Stainless Steel Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (SS Coil Tube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered, continuous-length tubular product formed by cold-rolling stainless steel strip into a helical coil configuration. Designed primarily for HVAC (Heating, Ventilation, and Air Conditioning) applications — particularly in fan coil unit (FCU) air conditioning systems — this product delivers superior thermal conductivity, corrosion resistance, and hygienic performance under both wet and dry operating conditions.
The coil tube is engineered to meet the demands of modern antimicrobial air handling systems, including SARS-resistant antibacterial dry-condition operating configurations. Its seamless construction eliminates internal crevices where microbial growth could occur, making it an ideal conduit material for environments requiring high levels of indoor air quality (IAQ).
2. Material & Properties
2.1 Base Materials
- Austenitic Grades: SUS304 (UNS S30400), SUS316 (UNS S31600), SUS316L (UNS S31603)
- Option Grades: SUS304L (UNS S30403), SUS321 (UNS S32100), SUS310S (UNS S31008)
2.2 Key Mechanical Properties
- Tensile Strength (UTS): ≥ 520 MPa (SUS304), ≥ 570 MPa (SUS316)
- Yield Strength: ≥ 205 MPa (SUS304), ≥ 240 MPa (SUS316)
- Elongation: ≥ 40% (SUS304), ≥ 35% (SUS316)
- Hardness (HB): 100–200 (annealed condition)
- Operating Temperature Range: −196 °C to +870 °C
2.3 Corrosion & Hygienic Performance
- Pitting Resistance: SUS316 grade offers superior resistance to chloride-induced pitting corrosion (PREN ≥ 24)
- Antibacterial Surface: Nickel (Ni) and Chromium (Cr) content in austenitic stainless steel provides inherent passive film formation, inhibiting bacterial adhesion and proliferation
- Surface Roughness (Ra): ≤ 0.8 μm (electropolished finish available upon request)
- Passivation: Nitric acid or citric acid passivation treatment applied to all products
3. Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 50.8 mm (1/8" – 2") | ASME B73.1M / GB/T 14976 |
| Wall Thickness (WT) | 0.3 mm – 3.0 mm | ASME B73.1M / GB/T 14976 |
| Coil Diameter (CD) | 100 mm – 500 mm | Manufacturer Specification |
| Coil Length per Pack | 50 m – 500 m (customizable) | — |
| Material Grade | SUS304, SUS304L, SUS316, SUS316L, SUS321, SUS310S | JIS G4305 / ASTM A269 |
| Surface Finish | 2B (Cold Rolled Annealed), BA (Bright Annealed), Electropolished, Hairline | ASTM A480 |
| Tolerance (OD) | ±0.05 mm (standard), ±0.02 mm (precision grade) | GB/T 14976 |
| Tolerance (WT) | ±10% (standard), ±5% (precision grade) | GB/T 14976 |
| End Condition | Plain end, Beveled end, Threaded (BSP, NPT, Metric) | ISO 7-1 / ASME B1.20.1 |
| Heat Treatment | Annealed (Solution Annealed) | ASTM A269 |
| Maximum Working Pressure | Up to 1.6 MPa (standard), 4.0 MPa (heavy-wall) | ASME B31.3 |
| Packaging | Wooden pallet with moisture-proof wrapping; export-standard crating available | — |
4. Manufacturing Process
- Raw Material Procurement & Inspection: High-purity stainless steel strip sourced from certified mills (e.g., Outokumpu, POSCO, Taigang) undergoes incoming inspection for chemical composition (spectroscopy), mechanical properties, and surface quality per ASTM A480.
- Coil Forming (Cold Bending): Precision CNC-controlled coil forming machines bend the flat tube or strip into the desired helical coil geometry with controlled radius and pitch. Forming forces are calibrated to prevent work-hardening and micro-cracking.
- Welding (if applicable): For welded coil tube configurations, orbital TIG (Tungsten Inert Gas) welding is employed using argon shielding to produce a smooth, oxide-free weld seam. Weld quality is verified per ASME Section IX.
- Heat Treatment / Solution Annealing: Coils are annealed at 1050–1150 °C in a protective atmosphere (H₂/N₂ or vacuum) to relieve cold-work stresses, restore full austenitic microstructure, and maximize corrosion resistance.
- Pickling & Passivation: Chemical pickling removes oxide scale; subsequent acid passivation (nitric acid 20–30% or citric acid 5–15%) establishes a chromium-rich passive film for enhanced corrosion and antibacterial performance.
- Surface Finishing: Optional electropolishing reduces surface roughness to Ra ≤ 0.4 μm, creating a smooth, non-porous surface ideal for hygienic and pharmaceutical applications.
- Quality Control & Testing: Every coil batch undergoes dimensional verification (OD, WT, coil diameter), hydrostatic pressure testing, chemical composition analysis, and visual/surface inspection per ISO 9001 protocols.
- Packaging & Dispatch: Coils are wound onto steel or wooden reels, wrapped in moisture-proof PE film, and secured on export-grade wooden pallets with steel strapping.
5. Applications
5.1 HVAC & Fan Coil Unit Systems
- Heat exchanger coils in commercial and residential fan coil units (FCUs)
- Dry-condition operating systems designed for antimicrobial indoor air quality — preventing bacterial growth and cross-contamination in HVAC circuits
- Cold water piping in chilled beam and radiant cooling systems
5.2 Food & Pharmaceutical Industry
- CIP (Clean-in-Place) compatible piping and coil assemblies in dairy, beverage, and biopharmaceutical processing
- Hygienic heat exchangers requiring electropolished surfaces
5.3 Chemical & Petrochemical Industry
- Corrosive fluid transport in chloride-rich or acidic environments (SUS316/316L grades)
- Reactor coil inserts for temperature-controlled chemical processes
5.4 Medical & Cleanroom Environments
- Gas and fluid delivery coils in medical equipment and laboratory apparatus
- Antibacterial HVAC components in hospital operating rooms and cleanrooms
5.5 General Industrial Applications
- Compressed air and nitrogen piping systems
- Heat recovery and exhaust gas recirculation (EGR) systems
- Automotive and aerospace fluid circuits
6. Quality Certifications
| Certification / Standard | Scope of Compliance |
|---|---|
| ISO 9001:2015 | Quality Management System — Full manufacturing process |
| ISO 14001:2015 | Environmental Management System |
| ISO 45001:2018 | Occupational Health & Safety Management |
| CE Marking (EU) | Compliance with European Machinery & Pressure Equipment Directives |
| NSF/ANSI 61 | Drinking Water System Components — Health Effects |
| 3-A Sanitary Standards | Food, Dairy, and Beverage Processing Equipment |
| ASME B73.1M | Instrumentation, Control, and Gauging Tubing |
| EN 10217-7 | Non-alloy Steel Tubes for Pressure Purposes (reference for dimensional tolerances) |
| GB/T 14976 | Chinese National Standard — Seamless Stainless Steel Tubes for Fluid Transport |
| Mill Test Certificates (MTC) | EN 10204 Type 3.1 — Furnace-level chemical and mechanical analysis for every batch |
7. Unique Selling Points
- Inherent Antibacterial Properties: Austenitic stainless steel's passive chromium-oxide film actively inhibits microbial adhesion, making these coil tubes ideal for SARS-resistant and hygienic HVAC system designs where dry-condition operation is critical for indoor air quality.
- Exceptional Corrosion Resistance: SUS316 and SUS316L grades with molybdenum (Mo) content ≥ 2% provide outstanding resistance to chloride pitting and intergranular corrosion, ensuring long service life in aggressive environments.
- Seamless & Precision-Formed Geometry: CNC-controlled coil forming eliminates weld seams, reducing leak points and creating a smooth internal surface that resists fouling and biofilm formation.
- Full Traceability: Every coil is accompanied by an EN 10204 Type 3.1 Mill Test Certificate with complete chemical composition, mechanical test results, and heat treatment records.
- Customization Capability: Flexible OD, wall thickness, coil diameter, and length configurations to meet specific OEM and project requirements.
- Hygienic Surface Options: Electropolished finish (Ra ≤ 0.4 μm) available for pharmaceutical and food-grade applications requiring CIP/SIP (Sterilize-in-Place) compatibility.
- Global Compliance: Products certified to international standards (ASME, ASTM, EN, GB) enabling seamless integration into global supply chains and regulatory environments.
Note: All specifications listed above represent standard product capabilities. Custom configurations, non-standard grades, and special surface treatments are available upon request. Wenzhou Jixing Metal Materials Co., Ltd. maintains a dedicated engineering team to support project-specific material selection and dimensional optimization.