Stainless Steel Coil Tube for Wire-Coiled Condenser Applications

Product Overview

The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd, specifically designed for wire-coiled condenser systems. This product represents the culmination of advanced metallurgical research and optimization design principles applied to coil tube geometry, wall thickness, and material selection. The coil tube is formed into a continuous helical or spiral configuration that maximizes heat transfer surface area within a compact footprint, making it an indispensable component in thermal management systems across industrial, commercial, and domestic applications.

Based on the principles outlined in the study "Optimization Design of Wire Coiled Condensers" (《钢丝盘管式冷凝器的优化设计》), this product integrates optimized coil pitch, tube diameter, and cross-sectional geometry to achieve superior thermal-hydraulic performance while maintaining mechanical integrity under cyclic loading conditions.

Material & Properties

The coil tube is fabricated from high-grade austenitic stainless steel, offering exceptional corrosion resistance, high-temperature stability, and long-term mechanical reliability. The material composition and resulting properties are as follows:

Specifications

Parameter Specification / Range Standard Reference
Tube Outer Diameter (OD) Φ3.0 mm – Φ25.4 mm ASTM A269 / A213
Tube Wall Thickness 0.3 mm – 2.0 mm EN 10217-7
Coil Diameter (Mean) Φ50 mm – Φ500 mm Custom per design
Coil Pitch 1.5 × OD to 5 × OD Optimization per thermal design
Coil Length Up to 30 m continuous —
Surface Finish BA (Bright Annealed) / EP (Electropolished) Ra ≤ 0.4 μm ASTM A270
Tolerance on OD ±0.05 mm (precision grade) ISO 1307
Tolerance on Wall Thickness ±10% of nominal ASTM A269
Helix Angle 3° – 15° (adjustable) —
End Preparation Plain, threaded (BSP/NPT), or flanged ASME B1.20.1 / B16.5
Pressure Rating Up to 25 bar (PN25) EN 10217-7
Maximum Design Temperature 450°C (continuous service) —

Manufacturing Process

The production of high-performance stainless steel coil tubes follows a rigorous multi-stage manufacturing workflow optimized for dimensional accuracy and material integrity:

  1. Raw Material Selection & Incoming Inspection: Cold-rolled stainless steel strip or seamless tube stock is sourced from certified mills. Incoming material undergoes spectroscopic analysis (OES), mechanical testing, and visual inspection per ASTM E105 and ASTM A370.
  2. Coil Forming (Cold Bending): Precision CNC-controlled coil forming machines wind the straight tube into the desired helical geometry. The forming process is executed below the material's recrystallization temperature to retain cold-work hardening benefits. Forming fixtures ensure uniform bend radii without wall thinning exceeding 15%.
  3. Solution Annealing & Pickling: Post-forming annealing at 1050°C–1150°C in a protective atmosphere (argon or nitrogen) relieves residual stresses introduced during cold forming. Subsequent pickling with citric or nitric acid removes oxide scale, restoring the passive chromium oxide layer.
  4. Surface Treatment: Electropolishing or mechanical polishing is applied to achieve the specified surface roughness (Ra ≤ 0.4 μm), critical for minimizing fouling resistance in condenser applications.
  5. Hydrostatic Testing: Each coil assembly undergoes 100% hydrostatic pressure testing at 1.5× the maximum design pressure for a minimum of 30 seconds to verify weld integrity and absence of leakage paths (per ASME Section VIII).
  6. Non-Destructive Testing (NDT): Ultrasonic testing (UT) and dye penetrant inspection (DPI) are performed on critical joints and coil transitions per ASTM E164 and ASTM E709.
  7. Final Dimensional Inspection & Packaging: Laser scanning verifies coil geometry accuracy. Products are packaged in moisture-proof containers with protective end caps for transit.

Applications

The optimized wire-coiled condenser coil tube finds extensive application across multiple industries:

Unique Selling Points

1. Optimization-Driven Design: Product geometry is derived from computational fluid dynamics (CFD) and heat transfer optimization studies (as documented in the referenced academic work), ensuring maximum heat transfer coefficient (U-value) with minimum pressure drop.

2. Superior Corrosion Resistance: The austenitic stainless steel matrix with optimized alloy composition provides exceptional resistance to pitting, crevice, and intergranular corrosion — significantly extending service life compared to carbon steel or copper-nickel alternatives.

3. High Surface-to-Volume Ratio: The helical coil geometry provides up to 4× the heat transfer area of equivalent-length straight tubes, enabling compact system design without sacrificing thermal performance.

4. Mechanical Robustness: Cold-work hardening during coil forming enhances yield strength by 30–50% over annealed stock, providing resistance to vibration-induced fatigue in dynamic operating environments.

5. Food-Grade & Hygienic Compliance: Electropolished surface finish (Ra ≤ 0.4 μm) meets 3-A Sanitary Standards and FDA 21 CFR requirements, making the product suitable for food and pharmaceutical applications.

6. Customization Capability: Wenzhou Jixing Metal Materials Co., Ltd offers full customization of coil diameter, pitch, tube dimensions, and end preparations to match specific engineering requirements.

Quality Certifications & Standards Compliance

Wenzhou Jixing Metal Materials Co., Ltd maintains comprehensive quality management systems and certifications ensuring product conformity to international standards:

Each production batch is accompanied by a comprehensive documentation package including Material Test Reports (MTR), dimensional inspection certificates, hydrostatic test records, and NDT reports, ensuring full traceability and regulatory compliance for the end user.