Stainless Steel Coil Tube (盘管) — Technical Product Specification
1. Product Overview
The Stainless Steel Coil Tube (SS Coil Tube), also referred to as a Coiltube or Spiral Coil Pipe, is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is formed by cold-bending continuous lengths of seamless stainless steel tubing into a helical or serpentine coil configuration. The coil geometry maximizes surface area within a compact volume, making it particularly suitable for heat exchange applications, fluid distribution systems, and thermal energy transfer processes.
Coil tubes are widely deployed in the HVAC (Heating, Ventilation, and Air Conditioning) industry as integral components of Fan Coil Units (FCU), chiller coils, condenser coils, and evaporator coils. The rational selection and application of fan coil units — a principle emphasized in industry best practices — depends critically on the quality, dimensional accuracy, and material integrity of the coil tubes employed within these systems.
2. Material & Properties
Stainless steel coil tubes are fabricated from austenitic stainless steel grades that offer superior corrosion resistance, mechanical strength, and thermal stability across a wide operating range. The following table summarizes the key material grades and their characteristic properties:
| Parameter | 304 (06Cr19Ni10) Grade | 316 (06Cr17Ni12Mo2) Grade | 321 (06Cr18Ni11Ti) Grade |
|---|---|---|---|
| Standard Designation | ASTM A269 / A270; EN 10216-5 | ASTM A269 / A270; EN 10216-5 | ASTM A269 / A270; EN 10216-5 |
| Chromium (Cr) Content (%) | 18.0 – 20.0 | 16.0 – 18.0 | 17.0 – 19.0 |
| Nickel (Ni) Content (%) | 8.0 – 10.5 | 10.0 – 14.0 | 9.0 – 13.0 |
| Molybdenum (Mo) Content (%) | — | 2.0 – 3.0 | — |
| Titanium (Ti) Content (%) | — | — | 0.5 – 0.70 |
| Tensile Strength (MPa, min.) | 515 | 515 | 485 |
| Yield Strength (MPa, min.) | 205 | 205 | 205 |
| Elongation (%) | ≥ 40 | ≥ 35 | ≥ 40 |
| Thermal Conductivity (W/m·K, 20°C) | 16.3 | 16.3 | 16.3 |
| Operating Temperature Range (°C) | −196 to +870 | −196 to +870 | −196 to +900 |
| Corrosion Resistance | Excellent (general atmosphere) | Superior (chloride-rich environments) | Excellent (high-temperature oxidation) |
| Weldability | Excellent | Excellent | Excellent |
3. Specifications
The following table presents the dimensional and performance specifications for standard stainless steel coil tubes manufactured by Wenzhou Jixing Metal Materials Co., Ltd:
| Specification Parameter | Typical Range / Value | Unit | Notes |
|---|---|---|---|
| Tube Outer Diameter (OD) | 3.0 – 25.0 | mm | Custom diameters available upon request |
| Wall Thickness (WT) | 0.3 – 3.0 | mm | Tolerance: ±0.05 mm |
| Coil Diameter (CD) | 50 – 1000 | mm | Determined by application geometry |
| Coil Height / Length (CH) | 100 – 5000 | mm | Custom lengths available |
| Number of Turns | 5 – 200 | — | Dependent on coil diameter and tube length |
| Tube Pitch (Center-to-Center Spacing) | 1.5 – 10.0 | mm | Standard: 3.0 – 6.0 mm |
| Surface Finish | 2B / BA / No. 4 / Mirror | — | BA: Bright Annealed; 2B: Cold Rolled |
| Roughness (Ra) | 0.4 – 1.6 | μm | Mirror finish: Ra ≤ 0.4 μm |
| Pressure Rating (Working) | 0.6 – 2.5 | MPa | Hydrostatic test at 1.5× working pressure |
| End Preparation | Plain / Threaded / Flanged / Beveled | — | Custom end treatment available |
| Dimensional Tolerance | ±0.5 mm (OD); ±0.05 mm (WT) | mm | Conforming to ASTM A213 / EN 10216-5 |
| Coil Straightness Tolerance | ≤ 1.0 | mm/m | Measured after cold-bending |
4. Manufacturing Process
The production of high-quality stainless steel coil tubes follows a rigorous multi-stage manufacturing process designed to ensure dimensional precision, mechanical integrity, and surface quality:
- Raw Material Inspection: Incoming stainless steel seamless tubes are verified against mill test certificates (MTC), with spectroscopic analysis confirming chemical composition compliance with the specified grade (e.g., AISI 304, 316L).
- Cutting and End Preparation: Tubes are precision-cut to specified lengths using automated sawing equipment. End preparation (beveling, threading, or deburring) is performed to facilitate downstream welding and assembly.
- Cold Bending / Coiling: The straight tube is fed through a CNC-controlled coil-bending machine that applies controlled radial force to form the helical or serpentine geometry. The bending radius is carefully managed to prevent wall thinning, ovalization, or material work-hardening. Typical minimum bending radius is 3× the tube OD.
- Stress Relief / Annealing (if required): For applications demanding specific mechanical properties post-forming, the coiled assembly may undergo solution annealing at 1050–1150°C followed by controlled cooling to restore the austenitic microstructure and eliminate residual stresses.
- Surface Finishing: Depending on the application, the coil tube may receive a 2B finish, bright annealed (BA) treatment, electropolishing, or mechanical polishing to achieve the specified surface roughness.
- Hydrostatic Pressure Testing: Each coil tube assembly is subjected to hydrostatic pressure testing at 1.5× the maximum working pressure for a minimum dwell time of 10 seconds to verify leak-tightness and structural integrity.
- Final Dimensional Inspection: Coordinate Measuring Machine (CMM) or laser scanning is employed to verify coil diameter, pitch accuracy, overall dimensions, and straightness within specified tolerances.
- Packaging and Shipping: Qualified coil tubes are packaged with protective end caps, corrosion-inhibiting VCI (Vapor Corrosion Inhibitor) paper, and wooden or plastic crates suitable for international shipment.
5. Applications
Stainless steel coil tubes manufactured by Wenzhou Jixing Metal Materials Co., Ltd find extensive application across multiple industrial sectors:
5.1 HVAC (Heating, Ventilation, and Air Conditioning)
- Fan Coil Units (FCU): Coil tubes serve as the primary heat exchange element in fan coil units used for building climate control. The rational selection of fan coil unit configurations — including coil type, capacity, and refrigerant circuit design — is critical to achieving optimal thermal performance and energy efficiency.
- Chiller and Condenser Coils: Used in central air conditioning systems for large commercial and industrial facilities.
- VRF (Variable Refrigerant Flow) Systems: Indoor unit coil assemblies for multi-zone cooling and heating applications.
5.2 Food and Beverage Industry
- Heat exchangers for pasteurization, sterilization, and brewing processes
- Refrigeration coils for cold storage and cold chain logistics
- CIP (Clean-In-Place) compatible tubing for sanitary fluid transfer
5.3 Pharmaceutical and Medical
- Bioreactor heat transfer coils for controlled fermentation
- Medical device manufacturing (autoclave-resistant coil assemblies)
- Pharmaceutical fluid heating and cooling circuits
5.4 Chemical and Petrochemical
- Corrosion-resistant heat exchanger coils for aggressive chemical environments (316L grade)
- Reactor jacket cooling coils
- Distillation column condenser assemblies
5.5 Power Generation
- Boiler economizer and air preheater coils (321 grade for high-temperature service)
- Steam generator tube bundles
- Waste heat recovery system coils
5.6 Automotive and Transportation
- Brake cooling coils for heavy-duty vehicles
- Battery thermal management systems in electric vehicles (EV)
- Exhaust gas heat exchanger coils
6. Quality Certifications and Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system ensuring that all stainless steel coil tube products meet or exceed international standards. The following certifications and standards are applicable:
| 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/TS 22163 | Automotive quality management system (IATF 16949 aligned) |
| ASTM A269 / A270 | American standards for seamless and welded austenitic stainless steel tubes and pipe |
| EN 10216-5 | European standard for non-alloy and alloy steel tubes for pressure purposes — austenitic stainless steel |
| GB/T 14976 | Chinese national standard for cold-rolled or cold-drawn seamless stainless steel tubes |
| ASME B31.3 | American Society of Mechanical Engineers — Process Piping code compliance |
| 3-A Sanitary Standards | Dairy and food industry sanitary design certification (for food-grade applications) |
| CE Marking | European Conformity marking for products sold within the European Economic Area |
| Mill Test Certificate (MTC / EN 10204 3.1) | Third-party material certification with chemical and mechanical test data for each batch |
7. Unique Selling Points
- Precision CNC Coiling: Computer-controlled bending ensures repeatable coil geometry with pitch accuracy within ±0.3 mm, reducing assembly time and improving heat exchange efficiency.
- Multi-Grade Availability: Supply of 304, 316L, 321, and custom alloy grades from a single source, enabling customers to optimize material selection for specific corrosion and temperature requirements.
- Full Traceability: Each coil tube batch is accompanied by a complete traceability package including mill test certificates, heat numbers, dimensional inspection reports, and hydrostatic test records.
- Custom Engineering Support: Technical consultation available for rational coil design optimization, including coil diameter, pitch, and tube count calculations tailored to specific thermal load requirements