Stainless Steel Coil Tube — Coiltube (Product No. 1552)

Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.

Classification: Literature Learning — Technical Documentation Series

Product Overview

The Stainless Steel Coil Tube (Coiltube) is a continuously wound tubular product manufactured from high-grade austenitic or duplex stainless steel wire. Unlike straight-length tubes, coil tubes are produced in continuous helical or spiral configurations, enabling on-demand cutting and minimal material waste. This product line encompasses seamless and welded stainless steel tubes formed into coils, ranging from micro-bore precision tubes to larger diameter industrial-grade coil stock.

The coil tube format is particularly advantageous for applications requiring flexible deployment, such as heat exchangers, plumbing systems, refrigeration coils, and industrial piping networks. The continuous coil eliminates the need for butt welding at intermediate joints, thereby enhancing structural integrity, fluid-tightness, and fatigue resistance in dynamic service environments.

This technical documentation is derived from the study and practical analysis of the Heating Coil Tube Head Cutting Machine (发热盘管头切割机), a critical piece of equipment in the coil tube production line. The cutting process represents the final forming stage where continuous coil stock is severed into discrete lengths while maintaining dimensional accuracy and surface integrity.

Material & Properties

Material Grades

Mechanical Properties (Typical Values for AISI 304)

Chemical Composition (AISI 304, wt%)

Physical Properties

Corrosion Resistance

Specifications

Parameter Specification Standard Reference
Outer Diameter (OD) 3.0 mm – 159.0 mm (0.118" – 6.26") ASTM A213 / ASTM A269
Wall Thickness 0.25 mm – 12.0 mm (0.010" – 0.472") ASTM A213 / EN 10216-5
Coil Length (per spool) 50 m – 500 m (164 ft – 1,640 ft), customizable Manufacturer Specification
Coil Weight Up to 3,000 kg (6,614 lbs) per coil —
Surface Finish Bright Annealed (BA), Pickled & Passivated (2B), Polished, Hairline, Matte ASTM A240
Surface Roughness (Ra) 0.4 μm – 3.2 μm (16 μin – 126 μin), depending on finish ISO 1302
Manufacturing Method Seamless (Pierced & Drawn) or Welded (ERW, Laser Welded, Orbital TIG) ASTM A213 / ASTM A270
Heat Treatment Solution Annealed (1040–1150 °C, water quenched); Optional Stress Relief ASTM A213
Tolerance — OD ±0.05 mm – ±0.5 mm (per EN 10216-5 or customer spec) EN 10216-5
Tolerance — Wall Thickness ±10% of nominal (standard); ±5% (precision grade) ASTM A213
Curvature / Roundness ≤ 0.5% of OD ISO 1128
Winding Tolerance ±2% of nominal coil length Manufacturer Specification
End Condition Plain cut, chamfered, beveled, or threaded per customer requirement —
Coating (Optional) PVC protective coating, passivation film, or bare (clean) —
Delivery Condition Annealed & Pickled (AP), Cold Worked (CW), or Heat Treated (HT) ASTM A213

Manufacturing Process

1. Raw Material Selection and Inspection

High-purity stainless steel wire rod or tube blanks are sourced from certified mills. Incoming materials undergo rigorous inspection including spectrographic analysis (OES), dimensional verification, and visual surface examination. Each batch is traceable via heat number and mill test certificate (MTC).

2. Pipe/Tube Forming

3. Heat Treatment (Solution Annealing)

Tubes are solution-annealed at 1040–1150 °C in a protective atmosphere (endothermic gas or vacuum) to dissolve carbide precipitates, restore full austenitic structure, and achieve maximum corrosion resistance. Quenching is performed in water or controlled cooling atmosphere.

4. Pickling and Passivation

Post-annealing, tubes are pickled using mixed acid solutions (HNO₃ + H₂SO₄) to remove oxide scale, followed by passivation treatment to establish a chromium-rich oxide film. This ensures a minimum 100-hour salt spray test resistance (ASTM B117) for standard grades.

5. Coil Winding

Continuous tube stock is wound into coils using precision coiling equipment with controlled tension and curvature. The winding process ensures uniform coil diameter, consistent layer-to-layer contact, and minimal surface damage. Anti-tangling guides and tension control systems maintain coil integrity throughout the winding operation.

6. Heating Coil Tube Head Cutting (Final Forming)

Key Process Highlight: The Heating Coil Tube Head Cutting Machine (发热盘管头切割机) is the definitive equipment in the coil tube finishing line. This machine performs the final severing of continuous coil stock into required discrete lengths while simultaneously managing thermal input to prevent work hardening, edge distortion, or heat-affected zone (HAZ) degradation.

The cutting process involves the following critical stages:

  1. Feeding and Positioning: The coil tube is fed through precision rollers into the cutting station. Encoder-based positioning ensures dimensional accuracy within ±0.5 mm.
  2. Thermal Softening (Controlled Heating): Induction or resistance heating is applied to the cutting zone to locally soften the material, reducing cutting force and minimizing edge deformation. Temperature is controlled within a narrow window (typically 400–600 °C for austenitic grades) to avoid grain growth or carbide precipitation.
  3. Precision Cutting: A high-speed rotating blade or shear mechanism performs the cut at the designated location. The blade geometry is optimized for stainless steel to produce clean, burr-free cross-sections.
  4. Cooling and Edge Treatment: Post-cut, the severed tube ends are cooled (air or water mist) and may undergo automated deburring or chamfering to meet dimensional and surface finish requirements.
  5. Quality Verification: Each cut length is inspected for dimensional accuracy, end squareness, surface integrity, and absence of thermal distortion or HAZ-related degradation.

7. Post-Processing (Optional)

8. Packaging and Shipping

Finished coils are wrapped with protective film or paper, secured with steel strapping, and placed on wooden or steel pallets. Export-grade packaging includes desiccant bags, anti-corrosion VCI (Vapor Corrosion Inhibitor) paper, and moisture-barrier wrapping. Each coil is labeled with product identification, heat number, dimensions, and quantity.

Applications

Heat Exchangers and HVAC Systems

Coil tubes are extensively used in air-cooled heat exchangers, condenser coils, evaporator coils, and radiator assemblies. The continuous coil format eliminates intermediate welds, reducing leak points and improving thermal efficiency. Applications include central air conditioning, refrigeration units, industrial chiller systems, and automotive radiators.

Plumbing and Sanitary Systems

Stainless steel coil tubes are employed in commercial and residential plumbing systems, including hot and cold water distribution, sanitary fixtures, and food-grade processing lines. The corrosion resistance and hygienic surface finish make them ideal for potable water systems and food/beverage processing.

Industrial Piping and Process Systems

Used in chemical processing plants, pharmaceutical manufacturing, semiconductor fabrication, and nuclear facilities. Coil tubes provide flexibility in routing while maintaining structural integrity under pressure and temperature cycling.

Automotive and Transportation

Applications include automotive exhaust systems, fuel lines, brake lines, and hydraulic systems. The coil format allows for automated cutting and forming in high-volume manufacturing environments.

Medical and Laboratory Equipment

Stainless steel coil tubes are used in medical gas delivery systems, surgical instrument manufacturing, laboratory apparatus, and MRI/CT scanner components where biocompatibility and corrosion resistance are critical.

Energy and Power Generation

Utilized in solar thermal collectors, geothermal systems, nuclear reactor coolant loops, and power plant boiler tubing. High-temperature grades (310S, Alloy 20) are used in furnace tubes and heat recovery steam generators.

Construction and Architecture

Stainless steel coil tubes are used in structural applications, decorative railings, building facades, and architectural cladding systems. The coil format enables efficient production of custom-length components.

Quality Certifications

International Standards Compliance