Stainless Steel Coil Tube (Coiltube) — Refrigeration & Heat Exchange Application Grade
Product Overview
The Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") is a precision-engineered seamless tube product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is supplied in coiled form to facilitate efficient downstream processing, bending, and installation in heat exchange systems, refrigeration circuits, and fluid conveying applications. The coil tube is designed to deliver superior thermal conductivity, exceptional corrosion resistance, and long-term structural integrity under demanding operating conditions.
The product has been extensively validated in practical applications including three-door, three-temperature refrigerator refrigerant circuit systems, where the coil tube configuration enables compact routing of refrigerant lines through multi-zone temperature compartments with minimal pressure drop and maximum heat transfer efficiency.
Material & Properties
Coiltube products are fabricated from austenitic stainless steel grades that offer an optimal balance of mechanical strength, weldability, and resistance to pitting and crevice corrosion. The primary material specification is as follows:
- Base Material: AISI 304 / AISI 316L austenitic stainless steel
- Chemical Composition (304 Grade): Carbon (C) ≤ 0.08%, Chromium (Cr) 18.0–20.0%, Nickel (Ni) 8.0–10.5%, Manganese (Mn) ≤ 2.0%, Silicon (Si) ≤ 1.0%
- Chemical Composition (316L Grade): Carbon (C) ≤ 0.03%, Chromium (Cr) 16.0–18.0%, Nickel (Ni) 10.0–14.0%, Molybdenum (Mo) 2.0–3.0%
- Surface Finish: Bright annealed (BA) or pickled and passivated
- Corrosion Resistance: Exceptional resistance to atmospheric, acidic, and chlorinated environments
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C
- Operating Temperature Range: −196°C to +870°C
- Hygienic Grade: Suitable for food-grade and pharmaceutical fluid conveyance
Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 50.8 mm (customizable) | GB/T 14976, ASTM A511 |
| Wall Thickness | 0.3 mm – 3.0 mm | GB/T 14976, EN 10217 |
| Coil Inner Diameter (Coil ID) | 150 mm – 600 mm | Manufacturer standard |
| Coil Length per Spool | 50 m – 500 m (configurable) | Manufacturer standard |
| Surface Roughness (Ra) | ≤ 0.8 μm (BA finish) | ASTM A580 |
| Pressure Rating | Up to 10.0 MPa (depending on wall thickness) | ASME B31.3 |
| Tensile Strength | 515 – 720 MPa (304 grade) | ASTM A240 |
| Yield Strength | ≥ 205 MPa | ASTM A240 |
| Elongation at Break | ≥ 40% | ASTM A240 |
| Hardness | ≤ 92 HRB (annealed condition) | ASTM A924 |
| Delivery Condition | Full Annealed (FA), Solution Treated | — |
Manufacturing Process
The production of high-quality stainless steel coil tubes follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, metallurgical homogeneity, and surface integrity:
- Raw Material Procurement & Inspection: Stainless steel billets or wire rods are sourced from certified mill suppliers. Incoming material undergoes spectroscopic analysis (OES) to verify chemical composition compliance with specified grade requirements.
- Piercing & Hot Rolling: Billets are heated to 1,150–1,250°C and pierced to form seamless tube blanks. Hot rolling reduces wall thickness to near-final dimensions while establishing initial geometry.
- Cold Drawing: Tubes are cold-drawn through precision dies to achieve final outer diameter and wall thickness tolerances (±0.05 mm). Multiple drawing passes may be employed for tight tolerance products.
- Intermediate Annealing: Tubes are annealed at 1,050–1,150°C followed by controlled cooling to relieve cold-work stresses, restore ductility, and prevent intergranular corrosion susceptibility.
- Pickling & Passivation: Tubes are chemically pickled (nitric/hydrofluoric acid bath) to remove oxide scale, followed by passivation treatment to establish a stable chromium oxide protective film on the surface.
- Bright Annealing (BA): Tubes are annealed in a controlled atmosphere (reducing hydrogen or argon) to achieve a mirror-like bright surface finish without scale formation, suitable for hygienic and aesthetic applications.
- Coiling: Finished tubes are wound onto spools of specified inner diameter using controlled tension winding to prevent deformation, kinking, or surface marring.
- Final Inspection & Packaging: Each coil undergoes dimensional verification, visual inspection, and hydrostatic pressure testing. Coils are wrapped in moisture-proof packaging with protective end caps and labeled with mill certificates.
Applications
The versatility of the Stainless Steel Coil Tube makes it suitable for a broad spectrum of industrial applications:
- Refrigeration Systems: Refrigerant circuit tubing for multi-zone refrigerators (including three-door, three-temperature configurations), commercial cold storage units, and heat pump systems. The coil form facilitates compact routing through constrained spaces with minimal bending fatigue.
- Heat Exchangers & Condensers: Coil tubes are formed into serpentine, spiral, or hairpin configurations for air-to-water heat exchangers, evaporators, and condensers in HVAC (Heating, Ventilation, and Air Conditioning) systems.
- Food & Beverage Processing: Hygienic-grade tubing for milk processing, brewing, pharmaceutical fluid transfer, and clean-in-place (CIP) systems where corrosion resistance and ease of sanitization are critical.
- Automotive & Aerospace: Fuel lines, brake lines, and hydraulic circuits requiring high-pressure resistance and lightweight construction.
- Medical Devices: Endoscopic tubing, infusion lines, and surgical instrument shafts requiring biocompatibility and sterilizability.
- Chemical Processing: Process piping and heat exchange coils handling aggressive chemicals, acids, and chlorinated solutions.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management infrastructure to ensure product reliability and regulatory compliance:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and continuous improvement.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices.
- EN 10204 3.1 — Third-party inspection certificates available upon request, providing independent verification of material composition and mechanical properties.
- Mill Test Certificates (MTC): Each batch is accompanied by a full material test certificate documenting chemical analysis, mechanical test results, and heat treatment records.
- Hydrostatic Testing: All tubes undergo 100% hydrostatic pressure testing at 1.5× the maximum operating pressure to verify wall integrity and absence of porosity.
- Food Contact Compliance: Products meet EU Regulation 1935/2004 and FDA 21 CFR requirements for materials intended for food contact applications.
Unique Selling Points
Practical Field-Validated Performance: The coil tube configuration has been extensively validated through practical engineering experience in multi-zone refrigerator refrigerant circuit systems. Field data confirms that the coil tube method enables efficient routing of refrigerant lines through three separate temperature zones with minimal pressure loss and uniform heat distribution, reducing system energy consumption by up to 12% compared to conventional straight-pipe configurations.
- Superior Bendability: The fully annealed condition and optimized wall thickness ratios allow the coil tube to be bent to radii as small as 3× OD without cracking, folding, or excessive ovality — critical for compact heat exchanger geometries.
- Coil Form Efficiency: Supply in coil form eliminates the need for butt-welding of short tube lengths, reducing labor costs, minimizing leak points, and improving system reliability by up to 30% compared to welded assemblies.
- Customizable Dimensions: A wide range of OD, wall thickness, and coil diameter combinations available to meet specific application requirements, with custom tolerances achievable upon request.
- Long Service Life: With proper installation, stainless steel coil tubes offer service life exceeding 25 years in refrigeration applications, significantly outperforming copper and aluminum alternatives in corrosive environments.
- Sustainability: Stainless steel is 100% recyclable without degradation of material properties, supporting circular economy principles and reducing lifecycle environmental impact.