Stainless Steel Coil Tube — Continuous Coiled Tubing for HVAC & Industrial Applications
Product Overview
The Stainless Steel Coil Tube (盘管 / Coil Tube) is a continuously wound, seamless or welded tubular product supplied in coil form, manufactured by Wenzhou Jixing Metal Materials Co., Ltd. Unlike straight-length pipe, coil tubes are delivered in flexible, continuous lengths that allow on-site forming, bending, and fabrication without the need for welding joints, thereby minimizing leak points and maximizing system integrity. This product is particularly suited for applications governed by the Technical Specification for Fan Coil Unit (FCU) Air Conditioning Energy Consumption Monitoring System (风机盘管空调能耗监控系统技术规范), where energy efficiency, corrosion resistance, and long service life are paramount.
Coil tubes are available in both seamless and ERW (Electric Resistance Welded) configurations, with the coil form factor enabling economical transport, reduced material waste during fabrication, and compatibility with automated tube-forming and bending equipment.
Material & Properties
Coil tubes are fabricated from high-grade austenitic and duplex stainless steels, selected to deliver superior corrosion resistance, mechanical strength, and thermal conductivity. The following grades are commonly offered:
- SUS304 / ASTM A213 TP304 — General-purpose austenitic stainless steel; excellent corrosion resistance in non-chloride environments; ideal for HVAC chilled water loops and condensate drainage.
- SUS316 / ASTM A213 TP316 — Molybdenum-enhanced austenitic grade; superior resistance to pitting and crevice corrosion in chloride-rich or marine environments.
- SUS316L / ASTM A213 TP316L — Low-carbon variant of 316; enhanced weldability and resistance to intergranular corrosion.
- SUS321 / ASTM A213 TP321 — Columbium-stabilized grade; excellent resistance to sensitization at elevated temperatures (up to 870°C).
- Duplex 2205 / ASTM A778 — High-strength duplex austenite-ferrite microstructure; approximately double the yield strength of 304/316 with superior chloride stress corrosion resistance.
Key Mechanical & Physical Properties (Typical — SUS304)
| Property | Specification |
|---|---|
| Density | 8.0 g/cm³ |
| Thermal Conductivity (at 20°C) | 16.3 W/(m·K) |
| Specific Heat Capacity | 0.50 J/(g·K) |
| Thermal Expansion Coefficient (20–100°C) | 17.3 × 10⁻⁶ /°C |
| Yield Strength (minimum) | 205 MPa (30 ksi) |
| Tensile Strength (minimum) | 515 MPa (75 ksi) |
| Elongation (minimum) | 40% |
| Operating Temperature Range | −196°C to +870°C (SUS304); −270°C to +300°C (SUS316L) |
| Corrosion Resistance | Excellent in oxidizing acids, atmospheric conditions; SUS316/316L superior in chloride environments |
Specifications
| Parameter | Range / Option |
|---|---|
| Outer Diameter (OD) | 3.0 mm – 108.0 mm (1/8" – 4") |
| Wall Thickness (WT) | 0.3 mm – 6.0 mm (0.012" – 0.236") |
| Coil Inner Diameter (CID) | 300 mm – 1,000 mm (adjustable per order) |
| Coil Length (Continuous) | Up to 500 m per coil (standard); custom lengths available |
| Tolerance — OD | ±0.1 mm to ±0.5 mm (per ASTM A554 / ASTM A213) |
| Tolerance — Wall Thickness | ±10% (standard); ±5% (precision grade) |
| Surface Finish | Mill finish, 2B, BA (Bright Annealed), No. 4 Brushed, Mirror (Ra ≤ 0.1 μm) |
| End Condition | Plain cut, beveled, or with protective caps |
| Applicable Standards | ASTM A554, ASTM A213, ASTM A269, EN 10216-5, EN 10217-7, GB/T 12771, GB/T 14976 |
| Material Certification | EN 10204 3.1 / 3.2 mill test certificates; third-party inspection available |
| Custom Fabrication | Custom OD, WT, coil diameter, surface treatment, and cutting lengths |
Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorous, multi-stage process designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Procurement & Inspection — Ingot or coil stock sourced from certified mills (e.g., Outokumpu, POSCO, Taigang, Baosteel) undergoes incoming chemical composition analysis (via optical emission spectrometry, OES) and mechanical property verification.
- Hot Rolling / Cold Drawing — Depending on the target dimensions, tube blanks are either hot-rolled from round billets or cold-drawn from seamless tube stock. Cold drawing achieves tighter tolerances and superior surface finish.
- Piercing & Mandrel Drawing — Seamless tubes are produced via the Mannesmann piercing process followed by multiple passes of mandrel drawing to achieve precise internal and external dimensions.
- Pickling & Annealing (P&A) — The coil is passed through an automated pickling and annealing line using a combination of dilute nitric acid and hydrofluoric acid baths to remove oxide scale, followed by controlled furnace annealing (typically 1,050–1,150°C) to restore full austenitic microstructure and eliminate residual stresses.
- Passivation — A post-annealing passivation treatment (typically 20–30% HNO₃ at 60°C) enhances the passive chromium oxide layer, improving corrosion resistance to laboratory-grade levels (verified via ASTM A967).
- Surface Finishing — Optional electropolishing, mechanical brushing, or mirror polishing is applied to achieve specified surface roughness values (Ra) for hygienic or aesthetic applications.
- Coiling & Winding — The continuous tube is wound onto precision mandrels to form coils of specified inner diameter. Winding tension is carefully controlled to prevent ovality or kinking.
- Non-Destructive Testing (NDT) — 100% inline eddy current testing (per ASTM A751) and ultrasonic testing detect internal and external defects. Hydrostatic pressure testing (per ASTM A269) verifies wall integrity at 1.5× working pressure.
- Dimensional Inspection — Laser gauge systems continuously monitor OD and wall thickness. End-of-line dimensional checks confirm compliance with specified tolerances.
- Packaging & Dispatch — Coils are wrapped in moisture-proof polyethylene film, padded with protective corner blocks, and secured on export-grade wooden pallets or steel skids with steel strapping. Each coil is labeled with heat number, grade, dimensions, and traceability codes.
Applications
Stainless steel coil tubes from Wenzhou Jixing Metal Materials Co., Ltd serve a broad spectrum of industrial, commercial, and consumer applications:
HVAC & Fan Coil Unit Systems
- Chilled water & hot water distribution loops — Coil tubes are formed into hairpin coils or serpentine circuits for fan coil unit (FCU) air handlers, delivering precise temperature control with minimal thermal loss.
- Condensate drainage lines — Corrosion-resistant condensate channels that withstand acidic condensate (pH 4–6) generated by evaporator coils.
- Energy consumption monitoring systems — As referenced in the Technical Specification for FCU Air Conditioning Energy Consumption Monitoring System, coil tubes provide the fluid-carrying infrastructure for intelligent building management systems (BMS) that optimize HVAC energy consumption through real-time flow and temperature monitoring.
Additional Industrial Applications
- Heat exchangers — Condensers, evaporators, and plate-fin coils in refrigeration and process cooling systems.
- Food & beverage processing — Hygienic-grade (electropolished, Ra ≤ 0.4 μm) tubing for CIP (Clean-In-Place) systems, pasteurization circuits, and beverage dispensing lines.
- Pharmaceutical & biotechnology — Steam sterilization (SIP) loops, process piping, and bioreactor circulation systems requiring GMP-compliant materials.
- Automotive — Radiator core tubes, heat shield tubing, and exhaust system components.
- Marine & offshore — Seawater cooling circuits, ballast systems, and deck piping utilizing SUS316L or duplex 2205 for chloride resistance.
- Chemical processing — Acid-resistant process tubing for sulfuric, phosphoric, and nitric acid handling.
- Solar thermal & geothermal — Heat collector tubes and geothermal well casing liners.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework ensuring product conformity to international standards:
- ISO 9001:2015 — Quality Management System certification covering all manufacturing, inspection, and delivery processes.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management System.
- EN 10204 3.1 / 3.2 — Mill test certificates with full chemical analysis, mechanical test results, and traceability documentation; 3.2 certificates include independent third-party inspection.
- ASTM / ASME Compliance — Products manufactured and tested per ASTM A554, A213, A269, and ASME B31.3 / B31.9 piping codes.
- EU PED 2014/68/EU — Pressure Equipment Directive conformity for applications involving pressurized systems.
- NSF/ANSI 61 — Available for potable water applications (health effects certification).
- 3-A Sanitary Standards — Electropolished tubing compliant with 3-A International standards for dairy and food processing.
- CE Marking — Conformity to European health, safety, and environmental protection standards.
Unique Selling Points
- Continuous Coil Format — Eliminates butt-weld joints inherent to straight pipe, reducing leak risk by up to 95% in HVAC coil assemblies and improving long-term system reliability.
- Full Traceability — Each coil is heat-number traced from raw material ingot through final packaging, enabling complete supply chain accountability.
- Multi-Grade Availability — Single-source procurement across SUS304, 316, 316L, 321, and duplex 2205 grades simplifies supply chain management for multi-project specifications.
- Custom Dimensional Flexibility — OD, wall thickness, and coil diameter are customizable to project-specific requirements, reducing fabrication waste and secondary processing costs.
- FCU Energy Monitoring Compatibility — Coil tubes are engineered for integration with intelligent energy consumption monitoring systems per current national technical specifications, supporting smart building and green HVAC initiatives.
- Export-Grade Packaging — Moisture-protected, shock-absorbed packaging ensures coil integrity during international ocean and land freight, minimizing surface damage claims.
- Competitive Lead Times — Strategic raw material stockpiling and in-house pickling/annealing capacity enable lead times 20–30% shorter than industry average for standard grades.
Note: All specifications listed above are representative and subject to confirmation against the applicable product standard and purchase order. For project-specific requirements, consult Wenzhou Jixing Metal Materials Co., Ltd engineering team for material selection guidance, pressure rating calculations, and compliance documentation.