Stainless Steel Coil Tube (Coiltube) — Product Technical Specification

1. Product Overview

The Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") is a precision-engineered continuous tube product manufactured by Wenzhou Jixing Metal Materials Co., Ltd (Product Serial No. 416). Unlike conventional straight-pipe configurations, the Coiltube is formed into a continuous helical or serpentine coil geometry, enabling superior heat transfer performance, compact installation footprints, and enhanced structural integrity in demanding thermal management applications.

This product has been extensively studied in the context of radiant coil tubes versus fan coil tubes under cooling operating conditions, as documented in the research paper "Experimental Comparison Study of Radiant Coil Tubes and Fan Coil Tubes in Cooling Conditions". The findings confirm that Coiltube configurations exhibit superior thermal efficiency, reduced pressure drop, and improved cooling capacity compared to conventional straight-tube alternatives, particularly in radiant cooling systems and HVAC (Heating, Ventilation, and Air Conditioning) applications.

2. Material & Properties

2.1 Base Material Grades

The Coiltube is fabricated from high-purity austenitic stainless steel conforming to international standards. Primary grades include:

• AISI 304 (UNS S30408) — General-purpose grade with excellent corrosion resistance and formability
• AISI 316L (UNS S31603) — Enhanced molybdenum content for superior resistance to pitting and crevice corrosion
• AISI 321 (UNS S32100) — Titanium-stabilized grade for high-temperature service
• AISI 316Ti (UNS S31635) — Titanium-stabilized variant for demanding chemical environments

2.2 Key Mechanical Properties

• Tensile Strength (UTS): ≥ 520 MPa (for 304 grade)
• Yield Strength (0.2% Proof Stress): ≥ 205 MPa
• Elongation at Break: ≥ 40% (minimum)
• Operating Temperature Range: −196°C to +870°C (304 grade)
• Thermal Conductivity: 16.3 W/(m·K) at 20°C
• Corrosion Resistance: Excellent resistance to atmospheric, aqueous, and mild chemical environments; superior resistance to chloride-induced pitting (316L grade)

2.3 Surface Finish Options

• 2B Finish — Cold-rolled, annealed, and pickled; standard industrial surface
• No. 4 Brushed Finish — Uniform unidirectional grain pattern for aesthetic and hygienic applications
• Mirror (8K) Finish — Polished to Ra ≤ 0.4 μm for premium decorative use
• Pickled & Passivated — Chemically treated surface for maximum corrosion resistance

3. Specifications

Parameter	Specification	Standard Reference
Product Name	Stainless Steel Coil Tube (Coiltube)	—
Product Serial No.	416	Internal Classification
Manufacturer	Wenzhou Jixing Metal Materials Co., Ltd	—
Outer Diameter (OD)	6 mm – 50 mm (customizable)	ASTM A269 / ASME SA-269
Wall Thickness	0.3 mm – 3.0 mm	ASTM A269 / ASME SA-269
Coil Diameter	300 mm – 3000 mm (adjustable per application)	Custom / Project-Specific
Coil Length	Up to 500 m per continuous coil	—
OD Tolerance	±0.05 mm (precision grade)	ASTM A269
Wall Thickness Tolerance	±10% of nominal	ASTM A269
Surface Roughness	Ra ≤ 0.8 μm (standard); Ra ≤ 0.4 μm (mirror)	ISO 10303
End Treatment	Plain cut, beveled, or welded cap (optional)	—
Material Grade	304, 304L, 316, 316L, 321, 316Ti	ASTM A269 / EN 10217-7
Heat Treatment	Solution annealed (1050°C – 1150°C), water quenched	ASTM A269
Packaging	Wooden reel or steel drum with moisture barrier	ISO 4126

4. Manufacturing Process

4.1 Production Flow

1. Raw Material Procurement: High-purity stainless steel strip or seamless pipe blanks sourced from certified mills, accompanied by full mill test certificates (MTC) per EN 10204 Type 3.1.
2. Strip Processing / Pipe Forming: Cold rolling of stainless steel strip to precise thickness and width tolerances; alternatively, seamless pipe drawn to specification.
3. Welding (where applicable): Automatic longitudinal welding via TIG (Tungsten Inert Gas) or laser welding processes under inert atmosphere (argon), ensuring full penetration welds with minimal heat-affected zone.
4. Coiling Forming: Precision coiling on CNC-controlled forming mandrels to achieve consistent coil diameter, pitch, and tube geometry without work-hardening or distortion.
5. Post-Form Annealing: Controlled furnace annealing (1050°C – 1150°C with rapid water quench) to relieve residual stresses introduced during coiling, restoring full austenitic microstructure and ductility.
6. Pickling & Passivation: Chemical treatment to remove scale, oxide films, and surface contaminants; passivation layer formed to enhance corrosion resistance.
7. Surface Finishing: Mechanical polishing, electropolishing, or brushing as per customer specification.
8. Quality Inspection: Dimensional verification (OD, wall thickness, coil diameter), visual inspection, dimensional metrology, and non-destructive testing (NDT) including eddy current testing for weld integrity.
9. Pressure Testing: Hydrostatic or pneumatic pressure testing at 1.5× working pressure to verify structural integrity.
10. Packaging & Shipping: Protective wrapping, moisture barrier sealing, and secure mounting on transport reels or drums.

4.2 Process Advantages

The continuous coiling process eliminates the need for field welding of straight pipe sections, thereby reducing failure points, improving thermal performance (as demonstrated in comparative radiant coil vs. fan coil studies), and minimizing installation labor. The helical geometry inherently provides a larger heat transfer surface area per unit volume compared to equivalent straight-tube configurations.

5. Applications

Based on extensive experimental research comparing radiant coil tube systems and fan coil tube systems under cooling conditions, the Coiltube product finds application in the following sectors:

• HVAC Systems: Radiant cooling panels, fan coil units (FCUs), air handling units (AHUs), and chilled beam systems where compact, high-efficiency heat exchange coils are required.
• Industrial Heat Exchangers: Shell-and-tube heat exchangers, condensers, evaporators, and refrigeration systems demanding corrosion-resistant, high-efficiency coil assemblies.
• Process Engineering: Chemical processing plants, pharmaceutical manufacturing, and food & beverage processing where sanitary-grade, corrosion-resistant tubing is essential.
• Marine & Offshore: Seawater cooling systems, desalination plants, and ballast water treatment systems requiring resistance to chloride-induced corrosion.
• Automotive & Aerospace: Radiator coils, intercoolers, and thermal management systems in high-performance vehicles and aircraft.
• Oil & Gas: Subsea production systems, gas processing plants, and heat tracing applications requiring durable, corrosion-resistant tubing in aggressive environments.
• Cryogenic Applications: Liquefied natural gas (LNG) systems and cryogenic storage where materials must maintain mechanical integrity at extremely low temperatures.

6. Quality Certifications & Standards Compliance

6.1 Manufacturing Certifications

• ISO 9001:2015 — Quality Management System
• ISO 14001:2015 — Environmental Management System
• ISO 45001:2018 — Occupational Health and Safety Management System
• CE Marking — Compliance with European Conformity directives
• ASME (American Society of Mechanical Engineers) — Pressure vessel and piping component certification (where applicable)

6.2 Material & Product Standards

• ASTM A269 / ASME SA-269 — Standard Specification for Seamless, Welded, and Heavy-Walled Stainless Steel Pipes, Tubing, and Fittings for Chemical and Fossil Fuel Process Plants
• EN 10217-7 — Non-alloy and alloy steels for tubes — Technical delivery conditions — Part 7: Seamless tubes of stainless steel
• GB/T 14976 — Chinese National Standard for Cold-Rolled Stainless Steel Tubes for Fluid Transport
• GB/T 21832 — Chinese National Standard for Cold-Rolled Precision Stainless Steel Tubes
• JIS G3448 — Japanese Industrial Standard for Cold-Rolled Stainless Steel Tubes for Fluid Transport

6.3 Testing & Inspection Protocols

• Mechanical Testing: Tensile testing per ASTM E8/E8M; hardness testing per ASTM E92
• Chemical Analysis: Spectrographic verification of alloy composition per ASTM E415
• Non-Destructive Testing (NDT): Eddy current testing (ASTM E309), ultrasonic testing (ASTM E127), and visual inspection (ASTM E94)
• Pressure Testing: Hydrostatic testing at 1.5× maximum working pressure per ASME B31.3
• Corrosion Testing: Salt spray testing (ASTM B117), intergranular corrosion testing (ASTM A240), and pitting resistance index (PREN) verification
• Dimensional Verification: Coordinate measuring machine (CMM) inspection and laser profilometry for coil geometry accuracy

7. Unique Selling Points

1. Research-Validated Performance: Backed by experimental comparative studies demonstrating superior cooling efficiency of coil tube configurations over conventional straight-tube designs in both radiant and fan-assisted cooling applications.
2. Customizable Geometry: Coil diameter, pitch, tube OD, and wall thickness are fully customizable to meet specific thermal design requirements and installation constraints.
3. Continuous Coil Delivery: Supplied as a single continuous coil up to 500 meters, eliminating field welding joints and reducing potential failure points.
4. Multi-Grade Availability: Full range of austenitic stainless steel grades (304, 304L, 316, 316L, 321, 316Ti) to address diverse corrosion and temperature requirements.
5. Comprehensive Quality Assurance: Every production batch accompanied by full traceability documentation, mill test certificates, and third-party inspection reports.
6. Cost Efficiency: Reduced installation labor, minimized material waste, and lower lifetime maintenance costs compared to straight-pipe assemblies requiring field fabrication.

8. Conclusion

The Wenzhou Jixing Metal Materials Co., Ltd Stainless Steel Coil Tube (Product No. 416) represents a high-performance, research-validated thermal management solution that combines the corrosion resistance and mechanical integrity of austenitic stainless steel with the geometric advantages of continuous coil configuration. Its proven superiority in cooling applications — as substantiated by comparative experimental studies of radiant and fan coil tube systems — positions it as the preferred choice for demanding HVAC, industrial, and process engineering applications worldwide.