Stainless Steel Coil Tube (Coiltube) — Wenzhou Jixing Metal Materials Co., Ltd
Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered continuous stainless steel tubing product, supplied in coiled configuration to facilitate downstream processing, installation, and integration into thermal exchange systems. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd, this product is specifically designed for high-performance applications in heat exchangers, condensers, and refrigeration circuits where compact geometry, superior heat transfer efficiency, and long-term corrosion resistance are critical design parameters.
Coil tubes differ from straight-length seamless or welded tubes in that they are drawn and coiled during or after the forming process, resulting in a continuous, kink-free product that can be deployed without the need for field welding or mechanical joining. This coiled geometry is particularly advantageous in coil-type water condensing heat exchangers (Coil-Type Water Condensing Heat Exchanger), where the helical arrangement maximizes the heat transfer surface area within a compact envelope, as documented in performance analyses of such systems.
Material & Properties
Wenzhou Jixing Metal Materials Co., Ltd supplies coil tubes in a range of stainless steel grades selected to meet the demanding thermal, mechanical, and corrosion-resistance requirements of heat exchanger and condenser applications. The primary alloy systems offered include:
- Austenitic Stainless Steels (奥氏体不锈钢): Grades 304 (UNS S30400) and 316 (UNS S31600) — offering excellent general corrosion resistance, good formability, and reliable performance across a wide temperature range.
- Duplex Stainless Steels (双相不锈钢): Grade 2205 (UNS S31803) — providing enhanced yield strength (approximately double that of austenitic grades) and superior resistance to chloride-induced stress corrosion cracking (Cl-SCC).
- Super Austenitic Stainless Steels (超级奥氏体不锈钢): Grades 904L (UNS N08904) and 254 SMO (UNS S31254) — reserved for highly aggressive chemical and marine environments.
| Property | Grade 304 (UNS S30400) | Grade 316 (UNS S31600) | Grade 2205 (UNS S31803) |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 515 | ≥ 515 | ≥ 550 |
| Yield Strength (MPa, 0.2% Offset) | ≥ 205 | ≥ 205 | ≥ 450 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 25 |
| Density (g/cm³) | 8.00 | 8.03 | 7.85 |
| Thermal Conductivity (W/m·K, at 20 °C) | 16.3 | 14.6 | 12.1 |
| Linear Expansion Coefficient (×10⁻⁶/°C) | 17.3 | 16.0 | 13.0 |
| Operating Temperature Range (°C) | −196 to +870 | −196 to +870 | −196 to +350 |
| Surface Finish (Ra) | ≤ 0.4 μm (Electropolished) | ≤ 0.4 μm (Electropolished) | ≤ 0.8 μm (Pickled & Passivated) |
Specifications
Wenzhou Jixing Metal Materials Co., Ltd provides coil tubes across a broad dimensional envelope, compliant with international standards including ASTM A269/A269M (Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing), ASTM A312/A312M (Standard Specification for Seamless, Welded, and Heavy-Walled Austenitic Stainless Steel Pipes), and EN 10217-7 (Non-ferrous metal tubes — Seamless stainless steel tubes for particular service).
| Parameter | Range | Notes |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 108 mm | Custom sizes available upon request |
| Wall Thickness | 0.3 mm – 6.0 mm | ±0.1 mm tolerance (per ASTM A269) |
| Coil Length | 10 m – 500 m per coil | Continuous length; no butt welds within coil |
| Coil Inner Diameter (CID) | 200 mm – 600 mm | Adaptable to customer spooling equipment |
| Coil Weight | Up to 2,000 kg per coil | Subject to dimensional configuration |
| End Condition | Clean-cut, deburred, or threaded | Custom end treatment available |
| Surface Condition | Pickled & Passivated, Polished, Electropolished, Matte | Electropolished finish preferred for heat exchanger service |
| Ends | Plain, Beveled, or Threaded (NPT / BSP) | Bevel angle: 37.5° ± 1° (per ASME B16.25) |
Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorously controlled multi-stage process to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: Ingot or strip stock is procured from certified suppliers and subjected to spectroscopic analysis (OES — Optical Emission Spectroscopy) to verify alloy composition within ASTM/EN specification tolerances.
- Hot Rolling / Forging: Billet or slab stock is hot-rolled to approximate tube dimensions, establishing the initial microstructure and reducing oxide scale through controlled heating cycles.
- Piercing / Tube Forming: The hot-rolled blank is pierced (for seamless tubes) or formed from precision strip (for welded tubes) to create the initial tubular geometry.
- Cold Drawing / Cold Reduction: The tube is cold-drawn through a series of dies and mandrels to achieve the final OD, wall thickness, and surface finish. This process induces beneficial work hardening, improving mechanical properties and dimensional precision.
- Heat Treatment: Solution annealing is performed at temperatures between 1010 °C and 1150 °C (depending on grade), followed by rapid quenching to restore full austenitic microstructure, eliminate residual stresses, and achieve maximum corrosion resistance. For duplex grades, a controlled cooling rate is maintained to preserve the optimal austenite-ferrite balance (typically 40:60 to 50:50).
- Pickling and Passivation: Tubes are immersed in a mixed acid solution (nitric + hydrofluoric acid) to remove surface oxides and scale. Subsequent passivation with a dilute nitric acid solution (typically 20–30% HNO₃) forms a stable chromium oxide (Cr₂O₃) passive film on the surface, providing critical corrosion protection.
- Coiling: The finished tube is coiled onto a pay-off reel under controlled tension to prevent kinking, ovality, or surface damage. The coiling process ensures a uniform helical pitch suitable for downstream installation.
- Non-Destructive Testing (NDT): Each coil undergoes 100% inspection via electromagnetic testing (ECT — Electromagnetic Testing) or eddy current testing to detect internal and external defects. Hydrostatic or pneumatic pressure testing is performed to verify wall integrity at 1.5 times the maximum working pressure.
Applications
The stainless steel coil tube is a versatile product with a wide range of industrial and commercial applications, particularly where heat transfer, fluid containment, and corrosion resistance are paramount:
- Coil-Type Water Condensing Heat Exchangers (盘管式水冷凝热换热器): The helical coil geometry enables high heat transfer coefficients through turbulent flow induction and maximized surface-to-volume ratios. Performance analyses demonstrate that coil-type condensers achieve condensation coefficients (h) significantly higher than straight-tube equivalents due to secondary flow effects within the curved geometry.
- Refrigeration and Air Conditioning (HVAC/R): Used as evaporator and condenser coils in commercial refrigeration units, heat pumps, and industrial air conditioning systems.
- Chemical Processing: Deployed in reactors, heat exchangers, and distillation columns where resistance to aggressive chemical media (acids, caustics, halides) is required.
- Food and Beverage Industry: Compliant with FDA and 3-A Sanitary Standards for hygienic fluid handling, pasteurization systems, and CIP (Clean-in-Place) compatible installations.
- Pharmaceutical Manufacturing: Electropolished coil tubes meet GMP (Good Manufacturing Practice) requirements for aseptic processing, fermentation tanks, and heat recovery systems.
- Marine and Offshore: Grade 316L and 2205 coil tubes are employed in seawater cooling systems, ballast water treatment, and offshore platform heat exchangers.
- Petrochemical and Energy: Used in heat exchangers, condensers, and distillation columns in oil refining and natural gas processing facilities.
Unique Selling Points
- Seamless Continuous Length: The coil format eliminates butt welds, reducing potential failure points and enabling leak-free installation in critical heat exchanger circuits.
- Superior Heat Transfer Performance: The helical coil geometry inherently promotes turbulence and secondary flow, enhancing the overall heat transfer coefficient by 20–40% compared to straight-tube configurations, as validated in performance analyses of coil-type water condensing heat exchangers.
- Compact Envelope: The coiled form factor maximizes heat transfer area within a minimal footprint, reducing installation space and capital costs.
- Wide Grade Selection: Availability across austenitic, duplex, and super-austenitic grades enables precise material selection tailored to specific service environments.
- Customization: Wenzhou Jixing Metal Materials Co., Ltd offers bespoke OD, wall thickness, coil length, and surface finish configurations to meet project-specific requirements.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework ensuring product conformity and traceability:
- ISO 9001:2015 — Quality Management Systems certification, demonstrating commitment to consistent quality and continuous improvement.
- ISO 14001:2015 — Environmental Management Systems certification, reflecting responsible environmental practices throughout the manufacturing lifecycle.
- ISO 45001:2018 — Occupational Health and Safety Management Systems certification.
- EN 10204 Type 3.1 Test Certificates — Material test certificates issued for each production lot, documenting chemical composition, mechanical properties, and dimensional compliance.
- Mill Test Reports (MTR): Full traceability from raw material ingot to finished coil, including heat numbers, production dates, and inspection records.
- Pressure Vessel and Heat Exchanger Standards Compliance: Products certified for use in systems governed by ASME Boiler and Pressure Vessel Code (BPVC) Section VIII and TEMA (Tubular Heat Exchanger Manufacturers Association) Standards.
- Hygienic Certification: Electropolished variants comply with FDA 21 CFR 178.301 and 3-A Sanitary Standards for food-grade and pharmaceutical applications.
Note: All specifications and properties described herein are representative values based on standard manufacturing conditions. Actual product specifications should be confirmed through direct consultation with Wenzhou Jixing Metal Materials Co., Ltd, as custom configurations and grade-specific variations may apply. Performance data referenced in coil-type water condensing heat exchanger analyses assumes proper installation geometry, flow conditions, and maintenance protocols.