Stainless Steel Coil Tube — Technical Product Specification
Product Overview
The Stainless Steel Coil Tube (盘管, Coiltube) is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd, designed for applications requiring continuous, coiled stainless steel tubing with high dimensional accuracy and thermal performance. This product line encompasses a comprehensive range of cold-drawn stainless steel coil tubes that are wound into uniform coils, facilitating downstream processing, installation, and integration into complex systems such as heat exchangers, refrigeration circuits, HVAC components, and industrial fluid transport networks.
A critical engineering consideration for coil tubes deployed in cold-climate or cryogenic environments is the phenomenon of external ice accretion (外融冰问题). Advanced mathematical modeling and numerical analysis of the ice accretion process on coil tube surfaces have been developed to predict icing behavior, optimize coil geometry, and ensure reliable long-term operation under freezing conditions. This analytical framework considers heat transfer between the tube wall and ambient environment, phase-change thermodynamics of moisture deposition, and the mechanical stress induced by ice buildup on the coiled configuration.
Material & Properties
Coil tubes are fabricated from high-grade austenitic stainless steels, selected for their outstanding combination of corrosion resistance, mechanical strength, and formability. The primary material grades include:
- AISI 304 (UNS S30408) — General-purpose austenitic stainless steel with excellent corrosion resistance and weldability.
- AISI 316 (UNS S31608) — Enhanced corrosion resistance due to molybdenum (Mo) addition, suitable for aggressive chemical environments.
- AISI 321 (UNS S32108) — Stabilized with titanium (Ti), offering superior resistance to intergranular corrosion at elevated temperatures.
- AISI 316L (UNS S31603) — Low-carbon variant of 316L for improved weldability and reduced sensitization risk.
Mechanical Properties (Typical Values for Annealed Condition)
- Tensile Strength (抗拉强度): ≥ 515 MPa (ASTM A213)
- Yield Strength (屈服强度): ≥ 205 MPa
- Elongation (延伸率): ≥ 40% (at 2-inch gauge length)
- Hardness (硬度): ≤ 225 HB (Brinell)
- Density (密度): 7.93 g/cm³ (AISI 304); 8.00 g/cm³ (AISI 316)
Thermal & Physical Properties
- Thermal Conductivity (热导率): 16.3 W/(m·K) at 20°C (AISI 304)
- Thermal Expansion Coefficient (热膨胀系数): 17.3 × 10⁻⁶ /K (20–100°C)
- Specific Heat Capacity (比热容): 500 J/(kg·K) at 20°C
- Melting Range (熔点范围): 1400–1450°C
Specifications
| Parameter | Specification / Range | Standard / Reference |
|---|---|---|
| Outer Diameter (OD, 外径) | Φ 3.0 mm – Φ 63.5 mm | Customizable |
| Wall Thickness (壁厚) | 0.3 mm – 3.0 mm | ASTM A269 / A213 |
| Coil Inner Diameter (C.D., 盘圈内径) | Φ 200 mm – Φ 600 mm | ISO 15552 |
| Coil Length per Pack (单盘长度) | 50 m – 300 m (continuous) | Customizable |
| OD Tolerance (外径公差) | ± 0.05 mm (precision grade); ± 0.1 mm (standard grade) | ASTM A269 |
| Wall Thickness Tolerance (壁厚公差) | ± 0.03 mm (precision); ± 0.05 mm (standard) | ASTM A213 |
| Surface Finish (表面粗糙度) | Ra 0.4 – Ra 1.6 μm (polished); Ra 3.2 – Ra 6.3 μm (standard) | ASTM A270 |
| Material Grade (材质牌号) | 304, 304L, 316, 316L, 321, 310S | AISI / UNS |
| Maximum Operating Temperature (最高使用温度) | 870°C (304/316); 1150°C (321/310S) | ASME BPV Code |
| Minimum Operating Temperature (最低使用温度) | −196°C (cryogenic compatible) | ASTM A269 |
| Coil Winding Tension (盘绕张力) | Controlled to prevent deformation; ≤ 50 N (typical) | Internal standard |
Manufacturing Process
The production of stainless steel coil tubes follows a rigorous multi-stage process to ensure dimensional precision, metallurgical integrity, and surface quality:
- Hot Rolling & Annealing (热轧与退火): Stainless steel strip is hot-rolled to approximate dimensions, followed by solution annealing at 1050–1150°C to dissolve carbides and restore full austenitic microstructure.
- Pickle & Passivation (酸洗钝化): The annealed strip undergoes pickling in mixed acid solutions (HNO₃/HF) to remove oxide scale, followed by passivation to form a protective chromium oxide layer.
- Cold Forming / Pipe Making (冷成型/制管): The prepared strip is fed through a roll-forming or weld-seam pipe-making line. Options include:
- Welded Tube (焊接管): Longitudinal TIG (Tungsten Inert Gas) or laser welding with internal gas shielding.
- Seamless Tube (无缝管): Produced via cold-drawing or cold-rolling through a capstan mill, followed by coil winding.
- Cold Drawing & Sizing (冷拔定径): Tubes are cold-drawn through calibrated dies to achieve precise OD and wall thickness tolerances. Multiple passes may be employed for high-precision grades.
- Intermediate Annealing (中间退火): Periodic annealing between cold-drawing passes to relieve accumulated cold work and prevent cracking.
- Coil Winding (盘绕): The finished tube is wound onto a mandrel reel under controlled tension to form the coil configuration. Winding parameters are optimized to prevent inter-coil contact damage and elastic springback.
- Final Annealing & Pickling (最终退火与酸洗): For seamless products, a final solution anneal is performed to restore corrosion resistance and mechanical properties.
- Quality Inspection & Packaging (质量检测与包装): Each coil undergoes dimensional measurement, visual inspection, and non-destructive testing (EDD/UT) before protective packaging.
Applications
Stainless steel coil tubes find extensive use across multiple industrial sectors:
- Heat Exchangers & HVAC Systems (热交换器与暖通空调系统): Coil tubes serve as the primary heat transfer medium in air-cooled heat exchangers, condenser coils, evaporator coils, and refrigeration systems. The mathematical modeling of external ice accretion (外融冰) on coil surfaces is critical for designing de-icing strategies and ensuring uninterrupted thermal performance in cold environments.
- Refrigeration & Cryogenic Systems (制冷与深冷系统): Used in ammonia refrigeration circuits, LNG (Liquefied Natural Gas) handling systems, and cryogenic transfer lines where low-temperature ductility is essential.
- Automotive Industry (汽车工业): Fuel lines, brake lines, and HVAC tubing for passenger vehicles and commercial transport.
- Food & Pharmaceutical Processing (食品与制药加工): Sanitary-grade tubing for fluid transfer in hygienic processing environments (3-A Sanitary Standards compliant).
- Chemical & Petrochemical Industry (化工与石化行业): Corrosion-resistant tubing for aggressive chemical transport, reactor internals, and heat exchange systems.
- Medical Devices (医疗器械): High-purity tubing for medical gas delivery, dialysis machines, and surgical equipment.
- Aerospace (航空航天): Hydraulic lines, fuel systems, and environmental control system tubing.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and holds the following certifications and standards compliance:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health & Safety Management System
- EN 10204 3.1 — Material Test Certificate (MTC) provided for every shipment
- ASTM A269 / A213 / A270 — Conformance to American Society for Testing and Materials standards for stainless steel tubing
- EN 10217-7 — European standard for austenitic stainless steel tubes
- JIS G3459 — Japanese Industrial Standard for stainless steel tubing
- ASME BPV Code Section I — Boiler and Pressure Vessel Code compliance (for pressure applications)
- NORSOK M-650 — Materials specification for offshore applications
- NSF/ANSI 61 — Drinking water system components certification (for food-grade applications)
Unique Selling Points
1. Advanced Thermal-Icing Performance Modeling: The company has developed and validated mathematical models for external ice accretion on coil tube surfaces (盘管外融冰数学模型), enabling predictive analysis of icing behavior under various environmental conditions. This allows customers to optimize coil design parameters (pitch, diameter, surface finish) for minimum ice adhesion and maximum de-icing efficiency.
2. Precision Dimensional Control: Cold-drawing processes achieve OD and wall thickness tolerances as tight as ± 0.03 mm, ensuring consistent hydraulic performance and interchangeability in high-volume production environments.
3. Wide Material Grade Availability: From standard 304 to specialized super-austenitic grades (e.g., 310S, 904L), the product line addresses the full spectrum of corrosion and temperature requirements.
4. Cryogenic Reliability: Maintains full ductility and fracture toughness down to −196°C, making it ideal for LNG and cryogenic process applications without risk of brittle failure.
5. Continuous Coil Supply: Uninterrupted coil lengths of up to 300 meters minimize splices and joints, reducing leak points and maintenance requirements in critical fluid systems.