Stainless Steel Coil Tube — Product Technical Specification
Product Overview
The Stainless Steel Coil Tube (Product Code: 787) is a precision-engineered continuous coil form of stainless steel tubing manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is designed for high-performance applications requiring exceptional corrosion resistance, mechanical integrity, and dimensional consistency. The coil tube is supplied in continuous helical form, enabling seamless downstream processing including straightening, cutting, bending, and welding without the introduction of mechanical stress or deformation at joint interfaces.
The product falls under the category of Coil Tube (盘管), a form factor distinct from cut-to-length straight pipe, offering logistical advantages including reduced handling losses, lower material waste, and enhanced supply chain efficiency. The coil tube is particularly suited for integration into Fan Coil Units (FCU), heat exchangers, fluid transport systems, and precision manufacturing applications where reliability and thermal performance are critical.
Material & Properties
The stainless steel coil tube is fabricated from austenitic stainless steel grades conforming to international standards, with the primary grade being 304 (UNS S30400) and 316 (UNS S31600). The material selection ensures optimal resistance to pitting, crevice corrosion, and intergranular corrosion under a wide range of environmental conditions.
Key Material Characteristics
- Chemical Composition (Grade 304): Chromium (Cr) 18.0–20.0%, Nickel (Ni) 8.0–10.5%, Manganese (Mn) ≤2.0%, Carbon (C) ≤0.08%, Silicon (Si) ≤1.0%, Phosphorus (P) ≤0.045%, Sulfur (S) ≤0.030%
- Chemical Composition (Grade 316): Chromium (Cr) 16.0–18.0%, Nickel (Ni) 10.0–14.0%, Molybdenum (Mo) 2.0–3.0%, Carbon (C) ≤0.08%
- Yield Strength: ≥205 MPa (Grade 304), ≥170 MPa (Grade 316)
- Tensile Strength: ≥515 MPa (Grade 304), ≥485 MPa (Grade 316)
- Elongation: ≥40% (Grade 304), ≥35% (Grade 316)
- Operating Temperature Range: −196 °C to +870 °C
- Surface Finish Options: 2B (Cold Rolled and Annealed), No. 4 (Brushed), No. 8 (Mirror), BA (Bright Annealed)
- Corrosion Resistance: Superior resistance to atmospheric, chemical, and aqueous environments; Grade 316 offers enhanced chloride ion resistance
Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 3.0 mm – 50.0 mm (customizable up to 100.0 mm) |
| Wall Thickness | 0.3 mm – 3.0 mm |
| Coil Length (Continuous) | Up to 1,200 meters per coil |
| Coil Inner Diameter (ID) | 300 mm – 600 mm |
| OD Tolerance | ±0.05 mm (precision grade); ±0.10 mm (standard grade) |
| Wall Thickness Tolerance | ±10% of nominal |
| Roundness | ≤0.5% of OD |
| Linearity | ≤1.5 mm/m |
| Surface Roughness (Ra) | ≤0.4 μm (polished); ≤0.8 μm (standard) |
| End Condition | Plain, Beveled, or Threaded (per customer requirement) |
| Applicable Standards | ASTM A554, ASTM A213, EN 10216-5, GB/T 14976 |
| Delivery Form | Continuous Coil / Cut-to-Length |
| Minimum Order Quantity | 500 kg per grade |
Manufacturing Process
The production of the stainless steel coil tube at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorously controlled multi-stage process ensuring dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Procurement and Inspection: High-purity stainless steel slabs or ingots are sourced from certified mills. Incoming material undergoes spectroscopic analysis (Optical Emission Spectrometry, OES) to verify chemical composition compliance with specified grades.
- Hot Rolling and Forging: Slabs are heated to forging temperature (1,150–1,250 °C) and hot-rolled into seamless tube blanks. This stage establishes the initial geometry and eliminates internal voids or segregation.
- Piercing and Elongation: The hot-rolled blanks are pierced using a plug mill to form hollow tubes, followed by elongation through a series of rolls to achieve the target OD and wall thickness.
- Cold Drawing and Sizing: Tubes are cold-drawn through precision-die tooling to achieve final dimensional tolerances. This process enhances mechanical properties through strain hardening and produces superior surface finish quality.
- Solution Annealing (Stress Relief): Tubes are annealed at 1,050–1,100 °C followed by rapid water quenching. This process dissolves carbide precipitates, restores full ductility, and ensures uniform microstructure throughout the cross-section.
- Coil Winding and Packaging: Finished tubes are coiled onto precision-wound reels with controlled tension to prevent deformation or surface damage. Coils are wrapped in protective film and shrink-wrapped for shipping.
Quality Control Measures
- Hydrostatic Testing: All tubes undergo hydrostatic pressure testing at 1.5× the maximum operating pressure to verify wall integrity and absence of defects.
- Eddy Current Testing (ECT): Non-destructive testing to detect surface and near-surface discontinuities, ensuring defect-free tube walls.
- Dimensional Verification: Automated OD, wall thickness, and roundness measurement at intervals of ≤10 meters along the coil length.
- Spectrographic Analysis: Batch-level chemical composition verification to ensure grade compliance.
Applications
The stainless steel coil tube is engineered for diverse industrial and commercial applications, with particular relevance to the following sectors:
- Fan Coil Units (FCU) and HVAC Systems: The coil tube serves as the primary heat exchange element in fan coil unit motors and air handling systems. Its high thermal conductivity and corrosion resistance ensure long-term reliability in humid and chemically aggressive environments. Reliability improvement studies of FCU motor assemblies have demonstrated that precision coil tubes with tight tolerances reduce vibration, improve heat transfer efficiency, and extend service life significantly.
- Heat Exchangers and Condensers: Used in shell-and-tube heat exchangers, plate-fin condensers, and evaporators for refrigeration and industrial process applications.
- Automotive Industry: Fuel lines, brake lines, and exhaust system components requiring high-temperature resistance and fatigue durability.
- Medical and Pharmaceutical Equipment: Sterilizable fluid transport lines, instrument tubing, and equipment housings requiring biocompatibility and corrosion resistance.
- Food and Beverage Processing: Sanitary-grade fluid transfer lines, CIP (Clean-in-Place) systems, and process equipment requiring adherence to FDA and 3-A sanitary standards.
- Chemical and Petrochemical Processing: Process piping, heat exchanger tubes, and pressure vessels operating under aggressive chemical media and elevated temperatures.
- Electronics and Semiconductor Manufacturing: Ultra-pure gas delivery lines and vacuum system components requiring exceptional surface quality and low outgassing rates.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains comprehensive quality management systems and certifications that validate product conformity and manufacturing excellence:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and customer satisfaction through documented processes and continuous improvement.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices and environmental stewardship.
- CE Marking — Conformity with European Union directives for safety, health, and environmental protection requirements.
- EN 10204 — Type 3.1/3.2 Test Certificate capability providing full traceability from raw material mill certification through final product delivery.
- ASTM Compliance — Products manufactured and tested in accordance with ASTM A554, ASTM A213, and ASTM A778 standards.
- Mill Test Reports (MTR): Available for every production batch, documenting chemical composition, mechanical properties, and non-destructive testing results.
Unique Selling Points
1. Precision Coiling Technology: Proprietary coiling process ensures uniform coil geometry with minimal springback, enabling seamless integration into automated downstream processing equipment without additional straightening steps.
2. Enhanced Reliability for FCU Applications: Drawing from industry research on fan coil unit motor reliability improvement, the coil tube's dimensional precision and metallurgical uniformity directly contribute to reduced motor vibration, improved thermal performance, and extended operational life in HVAC applications.
3. Customizable Specifications: Flexible manufacturing capability accommodates non-standard OD, wall thickness, and coil length configurations, enabling tailored solutions for specialized engineering requirements.
4. Full Traceability: Every coil is assigned a unique batch identifier linked to complete mill test documentation, ensuring full material traceability from upstream steel production through final delivery.
5. Cost-Efficient Continuous Supply: The coil format eliminates cut-off waste and reduces handling labor, delivering total cost of ownership advantages over traditional straight-length pipe procurement.
6. Multi-Grade Availability: Comprehensive grade portfolio including 304, 316, 316L, 321, and 347 stainless steels provides material flexibility for diverse application environments.
Conclusion
The Stainless Steel Coil Tube (Code: 787) from Wenzhou Jixing Metal Materials Co., Ltd represents a benchmark product in the precision stainless steel tubing category. Combining rigorous manufacturing controls, comprehensive quality certifications, and application-specific engineering optimization, this product delivers the performance, reliability, and value proposition required by demanding industrial and commercial sectors. Its particular suitability for Fan Coil Unit applications, informed by ongoing research into motor reliability improvement, underscores its role as a critical component in next-generation HVAC and thermal management systems.