Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product supplied in coiled configuration, manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically designed for industrial heat transfer systems, including organic heat carrier furnaces, where continuous fluid circulation and uniform thermal distribution are critical to operational safety and efficiency.
Unlike straight-segment stainless steel tubes, coil tubes are formed into continuous helical or spiral configurations during the manufacturing process. This coiled geometry provides significant advantages in compact installation, enhanced heat exchange surface area per unit volume, and improved fluid dynamics within heat transfer circuits. The product is classified under industrial literature reference No. 1239 and is widely adopted in petrochemical, pharmaceutical, textile dyeing, and food processing industries.
Particular attention is drawn to the application of coil tubes in organic heat carrier furnaces (燃油有机热载体炉), where safety hazard analysis and risk mitigation are paramount. The integrity, corrosion resistance, and mechanical durability of the coil tube directly determine the long-term reliability and safety of the entire thermal system.
2. Material & Properties
2.1 Base Material Grades
The coil tube is fabricated from austenitic stainless steel grades that meet or exceed international standards. Commonly available grades include:
- SUS304 / ASTM A269 TP304 — Chromium-Nickel austenitic stainless steel with excellent general corrosion resistance and formability.
- SUS316 / ASTM A269 TP316 — Molybdenum-enhanced austenitic stainless steel offering superior resistance to pitting and crevice corrosion in aggressive chemical environments.
- SUS316L / ASTM A269 TP316L — Low-carbon variant of 316 with enhanced resistance to intergranular corrosion during welding operations.
- SUS321 / ASTM A269 TP321 — Titanium-stabilized grade suitable for elevated temperature applications up to 870°C.
2.2 Mechanical Properties
| Property | Unit | Typical Value (SUS304) | Typical Value (SUS316L) |
|---|---|---|---|
| Tensile Strength (抗拉强度) | MPa | ≥ 520 | ≥ 485 |
| Yield Strength (屈服强度) | MPa | ≥ 205 | ≥ 170 |
| Elongation (延伸率) | % | ≥ 40 | ≥ 40 |
| Hardness (硬度) | HV | ≤ 200 | ≤ 200 |
2.3 Thermal and Chemical Properties
- Maximum Service Temperature (最高使用温度): 870°C (SUS321) / 800°C (SUS316L)
- Thermal Conductivity (热导率): 16.3 W/(m·K) at 100°C (SUS304)
- Thermal Expansion Coefficient (热膨胀系数): 17.3 × 10⁻⁶ /°C (20–300°C)
- Corrosion Resistance (耐腐蚀性): Excellent resistance to atmospheric, aqueous, and mild chemical environments; pitting resistance equivalent number (PREN) ≥ 24 for SUS316L
- Non-magnetic (无磁性): Austenitic structure ensures non-magnetic properties in the annealed condition
3. Specifications
| Parameter | Specification Range | Standard Reference |
|---|---|---|
| Outer Diameter (外径) | Φ6 mm – Φ108 mm | ASTM A269 / GB/T 12771 |
| Wall Thickness (壁厚) | 0.5 mm – 6.0 mm | ASTM A269 / GB/T 12771 |
| Coil Diameter (盘管外径) | Φ100 mm – Φ1500 mm | Manufacturer specification |
| Tube Length per Coil (单盘管长度) | 5 m – 500 m (configurable) | Customer requirement |
| Bend Radius (弯曲半径) | ≥ 3D (D = outer diameter) | ASTM A269 Section 7 |
| Surface Finish (表面光洁度) | Mirror (Ra ≤ 0.4 μm) / BA / Pickled / Matte | ASTM A473 / GB/T 12771 |
| Tolerance — Outer Diameter (外径公差) | ± 0.05 mm – ± 0.50 mm (per diameter class) | ASTM A269 Table 1 |
| Tolerance — Wall Thickness (壁厚公差) | ± 10% of nominal (max ± 0.5 mm) | ASTM A269 Table 2 |
| End Condition (端部状态) | Plain / Beveled / Threaded / Flanged | Customer requirement |
| Heat Treatment (热处理) | Solution Annealing (固溶退火) at 1010–1150°C, followed by water quench | ASTM A269 / GB/T 12771 |
| Coil Packaging (盘管包装) | Steel band strapping + moisture-proof wrapping + wooden crate / pallet | ISO 4180 |
4. Manufacturing Process
The production of stainless steel coil tubes follows a rigorous multi-stage manufacturing workflow to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection (原材料选用): Hot-rolled stainless steel strips (钢带) are procured from certified suppliers and subjected to incoming inspection including chemical composition analysis (OES spectroscopy) and mechanical property verification.
- Slitting (分条): The master coil is slit into narrow strips of precise width using a high-precision slitting line to achieve the target outer diameter and wall thickness specifications.
- Forming & Welding (成型与焊接): Strips are fed into a high-speed TIG (Tungsten Inert Gas) or laser welding machine to form seamless or welded tubes. The welding process employs high-purity argon shielding (99.999%) to prevent oxidation and ensure a clean weld seam.
- Solution Annealing (固溶退火): The formed tubes undergo solution annealing at 1010–1150°C in a controlled atmosphere furnace, followed by rapid water quenching. This process dissolves carbides, restores full austenitic structure, and ensures maximum corrosion resistance.
- Pickling & Passivation (酸洗钝化): Tubes are immersed in a mixed acid bath (HNO₃ + HF) to remove oxide scale, followed by passivation treatment to form a protective chromium oxide film on the surface.
- Cold Drawing / Calibrating (冷拔/定径): Tubes pass through precision die sets to achieve tight dimensional tolerances on both outer diameter and wall thickness.
- Coiling (盘绕): The finished straight tubes are coiled into the target coil geometry using a programmable coiling machine. The bending process is controlled to maintain a minimum bend radius of 3D, preventing wall thinning, ovality, or material deformation.
- Quality Inspection (质量检验): Each coil undergoes comprehensive inspection including hydrostatic testing (水压试验), dimensional measurement, surface defect detection (eddy current testing), and visual examination of weld seams.
- Packaging & Storage (包装与仓储): Coils are wrapped in moisture-proof materials, strapped with steel bands, and packed in wooden crates or on export-grade pallets for safe transportation and storage.
5. Applications
5.1 Organic Heat Carrier Furnaces (有机热载体炉)
The primary application domain for this coil tube product is in oil-fired organic heat carrier furnaces (燃油有机热载体炉). These systems utilize synthetic organic heat transfer fluids (导热油) as the working medium to transfer thermal energy to industrial processes. The coil tube serves as the heat exchange element, where the circulating heat transfer fluid absorbs thermal energy from the furnace combustion chamber and delivers it to the process load.
Safety Considerations: As highlighted in the referenced safety hazard analysis document, the integrity of coil tubes in organic heat carrier furnace systems is critical. Potential hazards include:
- Tube wall thinning and rupture (管壁减薄与破裂): Prolonged exposure to high-temperature heat transfer fluid can cause oxidative thinning of the tube wall, leading to catastrophic failure.
- Thermal stress fatigue (热应力疲劳): Repeated thermal cycling induces cyclic stress in the coil tube, particularly at bend regions, which may lead to fatigue cracking over time.
- Clogging and overheating (堵塞与过热): Polymerization or coking of heat transfer fluid within the coil tube can cause localized overheating, accelerating material degradation.
- Weld seam failure (焊缝失效): Welded coil tubes are susceptible to weld seam degradation under sustained high-temperature and high-pressure conditions.
Wenzhou Jixing's coil tubes are engineered with enhanced wall thickness margins and superior material grades to mitigate these safety risks.
5.2 Additional Applications
- Petrochemical Industry (石油化工): Heat exchanger coils, reactor internals, and process piping for chemical production facilities.
- Pharmaceutical Industry (制药行业): Sterile fluid transfer lines, CIP (Clean-in-Place) systems, and heat recovery coils requiring hygienic surface finishes.
- Food Processing (食品加工): Pasteurization systems, drying equipment, and thermal processing coils where food-grade stainless steel is mandatory.
- Textile Dyeing (纺织印染): Heat exchange coils for dyeing and finishing machines requiring high-temperature resistance and corrosion resistance against acidic dye solutions.
- Wood Processing (木材加工): Heat transfer coils in drying kilns and continuous drying equipment.
- Plastic Processing (塑料加工): Temperature control coils in injection molding machines and extrusion lines.
- Power Generation (电力): Auxiliary heating coils and steam generation components in power plant systems.
6. Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework to ensure product conformity with international and national standards:
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification covering all manufacturing and quality assurance processes. |
| ISO 14001:2015 | Environmental Management System certification demonstrating commitment to sustainable manufacturing practices. |
| ASTM A269 / A270 | Product conformity with American Society for Testing and Materials standards for seamless and welded austenitic stainless steel tubing. |
| GB/T 12771 | Conformity with Chinese national standard for welded austenitic stainless steel seamless tubes. |
| EN 10217-7 | European standard for heat-resistant austenitic stainless steel tubes for mechanical and thermal applications. |
| PED (Pressure Equipment Directive) | Compliance with European Union Directive 2014/68/EU for pressure equipment and components. |
| Material Test Report (MTR) | Each batch is accompanied by a full material test report including chemical analysis, mechanical test results, and heat treatment records. |
| Third-Party Inspection | Available upon request — SGS, BV (Bureau Veritas), or TUV certification for export orders. |
7. Unique Selling Points
- Engineered for Safety-Critical Applications: Coil tubes are specifically designed and tested for use in organic heat carrier furnace systems, with enhanced wall thickness margins and superior fatigue resistance to address documented safety hazard concerns.
- Precision Coiling Technology: Advanced programmable coiling machines ensure consistent bend radii, minimal wall thinning, and uniform coil geometry — critical for predictable fluid flow and heat transfer performance.
- Multi-Grade Material Availability: Comprehensive range of austenitic stainless steel grades (304, 316L, 321, 310S) to match specific service conditions, from ambient to extreme high-temperature environments.
- Customizable Specifications: Full customization of outer diameter, wall thickness, coil diameter, tube length, surface finish, and end conditions to meet exact project requirements.
- End-to-End Quality Assurance: From raw material incoming inspection to final product hydrostatic testing and third-party verification, a documented quality chain ensures traceability and reliability.
- Export-Ready Packaging: Robust packaging solutions compliant with international shipping standards (ISO 4180), ensuring product integrity during global transportation.
- Technical Support & Consultation: Professional engineering team available for application-specific design consultation, safety hazard assessment, and system integration guidance.
Note: This technical specification is based on the product knowledge point reference "盘管式燃油有机热载体炉安全隐患探析" (Safety Hazard Analysis of Coil-Type Oil-Fired Organic Heat Carrier Furnace), classified under literature study category No. 1239. The specifications provided represent standard product capabilities; exact parameters should be confirmed with Wenzhou Jixing Metal Materials Co., Ltd. for each specific project application.