Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 1264) manufactures high-grade Stainless Steel Coil Tubes (also referred to as Coiltube or Spiral Coil Pipe), which are precision-engineered continuous length stainless steel tubes wound into coil form for efficient transport, storage, and downstream processing. These coil tubes are predominantly designed for applications in HVAC (Heating, Ventilation, and Air Conditioning) systems, particularly for fan coil unit condensate drainage piping (风机盘管冷凝水管道), as well as general fluid conveyance, heat exchanger construction, and industrial plumbing.
The coil tube format eliminates the need for field welding at installation joints, significantly reducing labor costs, improving system reliability, and minimizing the risk of leakage points. This continuous coil configuration also facilitates seamless integration with automated forming and bending equipment on construction sites.
Material & Properties
The stainless steel coil tubes are fabricated from austenitic stainless steel grades, with the following primary material options:
- 304 (UNS S30400 / 1.4301) — The most widely used grade, offering excellent corrosion resistance in atmospheric and mildly aggressive environments. Chromium content ≥18%, Nickel content ≥8%.
- 316 (UNS S31600 / 1.4401) — Enhanced pitting and crevice corrosion resistance due to the addition of 2–3% Molybdenum (Mo). Preferred for coastal or chemically aggressive applications.
- 304L (UNS S30403 / 1.4307) — Low-carbon variant (C ≤ 0.03%) suitable for welding-intensive applications where sensitization must be avoided.
- 316L (UNS S31603 / 1.4404) — Low-carbon 316 variant combining superior weldability with outstanding corrosion resistance.
Key Mechanical and Physical Properties (Typical for Grade 304)
- Tensile Strength (UTS): ≥ 515 MPa (74,700 psi)
- Yield Strength (0.2% Offset): ≥ 205 MPa (29,700 psi)
- Elongation at Break: ≥ 40%
- Density: 8.0 g/cm³
- Thermal Conductivity (at 20°C): 16.3 W/(m·K)
- Thermal Expansion Coefficient (20–100°C): 17.3 × 10⁻⁶ /°C
- Maximum Service Temperature: 870°C (1,598°F)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, dilute acids, and organic/inorganic solutions; superior resistance to chlorides in 316 grade.
Specifications
| Parameter | Specification / Range |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product Code | 1264 |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. |
| Material Grades | 304, 304L, 316, 316L, 321, 310S (custom upon request) |
| Outer Diameter (OD) | 6 mm – 114.3 mm (¼" – 4½") |
| Wall Thickness | 0.5 mm – 3.0 mm (0.020" – 0.118") |
| Coil Inner Diameter (CID) | 300 mm – 1,200 mm (adjustable per order) |
| Coil Length per Spool | 50 m – 300 m (continuous) |
| Surface Finish | 2B (Cold Rolled & Annealed), No. 1 (Pickled & Annealed), Mirror Polished (Ra ≤ 0.1 μm), Brushed (HL) |
| End Condition | Plain cut, beveled, or formed per customer specification |
| Tolerance (OD) | ±0.1 mm (±0.004") |
| Tolerance (Wall Thickness) | ±10% of nominal |
| Standards Compliance | ASTM A269/A269M, ASTM A213/A213M, EN 10217-7, GB/T 12771, JIS G3459 |
| Packaging | Coil wound with protective paper wrapping, steel banding, and export-grade wooden pallet/crate |
Manufacturing Process
The production of high-quality stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing workflow:
- Raw Material Selection: Hot-rolled stainless steel strips (coil) are sourced from certified mills and inspected for chemical composition (via Optical Emission Spectroscopy — OES) and mechanical properties before acceptance.
- Strip Annealing & Pickling: The incoming strip undergoes controlled annealing in a continuous annealing line (CAL) with protective atmosphere (H₂/N₂ or dew-point-controlled air) to achieve the desired grain structure and stress-free condition. Subsequent pickling removes oxide scale and restores passive chromium oxide layer.
- Coil Tubing Forming (Spiral or ERW): The flat strip is fed through a series of progressively shaped roll stands that gradually form the strip into a circular cross-section. The longitudinal seam is joined via either:
- Electric Resistance Welding (ERW): Induction heating with controlled pressure welding for thin-wall tubing.
- Argon Arc Welding (TIG/GTAW): Used for premium-grade tubing requiring superior seam quality and visual appearance.
- Heat Treatment (Post-Weld Annealing): The formed tube is passed through a continuous solution annealing furnace at 1,050–1,150°C (1,922–2,092°F) followed by controlled cooling to eliminate residual welding stresses and restore full corrosion resistance.
- Precision Sizing & Straightening: The tube passes through a cold sizing unit with hard alloy rolls to ensure dimensional accuracy (OD and wall thickness tolerances).
- Surface Treatment: Depending on customer specification, the tube receives 2B finish, acid pickling, mechanical polishing, or electropolishing.
- Quality Inspection: Each coil undergoes 100% inline inspection including:
- Dimensional measurement (laser or ultrasonic)
- Visual surface inspection
- Eddy current testing for seam weld integrity
- Hydrostatic pressure testing (where applicable)
- Spectrographic verification of chemical composition
- Coiling & Packaging: The finished tube is wound onto a coil core, secured with steel strapping, wrapped in protective material, and packaged for shipment.
Applications
The stainless steel coil tube from Wenzhou Jixing Metal Materials Co., Ltd. serves a diverse range of industrial and commercial applications:
- HVAC Condensate Drainage Systems: Primary application — used as condensate drain piping for fan coil units (FCUs) in commercial buildings, hospitals, and data centers. The continuous coil format allows for seamless routing without field-welded joints, ensuring leak-free operation and compliance with building codes.
- Heat Exchanger Tubes: Coil tubes are cut and formed into hairpin or U-bend configurations for shell-and-tube heat exchangers in refrigeration, power generation, and chemical processing.
- Food & Beverage Industry: Sanitary-grade tubing for processing lines, CIP (Clean-In-Place) systems, and equipment fabrication where hygiene and corrosion resistance are critical.
- Pharmaceutical & Medical Equipment: Used in process piping, reactor components, and medical device manufacturing requiring biocompatibility and sterilizability.
- Automotive & Aerospace: Fuel lines, exhaust system components, brake lines, and structural tubing where weight-to-strength ratio and corrosion resistance are paramount.
- General Plumbing & Piping: Domestic water supply, gas distribution, and industrial fluid conveyance systems.
- Structural & Architectural Applications: Decorative railings, handrails, and structural framing where aesthetic finish and durability are required.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring that every product batch meets or exceeds international standards:
- ISO 9001:2015 — Quality Management System certification ensuring consistent production quality and continuous improvement processes.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to environmentally responsible manufacturing.
- ISO 45001:2018 — Occupational Health and Safety Management System.
- EN 10204 Type 3.1 — Third-party inspection certificates available for all shipments, verifying conformance to specified standards.
- ASTM / ASME Compliance: Full material traceability from mill heat number through final product, with certified Chemical Analysis Reports (CAR) and Mechanical Test Reports (MTR) provided per batch.
- NACE MR0175 / ISO 15156 — Available for sour service applications (upon request, with appropriate grade selection and testing).
- CE Marking: Product conformity with European directives for construction products and pressure equipment where applicable.
- Mill Test Reports (MTR): Provided for every coil, documenting chemical composition, mechanical properties, and dimensional verification.
Unique Selling Points
Why Choose Wenzhou Jixing Metal Materials Co., Ltd. Stainless Steel Coil Tubes:
- Seamless Continuous Coil Format: Eliminates field-welded joints, reducing installation time by up to 60% and virtually eliminating leakage risk — particularly critical for condensate drainage applications.
- Premium Material Grades: Full range of austenitic stainless steel grades (304, 316, 304L, 316L, 321, 310S) sourced from certified mills with full traceability.
- Customizable Specifications: Flexible OD, wall thickness, coil diameter, and surface finish options tailored to customer-specific engineering requirements.
- Comprehensive Quality Assurance: 100% inline inspection with non-destructive testing (NDT), spectrographic analysis, and dimensional verification at every production stage.
- Cost-Effective Solution: The coil format reduces material waste (minimal cutting loss), lowers transportation costs (higher density loading), and decreases installation labor — delivering superior total cost of ownership (TCO).
- Long Service Life: Superior corrosion resistance ensures 25–50+ year service life in most environments, minimizing maintenance and replacement costs.
- Global Standards Compliance: Products manufactured to ASTM, EN, GB/T, and JIS standards with full certification documentation for international market access.
Technical Notes for Condensate Drainage Applications
For fan coil unit (FCU) condensate drainage installations, the following design considerations are recommended:
- Minimum Slope: 1:100 (1%) gradient toward the drain point to ensure gravity-driven condensate flow.
- Recommended Tube Size: 12 mm OD × 1.0 mm wall (½" nominal) for standard FCU units; 16 mm OD × 1.0 mm wall (¾" nominal) for high-capacity or multi-unit systems.
- Material Selection: 304 grade is sufficient for indoor HVAC condensate applications; 316 grade is recommended for outdoor installations or coastal environments.
- Support Spacing: Maximum 1.5 m between supports for tubes ≤ 20 mm OD; 2.0 m for larger diameters.
- Insulation: External thermal insulation (closed-cell rubber or foam) recommended to prevent condensation on tube exterior surfaces.
- Trap Installation: P-trap or siphon break required at appropriate intervals to maintain proper drainage pressure balance.