Stainless Steel Coil Tube (Coiltube) — Cryogenic-Grade Heat Exchanger Tube
Product Series No.: 554 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product designed for high-efficiency heat exchange applications, particularly in large-scale helium cryogenic systems. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this coiltube product is formed by winding seamless or welded stainless steel tubing into a continuous helical or spiral configuration, offering an exceptional surface-area-to-volume ratio that significantly enhances thermal transfer performance. The product is engineered to meet the stringent demands of cryogenic, petrochemical, pharmaceutical, and advanced energy systems where reliable heat dissipation, corrosion resistance, and structural integrity are paramount.
Based on extensive research into heat exchanger performance characteristics and structural optimization within large helium cryogenic systems, this coiltube product integrates advanced metallurgical design with precision manufacturing to deliver superior thermal conductivity, mechanical stability, and long-term operational reliability under extreme temperature differentials.
Material & Properties
Base Material Composition
- Primary Alloy Grades: ASTM A269 / ASME SA-269 — Type 304 (UNS S30400), Type 316L (UNS S31603), Type 321 (UNS S32100), and Type 347 (UNS S34700)
- Cryogenic-Grade Options: 904L (UNS N08904), Inconel 625 (UNS N06625), and Hastelloy C-276 (UNS N10276) for specialized low-temperature service
- Chromium (Cr) Content: 18–22% (providing outstanding oxidation and corrosion resistance)
- Nickel (Ni) Content: 8–22% (ensuring austenitic stability at cryogenic temperatures)
- Molybdenum (Mo) Content: 2–3% in Type 316L (enhancing pitting and crevice corrosion resistance)
Key Physical & Mechanical Properties
- Thermal Conductivity: 14–16 W/(m·K) at 20°C; increases significantly at cryogenic temperatures (up to 30–40 W/(m·K) at 4.2 K for Type 304)
- Operating Temperature Range: −269°C (4.2 K) to +800°C (1,472°F)
- Tensile Strength: 515–750 MPa (depending on grade and heat treatment condition)
- Yield Strength: 205–310 MPa (minimum, annealed condition)
- Elongation: ≥40% (ensuring excellent ductility for coil winding without cracking)
- Density: 7.90–8.00 g/cm³
- Coefficient of Thermal Expansion: 17.3 × 10⁻⁶ /K (20–100°C)
- Surface Roughness (Ra): ≤0.8 μm (electropolished finish available upon request)
Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (¼" – 2") | ASTM A269 / ASME B36.19M |
| Wall Thickness | 0.5 mm – 3.0 mm (0.020" – 0.118") | ASTM A269 |
| Coil Inner Diameter (CID) | 50 mm – 500 mm (2" – 20") | Customer-Specific |
| Coil Length per Spool | 5 m – 120 m (customizable) | — |
| Winding Pitch | 1.05 × OD – 1.5 × OD (adjustable) | ISO 4427 |
| Winding Tolerance | ±0.1 mm (diameter), ±0.5 mm (pitch) | Internal QC Standard |
| End Preparation | Plain, Beveled (37.5°), Threaded (NPT/BSP), or Flanged | ASME B1.20.1 / ASME B16.5 |
| Surface Finish | Pickled & Passivated, Brushed, or Electropolished (Ra ≤ 0.4 μm) | ASTM A967 / ASTM B919 |
| Heat Treatment Condition | Annealed (Solution Annealed) at 1050–1150°C with rapid water quench | ASTM A269 |
| Pressure Rating | Up to 30 MPa (4,350 psi) — depends on OD, wall thickness, and temperature | ASME BPV Section VIII |
| Available Grades | 304, 304L, 316, 316L, 321, 347, 904L, Inconel 625, Hastelloy C-276 | ASTM A269 / ASME SA-269 |
| Packaging | Wooden crate with desiccant, foam cushioning, or export-grade steel frame | ISO 4180 |
Manufacturing Process
The production of Wenzhou Jixing's Stainless Steel Coil Tubes follows a rigorous, multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and consistent performance:
- Raw Material Selection & Inspection: Premium-grade stainless steel round bars or seamless tubes sourced from certified mills are subjected to spectroscopic analysis (OES) and mechanical testing to verify chemical composition and tensile properties prior to processing.
- Tube Drawing & Sizing: Stainless steel wire or bar stock is cold-drawn through precision tungsten carbide dies to achieve the target outer diameter and wall thickness. This process induces beneficial work hardening while maintaining the required ductility for subsequent coiling operations.
- Solution Annealing: Drawn tubing undergoes solution annealing at temperatures between 1,050°C and 1,150°C followed by rapid water quenching. This eliminates residual stresses, restores full austenitic microstructure, and maximizes corrosion resistance.
- Precision Coil Winding: The annealed tubing is fed through CNC-controlled winding machines equipped with laser-guided positioning systems. The winding process maintains a consistent pitch, concentricity, and tension profile, producing coils with geometric tolerances of ±0.1 mm.
- Welding & Seam Integrity (for welded variants): Where applicable, orbital GTAW (Gas Tungsten Arc Welding) is employed to create seamless, full-penetration welds with minimal heat-affected zone (HAZ). Post-weld heat treatment ensures weld nugget homogeneity.
- Surface Treatment: Coils receive pickling and passivation treatment per ASTM A967 to remove oxide scales and form a stable chromium oxide passive film. Electropolishing is available for ultra-clean applications requiring surface roughness Ra ≤ 0.4 μm.
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Quality Inspection & Testing: Every production batch undergoes comprehensive non-destructive testing (NDT), including:
- Eddy current inspection (ASTM E309) for surface and near-surface defects
- Helium leak testing (ASTM E376) for weld and seam integrity at pressures up to 0.1 Pa·L/s
- Dimensional verification via coordinate measuring machines (CMM)
- Hydrostatic pressure testing at 1.5× the maximum working pressure per ASME standards
- Spectroscopic composition verification (PMI — Positive Material Identification)
- Packaging & Shipping: Finished coils are individually wrapped in anti-corrosion film, cushioned with foam padding, and secured in export-grade wooden crates or steel frames to prevent mechanical damage during transit.
Applications
The versatility and performance characteristics of Wenzhou Jixing's Stainless Steel Coil Tubes make them suitable for a wide range of demanding industrial applications:
- Cryogenic Systems: Primary heat exchangers in large helium liquefaction and superconducting magnet cooling systems (4.2 K to 77 K), where the coiltube geometry provides maximum heat transfer area within compact envelope volumes. The cryogenic-grade material options maintain ductility and thermal conductivity at temperatures below −200°C.
- Petrochemical & Oil/Gas Processing: Refinery heat exchangers, distillation column reboilers, and process fluid coolers where resistance to sour gas (H₂S), chlorides, and high-pressure hydrocarbon service is essential.
- Pharmaceutical & Biotechnology: Sterilizable heat exchange units in cleanroom environments, bioreactor cooling loops, and CIP (Clean-in-Place) systems, where electropolished surfaces and corrosion-free operation are critical for product purity.
- Food & Beverage Processing: Dairy pasteurization, beer brewing, and juice processing systems requiring sanitary-grade tubing with smooth, non-porous surfaces that resist bacterial adhesion.
- Power Generation: Supercritical steam generators, nuclear reactor coolant loops, and waste heat recovery systems where thermal cycling resistance and long-term structural reliability are mandatory.
- Space & Aerospace: Thermal management systems, propellant pre-coolers, and radiation-cooled heat exchangers for spacecraft and satellite platforms.
- Research & Scientific Facilities: Particle accelerator cryoplants, fusion reactor (ITER-type) superconducting magnet cooling circuits, and national laboratory cryogenic infrastructure.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring every coil tube product meets or exceeds international standards:
- ISO 9001:2015 — Quality Management Systems certification
- ISO 14001:2015 — Environmental Management Systems certification
- ASME "S" Stamp — Section VIII, Division 1 & 2 pressure vessel components
- ASTM International — Full compliance with ASTM A269, A270, A967, and related standards
- EN 10216-5 / EN 10217-7 — European stainless steel tube standards
- JIS G3459 / JIS G3460 — Japanese Industrial Standards for austenitic stainless steel tubes
- GB/T 12771 — Chinese National Standard for stainless steel seamless tubes
- PED (EU 2014/68/EU) — Pressure Equipment Directive compliance for European market
- 3.1 / 3.2 Material Certificates — Full traceability per EN 10204
- Material Test Reports (MTR) — Provided with every shipment, including chemical analysis, mechanical test data, and NDT results
Unique Selling Points
- Cryogenic-Optimized Design: Informed by peer-reviewed research on heat exchanger performance in large helium cryogenic systems, the coiltube geometry and material selection are specifically optimized for maximum thermal efficiency at ultra-low temperatures (down to 4.2 K).
- Ultra-Precision Winding: CNC-controlled winding with laser-guided positioning ensures geometric accuracy of ±0.1 mm, enabling seamless integration into compact heat exchanger assemblies with minimal thermal contact resistance.
- Full Material Traceability: Every coil tube is accompanied by a complete EN 10204 3.1/3.2 certificate, ensuring full traceability from mill heat number through final inspection — a critical requirement for nuclear, aerospace, and pharmaceutical applications.
- Multi-Grade Flexibility: Availability in over 10 alloy grades, from standard 304/316L to exotic superalloys (Inconel 625, Hastelloy C-276), allows customers to match material properties precisely to their service environment.
- Comprehensive NDT Protocol: Eddy current, helium leak, hydrostatic pressure, and spectroscopic testing on every production batch ensures zero-defect delivery for safety-critical applications.
- Custom Engineering Support: Wenzhou Jixing offers OEM/ODM services with custom coil dimensions, end preparations, surface finishes, and special alloy compositions tailored to specific thermal performance requirements.
Technical Note: For cryogenic service below 77 K, it is strongly recommended to specify solution-annealed Type 304L or 316L with a maximum carbon content of 0.030% to prevent intergranular sensitization during any potential welding operations. For service below 20 K, Inconel 625 or custom low-expansion alloys should be considered to minimize thermal contraction mismatch with adjacent structural components.