Stainless Steel Coil Tube — Product Technical Specification
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd
Product Code: JX-CT-1115
Classification: Technical Literature & Application Reference
1. Product Overview
The Stainless Steel Coil Tube (Coil Tube) is a precision-engineered metallic tube product supplied in a coiled configuration, designed for seamless integration into HVAC (Heating, Ventilation, and Air Conditioning), plumbing, refrigeration, and industrial fluid conveyance systems. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd, this product is specifically optimized for performance in cold-climate environments, addressing critical anti-freezing and thermal cycling challenges prevalent in northern regions of China and similar latitudes worldwide.
The coil tube is formed from high-grade austenitic stainless steel wire, cold-drawn to precise dimensional tolerances, and coiled into continuous lengths to minimize waste, facilitate automated processing, and ensure uniform mechanical properties throughout the entire production run. This product line is the subject of extensive technical literature and field validation, including documented case studies on freeze-protection strategies for fan coil units (FCU) deployed in northern Chinese installations.
2. Material & Properties
2.1 Base Material Composition
The coil tube is fabricated from austenitic stainless steel conforming to international and national standards. The primary grades employed are as follows:
- 304 (UNS S30408): General-purpose grade offering excellent corrosion resistance and formability. Chromium (Cr) content ≥18%, Nickel (Ni) content ≥8%.
- 316 (UNS S31608): Enhanced grade with Molybdenum (Mo) addition (2%–3%) for superior resistance to pitting and crevice corrosion in aggressive environments.
- 321 (UNS S32108): Titanium-stabilized grade suitable for elevated-temperature service and welding applications.
2.2 Mechanical Properties
- Tensile Strength (UTS): ≥520 MPa (typical for 304 grade, cold-worked condition)
- Yield Strength (0.2% Offset): ≥205 MPa
- Elongation at Break: ≥35% (indicating high ductility and formability)
- Hardness: ≤95 HRB (annealed condition)
- Impact Toughness: Excellent low-temperature toughness, retaining ductility down to −196°C (cryogenic service capability)
2.3 Physical & Chemical Properties
- Density: 8.0 g/cm³
- Thermal Conductivity: 16.3 W/(m·K) at 20°C
- Specific Heat: 500 J/(kg·K) at 20°C
- Thermal Expansion Coefficient: 17.3 × 10⁻⁶ /°C (20–100°C)
- Corrosion Resistance: Excellent resistance to atmospheric, aqueous, and many chemical environments; passive oxide layer (Cr₂O₃) provides self-healing protection
- Non-magnetic: In annealed condition (austenitic structure)
2.4 Anti-Freezing Performance Characteristics
Based on documented field studies and technical literature, the stainless steel coil tube demonstrates exceptional performance in freeze-thaw cycling scenarios. The material's retained ductility at sub-zero temperatures prevents brittle fracture, while the corrosion-resistant surface eliminates degradation from de-icing salts or glycol-based antifreeze solutions. This makes the product particularly suited for fan coil units (FCU) and radiator systems operating in northern regions where ambient temperatures routinely drop below −20°C.
3. Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 50.0 mm (customizable) | GB/T 14976, ASTM A269 |
| Wall Thickness | 0.3 mm – 3.0 mm (customizable) | GB/T 14976, ASTM A269 |
| Dimensional Tolerance (OD) | ±0.05 mm (precision grade); ±0.1 mm (standard grade) | GB/T 14976 |
| Dimensional Tolerance (Wall) | ±0.02 mm (precision grade); ±0.05 mm (standard grade) | GB/T 14976 |
| Coil Inner Diameter (ID) | 150 mm – 500 mm | Manufacturer specification |
| Coil Length (Continuous) | 50 m – 500 m per coil | Manufacturer specification |
| Surface Finish | Bright annealed (BA), pickled & passivated, or polished (Ra ≤ 0.4 μm) | ASTM A473 |
| End Condition | Flat cut, notched, or beveled | Customer requirement |
| Operating Temperature Range | −196°C to +800°C (grade-dependent) | ASME BPV Code Section II |
| Pressure Rating | Up to 16 MPa (PN16), grade and dimension dependent | GB/T 14976, EN 10217 |
| Weight per Meter | Calculated per OD × Wall × Density | — |
| Material Grades Available | 304, 304L, 316, 316L, 321, 310S, 2205 (Duplex) | ASTM A270, EN 10216-5 |
4. Manufacturing Process
The production of Wenzhou Jixing's stainless steel coil tubes follows a rigorous, multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection & Inspection: Hot-rolled stainless steel strip or wire is procured from certified mills. Incoming material undergoes chemical composition analysis (via optical emission spectrometry), mechanical testing, and visual inspection to verify conformance with specified grades.
- Decoiling & Straightening: The raw coil is fed through a precision straightening unit to remove coil set and achieve a flat, uniform strip profile.
- Forming (Roll Forming): The straightened strip passes through a series of progressive roller dies that incrementally bend the flat profile into a circular cross-section. Roller tooling is CNC-ground to ensure dimensional consistency.
- Welding (if applicable): For welded coil tubes, a high-frequency induction welding (HF welding) or laser welding process is employed. The weld seam is subsequently ground or buffed to achieve a smooth, continuous interior surface.
- Heat Treatment (Annealing): Tubes are annealed in a protective atmosphere (vacuum or argon) furnace at temperatures between 1050°C and 1150°C to relieve residual stresses, restore full austenitic microstructure, and achieve the desired softness and ductility.
- Pickling & Passivation: Post-annealing, tubes are immersed in a citric acid or dilute nitric acid solution to remove oxide scale and form a protective passive chromium oxide layer on the surface.
- Precision Sizing & Coiling: The finished tubes pass through a final sizing die to ensure dimensional tolerances, then are coiled onto mandrels of specified inner diameter. Coil ends are secured with stainless steel strapping.
- Quality Control & Testing: Each production batch undergoes comprehensive testing including hydrostatic pressure testing (at 1.5× working pressure for minimum 10 seconds), dimensional verification via ultrasonic wall thickness gauging, visual surface inspection, and sampling for mechanical property verification.
- Packaging & Dispatch: Coils are wrapped in moisture-proof film, secured with protective end caps, and packed in wooden or steel crates for export. Each coil is tagged with a material test certificate (MTC) and traceability code.
5. Applications
The stainless steel coil tube from Wenzhou Jixing Metal Materials Co., Ltd is deployed across a broad spectrum of industrial and commercial applications:
5.1 HVAC & Refrigeration Systems
- Fan Coil Units (FCU): Primary application in commercial and residential heating/cooling systems. The coil tube serves as the heat exchange element, where its thermal conductivity and corrosion resistance ensure long service life. Technical literature specifically addresses anti-freezing design considerations for FCUs in northern regions, including glycol-based coolant systems and thermal insulation strategies.
- Radiators & Underfloor Heating: Continuous coil lengths facilitate efficient installation in radiant heating systems.
- Chiller & Condenser Coils: Used in industrial refrigeration and air conditioning equipment.
5.2 Plumbing & Water Supply Systems
- Potable water distribution pipelines
- Hot and cold water supply in residential and commercial buildings
- Sanitary and drainage systems requiring hygienic-grade surfaces
5.3 Food & Pharmaceutical Industry
- Food-grade fluid conveyance (milk, juice, beverage processing)
- Pharmaceutical CIP (Clean-in-Place) systems
- Brewery and distillery equipment
5.4 Industrial Applications
- Chemical processing and transport
- Oil & gas instrumentation lines
- Automotive exhaust and fuel systems
- Medical gas supply systems
- Aerospace hydraulic lines
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains comprehensive quality management systems and certifications to ensure product reliability and international market acceptance:
- ISO 9001:2015 — Quality Management Systems
- ISO 14001:2015 — Environmental Management Systems
- ISO 45001:2018 — Occupational Health & Safety Management
- CE Marking — European Conformity for construction products
- PED (Pressure Equipment Directive 2014/68/EU) — For pressure-containing applications
- NSF/ANSI 61 — Drinking water system components (where applicable)
- GB/T 14976 — Chinese national standard for seamless and welded stainless steel tubes
- ASTM A269 / A270 — American standards for austenitic stainless steel tubing
- EN 10216-5 — European standard for welded austenitic stainless steel tubes
- JIS G3446 — Japanese Industrial Standard for stainless steel tubes
Every shipment is accompanied by a Mill Test Certificate (MTC) in accordance with EN 10204 3.1 or 3.2 requirements, providing full traceability of chemical composition, mechanical properties, heat treatment records, and non-destructive testing (NDT) results.
7. Unique Selling Points
Wenzhou Jixing Metal Materials Co., Ltd distinguishes its stainless steel coil tube product through the following competitive advantages:
- Superior Low-Temperature Performance: Extensive technical documentation and field validation of anti-freezing performance for fan coil units in northern climates, providing engineers with data-driven design guidance for freeze-protection strategies.
- Precision Dimensional Control: Advanced CNC roll-forming and sizing technology achieves tolerances as tight as ±0.02 mm on wall thickness, ensuring consistent heat transfer performance and leak-free assembly.
- Multi-Grade Availability: Comprehensive grade portfolio from standard 304/316 to high-alloy 310S and duplex 2205, enabling customers to select the optimal material for specific service conditions.
- Customization Capability: Flexible production parameters (OD, wall thickness, coil length, surface finish) tailored to customer specifications, supported by rapid prototyping and short lead times.
- End-to-End Traceability: Full production traceability from raw material mill certificates through final inspection, ensuring compliance with stringent industry audit requirements.
- Technical Literature & Application Support: Proprietary technical documentation library covering specialized topics such as freeze protection, thermal cycling durability, and system integration best practices, supporting customers' engineering design phases.
- Sustainable Manufacturing: Environmentally responsible production practices including closed-loop water recycling, energy-efficient annealing furnaces, and recyclable packaging materials.
Document Reference: JX-CT-1115-TECHSPEC | Wenzhou Jixing Metal Materials Co., Ltd | Revision: 1.0