Stainless Steel Coil Tube for Thermal Heating Systems
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product specifically designed for thermal heat transfer applications in industrial storage and processing systems. This product line is particularly optimized for integration into steam coil heating systems used in large crude oil floating roof storage tanks (Floating Roof Tanks, FRTs), where efficient and uniform heat distribution is critical to maintaining fluid viscosity and flow characteristics.
Coil tubes differ fundamentally from straight seamless or welded pipes in their manufacturing methodology and geometric configuration. The continuous helical winding process imparts superior residual stress distribution and enhanced flexibility, making these tubes exceptionally well-suited for applications requiring compact heat exchange surfaces within confined vessel geometries. The numerical simulation and finite element analysis (Finite Element Method, FEM) of steam coil heating processes in large crude oil storage tanks have validated the thermal performance characteristics of these products under extreme operating conditions.
Material & Properties
The coil tubes are fabricated from high-grade austenitic and duplex stainless steels, selected to meet the demanding requirements of thermal cycling, corrosion resistance, and mechanical integrity in hydrocarbon storage environments.
Primary Material Grades
- ASTM A269 / ASTM B462 – 304 (UNS S30400): General-purpose austenitic stainless steel with excellent corrosion resistance, formability, and weldability. Suitable for non-chloride-containing hydrocarbon media.
- ASTM A269 / ASTM B462 – 316L (UNS S31603): Enhanced corrosion resistance grade with molybdenum addition (2.0–3.0% Mo), providing superior resistance to pitting and crevice corrosion in chloride-containing environments.
- ASTM A269 – 321 (UNS S32100): Titanium-stabilized austenitic grade offering excellent resistance to intergranular corrosion, ideal for high-temperature service above 425°C.
- Duplex 2205 (UNS S31803): High-strength duplex austenitic-ferritic stainless steel with equivalent corrosion resistance to 316L at approximately double the yield strength.
Key Mechanical and Thermal Properties
- Operating Temperature Range: −196°C to +800°C (depending on grade)
- Thermal Conductivity: 14–25 W/(m·K) at 25°C
- Thermal Expansion Coefficient: 16–18 × 10⁻⁶ /°C
- Yield Strength: 205–550 MPa (depending on grade and condition)
- Tensile Strength: 515–800 MPa (minimum)
- Corrosion Resistance: Equivalent to or exceeding ASTM G48 (pitting) and ASTM G53 (crevice) test standards
Specifications
| Parameter | Specification |
|---|---|
| Product Type | Stainless Steel Coil Tube (Coiltube) |
| Material Standard | ASTM A269 / ASTM B462 / ASME SA-213 |
| Available Grades | 304, 304L, 316, 316L, 321, 347, Duplex 2205 |
| Outer Diameter (OD) | 6.0 mm – 114.3 mm (1/4" – 4-1/2") |
| Wall Thickness | 0.30 mm – 6.35 mm (0.012" – 1/4") |
| Coil Diameter | Custom, typically 300 mm – 2,000 mm |
| Coil Length | Up to 500 m per coil (continuous production) |
| Surface Finish | No. 4 Brushed, Mirror (2B), Matte, or Custom |
| End Condition | Plain, Beveled, Threaded, or Flanged |
| Manufacturing Process | Continuous Cold Winding (CW) / Hot Forming |
| Applicable Standards | ASME BPV Section I, EN 10217-7, GB/T 12771 |
| Heat Treatment | Solution Annealing + Pickling & Passivation |
| Pressure Rating | Up to 40 bar (PN40), grade-dependent |
| Welding Compatibility | TIG (GTAW), MIG (GMAW), Orbital |
Manufacturing Process
The production of high-quality stainless steel coil tubes involves a multi-stage manufacturing sequence designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection & Inspection: Ingot or strip material is procured from certified suppliers and subjected to spectrographic analysis (Optical Emission Spectroscopy, OES) to verify chemical composition compliance with specified standards.
- Blank Preparation: Strip or rod stock is cut to required dimensions and inspected for surface defects using ultrasonic testing (Ultrasonic Testing, UT) and eddy current methods.
- Forming & Winding: The strip material is fed through precision forming rollers and continuously wound into the desired helical coil geometry. This continuous cold winding process ensures uniform wall thickness, consistent coil pitch, and minimal residual stress concentration.
- Welding (if applicable): Longitudinal seams, where present, are welded using Automatic Orbital TIG welding with inert gas shielding (Argon/ Helium mixture) to achieve high-quality, defect-free weld joints.
- Heat Treatment: Coils undergo solution annealing at 1010–1100°C followed by controlled water quenching to achieve the desired austenitic microstructure and mechanical properties.
- Pickling & Passivation: The surface is treated with nitric/hydrofluoric acid pickling solution to remove oxide scale, followed by passivation to establish a protective chromium oxide layer.
- Quality Control & Testing: Each coil undergoes hydrostatic pressure testing, dimensional verification, and surface inspection. Non-Destructive Testing (NDT) including dye penetrant inspection and radiographic testing (Radiographic Testing, RT) is performed on weld seams.
- Packaging & Dispatch: Coils are wrapped in protective materials and packaged for shipment with accompanying Mill Test Certificates (Mill Test Certificate, MTC).
Applications
Primary Application: Crude Oil Storage Tank Heating
The most critical application of these coil tubes is in steam coil heating systems for large crude oil floating roof storage tanks. As validated through numerical simulation and computational fluid dynamics (Computational Fluid Dynamics, CFD) analysis of the heating process, these coils provide:
- Uniform heat distribution across large tank volumes (up to 100,000 m³)
- Controlled viscosity reduction of heavy crude oils to facilitate pumping and transfer
- Elimination of hot spots and thermal stratification through optimized coil layout design
- Energy efficiency through high surface-area-to-volume ratios
Additional Applications
- Petrochemical Processing: Heat exchangers, reboilers, and condensers in refinery and petrochemical plants
- Power Generation: Boiler economizers, superheaters, and steam generators
- Pharmaceutical & Food Processing: Sanitary heat exchangers requiring CIP (Clean-in-Place) compatibility
- Marine Engineering: Sea water cooling coils, ballast water heating systems
- Automotive Industry: Exhaust system components, turbocharger intercoolers
- Chemical Processing: Reactor jacket coils, distillation column reboilers
- HVAC Systems: Chilled water coils, condenser tubing in commercial refrigeration
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and holds the following certifications:
- ISO 9001:2015 – Quality Management System Certification
- ISO 14001:2015 – Environmental Management System Certification
- ISO 45001:2018 – Occupational Health and Safety Management System
- EN 10204 3.1 – Material Testing Certificate compliance
- ASME "S" Stamp – Authorized Manufacturer for Pressure Vessels and Piping
- API 5L / API 5CT – American Petroleum Institute certification for oil and gas applications
- PED 2014/68/EU – European Pressure Equipment Directive compliance
- NORSOK M-650 – Norwegian standard for oil and gas equipment (where applicable)
Unique Selling Points
1. Simulation-Validated Thermal Performance: Product designs are informed by rigorous numerical simulation of steam coil heating processes in large crude oil floating roof storage tanks, ensuring optimal thermal efficiency and heat distribution under real-world operating conditions.
2. Continuous Coil Manufacturing: The continuous cold winding process eliminates butt weld joints found in traditional coil assemblies, providing superior pressure containment integrity and reduced failure points.
3. Custom Geometric Configuration: Full customization of coil diameter, pitch, length, and end conditions allows precise integration into specific vessel geometries and process requirements.
4. Comprehensive Grade Selection: From standard 304/316L to advanced duplex and super-austenitic grades, accommodating the most aggressive chemical and thermal environments.
5. End-to-End Traceability: Full material traceability from ingot to finished coil, with comprehensive testing documentation at every production stage.
Wenzhou Jixing Metal Materials Co., Ltd. – Delivering precision-engineered stainless steel coil tube solutions for demanding industrial thermal applications worldwide.