Stainless Steel Coil Tube (Coil Tube) for Industrial Thermal Systems
Product Overview
The Stainless Steel Coil Tube (hereinafter referred to as "Coil Tube") is a precision-engineered tubular product supplied by Wenzhou Jixing Metal Materials Co., Ltd (Product No. 1596). This product is specifically designed for integration into vertical coil-tube coal oil bath boilers, with a primary application in the manufacturing of plastic oil paste (plastic-based adhesive compounds). The Coil Tube functions as a critical heat-transfer component within closed-loop thermal systems, where it circulates thermal media through a serpentine or helical configuration to achieve uniform and efficient heat distribution.
Unlike straight tubular sections, the Coil Tube's helical geometry provides a significantly greater surface-area-to-volume ratio, enabling superior convective heat exchange within a compact spatial footprint. This makes the product particularly advantageous for industrial processes that demand precise temperature control in confined equipment envelopes, such as plastic oil paste production reactors and thermal oil bath systems.
Material & Properties
The Coil Tube is manufactured from high-grade austenitic stainless steel, selected for its exceptional combination of corrosion resistance, thermal stability, and mechanical durability under continuous industrial operating conditions.
- Primary Alloy Grades: AISI 304 (UNS S30400), AISI 316 (UNS S31600), and AISI 321 (UNS S32100) are the standard material options, with custom grades available upon request.
- Corrosion Resistance: The chromium (Cr) content of 18–20% and nickel (Ni) content of 8–12% provide a robust passive oxide layer, ensuring resistance to oxidation, sulfidation, and chemical attack from petroleum-based thermal fluids.
- Thermal Conductivity: Approximately 16.3 W/(m·K) for 304 grade, providing reliable heat transfer performance across the operational temperature range of 200°C to 350°C.
- Operating Temperature Range: Continuous service from cryogenic temperatures up to 870°C (short-term), with sustained thermal cycling resistance exceeding 10,000 cycles.
- Mechanical Properties: Yield strength of ≥205 MPa (304 grade); ultimate tensile strength of ≥515 MPa; elongation of ≥40%.
- Surface Finish: Available in 2B (cold-rolled and annealed), No. 4 brushed, and mirror polish (Ra ≤ 0.4 μm) finishes to suit specific thermal and cleanliness requirements.
Technical Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Code | 1596 | — |
| Product Name | Stainless Steel Coil Tube (Coil Tube / 盘管) | — |
| Outer Diameter (OD) | φ6 mm – φ51 mm (customizable) | ASTM A213 / ASTM A269 |
| Wall Thickness | 0.5 mm – 4.0 mm (customizable) | ASTM A213 |
| Coil Diameter | φ100 mm – φ2000 mm (customizable) | — |
| Coil Length / Turns | Up to 200 m per coil (customizable) | — |
| Material Grade | 304 / 316 / 321 / 310S / 347H (standard); custom upon request | ASTM A213 / GB/T 12771 |
| Manufacturing Standard | ASTM A213, ASTM A269, GB/T 12771, EN 10216-5 | — |
| Surface Finish | 2B / No. 4 / Mirror (Ra ≤ 0.4 μm) | ASTM A480 |
| Maximum Operating Temperature | 350°C (continuous); 870°C (short-term, 304 grade) | — |
| Maximum Operating Pressure | 1.6 MPa – 6.4 MPa (dependent on OD and wall thickness) | ASME Section VIII |
| Tolerance on OD | ±0.1 mm (standard); ±0.05 mm (precision) | — |
| Tolerance on Wall Thickness | ±10% (standard); ±5% (precision) | ASTM A213 |
| End Treatment | Plain end / Beveled / Threaded / Socket-weld fitting | — |
| Packaging | Wooden crate / Steel pallet with moisture-proof wrapping | — |
Manufacturing Process
The production of the Stainless Steel Coil Tube at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorous, multi-stage manufacturing process designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection & Incoming Inspection: Certified stainless steel seamless tube blanks are sourced from approved mills. Each batch undergoes spectroscopic analysis (Optical Emission Spectrometry, OES) to verify chemical composition against ASTM specifications, along with visual and dimensional inspection.
- Tube Straightening & Cutting: The seamless tube blanks are precisely straightened using a hydraulic straightening machine to achieve a straightness tolerance of ≤0.5 mm/m, followed by automated plasma or laser cutting to the specified coil length.
- Coil Forming (Cold Bending): The straight tube segments are fed through a multi-die coil forming machine equipped with a hydraulic drive system. The forming process is carefully controlled to prevent work hardening, ovalization, or wall thinning. The bending radius is precisely set according to the target coil diameter, with tooling designed to accommodate the specific OD and wall thickness of the tube.
- Stress Relief Annealing (Optional): For applications requiring reduced residual stresses, the formed coil is subjected to a stress relief annealing cycle at 1050°C – 1150°C followed by controlled cooling, restoring full austenitic microstructure and mechanical ductility.
- Pickling & Passivation: The coil tube is treated with a mixed acid solution (nitric acid + hydrofluoric acid) to remove oxide scale, followed by passivation to re-establish the protective chromium oxide layer. This ensures optimal corrosion resistance for thermal oil service.
- Surface Polishing (Optional): For applications requiring a mirror finish (e.g., food-grade or pharmaceutical-grade thermal systems), the coil undergoes electro-polishing or mechanical polishing to achieve a surface roughness of Ra ≤ 0.4 μm.
- Dimensional & Non-Destructive Testing (NDT): Each coil is inspected for dimensional accuracy (OD, wall thickness, coil diameter, and pitch) using calibrated calipers, ultrasonic thickness gauges, and optical comparators. Helium leak testing or pneumatic pressure testing is performed to verify weld and joint integrity.
- Final Inspection & Packaging: Approved coils are labeled with material certification, heat number, and dimensional data, then packaged in moisture-proof wrapping and secured in wooden crates or on steel pallets for shipment.
Applications
The Stainless Steel Coil Tube is engineered for demanding industrial thermal applications, with the following primary use cases:
- Vertical Coil-Tube Coal Oil Bath Boilers: The Coil Tube serves as the core heat-transfer element in vertical boiler configurations used for heating thermal oils (coal-based or synthetic heat transfer fluids). The helical design maximizes heat exchange surface area within a compact vertical envelope, making it ideal for space-constrained production facilities.
- Plastic Oil Paste Production: In the manufacturing of plastic-based adhesives and oil paste compounds, the Coil Tube provides uniform and controllable heating within reaction vessels. The stainless steel construction prevents contamination of the product by metallic impurities, ensuring product purity and compliance with industry standards.
- Chemical Processing Heat Exchangers: Suitable for use in chemical reactors, distillation columns, and heat exchangers where corrosion resistance to aggressive chemical media is required.
- Food & Pharmaceutical Processing: Mirror-polished 316L Coil Tubes are employed in food-grade heating systems and pharmaceutical reactors where sanitary standards (FDA, 3-A) must be met.
- Power Generation & Auxiliary Heating Systems: Used in feedwater heaters, economizers, and auxiliary heating loops in power plants and industrial facilities.
- Textile & Dyeing Industry: Employed in dyeing baths and finishing equipment requiring consistent temperature profiles.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and adheres to the following international and national standards:
- ISO 9001:2015 — Quality Management System certification, ensuring consistent product quality and process control.
- ISO 14001:2015 — Environmental Management System certification, demonstrating commitment to environmentally responsible manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management System certification.
- ASTM A213 — Standard Specification for Seamless Ferritic, Austenitic, and Ferritic-Austenitic Alloy Steel Tubing for High Temperature and High Pressure Boilers and Heaters.
- ASTM A269 — Standard Specification for Seamless and Welded Austenitic Chromium-Chromium-Nickel Stainless Steel Tubing for Chemical and Other Severely Corrosive Services.
- GB/T 12771 — Chinese National Standard for Stainless Steel Seamless Tubes for Fluid Transportation.
- EN 10216-5 — European Standard for Non-alloy and Alloy Steel Tubes for Technical Purposes (Stainless Steel Tubes).
- ASME Section VIII — Pressure Vessel Code compliance for high-pressure applications.
- Mill Test Certification (MTC / EN 10204 3.1): Each shipment is accompanied by a full material test certificate documenting chemical composition, mechanical properties, and heat treatment records.
Unique Selling Points
- Superior Heat Transfer Efficiency: The helical coil geometry provides up to 40% greater effective heat transfer surface area compared to equivalent-length straight tubing, significantly reducing energy consumption in thermal oil bath systems.
- Compact Vertical Integration: Designed specifically for vertical boiler configurations, the Coil Tube maximizes thermal performance within minimal floor space — a critical advantage for facilities with limited footprint.
- Customizable Engineering: Wenzhou Jixing Metal Materials Co., Ltd offers fully customizable coil dimensions (OD, wall thickness, coil diameter, and turn count) to match specific system design requirements, from small-scale laboratory reactors to large industrial thermal oil systems.
- Corrosion-Resistant Longevity: The use of premium austenitic stainless steel grades ensures a service life exceeding 15 years in continuous thermal oil service, with minimal maintenance requirements.
- End-to-End Quality Assurance: From raw material spectroscopic verification through to final NDT and dimensional inspection, every stage of production is governed by ISO 9001-compliant quality control protocols, with full traceability via Mill Test Certificates.
- Industry-Specific Application Expertise: The product is specifically validated for use in plastic oil paste production systems and coal oil bath boilers, providing proven performance in these demanding industrial environments.
Note: All specifications listed herein are based on standard configurations. Wenzhou Jixing Metal Materials Co., Ltd welcomes inquiries for custom-engineered solutions tailored to specific project requirements. Technical data sheets, material certifications, and sample testing reports are available upon request.