Stainless Steel Coil Tube (Coiltube) for Fan Coil Unit Applications
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product designed primarily for heating, ventilation, and air conditioning (HVAC) systems, particularly for fan coil unit (FCU) assemblies. This coiltube represents a critical component in modern building services engineering, serving as the heat exchange medium within chilled or hot water circulation systems. The product is fabricated from high-grade stainless steel to ensure long-term durability, resistance to corrosion, and compatibility with aggressive fluid environments encountered in commercial and industrial applications.
Wenzhou Jixing Metal Materials Co., Ltd. specializes in the production of metallic tubing and coil products with stringent adherence to international quality standards. The coiltube product line is engineered to meet the demands of prefabricated installation methodologies, including Building Information Modeling (BIM)-integrated assembly approaches, which emphasize dimensional accuracy, interchangeability, and rapid field deployment.
Material & Properties
The coiltube is manufactured from austenitic stainless steel, with the following primary material grades available:
- Grade 304 (UNS S30400 / AISI 304): The standard grade offering excellent corrosion resistance, formability, and weldability. Suitable for most HVAC applications involving chilled water, hot water, and moderate chemical exposure.
- Grade 316 (UNS S31600 / AISI 316): Enhanced corrosion resistance due to molybdenum (Mo) addition, suitable for applications involving chlorinated water, seawater cooling systems, or chemically aggressive environments.
- Grade 316L (UNS S31603 / AISI 316L): Low-carbon variant of Grade 316 providing superior resistance to intergranular corrosion, ideal for welded assemblies and high-purity fluid handling.
Key Mechanical and Physical Properties
| Property | Grade 304 | Grade 316 | Grade 316L |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 520 | ≥ 515 | ≥ 485 |
| Yield Strength (MPa) | ≥ 205 | ≥ 205 | ≥ 170 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 45 |
| Density (g/cm³) | 8.00 | 8.00 | 8.00 |
| Thermal Conductivity (W/m·K) at 20°C | 16.3 | 14.6 | 14.6 |
| Maximum Service Temperature (°C) | 870 | 870 | 870 |
| Corrosion Resistance (Pitting) | Moderate | Excellent | Excellent |
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Catalog No. | 562 |
| Outer Diameter (OD) | 9.52 mm / 12.70 mm / 15.88 mm (3/8" / 1/2" / 5/8") |
| Wall Thickness | 0.50 mm – 1.50 mm (customizable) |
| Coil Pitch (Helical Spacing) | 10 mm – 25 mm (adjustable per design requirements) |
| Coil Diameter | 150 mm – 600 mm (as per project specification) |
| Tube Length per Coil | 3 m – 12 m (standard); custom lengths available |
| Surface Finish | No. 4 Brushed / Mirror Polished / Matte |
| Tolerance on OD | ±0.05 mm (per ASTM A213/A269) |
| End Preparation | Flat cut / Beveled (15°–37.5°) / Threaded |
| Standard References | ASTM A213, ASTM A269, EN 10217-7, GB/T 12771 |
| Maximum Working Pressure | 1.6 MPa (standard); 2.5 MPa (reinforced wall) |
| Applicable Fluids | Chilled water, hot water, glycol solutions, district heating/cooling media |
Manufacturing Process
The production of the stainless steel coiltube follows a rigorous multi-stage manufacturing sequence to ensure dimensional precision, mechanical integrity, and surface quality:
- Raw Material Inspection: Incoming stainless steel strip or seamless tube stock undergoes chemical composition verification (via optical emission spectrometry, OES), mechanical testing, and visual surface inspection in accordance with ASTM A999.
- Coiling / Forming: The straight tube stock is fed through precision CNC-controlled bending equipment that progressively forms the helical coil geometry. The bending process utilizes synchronized mandrel support to prevent ovalization, wrinkling, or wall thinning beyond acceptable limits. Bending radius is controlled to maintain a minimum of 5× the tube OD to ensure structural integrity.
- Heat Treatment (if required): For applications requiring solution annealing, the formed coils undergo controlled heating to 1010–1150°C followed by rapid water quenching to restore full austenitic microstructure and eliminate residual stresses introduced during forming.
- Surface Treatment: Depending on the specified finish, coils undergo mechanical polishing (brushing, buffing) or chemical passivation (nitric acid or citric acid pickling) to remove scale, enhance surface smoothness, and improve corrosion resistance.
- Dimensional Verification: Each coil is inspected for OD tolerance, wall thickness uniformity, coil pitch consistency, and overall length using laser measurement systems and coordinate measuring machines (CMM).
- Pressure Testing: Hydrostatic or pneumatic pressure testing is performed at 1.5× the maximum working pressure for a minimum dwell time of 5 minutes to verify leak-tightness and structural soundness.
- Final Inspection & Packaging: Completed coils are visually inspected, tagged with material traceability information, and packaged with protective end caps and moisture-barrier wrapping for shipment.
Applications
The stainless steel coiltube from Wenzhou Jixing Metal Materials Co., Ltd. finds extensive application across multiple sectors:
- HVAC Systems: Primary application in fan coil units (FCU), air handling units (AHU), and chilled beam systems where the coil serves as the heat exchange surface for cooling or heating indoor air.
- Building Services Engineering: Integrated into BIM-based prefabricated installation schemes, enabling modular assembly of HVAC components off-site for rapid on-site deployment, reducing installation time and labor costs.
- Commercial Buildings: Office towers, shopping malls, hotels, hospitals, and educational facilities requiring reliable temperature and humidity control.
- Industrial Processes: Process heating and cooling in food and beverage processing, pharmaceutical manufacturing, and chemical plants where corrosion resistance is paramount.
- District Energy Systems: Connection piping for centralized heating and cooling distribution networks, where long-term durability and minimal maintenance are critical.
- Marine and Coastal Environments: Grade 316/316L variants suitable for marine HVAC systems and coastal facility installations exposed to salt-laden atmospheres.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and certifications to ensure product reliability and international market access:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO 45001:2018 — Occupational Health and Safety Management System
- CE Marking — Compliance with European directives for construction products (EN 10217-7)
- ASTM Compliance — ASTM A213 (seamless austenitic stainless steel tubing), ASTM A269 (welded austenitic stainless steel tubing)
- GB/T Standards — Chinese National Standards for stainless steel pipes and tubes
- Mill Test Certificates (MTC) — Third-party EN 10204 3.1 certificates provided with every shipment
Unique Selling Points
- BIM-Compatible Design: Dimensional precision and standardization enable seamless integration into BIM-based prefabricated installation workflows, supporting modular construction methodologies that reduce on-site assembly time by up to 40%.
- Superior Corrosion Resistance: Austenitic stainless steel construction provides exceptional resistance to pitting, crevice corrosion, and general oxidation, ensuring service life exceeding 25 years without replacement in standard HVAC duty cycles.
- Hygienic Surface Quality: Mirror-polished or passivated finishes minimize biofilm formation and facilitate cleaning, making the product suitable for pharmaceutical, food-grade, and healthcare facility applications.
- Customizability: Full range of OD, wall thickness, coil pitch, and finish options available to meet project-specific engineering requirements.
- Full Traceability: Each production batch is traceable from raw material mill certificate through final inspection, ensuring complete supply chain transparency and compliance with regulatory requirements.
Note: All specifications listed above are subject to engineering review and project-specific design calculations. For detailed material certifications, welding procedure specifications (WPS), or custom fabrication inquiries, please contact Wenzhou Jixing Metal Materials Co., Ltd. technical sales department directly.