Stainless Steel Dry Coil Tube — Product Technical Specification

Product Overview

The Stainless Steel Dry Coil Tube (also known as a Dry Coil Tube or Coil Tube) is a precision-engineered tubular component manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically designed for integration into Dry Coil Tube Technology Systems, which represent a class of energy-efficient thermal exchange and fluid conveyance solutions. The coil tube is formed by continuously winding a seamless or welded stainless steel tube into a helical or spiral configuration, yielding a high surface-area-to-volume ratio that is critical for efficient heat transfer, fluid distribution, and compact system integration.

The applicability of dry coil tube technology extends across industrial, commercial, and specialized engineering domains where space-constrained heat exchange, uniform fluid distribution, and corrosion-resistant performance are paramount. Wenzhou Jixing Metal Materials Co., Ltd. supplies coil tubes conforming to international standards, ensuring compatibility with a wide range of system architectures.

Material and Properties

Base Material Composition

The dry coil tube is fabricated from high-grade austenitic stainless steel, with the following commonly specified grades:

Mechanical Properties

Corrosion and Environmental Resistance

The austenitic microstructure of the selected stainless steel grades provides inherent resistance to atmospheric corrosion, acid media, and aqueous environments. The 316L grade, in particular, demonstrates excellent resistance to Pitting Resistance Equivalent Number (PREN) ≥26, making it suitable for marine, chemical processing, and pharmaceutical applications. The coil tube surface finish (typically No. 4 brushed, 2B mill finish, or electropolished to Ra ≤0.4 μm) further enhances corrosion performance by minimizing surface roughness and eliminating micro-galvanic sites.

Specifications

Parameter Specification Standard Reference
Product Name Stainless Steel Dry Coil Tube (盘管 / Coil Tube) —
Product Code No. 1193 —
Outer Diameter (OD) Φ3.0 mm – Φ50.8 mm (customizable) ASTM A213 / A269
Wall Thickness 0.3 mm – 3.0 mm (customizable) ASTM A213 / A269
Coil Diameter (Mean) Φ15 mm – Φ300 mm (customizable) ISO 4413
Coil Length 1 m – 50 m per coil (or continuous spool) —
Material Grades 304, 304L, 316, 316L, 321, 310S ASTM A213 / EN 10216-5
Surface Finish 2B, No. 4 Brushed, Mirror (Ra ≤0.2 μm), Electropolished ASTM A240
Maximum Operating Temperature −196 °C to +870 °C (grade-dependent) ASME BPVC Section VIII
Maximum Working Pressure Up to 30 MPa (design-dependent) ASME BPVC / PED 2014/68/EU
End Treatment Plain ends, beveled, threaded (NPT/BSP), flanged, or socket-weld ASME B1.20.1 / B16.11
Tolerance (OD) ±0.05 mm (precision grade); ±0.10 mm (standard grade) ISO 2852-1
Tolerance (Wall Thickness) ±10% of nominal (standard); ±5% (precision) ASTM A269
Coil Pitch 1.5× OD – 3.0× OD (customizable) —
Minimum Bend Radius 3× OD (cold-forming); 2× OD (hot-forming) EN 10216-5

Manufacturing Process

The production of the stainless steel dry coil tube follows a rigorously controlled multi-stage manufacturing workflow, ensuring dimensional accuracy, metallurgical integrity, and surface quality:

  1. Raw Material Selection and Inspection:

    Stainless steel wire rod or seamless pipe stock is sourced from certified mills (e.g., Outokumpu, Voestalpine, POSCO, or domestic Chinese mills). Incoming material undergoes spectroscopic analysis (OES / PMI) to verify chemical composition, and ultrasonic testing (UT) to detect internal defects.

  2. Pipe / Tube Forming:

    Depending on the target specification, the base tube is produced via one of the following routes:

    • Seamless Tube (Piercing / Mannesmann Process): Hot piercing of solid billets, followed by cold drawing to achieve final dimensions. Preferred for high-pressure and critical applications.
    • Welded Tube (ERW / LTW): Electric Resistance Welding (ERW) or Laser Tube Welding (LTW) for cost-effective production of smaller diameters with high dimensional consistency.
  3. Cold Drawing and Sizing:

    The tube is cold-drawn through calibrated die sets to achieve precise outer diameter and wall thickness tolerances. Multi-pass drawing may be employed for high-precision applications (tolerance ≤±0.05 mm).

  4. Coil Winding (Coiling):

    The formed tube is wound onto precision mandrels using CNC-controlled coiling machines. The winding process maintains constant tension to prevent ovalization, kinking, or cold-work hardening. The coil pitch and diameter are controlled within ±0.5 mm tolerance.

  5. Heat Treatment (Annealing):

    Post-coiling annealing (solution annealing) is performed at 1050–1150 °C followed by controlled cooling (air or furnace cool) to restore full austenitic microstructure, relieve residual stresses, and ensure maximum corrosion resistance. For 304L/316L grades, intergranular corrosion resistance is verified via ASTM A262 Practice 1E (5% HCl test).

  6. Surface Treatment:

    Depending on application requirements, the coil tube may undergo:

    • Pickling and Passivation: Acid pickling (HNO₃/HF blend) to remove oxide scale, followed by passivation to establish a protective chromium oxide (Cr₂O₃) film.
    • Electropolishing: Electrochemical polishing to achieve mirror finish (Ra ≤0.2 μm) and enhance corrosion resistance.
    • Chemical Polishing: For internal surface finishing of small-bore tubes.
  7. Quality Inspection and Testing:

    Every production batch undergoes comprehensive quality verification, including:

    • Dimensional measurement (OD, wall thickness, coil diameter, pitch)
    • Hydrostatic pressure testing (1.5× working pressure, held for minimum 10 seconds)
    • Visual inspection for surface defects, kinks, and deformation
    • Chemical composition verification (OES spectroscopy)
    • Mechanical property testing (tensile, hardness)
    • Corrosion testing (ASTM A262, ASTM G48)
  8. End Processing and Packaging:

    Tube ends are cut square, beveled, threaded, or prepared for welding as specified. Finished coil tubes are wrapped in protective film, packed in export-grade wooden crates or cardboard boxes, and labeled with traceability information (heat number, batch code, material certificate reference).

Applications

The stainless steel dry coil tube is deployed across a diverse range of industrial and commercial applications:

1. HVAC and Refrigeration Systems

Dry coil tubes serve as evaporator and condenser coils in commercial refrigeration units, air handling units (AHUs), chiller systems, and heat pump applications. The high surface-area-to-volume ratio of the coiled configuration maximizes heat transfer efficiency while minimizing footprint. The dry coil design eliminates the need for liquid refrigerant contact with the external environment, reducing environmental risk and improving system reliability.

2. Pharmaceutical and Biotechnology

In pharmaceutical manufacturing, the stainless steel dry coil tube is used in clean-in-place (CIP) systems, sanitizing-in-place (SIP) loops, and process fluid distribution networks. The electropolished surface (Ra ≤0.4 μm) meets FDA 21 CFR Part 117 and EU GMP Annex 1 requirements for hygienic processing. Grades 316L are standard for pharmaceutical applications due to their superior resistance to cleaning agents and process chemicals.

3. Food and Beverage Processing

Coil tubes are integrated into pasteurization systems, cooling loops, and fluid transfer lines in dairy, beverage, and food processing industries. Compliance with 3-A Sanitary Standards and FDA 21 CFR Part 117 ensures suitability for direct food contact applications.

4. Chemical Processing

In chemical plants, dry coil tubes are employed in heat exchangers, reactor cooling systems, and process fluid conveyance where resistance to aggressive chemicals (acids, bases, solvents) is required. The 316L and 310S grades provide robust performance in corrosive environments.

5. Energy and Power Generation

Coil tubes are utilized in solar thermal collectors, geothermal heat exchange systems, and industrial waste heat recovery units. The compact coil geometry enables efficient thermal energy capture within constrained spaces.

6. Medical Devices

Small-bore stainless steel coil tubes are used in medical instrument manufacturing, including endoscopy tubing, infusion lines, and diagnostic equipment fluid channels. The biocompatibility of austenitic stainless steel (per ASTM F138 / ISO 10993) ensures safety for medical applications.

7. Automotive and Aerospace

In automotive applications, coil tubes are used in fuel lines, brake lines, and HVAC components. In aerospace, they serve in hydraulic systems, environmental control systems (ECS), and fuel delivery networks where lightweight, corrosion-resistant, and high-strength tubing is essential.

8. Oil and Gas Industry

Dry coil tubes are applied in downhole instrumentation, pressure monitoring systems, and subsea fluid conveyance. The 316L grade offers resistance to sour gas (H₂S) environments when combined with appropriate metallurgical controls.

Quality Certifications and Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and holds the following certifications and complies with the following standards:

Management System Certifications

Product and Material Standards