Stainless Steel Coil Tube — Fan Coil Unit (FCU) Heat Exchanger Tubing
Product Overview
The Stainless Steel Coil Tube is a precision-engineered coiled piping component manufactured by Wenzhou Jixing Metal Materials Co., Ltd, specifically designed for integration into Fan Coil Unit (FCU) systems and Fresh Air Handling Units (FAHU). These coil tubes serve as the primary heat exchange medium in commercial and residential HVAC (Heating, Ventilation, and Air Conditioning) applications, facilitating efficient thermal transfer between a circulating working fluid (typically chilled water or hot water) and the airstream directed through the fan coil assembly.
As part of the Office Fan Coil Unit with Fresh Air System architecture, the coil tube is a critical sub-assembly that directly influences the overall air supply method, thermal comfort levels, and energy efficiency of the ventilation system. The product has been extensively studied in the context of optimizing indoor air distribution patterns, minimizing temperature stratification, and achieving balanced air supply in office environments.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of corrosion resistance, thermal conductivity, mechanical strength, and long-term service durability.
- Base Material: Austenitic Stainless Steel (e.g., SUS304 / SUS316L equivalents per ASTM A269 / ASTM A312)
- Corrosion Resistance: Superior resistance to atmospheric corrosion, condensation-induced pitting, and chemical attack from humid indoor air environments
- Thermal Conductivity: Approximately 15–16 W/(m·K) at 20°C, ensuring efficient heat transfer between the working fluid and the airstream
- Mechanical Properties: High tensile strength with excellent ductility, enabling reliable cold-forming into precise coil geometries without cracking or work-hardening failure
- Surface Finish: Mirror-polished or electropolished inner surface to minimize flow resistance and prevent biofilm accumulation
- Temperature Range: Operational from −40°C to +250°C, accommodating both chilled water cooling and hot water heating cycles
- Hygienic Compliance: Non-toxic, non-reactive surface suitable for potable air quality standards
Specifications
| Parameter | Specification / Value |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管 / Coil Tube) |
| Material Grade | SUS304 / SUS316L (ASTM A269 / A312) |
| Outer Diameter (OD) | 6.35 mm – 25.4 mm (1/4" – 1") |
| Wall Thickness | 0.3 mm – 1.0 mm |
| Coil Pitch (Turn-to-Turn Spacing) | 4 mm – 12 mm (adjustable per thermal load requirements) |
| Coil Diameter (Overall) | 100 mm – 800 mm |
| Tube Length per Coil | 2 m – 30 m |
| Surface Treatment | Mirror Polishing / Electropolishing / Passivation |
| Operating Pressure | Up to 1.6 MPa (232 PSI) |
| Operating Temperature | −40°C to +250°C |
| Thread / Connection | Brazed, Welded, or Flanged (per system design) |
| Applicable Standards | ASTM A269, ASTM A312, EN 10217-7, GB/T 12771 |
| Finish Tolerance | ±0.02 mm (diameter), ±0.05 mm (pitch) |
| Minimum Order Quantity | 100 coils |
| Customization | Available (dimensions, pitch, coil diameter, surface finish) |
Manufacturing Process
The production of stainless steel coil tubes for FCU heat exchanger applications involves a multi-stage precision manufacturing workflow:
- Material Selection & Incoming Inspection: Raw stainless steel seamless or welded tubing is sourced from certified mills and subjected to spectroscopic analysis (OES), chemical composition verification, and mechanical property testing to confirm grade compliance.
- Cold Drawing & Sizing: Tubing is cold-drawn to achieve precise outer diameter and wall thickness tolerances (±0.02 mm), ensuring dimensional accuracy critical for coil winding uniformity.
- Surface Preparation & Polishing: The inner and outer surfaces are polished using multi-stage abrasive processes, followed by electropolishing and passivation treatment to achieve a low-roughness surface (Ra ≤ 0.4 μm) that minimizes fluid friction and inhibits microbial growth.
- Cold Coiling / Spiral Winding: The prepared tubing is cold-wound onto a precision mandrel to form the coil geometry. The coil pitch, coil diameter, and number of turns are controlled by CNC-guided winding equipment to ensure consistent spacing and structural integrity.
- Welding & Brazing: End connections are fabricated using TIG (Tungsten Inert Gas) welding or high-temperature brazing to maintain metallurgical continuity and leak-tight integrity at all joints.
- Pressure Testing & Leak Detection: Each coil assembly undergoes hydrostatic pressure testing at 1.5× the rated operating pressure, followed by helium leak detection to verify absolute leak-tightness.
- Final Inspection & Packaging: Dimensional verification, surface quality assessment, and material traceability documentation are completed before protective packaging for shipment.
Applications
The stainless steel coil tube is integral to a wide range of HVAC and thermal management systems:
- Commercial Office Fan Coil Units: Primary heat exchange element in ceiling-mounted, floor-standing, or concealed FCUs used in corporate offices, hotels, and retail spaces. The coil tube enables precise temperature regulation through chilled water or hot water circulation.
- Fresh Air Handling Systems: Integration into Fresh Air Units (FAU) and Variable Air Volume (VAV) systems to precondition incoming outdoor air before distribution, contributing to optimized air supply methods that minimize energy waste and maintain indoor air quality (IAQ).
- Residential HVAC: Compact coil tubes for split-system air conditioners, heat pumps, and underfloor heating systems in residential and light commercial buildings.
- Industrial Process Cooling/Heating: Heat exchangers in pharmaceutical, food processing, and semiconductor manufacturing facilities where hygienic and corrosion-resistant materials are mandatory.
- Medical Facilities: Cleanroom and hospital ventilation systems requiring sterile, non-reactive heat exchange components.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems to ensure product reliability and regulatory compliance:
- ISO 9001:2015 — Quality Management System certification, ensuring consistent manufacturing processes and continuous improvement
- ISO 14001:2015 — Environmental Management System certification, demonstrating commitment to sustainable and environmentally responsible production
- CE Marking — Conformity with European health, safety, and environmental protection standards for HVAC components
- ASTM Compliance — Full compliance with ASTM A269 (seamless tubing) and ASTM A312 (welded tubing) specifications
- EN 10217-7 — European standard for cold-drawn stainless steel tubes for general applications
- GB/T 12771 — Chinese national standard for cold-rolled stainless steel seamless tubes
- Material Traceability: Full lot-level traceability with mill certificates (MTC / EN 10204 3.1) provided for every batch
Unique Selling Points
- Superior Corrosion Resistance: Austenitic stainless steel construction provides exceptional longevity in humid, condensation-prone HVAC environments, significantly outperforming traditional copper or carbon steel alternatives in service life.
- Optimized Thermal Performance: Precision-controlled coil pitch and polished inner surfaces minimize pressure drop while maximizing heat transfer coefficient, contributing to lower fan energy consumption and improved system COP (Coefficient of Performance).
- Hygienic Surface Quality: Electropolished surfaces with Ra ≤ 0.4 μm prevent biofilm formation and ensure consistent indoor air quality — a critical advantage in medical and food-grade applications.
- Full Customization Capability: Tailored coil dimensions, pitch configurations, and connection types to meet specific thermal load calculations and system integration requirements.
- Energy Efficiency Contribution: The coil tube design directly supports the optimization of air supply methods in fan coil plus fresh air systems, reducing overall HVAC energy consumption by up to 20–30% compared to conventional designs.
- Proven Manufacturing Heritage: Backed by Wenzhou Jixing Metal Materials Co., Ltd's extensive experience in stainless steel tube fabrication and deep understanding of HVAC thermal dynamics through applied research in office ventilation system optimization.