Stainless Steel Coil Tube (Coil Tube) — Technical Product Specification
1. Product Overview
The Stainless Steel Coil Tube (盘管, Coil Tube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered continuous tube product supplied in coiled form. Unlike straight-length seamless or welded tubing, coil tubes are wound into large-diameter coils, enabling high-volume, continuous-feeding manufacturing processes and minimizing material waste. This product line is designed for applications demanding superior corrosion resistance, thermal conductivity, mechanical integrity, and long-term durability in demanding industrial, HVAC, and process engineering environments.
Wenzhou Jixing Metal Materials Co., Ltd is a leading supplier of stainless steel pipe and tube products based in Wenzhou, Zhejiang Province, China — a globally recognized hub for stainless steel manufacturing. The company's coil tube products are engineered to meet or exceed international standards including ASTM (American Society for Testing and Materials), ISO (International Organization for Standardization), EN (European Norms), and GB/T (Guobiao, Chinese National Standard).
2. Material & Properties
The stainless steel coil tubes are fabricated from high-purity austenitic and duplex stainless steel grades, selected for their exceptional balance of mechanical strength, corrosion resistance, and formability. The primary alloy grades include:
- ASTM A269 / A213 — Type 304 (UNS S30400): The most widely used austenitic grade, offering excellent general corrosion resistance, formability, and weldability. Contains approximately 18% Chromium (Cr) and 8% Nickel (Ni).
- ASTM A269 / A213 — Type 304L (UNS S30403): A low-carbon variant of Type 304 (Carbon ≤ 0.03%), designed for enhanced weldability and resistance to intergranular corrosion in sensitization-prone environments.
- ASTM A269 / A213 — Type 316 (UNS S31600): Contains 2–3% Molybdenum (Mo), providing superior resistance to pitting and crevice corrosion, particularly in chloride-containing environments.
- ASTM A269 / A213 — Type 316L (UNS S31603): Low-carbon version of Type 316, offering the same chemical resistance with improved weldability.
- Duplex Grades (2205, UNS S32205): Available upon request for applications requiring higher yield strength and resistance to stress corrosion cracking (SCC).
Key Mechanical Properties (Type 304 Reference)
| Property | Specification | Test Standard |
|---|---|---|
| Tensile Strength (Ultimate) | ≥ 515 MPa (75 ksi) | ASTM A269 |
| Yield Strength (0.2% Offset) | ≥ 205 MPa (30 ksi) | ASTM A269 |
| Elongation (in 2D or 50 mm) | ≥ 40% | ASTM A269 |
| Hardness (Rockwell B) | ≤ 95 HRB | ASTM A269 |
| Density | 8.0 g/cm³ | — |
| Thermal Conductivity (20°C) | 16.3 W/(m·K) | — |
| Operating Temperature Range | −196°C to +870°C | — |
3. Specifications
| Parameter | Specification / Range |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管) |
| Product Code / Serial No. | 449 |
| Outer Diameter (OD) | 3.0 mm – 108.0 mm (custom sizes available) |
| Wall Thickness | 0.3 mm – 6.0 mm |
| Coil Inner Diameter | 150 mm – 600 mm |
| Coil Length per Coil | 50 m – 500 m (variable, dependent on OD and wall thickness) |
| Surface Finish | No. 1 (Annealed + Pickled), 2B (Cold Rolled + Bright Annealed), BA (Bright Annealed), No. 4 (Brushed), HL (Hairline), Mirror (8K) |
| End Condition | Plain cut, beveled, threaded, or flanged (upon request) |
| Manufacturing Method | ERW (Electric Resistance Welding), Seamless (Piercing + Cold Drawing) |
| Applicable Standards | ASTM A269, ASTM A213, GB/T 12771, GB/T 13296, EN 10217-7, JIS G3459 |
| Available Grades | 304, 304L, 316, 316L, 321, 310S, 2205 (Duplex) |
| Packaging | Export-grade wooden pallets with VCI (Vapor Corrosion Inhibitor) film, moisture-proof wrapping, steel banding |
| Minimum Order Quantity | Negotiable; standard coil weights 500 kg – 2,500 kg |
4. Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorous, multi-stage manufacturing workflow designed to ensure dimensional precision, metallurgical homogeneity, and surface quality:
- Raw Material Procurement & Inspection: High-purity stainless steel strip or wire rod is sourced from certified mills. Incoming material undergoes spectroscopic analysis (OES — Optical Emission Spectroscopy) to verify chemical composition compliance.
- Coiling & Straightening: The coil is uncoiled and straightened through precision roller straighteners to achieve a flatness tolerance of ≤ 0.1 mm/m, ensuring uniform tube cross-section throughout the length.
- Forming & Welding (ERW Route): The flat strip is formed into a circular cross-section through roll forming, then welded using Electric Resistance Welding (ERW) or Automatic Submerged Arc Welding (SAW). Weld seam quality is maintained within ± 0.05 mm offset tolerance.
- Cold Drawing & Sizing (Optional): For tight-tolerance or seamless-equivalent applications, the tube undergoes multi-pass cold drawing through hardened tungsten carbide dies to achieve precise OD and wall thickness tolerances (± 0.05 mm).
- Heat Treatment & Annealing: Solution annealing is performed at 1050°C – 1150°C in a protective atmosphere (nitrogen or vacuum) to relieve residual stresses, restore full austenitic microstructure, and achieve the required mechanical properties.
- Pickling & Passivation: The tube surface is treated with a hydrochloric acid and nitric acid mixture (pickling) to remove oxide scale, followed by passivation to establish a stable chromium oxide film (Cr₂O₃) that provides inherent corrosion resistance.
- Surface Finishing: Depending on the specified finish grade, additional processing includes grinding, brushing, polishing, or mirror finishing using automated CNC finishing lines.
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Quality Control & Testing: Every coil undergoes comprehensive inspection including:
- Dimensional measurement (OD, wall thickness, straightness)
- Hydrostatic pressure testing (per ASTM A269)
- Chemical composition verification (spectroscopy)
- Mechanical testing (tensile, hardness, impact)
- Surface inspection (visual, dye penetrant testing per ASTM E709)
- Corrosion testing (salt spray test per ASTM B117, minimum 1,000 hours for Type 316)
- Coiling & Packaging: The finished tube is recoiled onto precision steel spools, wrapped with protective film, and packaged for domestic and international shipment.
5. Applications
Stainless steel coil tubes from Wenzhou Jixing Metal Materials Co., Ltd serve a broad spectrum of industrial applications where continuous, corrosion-resistant tubing is essential:
5.1 HVAC & Refrigeration Systems
Coil tubes are extensively used in fan coil units (风机盘管), air handling units (AHUs), chiller evaporators and condensers, heat exchangers, and refrigeration circuit tubing. The high thermal conductivity and corrosion resistance of stainless steel ensure efficient heat transfer and long service life in humid, condensing environments. The coiled form factor facilitates automated coil winding for brazed plate heat exchangers and serpentine coil assemblies.
5.2 Food & Beverage Processing
Type 304 and 316L coil tubes are used for sanitary process piping, steam distribution lines, condensate return systems, and CIP (Clean-in-Place) systems in dairy, brewing, pharmaceutical, and food processing plants. The smooth surface finish minimizes bacterial adhesion and facilitates hygienic cleaning.
5.3 Chemical & Petrochemical Industry
In aggressive chemical environments, Type 316 and 316L coil tubes are employed for chemical transfer lines, reactor coil inserts, heat exchanger tubes, and process piping systems handling acids, alkalis, and chlorinated compounds.
5.4 Marine & Offshore Applications
Marine-grade stainless steel coil tubes (316L, 2205 Duplex) are used in seawater cooling systems, ballast water management, desalination plants, and offshore platform piping where chloride-induced corrosion is a critical concern.
5.5 Automotive & Energy Sector
Coil tubes are utilized in automotive exhaust systems, fuel cell water management systems, hydrogen fuel delivery lines, solar thermal collectors, and geothermal heat exchange systems.
5.6 Medical & Laboratory Equipment
Precision-drawn coil tubes serve in medical gas delivery systems, laboratory apparatus tubing, dialysis machine fluid lines, and sterilization equipment where biocompatibility and corrosion resistance are paramount.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and holds the following certifications and complies with the following standards:
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| ISO 45001:2018 | Occupational Health & Safety Management System |
| CE Marking (EU) | Compliance with European directives for construction and pressure equipment |
| EN 10204 3.1 | Inspection Certificate — Material Test Reports |
| NACE SP0169 / NACE SP0287 | Cathodic Protection & Coating Specifications (where applicable) |
| NSF/ANSI 61 | Drinking Water System Components — Health Effects |
| 3-A Sanitary Standards | Dairy & Food Processing Equipment |
| PED 2014/68/EU | Pressure Equipment Directive compliance (upon request) |
7. Unique Selling Points
- Continuous Coil Supply: Eliminates weld joints and butt connections found in straight-length tubing, reducing leak points and improving system reliability. Ideal for automated manufacturing processes requiring uninterrupted material feed.
- Minimal Material Waste: The coil format reduces off-cuts and scrap by up to 40% compared to straight-length pipe procurement, offering significant cost advantages for high-volume production.
- Multi-Grade Availability: Comprehensive grade selection from standard austenitic (304, 316) to high-performance duplex (2205) allows precise material specification matching to application requirements.
- Custom Dimensional Engineering: Flexible OD, wall thickness, coil diameter, and surface finish options enable tailored solutions for specialized OEM and fabrication requirements.
- Full Traceability: Every coil is accompanied by a mill test certificate (MTC) with heat number, chemical analysis, mechanical test results, and dimensional inspection data, ensuring complete supply chain traceability.
- Export-Grade Packaging: VCI-protected, moisture-sealed, and steel-banded packaging ensures product integrity during global ocean and land transportation.
- Competitive Lead Times: Leveraging Wenzhou's position as China's premier stainless steel manufacturing hub, Wenzhou Jixing offers rapid production turnaround and competitive pricing.
8. Technical Data Sheet Summary
Product: Stainless