Stainless Steel Coil Tube (Coiltube) — Product No. 1536
Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered flexible tubing product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. Designed primarily for integration into Fan Coil Unit (FCU) systems and HVAC (Heating, Ventilation, and Air Conditioning) applications, this coil tube serves as a critical component in fluid and air distribution networks. The product is engineered to provide superior flexibility, corrosion resistance, and structural integrity under continuous cyclic loading conditions inherent to mechanical ventilation and thermal exchange systems.
The coil tube is supplied in a coiled configuration, enabling easy handling, transportation, and on-site installation without the need for additional bending or forming operations. This inherent coil geometry reduces installation time, minimizes the risk of work-hardening damage, and ensures consistent dimensional accuracy throughout the product's service life.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional balance of mechanical strength, corrosion resistance, and formability. The following material characteristics define the product's performance envelope:
- Base Material: Austenitic Stainless Steel (SAE 304 / SAE 316 depending on application requirements)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, chloride ion pitting (316 grade), and oxidation at elevated temperatures up to 870°C (1600°F)
- Mechanical Properties: Tensile strength ≥ 515 MPa (74,700 psi); Yield strength ≥ 205 MPa (29,700 psi); Elongation ≥ 40%
- Thermal Conductivity: 16.3 W/(m·K) at 25°C — suitable for thermal exchange applications
- Operating Temperature Range: −196°C to +870°C (−321°F to +1600°F)
- Surface Finish: Electropolished or passivated finish; Ra ≤ 0.4 μm for hygienic and precision applications
- Chemical Composition (304 Grade): Carbon ≤ 0.08%, Chromium 18–20%, Nickel 8–10.5%, Manganese ≤ 2.0%, Silicon ≤ 1.0%
Specifications
| Parameter | Specification | Unit | Standard/Reference |
|---|---|---|---|
| Outer Diameter (OD) | 6.0 – 50.8 (customizable) | mm | ASME B36.19M |
| Wall Thickness | 0.5 – 3.0 | mm | ASME B36.19M |
| Coil Length | 5 – 50 (adjustable per order) | m | — |
| Coil Diameter | 300 – 1500 | mm | — |
| Maximum Working Pressure | ≤ 1.6 | MPa | GB/T 14976 |
| Hydrostatic Test Pressure | 2.5 × Working Pressure | MPa | ASME B31.3 |
| Minimum Bend Radius | ≥ 3 × OD | — | — |
| Surface Roughness | ≤ 0.4 | μm (Ra) | GB/T 10494 |
| Material Grade | SAE 304 / SAE 316 | — | ASTM A269 / A270 |
| Applicable Standards | ASTM A269, GB/T 14976, EN 10217-7 | — | — |
Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous multi-stage manufacturing process to ensure dimensional precision, metallurgical integrity, and surface quality:
- Raw Material Procurement: Cold-rolled stainless steel strip is sourced from certified mills and subjected to incoming inspection for chemical composition (via Spark Optical Emission Spectrometry, OES) and mechanical properties.
- Forming & Welding: The strip is formed into a tubular cross-section and longitudinally welded using Automatic Argon Arc Welding (TIG/GTAW) or Automatic Laser Welding, with continuous helium or argon back-purging to prevent internal oxidation.
- Heat Treatment: Solution annealing at 1040–1120°C followed by rapid water quenching to achieve a fully austenitic microstructure, eliminating residual stresses and ensuring uniform corrosion resistance.
- Coiling: The tube is coiled onto a mandrel of specified diameter using a controlled-speed coiling mechanism to prevent kinking, ovality distortion, or surface scratching.
- Precision Finishing: Includes deburring, internal/external grinding, and optional electropolishing or passivation treatment to achieve the required surface finish and corrosion protection.
- Quality Inspection: Every coil undergoes dimensional verification (OD, wall thickness, ovality), hydrostatic pressure testing, and surface inspection via ultrasonic testing (UT) or eddy current testing (ET).
Applications
The Stainless Steel Coil Tube is designed for demanding industrial and commercial applications where flexibility, durability, and corrosion resistance are paramount:
- Fan Coil Unit (FCU) Systems: Serves as the primary fluid distribution tubing connecting FCUs to central chilled water or heating water loops. The coil configuration accommodates thermal expansion and contraction inherent to HVAC operation.
- Rubber Joint Connection Interfaces: Designed for seamless integration with rubber expansion joints (rubber bellows joints) to absorb vibration, misalignment, and thermal displacement at pump stations and terminal units.
- HVAC Piping Systems: Chilled water, hot water, and condenser water distribution in commercial buildings, hospitals, and data centers.
- Food & Pharmaceutical Processing: Where sanitary-grade tubing (316L, electropolished) is required for CIP (Clean-In-Place) and SIP (Sterilize-In-Place) protocols.
- Chemical Processing: Handling of corrosive fluids, acids, and solvents in petrochemical and pharmaceutical plants.
- Marine & Offshore: Resistant to saltwater corrosion and marine atmospheric exposure.
- Cryogenic Applications: Suitable for low-temperature service down to −196°C in liquefied natural gas (LNG) and industrial gas systems.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and holds the following certifications ensuring product conformity with international and domestic standards:
- ISO 9001:2015 — Quality Management System (QMS) certification
- ISO 14001:2015 — Environmental Management System (EMS) certification
- ISO 45001:2018 — Occupational Health and Safety Management System certification
- CE Marking — Compliance with European Union directives for pressure equipment (PED 2014/68/EU)
- NACE MR0175 / ISO 15156 — Resistance to sulfide stress cracking (for oil and gas applications)
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes for fluid transport
- ASTM A269 / A270 — American standards for wrought austenitic stainless steel tubing
- EN 10217-7 — European standard for stainless steel seamless tubes for pressure purposes
Unique Selling Points
The Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. differentiates itself through the following value propositions:
- Ready-to-Install Coil Configuration: Eliminates the need for field bending, reducing installation labor by up to 40% and preventing work-hardening damage to the tube wall.
- FCU-Optimized Design: Specifically engineered for Fan Coil Unit integration, with dimensions and pressure ratings validated for HVAC terminal unit service conditions.
- Rubber Joint Compatibility: Pre-validated dimensional tolerances ensure leak-free, reliable connections with standard rubber expansion joints, absorbing vibration and thermal displacement.
- Full Traceability: Each coil is accompanied by a Mill Test Certificate (MTC) with heat number traceability, chemical analysis, mechanical test results, and dimensional inspection records.
- Customization Capability: Flexible ordering options for diameter, wall thickness, coil length, surface finish, and material grade to meet project-specific requirements.
- Cost-Effective Solution: Competitive pricing with premium quality assurance, offering an optimal balance of performance and total cost of ownership (TCO).