Stainless Steel Coil Tube (Coiltube) — Wenzhou Jixing Metal Materials Co., Ltd
Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product supplied in continuous coil form, manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is designed for applications requiring high-temperature resistance, corrosion resistance, and mechanical durability. The coil form factor enables seamless integration into automated forming, cutting, and bending processes, minimizing material waste and maximizing production efficiency in downstream manufacturing environments.
The coil tube is particularly valued in HVAC (Heating, Ventilation, and Air Conditioning) systems, heat exchanger assemblies, and industrial fluid transport applications where the geometric integrity and surface quality of the tube directly influence thermal performance and system longevity. Drawing upon advanced test methodologies — including optimized air volume testing protocols for Fan Coil Units (FCU) — the design parameters of this coil tube are validated against rigorous performance benchmarks to ensure consistent delivery of thermal and structural reliability.
Material and Properties
The coil tube is fabricated from austenitic stainless steel grades, selected for their exceptional combination of mechanical strength, oxidation resistance, and weldability.
- Primary Grades: AISI 304 (UNS S30400), AISI 316L (UNS S31603), and AISI 321 (UNS S32100)
- Carbon Equivalent (CE): ≤ 0.08% (304), ≤ 0.03% (316L — Low Carbon)
- Chromium (Cr) Content: 18.0–20.0%
- Nickel (Ni) Content: 8.0–10.5%
- Molybdenum (Mo) Content: 2.0–2.5% (316L only)
- Tensile Strength: ≥ 515 MPa (304), ≥ 485 MPa (316L)
- Yield Strength (0.2% offset): ≥ 205 MPa
- Elongation: ≥ 40%
- Maximum Service Temperature: 870°C (oxidation resistance in continuous air)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, dilute acids, and chloride-containing environments (316L)
Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 50.0 mm (customizable) | ASTM A554 / GB/T 12771 |
| Wall Thickness | 0.2 mm – 3.0 mm | ASTM A554 / GB/T 12771 |
| Coil Width | Up to 1200 mm (flat stock for slitting) | Manufacturer Specification |
| Coil Length | Continuous — up to 1000 m per coil | Manufacturer Specification |
| Surface Finish | No. 1, 2B, BA (Bright Annealed), 2D, or custom | ASTM A480 |
| Dimensional Tolerance (OD) | ±0.05 mm (precision grade) | ISO 1128 |
| Dimensional Tolerance (Wall) | ±10% of nominal thickness | ASTM A554 |
| Helix Pitch (Coil Winding) | 15 mm – 60 mm (configurable) | Manufacturer Specification |
| Roundness Tolerance | ≤ 2% of OD | GB/T 12771 |
| Maximum Operating Pressure | Dependent on OD, wall thickness, and grade — typically up to 1.6 MPa | EN 10216 / ASME B31.3 |
Manufacturing Process
The production of the stainless steel coil tube follows a multi-stage process ensuring dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: Certified stainless steel strip or seamless tube stock is sourced from approved mills with full mill test certificates (MTC) per EN 10204 Type 3.1.
- Cold Drawing / Slitting: The strip material is slit to precise widths and then formed into tubular geometry using cold-drawing or cold-rolling techniques to achieve tight dimensional tolerances.
- Welding (for welded coil tube): Automatic orbital TIG (Tungsten Inert Gas) welding is employed with argon gas shielding to produce high-quality, consistent weld seams with minimal heat-affected zone (HAZ).
- Heat Treatment / Annealing: Post-weld annealing at 1050°C – 1100°C followed by controlled cooling relieves residual stresses, restores austenitic structure, and enhances corrosion resistance.
- Pickling and Passivation: The tube is immersed in a citric acid or nitric acid solution to remove oxide scale, followed by passivation to form a protective chromium oxide layer on the surface.
- Coil Winding: The finished tube is wound onto a mandrel in a continuous coil configuration with controlled tension to prevent deformation or kinking.
- Quality Inspection: Each coil undergoes dimensional verification, surface inspection, hydrostatic pressure testing, and spectroscopic composition analysis before dispatch.
Applications
The stainless steel coil tube finds extensive application across multiple industrial sectors:
- HVAC Systems: Used in Fan Coil Units (FCU), air handling units, condenser and evaporator coils, where optimized airflow and thermal exchange efficiency are critical. The coil tube geometry directly contributes to the air volume performance characteristics validated in advanced FCU testing methodologies.
- Heat Exchangers: Spiral-wound heat exchangers, plate-fin assemblies, and shell-and-tube designs benefit from the tube's high thermal conductivity and corrosion resistance.
- Food and Beverage Industry: Sanitary-grade coil tubes for milk processing, brewing, and pharmaceutical fluid transfer systems compliant with 3-A Sanitary Standards.
- Chemical Processing: Transport of aggressive chemicals, acids, and solvents where 316L grade provides superior chloride pitting resistance.
- Automotive and Aerospace: Exhaust systems, fuel lines, and hydraulic circuits requiring high-temperature and fatigue resistance.
- Medical Equipment: Sterilizable fluid lines and component tubing in diagnostic and therapeutic devices.
Quality Certifications and Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems and holds the following certifications and complies with international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- CE Marking — European Conformity for pressure equipment (PED 2014/68/EU)
- ASTM A554 — Standard Specification for Stainless Steel Tubing, Cold Drawn
- ASTM A270 — Standard Specification for Austenitic Stainless Steel Tubing, Seamless, Welded, and Heavy Walled
- GB/T 12771 — Chinese National Standard for Stainless Steel Seamless Tubes for Fluid Transport
- EN 10216-5 — European Standard for Technical Delivery Conditions for Tubes Intended for Use as Heat Exchangers
- ASME B31.3 — Process Piping Code compliance
- Mill Test Certificate (MTC) — EN 10204 Type 3.1 provided with every shipment
Unique Selling Points
- Precision Engineering: Tight dimensional tolerances (±0.05 mm OD) ensure consistent thermal performance and seamless integration into automated production lines.
- Optimized for HVAC Performance: Design parameters are informed by advanced Fan Coil Unit air volume testing methodologies, ensuring the coil tube geometry supports peak airflow efficiency and thermal exchange capacity.
- Full Traceability: Every coil is accompanied by a complete traceability record including mill certificates, chemical composition analysis, and mechanical test results.
- Custom Configuration: Flexible customization of OD, wall thickness, surface finish, coil length, and helix pitch to meet specific application requirements.
- Sustainable Manufacturing: ISO 14001-certified processes with minimized material waste through coil-form delivery, reducing cutting losses by up to 15% compared to straight-length tubing.
Note: The technical specifications described herein are based on standard product configurations. Custom specifications, non-standard grades, or specialized surface treatments are available upon request. Wenzhou Jixing Metal Materials Co., Ltd provides technical consultation and sample testing services to support project-specific requirements.