Stainless Steel Coil Tube — Cast-Rolling Process Technology
Product Overview
The Stainless Steel Coil Tube (Coiltube) produced by Wenzhou Jixing Metal Materials Co., Ltd represents a high-precision, continuous-length tubular product engineered through advanced cast-rolling (casting and rolling) manufacturing technology. This process, originally pioneered in copper coil tube production and subsequently adapted for stainless steel applications, enables the seamless formation of long, uniform-diameter tubes in a continuous coiled format. The resulting product eliminates the need for traditional welding joints, delivering superior mechanical integrity, consistent wall thickness, and enhanced dimensional accuracy compared to conventional drawing or seamless tube manufacturing methods.
As part of the company's extensive catalog (Item No. 1180), this coil tube product is designed for demanding industrial applications where continuous length, corrosion resistance, and high thermal conductivity are critical performance requirements.
Material & Properties
The coil tube is manufactured from premium-grade stainless steel alloys, selected for their exceptional balance of mechanical strength, corrosion resistance, and thermal performance. Key material grades include:
- AISI 304 (UNS S30400) — General-purpose austenitic stainless steel with excellent corrosion resistance and formability.
- AISI 316 / 316L (UNS S31600 / S31603) — Enhanced molybdenum content providing superior resistance to pitting and crevice corrosion in aggressive chemical environments.
- AISI 321 (UNS S32100) — Titanium-stabilized grade offering excellent resistance to intergranular corrosion at elevated temperatures.
Mechanical & Physical Properties
- Tensile Strength: ≥ 520 MPa (AISI 304, annealed condition)
- Yield Strength: ≥ 205 MPa
- Elongation: ≥ 40% (50 mm gauge length)
- Thermal Conductivity: 14.9 W/(m·K) at 20°C
- Operating Temperature Range: −196°C to +870°C (depending on grade)
- Surface Finish: Bright annealed (BA), polished, or pickled & passivated
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Item Number | 1180 |
| Outer Diameter (OD) | 3.0 mm – 50.0 mm (customizable) |
| Wall Thickness | 0.3 mm – 3.0 mm |
| Coil Length | Up to 3,000 meters per coil (continuous, seamless) |
| OD Tolerance | ±0.05 mm (tight tolerance available upon request) |
| Wall Thickness Tolerance | ±0.03 mm |
| Material Grades | 304, 304L, 316, 316L, 321, 310S, 2205 (duplex) |
| Surface Treatment | BA finish, electropolished, passivated |
| Delivery Condition | Annealed (soft), half-hard, or full hard |
| Coil Inner Diameter | Standard: 200 mm / 300 mm / 500 mm |
| Standards Compliance | ASTM A213, ASTM A269, EN 10217-7, GB/T 12771 |
Manufacturing Process
The cast-rolling method employed in the production of these coil tubes represents a significant advancement over conventional seamless tube manufacturing. The process integrates continuous casting with hot rolling in a single, highly efficient production line:
- Raw Material Preparation: High-purity stainless steel billets or strip stock are melted under controlled atmosphere conditions to minimize oxide inclusions and ensure homogeneous alloy composition.
- Continuous Casting: Molten stainless steel is cast into a hollow tubular cross-section using a precision-molded casting system. The tube shell is formed continuously without interruption, ensuring uniform microstructure along the entire length.
- Hot Rolling & Reduction: The as-cast tube is immediately passed through a series of precision rolling mills that progressively reduce the outer diameter and wall thickness to target dimensions. This step refines the grain structure and enhances mechanical properties.
- Coiling: The continuous tube is wound onto a precision coil reel at controlled tension to maintain dimensional accuracy and prevent deformation.
- Heat Treatment (Annealing): The coiled tube undergoes solution annealing in a protective atmosphere (nitrogen or argon) to relieve internal stresses, restore full ductility, and achieve the desired mechanical properties.
- Surface Finishing: Final surface treatment includes pickling, passivation, and optionally bright annealing or electropolishing to achieve the specified surface finish and maximum corrosion resistance.
- Quality Inspection: Each coil undergoes comprehensive non-destructive testing (NDT), including eddy current testing, hydrostatic pressure testing, and dimensional verification.
Key Advantage of Cast-Rolling Technology: Unlike traditional extrusion or piercing methods, the cast-rolling process produces coil tubes with superior dimensional consistency, lower material waste (up to 40% reduction compared to conventional methods), and the ability to produce very long continuous lengths without weld seams — critical for applications requiring uninterrupted fluid or gas flow paths.
Applications
The versatility of stainless steel coil tubes manufactured via cast-rolling technology makes them suitable for a wide range of industrial applications:
- Heat Exchangers & Condensers: Ideal for refrigeration systems, air conditioning units, and industrial heat exchange equipment where high thermal conductivity and long tube lengths are required.
- Chemical Processing: Used in chemical transfer lines, reactor piping, and corrosive fluid handling systems, particularly with 316L and duplex grades.
- Food & Beverage Industry: Compliant with sanitary standards for milk processing, brewing, and pharmaceutical fluid transfer systems.
- Automotive & HVAC: Applied in automotive radiators, intercoolers, and HVAC evaporator/condenser coils.
- Petrochemical & Oil/Gas: Utilized in downhole tubing, surface gathering lines, and offshore platform piping systems.
- Medical & Laboratory Equipment: Employed in medical gas delivery systems, dialysis machines, and laboratory instrumentation.
- Power Generation: Used in boiler tubes, superheater elements, and nuclear-grade applications (special grades available).
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems and holds the following certifications and compliance standards:
- ISO 9001:2015 — Quality Management System certification ensuring consistent production quality and process control.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices.
- ASTM International Compliance — Full adherence to ASTM A213 (seamless austenitic stainless steel tubes for high-temperature service) and ASTM A269 (seamless and welded austenitic stainless steel tubing for chemical and similar severe service).
- EN 10217-7 — European standard for tubes of austenitic and austenitic-ferritic (duplex) stainless steels for pressure purposes.
- CE Marking — Conformity with European health, safety, and environmental protection standards.
- Mill Test Certificates (MTC) — EN 10204 3.1 certificates provided with every shipment, including full chemical analysis and mechanical test results.
- Third-Party Inspection — Available upon request from SGS, Bureau Veritas, or TÜV Rheinland.
Unique Selling Points
- Seamless Continuous Length: Up to 3,000 meters per coil without welding joints, eliminating potential leak points and reducing installation time.
- Superior Dimensional Accuracy: Cast-rolling process achieves ±0.05 mm OD tolerance, enabling direct use in precision assembly without secondary machining.
- Material Efficiency: Up to 40% material savings compared to traditional seamless tube manufacturing methods, offering significant cost advantages.
- Customization Capability: Full customization of dimensions, material grades, surface finishes, and delivery conditions to meet specific project requirements.
- Enhanced Microstructure: Uniform grain structure throughout the tube wall due to controlled casting and rolling parameters, ensuring consistent mechanical performance.
- Comprehensive Testing: Multi-stage quality assurance including spectroscopic analysis, ultrasonic testing, eddy current inspection, and hydrostatic pressure verification.