Enamel-Lined PTFE Composite Coil Tube Condenser — Model JX-CT1221
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd
Product Code: JX-CT1221 | Category: Technical Documentation & Literature Study
Product Overview
The Enamel-Lined PTFE (Polytetrafluoroethylene) Composite Coil Tube Condenser (Model JX-CT1221) is an advanced heat-exchange component engineered for demanding chemical processing environments. This coil tube assembly integrates the structural integrity of stainless steel with the exceptional chemical resistance of PTFE lining and the thermal durability of enamel (glass) coating, creating a multi-layer composite construction that addresses the limitations of conventional stainless steel coil tubes in highly corrosive applications.
Unlike standard austenitic stainless steel coil tubes (e.g., 304, 316L), which may suffer from pitting corrosion, intergranular corrosion, or stress corrosion cracking (SCC) when exposed to aggressive chemical media such as hydrofluoric acid, hot concentrated sulfuric acid, or strong alkali solutions, the JX-CT1221 coil tube provides a robust barrier through its composite lining system. The spiral coil geometry maximizes the heat-transfer surface area within a compact volume, making it ideal for condensers, evaporators, and reboilers in the chemical, pharmaceutical, and food processing industries.
Unique Selling Points
- Triple-Layer Composite Protection: Combines enamel glazing, PTFE lining, and stainless steel substrate for superior corrosion resistance across a wider range of chemical media.
- Optimized Spiral Coil Geometry: Provides high surface-area-to-volume ratio for enhanced heat transfer efficiency, reducing equipment footprint and energy consumption.
- Thermal Shock Resistance: The enamel layer offers excellent resistance to thermal shock (ΔT up to 120°C), preventing cracking during rapid heating or cooling cycles.
- Non-Adhesive PTFE Surface: The PTFE lining ensures non-stick properties, preventing product fouling and reducing maintenance downtime.
- Full Compliance with Industry Standards: Manufactured in accordance with GB, HG, ASME, and ISO standards with comprehensive quality certifications.
Material & Properties
Substrate Material — Stainless Steel
The core structural material is austenitic stainless steel, typically Grade 304 (UNS S30408) or 316L (UNS S31603), providing the mechanical strength and formability required for spiral coil winding. The stainless steel base ensures:
- Yield strength (Rp0.2) of ≥ 205 MPa for 304 and ≥ 170 MPa for 316L
- Ultimate tensile strength (Rm) of 515–730 MPa (304) and 485–620 MPa (316L)
- Elongation (A50) of ≥ 40% for ductile coil forming
- Operating temperature range from −196°C to +800°C (depending on grade)
- Excellent weldability for tube-to-header connections
Enamel (Glass) Coating Layer
The vitreous enamel (搪玻璃) coating is a high-silica glass frit fused to the stainless steel surface at temperatures between 800°C and 900°C. This layer provides:
- Chemical resistance to nearly all inorganic acids (except HF and hot concentrated phosphoric acid)
- Thermal conductivity of approximately 1.4 W/(m·K)
- Hardness of 6–7 Mohs scale
- Thickens of 0.3–0.5 mm per coat, with 2–3 coats typically applied
- Adhesion strength to substrate ≥ 1.5 MPa
PTFE (Polytetrafluoroethylene) Lining Layer
The innermost PTFE layer (聚四氟乙烯) provides the primary chemical barrier, offering:
- Resistance to virtually all chemicals, including aqua regia, concentrated sulfuric acid, and hydrofluoric acid
- Operating temperature range from −200°C to +260°C
- Surface friction coefficient of 0.04–0.10 (ultra-low adhesion)
- Dielectric strength of ≥ 60 kV/mm
- Chemical inertness with zero product contamination
Specifications
| Parameter | Specification | Unit | Standard Reference |
|---|---|---|---|
| Product Model | JX-CT1221 | — | — |
| Tube Outer Diameter (OD) | φ14, φ18, φ22, φ25, φ32, φ38, φ51, φ57, φ76 | mm | GB/T 14976 |
| Tube Wall Thickness | 1.0 – 3.0 | mm | GB/T 14976 |
| Coil Diameter | 300 – 3000 | mm | Custom |
| Coil Length (Developed) | 5 – 100 | m | Custom |
| Substrate Grade | 304 / 304L / 316 / 316L | — | ASTM A270 / GB/T 12771 |
| Enamel Coating Thickness | 0.3 – 0.5 (per coat); 0.6 – 1.5 (total) | mm | GB/T 9791 |
| PTFE Lining Thickness | 0.2 – 0.5 | mm | GB/T 15003 |
| Design Pressure | 0 – 1.6 | MPa | GB/T 150 |
| Design Temperature | −20 to +200 | °C | — |
| Surface Finish (Interior) | PTFE smooth, Ra ≤ 0.4 | μm | — |
| Surface Finish (Exterior) | Enamel glazed / Brushed | — | — |
| Connection Type | Flanged (PN16/PN40), Threaded (BSP/NPT), Welded | — | GB/T 9112 / ASME B1.20.1 |
| Heat Transfer Coefficient (U) | 200 – 800 | W/(m²·K) | Dependent on fluid conditions |
| Hydrostatic Test Pressure | 1.5 × Design Pressure | MPa | GB/T 150 |
| Coil Pitch | 5 – 50 | mm | Custom |
| Number of Coils (Turns) | 10 – 500 | — | Custom |
Manufacturing Process
The production of the JX-CT1221 composite coil tube follows a rigorous multi-stage process to ensure dimensional accuracy, coating integrity, and long-term reliability:
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Raw Material Inspection (Incoming QC):
Stainless steel seamless tubes are received and inspected for chemical composition (via OES — Optical Emission Spectroscopy), mechanical properties (tensile test, hardness test), and surface quality. Mill test certificates (MTC) per EN 10204 3.1 are verified.
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Tube End Preparation:
Tube ends are chamfered, deburred, and cleaned using ultrasonic bath (≥ 40 kHz) to remove oxide scale and contaminants. Surface roughness is verified to Ra ≤ 1.6 μm prior to coating.
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Spiral Coil Forming (Cold Bending):
Tubes are cold-bent on a CNC-controlled coil bending machine to the specified coil diameter and pitch. The bending process is controlled to maintain minimum bend radius (R ≥ 3D, where D is tube OD) to prevent wall thinning below 85% of original thickness. Post-bend stress relief annealing may be applied at 300–400°C for 30 minutes.
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PTFE Lining Application:
PTFE lining is applied via one of the following methods:
- Electrostatic Spraying (Electrostatic Powder Coating): PTFE powder is electrostatically deposited onto the electrically grounded tube surface, then cured at 300–360°C for 20–30 minutes. This method provides uniform, pinhole-free coverage.
- PTFE Film Bonding (Calendering): A PTFE sheet is bonded to the tube interior using a specialized adhesive system and heat-pressed. This method is preferred for thicker linings (≥ 0.3 mm).
- Chemical Vapor Deposition (CVD): For ultra-thin, conformal coatings, PTFE is deposited from a gaseous precursor in a vacuum chamber.
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Enamel (Glass) Coating Application:
Enamel frit (powdered glass) is applied to the exterior surface via:
- Dip Coating: The coil is dipped into a slurry of enamel frit suspended in a liquid medium (water or organic solvent). Multiple dips are performed to achieve the target total thickness.
- Spray Coating: Enamel frit is spray-applied using a specialized electrostatic spray gun for even coverage on complex coil geometries.
The coated coil is then fired in a controlled atmosphere furnace at 800–900°C for 10–30 minutes, during which the frit melts, flows, and vitrifies into a smooth glass surface fused to the metal substrate.
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Quality Control & Testing:
- Enamel Adhesion Test: Per GB/T 9791, cross-hatch adhesion testing ensures ≥ 1.5 MPa bond strength.
- Enamel Spark Test (Dielectric Test): High-voltage spark testing at 5–10 kV detects pinholes and thin spots in the enamel coating.
- PTFE Thickness Measurement: Ultrasonic thickness gauging verifies lining uniformity within ± 10% of nominal.
- Hydrostatic Pressure Test: Each coil assembly is pressure-tested at 1.5× design pressure for a minimum hold time of 30 minutes with zero leakage tolerance.
- Dimensional Inspection: Coil diameter, pitch, and tube dimensions are verified using CMM (Coordinate Measuring Machine) or laser scanning.
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Packaging & Shipping:
Finished coil tubes are wrapped in protective film, placed in wooden crates with desiccant packs, and shipped with accompanying documentation including MTC, test reports, and inspection certificates.
Applications
The JX-CT1221 Enamel-Lined PTFE Composite Coil Tube Condenser is designed for high-corrosion-duty heat exchange applications across multiple industrial sectors:
Chemical Processing Industry
- Acid Concentration Units: Condensing vapor in concentrated sulfuric acid (H₂SO₄), hydrochloric acid (HCl), and nitric acid (HNO₃) production processes.
- Chlor-Alkali Industry: Condensers for chlorine gas absorption towers and caustic soda (NaOH) concentration systems.
- Fluorine Chemicals: Heat exchange in hydrofluoric acid (HF) and fluorine-based chemical synthesis, where PTFE lining provides essential HF resistance.
Pharmaceutical & Biotechnology
- Drug Synthesis Reactors: Condensers in multi-step organic synthesis involving corrosive intermediates.
- Sterilization Systems: High-purity condensers for steam sterilization (SIP — Steam In Place) processes requiring zero contamination.
Food & Beverage Industry
- Fruit Juice Processing: Concentration and past