Stainless Steel Spiral Coil Tube (Coiltube)

Product Overview

The Stainless Steel Spiral Coil Tube (Coiltube) is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd., formed through a specialized spiral bending process utilizing industrial coil rolling machinery. This product represents a critical component in heat exchange technology, offering superior thermal efficiency compared to conventional straight-pipe configurations due to the inherent turbulence enhancement generated by the helical geometry. The spiral coil tube is designed to maximize heat transfer surface area within a compact volume, making it indispensable in industrial thermal management systems.

Material & Properties

The coil tubes are fabricated from high-grade austenitic and duplex stainless steel grades, selected to ensure optimal resistance to corrosion, oxidation, and mechanical degradation under demanding operational conditions.

Specifications

Parameter Specification Range Unit
Outer Diameter (OD) 6.0 – 38.0 mm
Wall Thickness 0.5 – 3.0 mm
Coil Diameter (Pitch) 50 – 300 mm
Coil Length 0.5 – 12.0 m
Number of Turns 3 – 500 —
Tolerance on OD ±0.05 – ±0.15 mm
Tolerance on Wall Thickness ±10% —
Surface Finish 2B, No.4 Brushed, BA (Bright Annealed), Polished (Ra ≤ 0.4 μm) —
End Condition Plain, Beveled, Threaded, Socket Weld —
Standard Reference ASTM A213, ASTM A269, GB/T 14976, EN 10216-5, ASME B31.3 —
Packaging Export-grade wooden crate or steel frame with desiccant protection —

Manufacturing Process

The production of spiral coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing protocol that ensures dimensional accuracy, metallurgical integrity, and consistent mechanical performance.

  1. Raw Material Procurement and Inspection: Stainless steel seamless or welded pipes are sourced from certified mills. Incoming materials undergo spectrographic analysis (Optical Emission Spectrometry, OES) to verify chemical composition, along with ultrasonic testing (UT) for internal defect detection.
  2. Cutting and Preparation: Pipes are cut to the required coil length using precision plasma or laser cutting systems. Cut ends are deburred and inspected for squareness and burr-free condition.
  3. Spiral Bending (Coil Rolling): The core forming operation employs a specialized coil rolling machine (卷板机) equipped with precision tooling and fixtures. The pipe is progressively rolled through calibrated rollers to achieve the target helical geometry. Key process parameters include:
    • Roller diameter and spacing calibration to control coil pitch
    • Gradual feed rate adjustment to prevent material work hardening
    • Fixture design to maintain consistent bend radius throughout all turns
    • In-process dimensional verification at each stage of coiling
  4. Stress Relief Annealing: Post-forming, the coil tubes are subjected to solution annealing at 1050°C – 1150°C (depending on grade) followed by controlled cooling (air or water quench) to relieve residual stresses induced during bending and restore full austenitic microstructure.
  5. Surface Treatment and Passivation: The finished coil tubes undergo acid pickling and passivation to remove oxide scale and form a protective chromium oxide layer, ensuring maximum corrosion resistance.
  6. Final Inspection and Testing: Comprehensive quality assurance includes:
    • Dimensional measurement (OD, wall thickness, coil diameter, pitch) using calibrated instruments
    • Visual inspection for surface defects, deformation, or cold work marks
    • Hydrostatic pressure testing at 1.5× maximum working pressure
    • Non-destructive testing (NDT): Eddy Current Testing (ECT) or Magnetic Particle Inspection (MPI) as applicable
    • Mechanical property verification on coupon samples
  7. Packaging and Dispatch: Finished products are individually wrapped in protective film, packed in ventilated wooden crates with moisture-absorbing desiccants, and prepared for export or domestic delivery.

Applications

The spiral coil tube is extensively deployed across multiple industries where efficient heat exchange, compact design, and corrosion resistance are critical requirements:

Quality Certifications

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

Unique Selling Points

1. Precision Spiral Forming Expertise: Leveraging proprietary coil rolling technology with dedicated tooling and fixtures, Wenzhou Jixing delivers spiral coil tubes with exceptional geometric consistency—maintaining uniform pitch, bend radius, and dimensional tolerance across all turns, even in high-turn-count configurations.

2. Superior Heat Transfer Efficiency: The helical configuration inherently induces secondary flow (Dean vortices), enhancing turbulent mixing and increasing the heat transfer coefficient by 30%–50% compared to equivalent straight-pipe bundles, enabling more compact exchanger designs.

3. Comprehensive Grade Selection: Offering an extensive range of stainless steel grades—from standard 304/316L to high-performance duplex and super duplex alloys—providing solutions for the most aggressive corrosion environments.

4. Custom Engineering Capability: Flexible customization of coil diameter, pitch, turn count, end conditions, and surface finish to meet specific project requirements and OEM specifications.

5. Rigorous Quality Assurance: End-to-end quality control from raw material spectrographic verification through final non-destructive testing, supported by full material traceability documentation and third-party inspection availability.

6. Cost-Effective Manufacturing: The coil rolling process eliminates the need for individual U-bends or hairpin bends, reducing fabrication labor, weld count, and overall manufacturing cost while maintaining structural integrity.