Stainless Steel Helical Coil Tube for Cryogenic Heat Exchanger Applications

Product Code: 529  |  Product Category: Coil Tube (盘管)  |  Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.

Product Overview

The Stainless Steel Helical Coil Tube is a precision-engineered tubular component designed specifically for cryogenic heat exchanger systems. This product is developed and manufactured in accordance with advanced numerical simulation data concerning Convective Heat Transfer of Cryogenic Helium in Helical Coil Heat Exchangers (低温氦气在螺旋盘管换热器中对流换热的数值模拟). The coil tube is engineered to optimize thermal performance under extreme low-temperature conditions, where conventional straight-tube heat exchangers exhibit insufficient heat transfer efficiency.

Helical coil geometry provides a significant advantage in cryogenic applications by inducing secondary flow patterns (Dean vortices) within the tube, which enhance turbulent mixing and substantially improve the heat transfer coefficient compared to straight tubes of equivalent cross-sectional area. This product leverages that geometric advantage to deliver superior thermal performance in liquid helium (LHe) and supercritical helium (SCHe) systems operating at temperatures as low as 4.2 K.

Material & Properties

The coil tube is fabricated from high-purity austenitic stainless steel grades, selected for their exceptional cryogenic mechanical properties, corrosion resistance, and thermal conductivity characteristics.

• Primary Grade: 304L (UNS S30403) — Low-carbon variant ensuring resistance to intergranular corrosion and maintaining ductility at cryogenic temperatures.
• Alternative Grade: 316L (UNS S31603) — Molybdenum-enhanced variant offering superior resistance to pitting and crevice corrosion in aggressive cryogenic environments.
• Specialty Grade: 310L (UNS S31008) — High-temperature-strength austenitic stainless steel for applications requiring elevated thermal cycling resistance.

Key Material Properties at Cryogenic Temperatures (4.2 K):

• Yield Strength (0.2% offset): ≥ 450 MPa
• Tensile Strength: ≥ 600 MPa
• Elongation: ≥ 35%
• Thermal Conductivity (λ): 10–18 W/(m·K) depending on temperature
• Linear Thermal Expansion Coefficient (α): 16–18 × 10⁻⁶ /K (20 K – 300 K)
• Density (ρ): 7,900 kg/m³

Specifications

Parameter	Specification / Range	Unit
Outer Diameter (OD)	6.0 – 25.4	mm
Wall Thickness	0.5 – 1.5	mm
Helical Coil Diameter (Mean)	200 – 800	mm
Coil Pitch	15 – 50	mm
Number of Turns	10 – 200	—
Total Coil Length	10 – 500	m
Operating Temperature Range	4.2 – 300	K
Maximum Operating Pressure	0 – 25	MPa
Surface Finish (Ra)	0.1 – 0.8	μm
Helix Angle	2° – 15°	°
D/Dt Ratio (Coil Diameter / Tube OD)	10 – 50	—

Manufacturing Process

The production of the Stainless Steel Helical Coil Tube follows a rigorous multi-stage manufacturing process, incorporating advanced numerical simulation validation at each critical phase:

1. Raw Material Selection & Certification: Cold-rolled stainless steel tubing is sourced from certified mills with full Chemical Composition Analysis (CCA) and Mechanical Property Test (MPT) documentation. Incoming material undergoes spectroscopic verification (OES — Optical Emission Spectroscopy).
2. Tube Straightening & Cutting: Precision straightening ensures uniform roundness (≤ 0.1 mm eccentricity) prior to coiling. Tubes are cut to calculated lengths based on helical geometry parameters.
3. Numerical Simulation & Geometric Optimization: Computational Fluid Dynamics (CFD) and Conjugate Heat Transfer (CHT) simulations are performed to model cryogenic helium flow within the proposed helical geometry. Key outputs include Nusselt number (Nu) distributions, pressure drop (ΔP) profiles, and flow maldistribution indices. The Dittus-Boelter and Hausen correlations are used as baseline benchmarks, with corrections for Dean number (De) effects.
4. Helical Coiling: The tube is wound onto precision mandrels using CNC-controlled coiling equipment. Tension and feed rate are continuously monitored to maintain constant helix angle and pitch throughout the coil length. Mandrel diameter tolerance is held to ±0.1 mm.
5. End Fitting & Welding: Coil ends are prepared for welding using TIG (Tungsten Inert Gas) welding with argon shielding. Weld joint geometry is optimized to minimize residual stress and ensure leak-tight integrity under cryogenic cycling.
6. Stress Relief Annealing: Where required, the assembled coil undergoes controlled annealing to relieve coiling-induced residual stresses while maintaining cryogenic mechanical properties.
7. Surface Treatment: Electropolishing or mechanical polishing achieves the specified surface roughness (Ra ≤ 0.8 μm), critical for minimizing flow resistance and enhancing heat transfer in cryogenic helium applications.
8. Non-Destructive Testing (NDT): 100% Helium Leak Testing (HLT) at a detection rate of ≤ 1 × 10⁻⁹ mbar·L/s. Radiographic Testing (RT) or Ultrasonic Testing (UT) is performed on weld joints per ASME Section VIII standards.
9. Pressure Testing & Cryogenic Cycling: Pneumatic pressure testing at 1.5× working pressure, followed by thermal cycling between 4.2 K and 300 K to validate dimensional stability and mechanical integrity.

Applications

The Stainless Steel Helical Coil Tube is deployed in a wide range of cryogenic and low-temperature engineering applications:

• Cryogenic Helium Refrigeration Systems: Primary heat exchanger elements in closed-cycle helium refrigerators (4.2 K – 77 K) used in superconducting magnet cooling.
• Superconducting Magnet Systems: Heat exchangers for Large Hadron Collider (LHC)-class magnets, fusion reactor magnets (ITER), and MRI (Magnetic Resonance Imaging) superconducting coils.
• Space Simulation & Cryogenic Testing: Thermal control components for satellite radiator testing and cryogenic qualification chambers.
• Liquid Hydrogen (LH₂) Systems: Heat exchangers in hydrogen liquefaction plants and rocket engine propellant feed systems.
• Quantum Computing Infrastructure: Dilution refrigerator insert components requiring ultra-low temperature (mK range) thermal management.
• Medical & Pharmaceutical: Cryogenic storage and transport systems for vaccines, biological samples, and pharmaceutical products.
• Natural Gas Liquefaction (LNG): Intermediate heat exchangers in cascade and mixed-refrigerant LNG processes.

Quality Certifications & Standards Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that every Stainless Steel Helical Coil Tube meets international standards:

• ISO 9001:2015 — Quality Management System certification covering the entire manufacturing and supply chain.
• ISO 14001:2015 — Environmental Management System certification for sustainable manufacturing practices.
• ASME BPV Code Section VIII — Compliance with pressure vessel and heat exchanger construction standards.
• EN 10204 3.1 Certificate — Third-party verified material certification for each production lot.
• ASTM A269 / ASTM A213 — Material specification compliance for austenitic stainless steel tubing.
• ASME B31.3 — Process piping code compliance for cryogenic service.
• API 660 — Where applicable, compliance with cryogenic process piping standards.

Unique Selling Points

• Simulation-Validated Design: Each coil geometry is validated through rigorous numerical simulation of cryogenic helium convective heat transfer, ensuring optimal Nusselt number and pressure drop performance before physical fabrication.
• Ultra-Low Temperature Capability: Proven performance down to 1.5 K (dilution refrigerator compatible), with demonstrated zero thermal fatigue failure over 10,000+ thermal cycles.
• Custom Geometric Engineering: Helix diameter, pitch, number of turns, and tube dimensions are fully customizable to match specific heat duty and pressure drop requirements.
• High Surface-to-Volume Ratio: Helical geometry inherently provides greater heat transfer area per unit volume compared to straight-tube configurations, enabling compact exchanger designs.
• Enhanced Turbulent Mixing: Dean flow effects at practical Reynolds numbers (Re > 500) ensure uniform temperature distribution and elimination of thermal dead zones.
• Full Traceability: Every coil is traceable from raw material mill certificate through final NDT and pressure test documentation.

Technical Note: The design philosophy behind this product is grounded in the fundamental research on "Numerical Simulation of Convective Heat Transfer of Cryogenic Helium in Helical Coil Heat Exchangers" (低温氦气在螺旋盘管换热器中对流换热的数值模拟). This research established critical correlations between helical geometry parameters (D/d ratio, pitch, helix angle) and thermal-hydraulic performance, directly informing the engineering specifications presented in this document.