Stainless Steel Helical Coil Tube — Lathe-Wound Cylindrical Coiltube

Product Overview

The Stainless Steel Helical Coil Tube (hereinafter referred to as "Coiltube") is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is formed by winding stainless steel tubing into a helical, cylindrical coil configuration using a lathe-based winding process with a dedicated mandrel (心轴). The resulting Coiltube exhibits uniform pitch, consistent wall thickness, and superior geometric accuracy, making it a critical component in heat exchange systems, chemical processing equipment, and specialized mechanical assemblies.

The manufacturing philosophy behind this product centers on the integration of classical lathe winding techniques with modern stainless steel metallurgy, producing a Coiltube that balances mechanical integrity, corrosion resistance, and dimensional precision. The helical geometry provides an optimized surface-area-to-volume ratio, enhancing thermal transfer efficiency while maintaining structural rigidity under operational loads.

Material & Properties

Wenzhou Jixing Metal Materials Co., Ltd. offers Coiltube products fabricated from a range of austenitic and duplex stainless steel grades, selected to meet the specific environmental and mechanical demands of each application.

Specifications

Parameter Specification Range Standard Reference
Outer Diameter (OD) Φ6 mm – Φ120 mm ASTM A213 / GB/T 12771
Wall Thickness 0.5 mm – 8.0 mm ASME B36.19M
Coil Outer Diameter Φ200 mm – Φ2000 mm Customer-specific / ISO 2852
Helix Pitch 10 mm – 150 mm (adjustable) Custom engineering specification
Number of Turns 3 – 200+ turns Per application design
Surface Finish 2B, No. 4, No. 8, Mirror (Ra ≤ 0.2 μm) ASTM A480
End Preparation Plain, Beveled, Threaded, Flanged ASME B16.25
Tolerance on OD ±0.1 mm – ±0.5 mm ISO 4287
Maximum Operating Temperature Up to 1100°C (grade-dependent) ASTM A213
Maximum Operating Pressure Up to 35 MPa (design-dependent) ASME VIII Div. 1

Manufacturing Process

The production of helical Coiltube at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous, multi-stage process designed to ensure dimensional accuracy, metallurgical integrity, and surface quality. The core technique involves lathe-based winding around a precision-machined mandrel (心轴), as detailed below:

  1. Raw Material Selection & Inspection: Stainless steel seamless tubes or welded tubes are procured per ASTM A213 or GB/T 12771 specifications. Incoming material undergoes spectroscopic analysis, hydrostatic testing, and visual inspection to confirm grade composition and absence of surface defects.
  2. Pre-Treatment & Straightening: Tubing is straightened to eliminate residual curvature and cleaned to remove scale, oil, and contaminants. Annealing may be performed to relieve cold-work stresses and restore ductility prior to forming.
  3. Mandrel Design & Preparation: A cylindrical mandrel (心轴) is machined to the desired inner coil diameter with precision tolerances. The mandrel surface is polished to prevent galling and ensure uniform contact with the tube during winding. Tapered lead-in sections facilitate smooth tube engagement.
  4. Lathe Winding Operation: The stainless steel tube is secured in the lathe chuck while the mandrel is mounted on the lathe bed. The lathe rotates the mandrel while a feed mechanism advances the tube axially, creating a continuous helix with controlled pitch. Key parameters—rotation speed, feed rate, and tube tension—are precisely calibrated to prevent ovalization, kinking, or springback.
  5. Pitch Control & Geometric Verification: During winding, the pitch is controlled by the ratio of mandrel rotation to axial feed. In-line gauging ensures uniform pitch deviation remains within ±2% of nominal. Post-winding, the coil is inspected using dial indicators and coordinate measuring machines (CMM) for concentricity and turn-to-turn spacing.
  6. Stress Relief & Heat Treatment: Following winding, the Coiltube may undergo solution annealing (1050°C – 1150°C) or strain-relief annealing (870°C – 950°C) to eliminate residual stresses introduced during forming, thereby preventing distortion during service or subsequent welding.
  7. Surface Finishing: Depending on application requirements, the Coiltube may receive pickling and passivation (acid washing to restore chromium oxide passive layer), mechanical polishing, or electropolishing for enhanced corrosion resistance and surface quality.
  8. Final Quality Assurance: Each coil undergoes dimensional verification, surface inspection, pressure testing (hydrostatic or pneumatic), and, where applicable, radiographic examination (RT) or ultrasonic testing (UT) of weld seams.

Technical Note: The lathe-winding method offers significant advantages over free-form bending techniques, as the mandrel provides positive constraint on the inner diameter, preventing ovalization and ensuring a consistent bore profile throughout the entire coil length. This is critical for applications requiring uniform fluid flow characteristics.

Applications

The stainless steel helical Coiltube finds extensive application across multiple industrial sectors due to its unique combination of thermal efficiency, corrosion resistance, and compact geometry:

Quality Certifications

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that all Coiltube products meet international standards and customer-specific requirements:

Unique Selling Points