Stainless Steel Coil Tube (Coiltube) — Model JX-1026 Series
1. Product Overview
The JX-1026 Series Stainless Steel Coil Tube is a precision-engineered coiled tubing product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. Designed for integration into HVAC (Heating, Ventilation, and Air Conditioning) systems — particularly fresh air supply units and fan coil unit (FCU) assemblies — this product serves as a critical heat exchange and fluid distribution component. The coil tube is supplied in continuous coiled form (coiltube configuration), enabling efficient installation, reduced joint points, and superior hydraulic performance in closed-loop and open-loop thermal management systems.
The product is engineered to meet the rigorous demands of modern building services engineering, where reliable thermal transfer, corrosion resistance, and long-term structural integrity are paramount. Wenzhou Jixing Metal Materials Co., Ltd. applies advanced metallurgical expertise and strict quality control protocols to ensure each coil tube meets international standards for stainless steel tubing.
2. Material & Properties
2.1 Base Material Composition
The coil tube is fabricated from austenitic stainless steel conforming to the following grades:
- SUS304 / AISI 304 (UNS S30400) — General-purpose grade with excellent corrosion resistance and formability. Chromium content ≥ 18%, Nickel content ≥ 8%.
- SUS316 / AISI 316 (UNS S31600) — Enhanced corrosion resistance grade with 2–3% Molybdenum addition, suitable for aggressive chemical and marine environments.
- SUS321 / AISI 321 (UNS S32100) — Stabilized grade with Titanium addition, resistant to intergranular corrosion at elevated temperatures (450–850°C).
2.2 Mechanical Properties
| Property | SUS304 | SUS316 | SUS321 |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 520 MPa | ≥ 515 MPa | ≥ 515 MPa |
| Yield Strength (Rp0.2) | ≥ 205 MPa | ≥ 170 MPa | ≥ 170 MPa |
| Elongation (A50mm) | ≥ 40% | ≥ 40% | ≥ 40% |
| Hardness (HBW) | ≤ 217 | ≤ 217 | ≤ 217 |
| Density | 7.93 g/cm³ | 8.00 g/cm³ | 7.99 g/cm³ |
| Thermal Conductivity (at 100°C) | 16.3 W/(m·K) | 14.6 W/(m·K) | 15.1 W/(m·K) |
| Maximum Operating Temperature | 870°C | 870°C | 900°C |
2.3 Surface Finish
The internal and external surfaces of the coil tube are available in the following finish conditions:
- Pickled & Passivated (2B Finish) — Standard finish with surface roughness Ra ≤ 0.8 μm, providing inherent corrosion protection.
- Mirror Polish (8K Finish) — High-lustre finish with Ra ≤ 0.2 μm, suitable for food-grade and pharmaceutical applications.
- Electro-polished — Ultra-clean internal surface with Ra ≤ 0.1 μm, critical for hygienic fluid handling.
3. Specifications
| Parameter | Specification |
|---|---|
| Product Model | JX-1026 Series |
| Outer Diameter (OD) | Φ6.0 mm – Φ25.4 mm (customizable) |
| Wall Thickness | 0.5 mm – 2.0 mm (tolerance ±0.05 mm) |
| Coil Diameter | Φ300 mm – Φ1000 mm |
| Coil Length | 50 m – 200 m per coil (continuous) |
| Material Grade | SUS304 / SUS316 / SUS321 |
| Manufacturing Standard | ASTM A269 / ASTM A213 / GB/T 12771 / EN 10217-7 |
| Surface Treatment | Pickled & Passivated / Mirror Polish / Electro-polished |
| Maximum Operating Pressure | 1.6 MPa (standard); 4.0 MPa (reinforced) |
| Operating Temperature Range | −196°C to +600°C |
| Coiling Tolerance | ±1 mm on coil diameter |
| Straightness (post-uncoiling) | ≤ 1.5 mm/m |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Procurement & Inspection — Hot-rolled stainless steel strip is sourced from certified mills and subjected to spectroscopic analysis (OES) to verify chemical composition compliance.
- Slitting & Leveling — The strip is slit to the required width and passed through a leveling mill to ensure flatness and dimensional accuracy.
- Forming (Roll Forming) — Precision roll-forming equipment shapes the strip into the specified tube geometry. Multi-stage forming ensures uniform wall thickness and consistent cross-sectional dimensions throughout the coil length.
- Welding (if applicable) — For welded coil tubes, a high-frequency resistance welding (HFRW) or orbital TIG welding process is employed. Weld seams are ground and inspected for integrity.
- Coiling — The formed tube is wound onto precision-diameter mandrels to produce the coiltube configuration. Tension control systems prevent kinking, flattening, or ovality defects.
- Pickling & Passivation — The coil is immersed in a mixed acid bath (HNO₃/HF or citric acid-based) to remove oxide scale, followed by a passivation treatment to establish a protective chromium oxide layer.
- Heat Treatment (Solution Annealing) — Where required, the coil tube undergoes solution annealing at 1050–1100°C with rapid water quenching to achieve full austenitic microstructure and optimal mechanical properties.
- Final Quality Inspection — Comprehensive testing including dimensional measurement, hydrostatic pressure testing, visual inspection, and corrosion testing (e.g., salt spray per ASTM B117).
4.2 Process Control Highlights
- In-process monitoring of coil tension and forming parameters ensures consistent geometry along the entire coil length.
- Non-destructive testing (NDT) via eddy current inspection is performed to detect internal and surface defects.
- Each coil batch is traceable via heat number and mill certificate documentation.
5. Applications
5.1 HVAC Systems — Fan Coil Units (FCU) & Fresh Air Systems
The primary application domain for the JX-1026 Series coil tube is in the construction of heat exchangers within fan coil units and fresh air handling systems. The coiltube configuration provides the following advantages in this context:
- Compact Heat Exchange Surface — The continuous coil geometry maximizes surface-to-volume ratio, enhancing thermal transfer efficiency between the refrigerant or hot water circuit and the air stream.
- Reduced Joint Points — The continuous coil minimizes the number of welds and mechanical connections, reducing potential leak points in the system.
- System Detectability & Control Integration — The uniform hydraulic characteristics of the coil tube facilitate accurate flow metering and temperature monitoring, which are essential for the detection and control of fresh air + fan coil unit systems. Proper coil tube geometry ensures predictable pressure drop profiles, enabling reliable sensor placement and control algorithm calibration.
- Corrosion Resistance — Stainless steel construction eliminates the risk of internal corrosion and biofilm formation, ensuring long-term system reliability without degradation of flow characteristics.
5.2 Additional Application Areas
- Food & Beverage Processing — Hygienic-grade coil tubes for CIP (Clean-in-Place) compatible heat exchangers and fluid transfer lines.
- Pharmaceutical Equipment — Electro-polished coil tubes for sterile fluid handling and GMP-compliant processing systems.
- Automotive & Aerospace — Lightweight coil tubing for fuel lines, hydraulic circuits, and brake systems requiring high fatigue resistance.
- Chemical Processing — SUS316-grade coil tubes for aggressive chemical environments requiring superior pitting and crevice corrosion resistance.
- Cryogenic Applications — Operating at temperatures as low as −196°C (LNG applications), leveraging the excellent low-temperature toughness of austenitic stainless steels.
6. Quality Certifications & Compliance
6.1 Standards Compliance
- ASTM A269 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tube for Chemical and Similar Severe Service.
- ASTM A213 — Standard Specification for Austenitic Stainless Steel and Heat-Resisting Alloy Tube, Pipe, and Fittings for Heat-Transfer Applications.
- GB/T 12771 — Chinese National Standard for Stainless Steel Seamless Tubes for General Purposes.
- EN 10217-7 — European Standard for Tubes for Heat Exchangers — Part 7: Nickel-Chromium-Iron-Cr-Ni-Fe Austenitic Steels.
- ISO 4326-1 — General Purpose Tubes — Part 1: Stainless Steel Tubes for General Purposes.
6.2 Certifications & Accreditations
- ISO 9001:2015 — Quality Management System certification for manufacturing operations.
- ISO 14001:2015 — Environmental Management System certification.
- ISO/TS 22163 (IATF 16949) — Quality management for automotive-related organizations (where applicable).
- CE Marking — Conformity with European Union directives for pressure equipment (PED 2014/68/EU).
- Mill Test Certificates (MTC) — EN 10204 3.1 and 3.2 certificates provided with each shipment, including chemical composition analysis, mechanical test results, and heat treatment records.
6.3 Testing & Inspection Protocol
- Chemical Analysis — Optical Emission Spectroscopy (OES) per ASTM E1409.
- Mechanical Testing — Tensile and hardness testing per ASTM E8/E8M and ASTM E18.
- Dimensional Inspection — CMM (Coordinate Measuring Machine) verification of OD, wall thickness, and coil diameter.
- Hydrostatic Testing — Per ASTM A269, pressure test at 1.5× maximum service pressure for 10 seconds minimum.
- Corrosion Testing — Salt spray test per ASTM B117 (≥ 1000 hours without red rust for SUS316 grade).
- Visual & Surface Inspection — 100% inspection for surface defects, weld seam quality, and passivation integrity.
7. Unique Selling Points
- Continuous Coil Configuration — Eliminates field welding requirements, reducing installation time by up to 40% and minimizing leak risk in critical HVAC systems.
- Multi-Grade Availability — SUS304, SUS316, and SUS321 options provide customers with material flexibility tailored to specific environmental and performance requirements.
- Precision Dimensional Control — Tight tolerances (±0.05 mm on wall thickness) ensure consistent hydraulic performance and compatibility with precision-fitted heat exchanger headers.
- Full Traceability — Every coil is linked to its mill heat number, enabling complete supply chain traceability for regulated industries.
- Integrated System Compatibility — Designed with awareness of fan coil unit and fresh air system detection and control requirements, ensuring predictable thermal and hydraulic behavior that supports accurate system monitoring and automated control.
- Long Service Life — Superior corrosion resistance extends system lifespan to 25+ years without replacement, reducing total cost of ownership.
Note: All specifications are subject