0–18.0 |
| Nickel Content (%) | 8.0–10.5 | 10.0–14.0 |
| Molybdenum Content (%) | — | 2.0–3.0 |
2.3 Surface Finish Options
- 2B Finish — Cold-rolled, annealed, and pickled; smooth, non-directional matte surface.
- No. 4 Brushed Finish — Unidirectional grain appearance with moderate reflectivity.
- Mirror Polish (8K) — High-gloss reflective surface suitable for aesthetic and sanitary applications.
- Pickled & Passivated — Free of scale and contaminants; optimized for maximum corrosion resistance.
3. Specifications
| Parameter | Specification Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 38.1 mm (1/8" – 1-1/2") | ASTM A269 / ASTM B482 |
| Wall Thickness | 0.3 mm – 3.0 mm | ASTM A269 |
| Coil Length | 10 m – 200 m (continuous) | Custom / Manufacturer Standard |
| Coil Inner Diameter (Winding) | 150 mm – 600 mm | Manufacturer Standard |
| Dimensional Tolerance (OD) | ±0.1 mm (precision grade) | ASTM A269 |
| Dimensional Tolerance (Wall) | ±10% of nominal | ASTM A269 |
| Roundness (Ovality) | ≤ 0.5% of nominal OD | ASTM A269 |
| Straightness (per meter) | ≤ 1.5 mm/m | ASTM A269 |
| Maximum Working Pressure | Up to 2.5 MPa (dependent on dimensions) | ASME B31.3 / EN 10217 |
| Operating Temperature Range | −196 °C to +870 °C | ASTM A269 |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Selection & Inspection — Incoming stainless steel strip or seamless tube stock is verified for chemical composition (via optical emission spectrometry), mechanical properties, and surface quality in accordance with ASTM A269 and ASTM A967.
- Coiling / Bending Operation — The tube is wound into the specified coil geometry using CNC-controlled coiling machinery. Bending radii are calculated to prevent wall thinning, ovalization, and material strain beyond the elastic limit. Finite element analysis (FEA) is employed to validate deformation behavior under forming loads.
- Heat Treatment (Annealing) — Post-forming solution annealing at 1050–1150 °C with rapid water quenching restores full austenitic microstructure, eliminates residual stresses, and recovers ductility for subsequent processing.
- Pickling & Passivation — Acid cleaning (per ASTM A967) removes oxide scale; passivation treatment establishes a chromium-rich passive film (≥ 100 nm) to maximize corrosion resistance.
- Quality Inspection & Testing — Includes hydrostatic pressure testing, dimensional measurement (laser scanning), eddy current testing for internal defects, and visual inspection of surface quality.
- Packaging & Dispatch — Coils are wrapped in moisture-proof film, secured with steel bands, and labeled with material traceability documentation.
4.2 Simulation-Driven Design Integration
A distinguishing feature of this coil tube product is the incorporation of computer simulation and performance analysis systems—principles analogous to those described in the referenced study on fan coil unit (FCU) design optimization. Computational modeling ensures that:
- Coil pitch and winding geometry minimize flow maldistribution and pressure drop.
- Wall thickness distribution is optimized to balance structural strength with thermal efficiency.
- Thermal performance predictions (U-value, NTU-effectiveness) are validated prior to physical production.
5. Applications
- HVAC Systems — Fan coil units (FCUs), air handling units (AHUs), and chiller coils where compact heat exchange surfaces are required.
- Refrigeration & Cryogenics — Evaporators, condensers, and expansion coil assemblies operating across wide temperature ranges.
- Process Industries — Chemical processing, pharmaceutical manufacturing, and food & beverage equipment requiring hygienic, corrosion-resistant fluid conveyance.
- Automotive & Transportation — Intercooler coils, exhaust heat recovery, and hydraulic circuit tubing.
- Electronics Cooling — Heat sink coils for power electronics and server thermal management.
- Water Treatment & Desalination — RO membrane feed loops and brine circulation coils in high-chloride environments.
6. Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent manufacturing quality. |
| ISO 14001:2015 | Environmental Management System compliance for sustainable production practices. |
| CE Marking (EN 10217) | European conformity for pressure equipment components. |
| ASTM A269 | Standard specification for seamless austenitic stainless steel tubing. |
| ASME BPV Code | Boiler and Pressure Vessel Code compliance for pressure-containing applications. |
| 3.1 Material Test Certificate | Independent third-party material verification per EN 10204. |
| NSF/ANSI 61 | Potable water contact compliance (where applicable). |
7. Unique Selling Points
- Simulation-Validated Geometry — Coil dimensions and winding parameters are optimized through computational analysis, ensuring predictable thermal-hydraulic performance without reliance on empirical trial-and-error.
- Precision Dimensional Control — Tight tolerances (±0.1 mm on OD) achieved through CNC coiling and post-forming inspection guarantee interchangeability and system integration reliability.
- Multi-Grade Flexibility — Availability in 304, 316, 321, and 304L grades allows specification matching to diverse environmental and service conditions.
- Full Traceability — Each coil batch is traceable from raw material heat number through final inspection, supporting regulatory compliance in critical industries.
- Reduced Installation Complexity — Continuous coil format minimizes field welding and mechanical joints, reducing leak points and installation labor.
8. Ordering Information
Wenzhou Jixing Metal Materials Co., Ltd provides custom coil tube configurations based on customer-specific dimensional requirements, grade selection, surface finish, and performance criteria. Technical consultation is available for applications requiring simulation-based design validation or non-standard specifications.