Stainless Steel Coil Tube (Coiltube) — Technical Specification
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubular product formed through continuous coiling of stainless steel seamless or welded pipe stock. This product category encompasses a wide range of coil tube geometries designed for applications in evaporative cooling systems, HVAC (Heating, Ventilation, and Air Conditioning), heat exchangers, condensers, evaporators, and industrial process piping. The coil tube is supplied in continuous coil form to facilitate downstream forming, bending, and fabrication processes with minimal material waste.
The product has been the subject of academic research, notably the study titled "Study on the Effect of Different Water Distribution Methods on the Uniformity of Evaporative Cooling Coil Tubes", which investigated the hydrodynamic performance and water distribution uniformity across various coil tube configurations used in evaporative cooling systems. This research validates the product's suitability for high-efficiency thermal management applications where uniform fluid distribution is critical to system performance.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its superior corrosion resistance, mechanical strength, and thermal stability across a broad operating temperature range.
- Primary Alloy Grades: AISI 304 (UNS S30400), AISI 316 (UNS S31600), AISI 316L (UNS S31603), AISI 321 (UNS S32100), and AISI 310S (UNS S31008)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, chemical media, and chlorinated environments (particularly 316/316L grades due to molybdenum addition)
- Temperature Range: Operating temperatures from −196 °C (−321 °F) to +870 °C (+1600 °F) depending on alloy grade
- Surface Finish: 2B mill finish, BA (Bright Annealed), or electropolished (Ra ≤ 0.4 μm available upon request)
- Hygiene Compliance: Suitable for food-grade and pharmaceutical applications per FDA 21 CFR and EU 1935/2004 regulations
Specifications
| Parameter | Specification Range | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | 3.18 mm – 108 mm (⅛" – 4") | ASTM A213 / ASME SA-213 |
| Wall Thickness | 0.30 mm – 6.35 mm (0.012" – 0.250") | ASTM A269 / ASME SA-269 |
| Coil Length | 10 m – 500 m per coil (customizable) | — |
| Coil Inner Diameter | 150 mm – 600 mm | — |
| Minimum Bend Radius | 3D – 5D (where D = tube OD) | ASTM B751 |
| Tolerance (OD) | ±0.05 mm to ±0.50 mm | ASTM A213 |
| Tolerance (Wall Thickness) | ±10% of nominal | ASTM A269 |
| Yield Strength (304) | ≥ 205 MPa (≥ 30 ksi) | ASTM A213 |
| Tensile Strength (304) | 515 – 700 MPa (75 – 100 ksi) | ASTM A213 |
| Heat Treatment | Solution annealed (1040 – 1150 °C, water quenched) | ASTM A213 |
| Delivery Form | Continuous coil, cut-to-length, or formed coil | — |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing sequence to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Procurement: High-purity stainless steel billets or strip are sourced from certified mills with full chemical composition traceability (PMI — Positive Material Identification verified).
- Hot Rolling / Cold Drawing: Depending on the target specification, the tube blank is produced via hot-rolled seamless (per ASTM A213) or cold-drawn from seamless tube stock (per ASTM A269) to achieve precise dimensional tolerances.
- Coiling: The continuous tube is wound onto precision-engineered coil spools using CNC-controlled coiling equipment to maintain consistent tension and prevent mechanical deformation or surface marking.
- Solution Annealing: The tube is subjected to solution heat treatment at 1040–1150 °C followed by rapid water quenching to dissolve carbide precipitates, restore full austenitic microstructure, and maximize corrosion resistance.
- Surface Finishing: The tube undergoes pickling and passivation (acid cleaning to remove oxide scale and form a protective chromium oxide passive layer). Optional electropolishing or mechanical polishing is available for critical applications.
- Quality Inspection: Every coil lot is subjected to hydrostatic pressure testing, ultrasonic flaw detection (UT), eddy current testing (ECT), and visual inspection per ASTM A999 and ASTM E709.
- Coil Packaging: Finished coils are wrapped in protective film, secured with steel banding, and placed on wooden pallets for shipment.
Applications
The stainless steel coil tube is widely employed across multiple industries due to its combination of corrosion resistance, formability, and thermal performance:
- Evaporative Cooling Systems: As highlighted in the referenced academic study on water distribution uniformity, coil tubes serve as the primary heat transfer elements in evaporative cooling modules. Uniform water distribution across the coil tube surface is critical for maximizing latent heat transfer efficiency and minimizing energy consumption. The study demonstrated that optimized water distribution methods significantly improve the evaporation rate and overall cooling performance.
- HVAC and Refrigeration: Condenser coils, evaporator coils, and heat exchanger bundles in commercial and industrial HVAC systems.
- Food and Beverage Processing: Sanitary-grade process piping, heat exchangers, and CIP (Clean-in-Place) systems in dairy, brewing, and pharmaceutical manufacturing.
- Chemical and Petrochemical Industry: Corrosion-resistant process piping, reactor internals, and heat exchange systems handling aggressive chemical media.
- Power Generation: Condenser tubes, feedwater systems, and steam distribution piping in thermal power plants.
- Automotive Industry: Exhaust systems, fuel lines, and heat management components requiring high-temperature stainless steel grades (321, 310S).
- Architectural and Decorative Applications: Formed architectural elements, handrails, and structural components leveraging the aesthetic and durability properties of stainless steel.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework with the following certifications and compliance standards:
- 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
- EN 10204 3.1 — Third-party material test certificates (MTC) available for every production lot, including chemical analysis, mechanical test results, and dimensional verification
- ASTM Compliance: Full compliance with ASTM A213, ASTM A269, ASTM A312, and related standards for stainless steel tube and pipe
- ASME SA-213 / SA-269 — Pressure vessel and piping component certification
- CE Marking — European Conformity marking for products intended for the European Economic Area
- Mill Test Reports (MTR): Comprehensive MTR documentation including spectroscopic analysis (OES), tensile test data, hardness testing, and non-destructive examination (NDE) reports
Unique Selling Points
The coil tube product from Wenzhou Jixing Metal Materials Co., Ltd distinguishes itself through the following competitive advantages:
- Academic Validation: The product's performance in evaporative cooling applications has been validated through peer-reviewed research on water distribution uniformity, providing data-backed confidence in thermal efficiency and system reliability.
- Precision Coiling Technology: CNC-controlled coiling ensures uniform coil geometry, minimal residual stress, and consistent tension throughout the coil length — critical for downstream forming and fabrication processes.
- Customizable Specifications: Flexible manufacturing capability accommodates custom OD, wall thickness, coil length, and surface finish requirements tailored to specific engineering applications.
- Full Traceability: Complete material traceability from mill certificate through final inspection, ensuring compliance with stringent industry regulations and procurement standards.
- Multi-Grade Availability: Comprehensive alloy grade selection (304, 316, 316L, 321, 310S, and others) enables optimal material matching for diverse operating environments and performance requirements.