Stainless Steel Coil Tube (Coiltube) — Product No. 1714
Product Overview
The Stainless Steel Coil Tube (Product No. 1714) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered continuous coil-form tubing product designed for high-performance fluid transport, thermal exchange, and mechanical applications. This coil tube is supplied in the form of a continuous helical coil (盘管), enabling seamless integration into heat exchangers, fan coil units (FCU), industrial piping systems, and custom fabrication workflows.
Building upon advanced research in positive-pressure fan coil unit technology (as exemplified by the FWY-600 series), this coil tube product is specifically engineered to withstand residual pressure loading conditions while maintaining dimensional integrity and corrosion resistance over extended service life. The coil-form configuration provides superior thermal transfer efficiency due to the compact winding geometry and reduced connection points.
Material & Properties
Base Material
- Material Grade: Austenitic stainless steel conforming to ASTM A213 / EN 10217-7 standards
- Common Grades: SUS304 (1.4301), SUS316 (1.4401), SUS321 (1.4541)
- Alloy Composition: Chromium (Cr) ≥ 18%, Nickel (Ni) ≥ 8%, Molybdenum (Mo) optional (≥ 2% for 316 grade)
- Carbon Content: ≤ 0.08% (standard); ≤ 0.03% (low-carbon variant for weldability)
Mechanical Properties
- Tensile Strength (UTS): ≥ 520 MPa (annealed condition)
- Yield Strength (0.2% Proof Stress): ≥ 205 MPa
- Elongation (A50): ≥ 35%
- Hardness: ≤ 210 HB (annealed)
- Operating Temperature Range: −196°C to +870°C (depending on grade)
Corrosion Resistance
- Excellent resistance to atmospheric corrosion, dilute acids, and alkaline solutions
- High pitting resistance (PREN ≥ 19 for 316 grade) against chlorides
- Outstanding resistance to intergranular corrosion after sensitization treatment
- Non-magnetic in annealed condition (relative permeability ≤ 1.05)
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product No. | 1714 | Internal Catalog |
| Product Name | Stainless Steel Coil Tube (Coiltube / 盘管) | — |
| Outer Diameter (OD) | Φ 3.0 mm – Φ 50.8 mm (customizable) | ASTM A213 |
| Wall Thickness | 0.3 mm – 3.0 mm | EN 10217-7 |
| Coil Diameter | Φ 100 mm – Φ 1,200 mm | Customer Specification |
| Coil Length (Continuous) | Up to 500 m per coil | — |
| Surface Finish | BA (Bright Annealed), 2B, No.4 Brushed, Mirror (#8) | ASTM A403 |
| Tolerance on OD | ± 0.05 mm (precision grade) | ISO 3519 |
| Tolerance on Wall Thickness | ± 10% of nominal | ASTM A213 |
| End Condition | Plain end, beveled end, or crimped (per request) | — |
| Heat Treatment | Solution annealed at 1050–1150°C, water quench | ASTM A213 |
| Residual Stress Level | Low (post-coiling stress-relief anneal available) | FWY-600 Pressure Study |
| Maximum Working Pressure | ≥ 1.5 MPa (residual pressure tested) | Positive Pressure Protocol |
| Delivery Form | Continuous coil on steel or wooden reel | ISO 14962 |
| Protective Packaging | Polyethylene wrap, moisture-absorbent desiccant, export-grade crate | — |
Manufacturing Process
- Raw Material Selection: Virgin stainless steel strip or seamless tube stock is sourced from certified mills and subjected to incoming material verification (chemical composition analysis via OES — Optical Emission Spectroscopy; mechanical property testing).
- Coil Winding / Forming: The tube is precisely wound into a helical coil configuration using CNC-controlled coiling machinery. The winding process maintains constant curvature to prevent ovalization and residual stress concentration at the inner diameter.
- Stress-Relief Annealing: Post-coiling, the product undergoes a stress-relief annealing cycle (typically 850–950°C, held for sufficient duration per wall thickness) to eliminate residual stresses introduced during forming. This step is critical for applications involving residual pressure loading, as demonstrated in the FWY-600 positive-pressure fan coil unit research.
- Surface Treatment: Bright annealing in a controlled atmosphere (H₂/N₂) or pickling and passivation (HNO₃/HF solution) is applied to achieve the specified surface finish and restore full corrosion resistance.
- Hydrostatic Testing: Each coil lot undergoes hydrostatic pressure testing at 1.5× the maximum working pressure with a minimum dwell time of 10 seconds per unit length, ensuring leak-free integrity.
- Dimensional Inspection: Outer diameter, wall thickness, coil diameter, and straightness are verified using automated optical measurement systems (AOI) and ultrasonic thickness gauging.
- Packaging & Dispatch: Approved coils are wrapped, desiccated, and secured on export-grade reels for shipment.
Applications
- Heat Exchangers & Fan Coil Units (FCU): Primary application in HVAC (Heating, Ventilation, and Air Conditioning) systems where compact coil geometry maximizes heat transfer surface area. Directly applicable to positive-pressure fan coil designs (e.g., FWY-600 series).
- Industrial Piping Systems: Chemical processing, pharmaceutical manufacturing, and food-grade fluid transport requiring hygienic, corrosion-resistant tubing.
- Cryogenic Applications: Liquefied natural gas (LNG) transfer lines and cryogenic cooling systems (SUS304L/SUS316L grades).
- Automotive & Aerospace: Fuel lines, brake lines, and hydraulic circuits requiring high-temperature and high-pressure resistance.
- Medical Equipment: Autoclave-compatible tubing for sterilization systems and fluid delivery in medical devices.
- Custom Fabrication: Base material for OEM coil tube assemblies in specialty equipment manufacturing.
Quality Certifications & Standards Compliance
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| ISO 3834 | Quality Requirements for Welding of Steel |
| EN 10204 Type 3.1 | Inspection Certificate (Third-Party Verified) |
| ASTM A213 / A269 | Seamless/Austenitic Stainless Steel Tubing |
| GB/T 12771 | Chinese National Standard for Stainless Steel Tubes |
| JIS G3446 | Japanese Industrial Standard for Stainless Steel Tubes |
| CE Marking | European Conformity (Machinery Directive 2006/42/EC) |
| Mill Test Reports (MTR) | Provided with each lot — chemical analysis, mechanical properties, heat treatment records |
Unique Selling Points
Residual Pressure Resilience: Drawing directly from the research and development of the FWY-600 positive-pressure fan coil unit, this coil tube product is specifically validated for performance under sustained residual internal pressure conditions — a critical differentiator for HVAC and thermal management applications where pressure cycling fatigue is a primary failure mode.
- Precision Coil Geometry: CNC-controlled winding ensures uniform curvature with minimal ovalization (< 1% of OD), optimizing heat transfer efficiency and reducing flow resistance.
- Full Traceability: Every coil lot is traceable to its mill heat number, with complete documentation including chemical analysis (OES), mechanical test results, and dimensional inspection records.
- Customization Capability: Wenzhou Jixing Metal Materials offers full customization of OD, wall thickness, coil diameter, surface finish, and end conditions to meet specific engineering requirements.
- Corrosion-Proof Longevity: The austenitic stainless steel matrix provides decades of service life in aggressive environments without degradation of mechanical properties.
- Hygienic Surface Quality: Available in electropolished or mirror finish (Ra ≤ 0.2 μm) for pharmaceutical and food-grade applications requiring CIP (Clean-in-Place) compatibility.
Technical Notes
When integrating this coil tube into pressure-containing systems, engineers should account for the following:
- The hoop stress (σ_θ) in the coil geometry is governed by the modified Barlow formula: σ_θ = (P × D) / (2 × t × K), where K is the curvature correction factor (typically 0.9–1.0 for coil tubes).
- Post-winding stress-relief annealing reduces residual stresses by up to 90%, significantly improving fatigue life under cyclic pressure loading.
- For applications exceeding 200°C continuous operation, a stabilized grade (SUS321 or SUS347) is recommended to prevent sensitization-induced intergranular corrosion.
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd | Product Catalog No. 1714 | Classification: Technical Literature Reference