Stainless Steel Coiled Tube — Product Technical Specification

1. Product Overview

The Stainless Steel Coiled Tube (also referred to as Coil Tube or Coiled Tubing) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered continuous tubular product formed into a coiled configuration. This product is designed for applications requiring compact heat exchange geometries, fluid conveyance in confined spaces, and high-performance thermal management systems. The coiled geometry provides an exceptional surface-area-to-volume ratio, making it particularly advantageous for evaporative and condensing heat exchanger applications.

This product specification is informed by advanced research findings from the study "Three-Dimensional Numerical Simulation of Evaporation Thermal Characteristics of Coiled Tubes", which provides critical insights into the thermal-hydraulic performance of coiled tube configurations under two-phase flow conditions. The simulation results confirm that coiled stainless steel tubes exhibit enhanced heat transfer coefficients due to centrifugal force effects, secondary flow generation, and turbulent mixing within the curved geometry — all of which contribute to superior evaporative performance compared to straight tube counterparts.

2. Material & Properties

2.1 Base Material Composition

The coiled tubes are fabricated from high-grade austenitic stainless steel, with the primary grade being SUS304 (ASTM 304 / 1.4301) and SUS316L (ASTM 316L / 1.4404), selected for their outstanding corrosion resistance, mechanical strength, and thermal stability.

2.2 Key Material Properties

• Corrosion Resistance: Excellent resistance to atmospheric corrosion, chemical media, and marine environments. The chromium oxide passive film provides self-healing protection.
• Thermal Conductivity: 14–16 W/(m·K) for SUS304; 13–14 W/(m·K) for SUS316L, ensuring efficient heat transfer in evaporative applications.
• Mechanical Strength: Tensile strength ≥ 520 MPa; Yield strength ≥ 205 MPa; Elongation ≥ 40%, providing structural integrity under pressure and thermal cycling.
• Temperature Range: Continuous service from −196 °C (liquid nitrogen) to +870 °C, with excellent cryogenic toughness.
• Hygienic Surface: Surface roughness (Ra) ≤ 0.4 μm achievable, suitable for pharmaceutical and food-grade applications.

2.3 Thermal-Hydraulic Performance Characteristics

Based on three-dimensional numerical simulation studies of coiled tube evaporation, the following performance enhancements have been validated:

• Enhanced Heat Transfer Coefficient: The curved geometry induces Dean vortices (secondary flow), increasing the local heat transfer coefficient by 15–35% compared to equivalent straight tubes.
• Improved Flow Distribution: Centrifugal force effects promote more uniform flow distribution across multi-tube configurations.
• Reduced Critical Heat Flux Margin: The turbulent mixing within the coil delays dryout onset, improving evaporative safety margins.
• Compact Heat Exchange: Achieves equivalent thermal duty in approximately 40–60% less footprint compared to straight-tube arrangements.

3. Specifications

Parameter	Specification	Standard / Reference
Product Name	Stainless Steel Coiled Tube	—
Material Grade	SUS304 / SUS316L / SUS321 / SUS310S	JIS G4304 / ASTM A213
Outer Diameter (OD)	Φ4.0 mm – Φ50.8 mm (customizable)	—
Wall Thickness	0.3 mm – 3.0 mm	—
Coil Diameter	Φ200 mm – Φ2000 mm	—
Tube Length per Coil	5 m – 500 m (continuous)	—
Surface Finish	Pickled & Passivated (PP) / Polished / Electropolished	—
Surface Roughness (Ra)	0.4 – 1.6 μm (as required)	—
Manufacturing Method	Cold Drawn & Seamless / ERW (Electric Resistance Welded)	ASTM A269 / A213
Pressure Rating	Up to 10 MPa (PN100), dependent on dimensions	ASME B31.3
Operating Temperature	−196 °C to +870 °C	—
Dimensional Tolerance	±0.05 mm (OD); ±0.05 mm (wall thickness)	ASTM A213
Coiling Standard	Min. bending radius ≥ 5× OD	ISO 11908
End Condition	Plain / Beveled / Flanged / Fitted	—
Packaging	Wooden crate / Pallet with protective wrapping	—

4. Manufacturing Process

4.1 Process Flow

1. Material Selection & Incoming Inspection: Stainless steel strip or tube blanks are sourced from certified mills. Each batch undergoes spectroscopic analysis (OES) to verify chemical composition and mechanical testing to confirm tensile/yield properties.
2. Coiling Preparation: The tube material is cut to predetermined lengths and inspected for surface defects using ultrasonic testing (UT) or eddy current testing (ECT).
3. Precision Coiling: Computer-controlled coiling machines form the straight tube into the specified coil diameter with controlled bending stress. The minimum bending radius is maintained at ≥ 5× OD to prevent ovality and wall thinning.
4. Welding (if applicable): For continuous coil production, butt welding is performed using TIG (Tungsten Inert Gas) or orbital welding techniques with 100% helium leak testing to ensure weld integrity.
5. Pickling & Passivation: Chemical treatment removes oxide scales and forms a protective chromium oxide layer, enhancing corrosion resistance. Passivation is verified via ferrite testing and surface contamination analysis.
6. Surface Finishing: Electropolishing or mechanical polishing is applied for hygienic-grade requirements, reducing surface roughness to specified Ra values.
7. Final Quality Control: Dimensional verification (OD, wall thickness, coil diameter), pressure testing, and visual inspection are performed on each coil.

4.2 Process Advantages

• Continuous coiling eliminates the need for field welding in many applications, reducing leak risk.
• Computerized coiling ensures uniform curvature and consistent mechanical properties throughout the coil length.
• Cold working during coiling provides beneficial work hardening, improving fatigue resistance in dynamic applications.

5. Applications

5.1 Primary Application Domains

• Refrigeration & Air Conditioning: Evaporator and condenser coils for commercial refrigeration units, heat pumps, and HVAC systems. The enhanced evaporative heat transfer characteristics make coiled tubes ideal for compact refrigeration circuits.
• Heat Exchangers: Plate-fin and shell-and-coil heat exchangers for process heating, cooling, and thermal recovery systems.
• Chemical Processing: Reactor cooling jackets, heat transfer coils, and process piping in aggressive chemical environments where corrosion resistance is paramount.
• Pharmaceutical & Biotechnology: Sterilization loops, CIP (Clean-in-Place) systems, and bioreactor heat exchange circuits requiring hygienic-grade tubing.
• Food & Beverage Industry: Milk pasteurization coils, beverage cooling systems, and sanitary process piping.
• Automotive & Aerospace: Fuel lines, hydraulic circuits, and thermal management systems requiring lightweight, corrosion-resistant tubing in compact configurations.
• Power Generation: Superheater and reheater coils in boilers; nuclear-grade heat transfer surfaces.
• Oil & Gas: Downhole tubing, flow lines, and subsea pipeline connections in corrosive offshore environments.

5.2 Thermal Performance Application Data

Three-dimensional numerical simulation studies have demonstrated that stainless steel coiled tubes operating in evaporative mode exhibit the following performance characteristics:

• Nusselt Number Enhancement: 1.2–1.5× compared to straight tubes at equivalent Reynolds numbers.
• Pressure Drop Penalty: 20–40% increase over straight tubes, which is acceptable given the significant heat transfer gains.
• Overall Performance Ratio (OPR): Consistently greater than 1.0, confirming net performance improvement in evaporative applications.

6. Quality Certifications & Compliance

6.1 Product Certifications

• ISO 9001:2015 — Quality Management System certification ensuring consistent manufacturing quality.
• ISO 14001:2015 — Environmental Management System compliance.
• CE Marking — Conformity with European Union safety, health, and environmental protection requirements.
• EN 10204 3.1 — Material test certificates for chemical composition, mechanical properties, and dimensional verification.
• ASTM A213 / A269 — Compliance with American standards for wrought austenitic stainless steel tubing.
• JIS G4304 — Japanese Industrial Standard for seamless stainless steel tubing.
• GB/T 14976 — Chinese National Standard for seamless stainless steel tubing.

6.2 Industry-Specific Compliance

• 3-A / EHEDG — Sanitary design compliance for food, dairy, and pharmaceutical applications.
• ASME BPE — Biopharmaceutical Equipment and Systems standards for pharmaceutical-grade tubing.
• ASME BPVC Section VIII — Pressure vessel code compliance for high-pressure applications.
• NORSOK M-601 — Offshore pipeline and piping standards for oil and gas applications.

6.3 Testing & Inspection Protocols

• 100% hydrostatic pressure testing at 1.5× working pressure with 2-minute hold time.
• 100% eddy current inspection for wall thickness verification and defect detection.
• Spectroscopic (OES) analysis on every heat lot for chemical composition verification.
• Hardness testing (HV) for work-hardening verification.
• Intergranular corrosion testing (ASTM A262 Practice E) for stabilization verification.
• Helium leak testing at 1×10⁻⁹ Pa·m³/s for high-integrity welded joints.

7. Unique Selling Points

Thermally Optimized Coiled Geometry: Backed by advanced three-dimensional CFD (Computational Fluid Dynamics) simulation research, this coiled tube product delivers validated enhancements in evaporative heat transfer performance, offering superior thermal efficiency in compact form factors.

• Validated Thermal Performance: Product design informed by peer-reviewed numerical simulation of evaporation characteristics, ensuring predictable and optimized thermal behavior in real-world applications.
• Precision Coiling Technology: CNC-controlled coiling ensures consistent geometry, minimizing performance variability between coils.
• Multi-Grade Availability: Wide range of stainless steel grades accommodates diverse corrosion and temperature requirements without redesign.
• Hygienic & Sanitary Grade Options: Electropolished surfaces with Ra ≤ 0.4 μm available for pharmaceutical and food-grade installations.
• Custom Engineering: Full customization of OD, wall thickness, coil diameter, length, and end configuration to meet specific application requirements.
• Traceability: Complete material traceability from mill certificate through final delivery, ensuring compliance with regulatory and audit requirements.

8. Ordering Information

Wenzhou Jixing Metal Materials Co., Ltd. provides comprehensive technical support for coiled tube selection, including thermal performance consultation, material specification guidance, and application-specific engineering recommendations. Custom orders are welcomed with minimum order quantities negotiable based on specification complexity.