Spiral Coil Tube (盘管) — Coiltube Product Series No. 1380

1. Product Overview

The Spiral Coil Tube (盘管, Coiltube) is a specialized form of stainless steel tubing produced through a helical forming process on conventional pipe-bending machinery. Unlike conventional straight-length stainless steel tubes, the spiral coil tube is wound into a continuous helical configuration, offering a high surface-area-to-volume ratio, superior thermal exchange performance, and compact spatial footprint. This product series, catalogued under Product No. 1380, is developed and supplied by Wenzhou Jixing Metal Materials Co., Ltd., a manufacturer with extensive expertise in stainless steel tube and pipe fabrication.

The defining technical innovation of this product lies in its manufacturability on ordinary bending machines (普通弯管机), eliminating the need for dedicated coil-forming equipment. This approach significantly reduces capital expenditure and production complexity while maintaining tight dimensional tolerances and metallurgical integrity of the final product.

2. Material & Properties

The spiral coil tube is fabricated from high-quality austenitic stainless steel grades, selected for their exceptional corrosion resistance, mechanical strength, and formability under cold-bending conditions.

3. Specifications

Parameter Specification Tolerance
Outer Diameter (OD) 3.18 mm – 38.10 mm (⅛" – 1½") ±0.10 mm
Wall Thickness 0.30 mm – 3.00 mm ±10%
Coil Pitch (Helix Spacing) 5 mm – 50 mm (adjustable) ±0.5 mm
Bend Radius (Helix Radius) 15 mm – 200 mm ±1.0 mm
Coil Length (Uncoiled) Custom, typically 1 m – 50 m ±2%
Coil Height (Stacked) 10 mm – 300 mm ±2.0 mm
Number of Turns 5 – 500+ (custom) ±1 turn
End Treatment Plain, threaded (BSPP/BSPT/NPT), flanged, or welded —
Surface Treatment Pickling & passivation (post-forming) —
Applicable Standards ASTM A213, ASTM A269, GB/T 12771, EN 10217-7 —

4. Manufacturing Process

The production of spiral coil tubes on ordinary bending machines follows a rigorously controlled multi-stage process that ensures both geometric accuracy and metallurgical soundness:

  1. Raw Material Inspection & Receiving: Incoming stainless steel seamless or welded tubes are verified against mill certificates (Mill Test Reports, MTR) for chemical composition, mechanical properties, and dimensional compliance. Ultrasonic testing (UT) or eddy current testing may be applied to detect internal defects.
  2. Pre-Forming Heat Treatment (Optional): Tubes may undergo solution annealing (1050–1150°C, water quench) to relieve residual stresses from prior cold working and restore full austenitic ductility prior to bending operations.
  3. Dimensional Preparation: Tubes are cut to required lengths using precision sawing or plasma cutting, with end deburring and chamfering to ensure proper engagement in the bending machine.
  4. Helical Coiling on Ordinary Bending Machine: The core process involves configuring a standard hydraulic or mechanical bending machine with a custom-formed die or mandrel to impart a continuous helical geometry. Key process parameters include:
    • Bending speed — controlled to prevent work hardening-induced cracking
    • Die radius — selected to avoid excessive ovalization (typically < 3% for critical applications)
    • Feed rate and pitch control — regulated to maintain uniform helix spacing
    • Support fixtures — employed to prevent tube buckling or flattening during the forming sequence
  5. Post-Forming Inspection: Dimensional verification using calipers, go/no-go gauges, and coordinate measuring machines (CMM) to confirm OD, wall thickness, coil pitch, and bend radius compliance. Visual inspection for surface defects, ovalization, or kinking.
  6. Pickling & Passivation: Cold-formed tubes are subjected to pickling (acid immersion, typically HNO₃/HF or citric acid-based solutions) to remove surface oxide and embedded contaminants, followed by passivation to restore the passive chromium oxide (Cr₂O₃) film critical for corrosion resistance.
  7. End Finishing: Threading, flanging, or welding of connection fittings as specified by the customer application.
  8. Final Quality Assurance: Comprehensive testing including hydrostatic pressure testing (typically 1.5× working pressure for 30 seconds), spectrometric analysis (PMI verification), and packaging preparation.

5. Applications

The spiral coil tube's unique geometry and stainless steel material properties make it suitable for a diverse range of industrial and commercial applications:

6. Quality Certifications & Standards Compliance

Wenzhou Jixing Metal Materials Co., Ltd. adheres to internationally recognized quality management and product standards:

7. Unique Selling Points

Cost-Efficient Manufacturing on Conventional Equipment: The ability to produce high-quality spiral coil tubes using ordinary bending machines — rather than specialized coil-forming machinery — represents a significant cost advantage. This approach reduces equipment investment, shortens production lead times, and enables flexible customization without the capital burden of dedicated forming systems.

8. Technical Notes

When specifying spiral coil tubes for high-temperature or high-pressure applications, customers should provide the following design parameters to ensure optimal product selection:

Wenzhou Jixing Metal Materials Co., Ltd. maintains an in-house engineering team capable of providing thermal analysis, finite element simulation (FEA) of coil deformation, and custom design support to ensure that each coil tube product meets or exceeds the performance requirements of its intended application.