Stainless Steel Coil Tube for Floating Roof Tank Heating Systems
Product Overview
The Stainless Steel Coil Tube (Coil Pipe) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered heat exchange element specifically designed for floating roof tank heating applications in the petrochemical and oil storage industries. This product represents a critical component in the thermal management systems of large-scale crude oil and refined product storage facilities, where maintaining consistent fluid viscosity and preventing product degradation under extreme ambient conditions is paramount.
Through rigorous numerical simulation studies of the floating roof tank coil heating process, Wenzhou Jixing has optimized the geometric configuration, material selection, and dimensional tolerances of this coil tube to achieve superior thermal efficiency, mechanical durability, and long-term operational reliability in demanding industrial environments.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel alloys, selected for their exceptional resistance to corrosion, thermal fatigue, and mechanical stress under continuous heating cycles.
- Primary Alloy Grades: AISI 304 (UNS S30400), AISI 316L (UNS S31603), and AISI 321 (UNS S32100)
- Corrosion Resistance: Superior resistance to pitting, crevice corrosion, and intergranular corrosion in hydrocarbon-containing environments
- Thermal Conductivity: Optimized thermal conductivity ranging from 14.9 to 16.3 W/(m·K) to ensure efficient heat transfer
- Mechanical Strength: Tensile strength of 515–720 MPa with elongation of 35–55%, providing excellent resistance to thermal cycling
- Temperature Range: Operational temperature range from –196 °C to 870 °C, accommodating extreme ambient and process conditions
- Surface Finish: Available in 2B, BA (Bright Annealed), and No. 4 finishes with surface roughness Ra ≤ 0.4 μm
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Coil Tube / Coil Pipe (盘管) |
| Product Code | 405 |
| Material Grade | 304 / 316L / 321 Stainless Steel |
| Outer Diameter (OD) | Φ 12 mm – Φ 60 mm (customizable) |
| Wall Thickness | 0.5 mm – 3.0 mm |
| Coil Pitch (Center-to-Center Spacing) | 25 mm – 150 mm |
| Coil Diameter (Mean) | Φ 300 mm – Φ 2,000 mm |
| Coil Length (Unwound) | Up to 200 m (continuous) |
| Number of Turns | Custom (typically 50 – 500 turns) |
| End Configuration | Threaded (NPT/BSP), Flanged, or Plain |
| Heat Transfer Medium | Hot water, steam, thermal oil |
| Maximum Operating Pressure | 1.6 MPa – 6.3 MPa |
| Maximum Operating Temperature | 250 °C (steam) / 350 °C (thermal oil) |
| Manufacturing Standard | ASTM A213 / ASTM A269 / EN 10216-5 / GB/T 14976 |
| Surface Treatment | Pickled & Passivated, optional epoxy coating |
Manufacturing Process
The production of the stainless steel coil tube follows a meticulously controlled multi-stage manufacturing process, informed by numerical simulation data to ensure optimal performance:
- Material Selection & Incoming Inspection: Stainless steel seamless tubes are procured from certified mills and subjected to spectroscopic analysis (OES), mechanical testing, and hydrostatic pressure testing to verify compliance with the specified alloy grade and mechanical properties.
- Dimensional Precision Cutting: Tubes are cut to precise lengths using CNC-controlled plasma or laser cutting systems, ensuring dimensional accuracy within ±0.5 mm tolerance.
- End Preparation: Tube ends are deburred, chamfered, and prepared for subsequent threading or flanging operations. Surface roughness is controlled to prevent flow restriction and corrosion initiation.
- Coil Forming (Rolling): The straight tube is mechanically formed into the designated coil geometry using CNC-controlled coil forming machines. The forming process employs controlled bending radii (minimum R ≥ 3D) to prevent wall thinning, ovality distortion, and material stress concentration. Numerical simulation data guides the optimization of coil pitch and mean diameter for maximum heat transfer efficiency.
- Welding & Joining: Where multiple coil sections are required, TIG (Tungsten Inert Gas) welding is employed with argon gas shielding to produce full-penetration welds. Weld joints are inspected via dye penetrant testing (DPT) or ultrasonic testing (UT).
- Pickling & Passivation: The completed coil assembly undergoes acid pickling (nitric-hydrofluoric acid mixture) followed by passivation treatment to remove welding oxides, restore the protective chromium oxide layer, and ensure maximum corrosion resistance.
- Pressure Testing: Each coil tube assembly undergoes hydrostatic pressure testing at 1.5 times the maximum operating pressure for a minimum hold time of 30 minutes to verify structural integrity and weld soundness.
- Final Inspection & Packaging: Finished products are inspected for dimensional accuracy, surface quality, and functional performance before being packaged with protective end caps, moisture-absorbing desiccants, and appropriate documentation.
Applications
The stainless steel coil tube is purpose-designed for the following industrial applications:
- Floating Roof Tank Heating: Primary application in heating heavy crude oil, bitumen, and high-viscosity refined products stored in floating roof tanks. The coil configuration maximizes the heat transfer surface area within the confined annular space of the tank, ensuring uniform thermal distribution and preventing localized overheating or underheating.
- Oil & Petrochemical Storage Facilities: Deployment in API 650 and API 620 compliant storage tanks for maintaining product flowability during cold weather conditions.
- Refinery Heat Recovery Systems: Integration into process heating loops where thermal oil or steam is circulated through the coil to maintain specified process temperatures.
- Chemical Processing Vessels: Application in reactor vessels and storage tanks requiring corrosion-resistant heating elements for aggressive chemical media.
- Marine Fuel Storage: Use in shipboard fuel oil tanks where space constraints and corrosion resistance requirements demand compact, durable heating solutions.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous 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
- API Q1 (API Specification Q1) – Quality Management Systems for Oil and Gas Industry
- PED 2014/68/EU – Pressure Equipment Directive Compliance (CE Marking)
- Material Compliance: ASTM, EN, GB standards with third-party material certification (MTC) per EN 10204 Type 3.1
- Testing Protocols: Hydrostatic testing, dimensional inspection, surface quality verification, and mechanical property testing performed per applicable standards
Unique Selling Points
The numerical simulation-driven design approach employed by Wenzhou Jixing distinguishes this coil tube product from conventional offerings in the market. By leveraging computational fluid dynamics (CFD) and finite element analysis (FEA) to model the thermal behavior of floating roof tank coil heating systems, the company achieves:
- Optimized Thermal Performance: Coil geometry (pitch, diameter, number of turns) is computationally optimized to maximize heat transfer coefficient and minimize thermal gradients, resulting in 15–25% improvement in heating efficiency compared to empirically designed alternatives.
- Reduced Thermal Stress: Simulation-informed material and geometry selection minimizes thermal stress concentrations, extending the service life of the coil tube under repeated heating and cooling cycles.
- Custom Engineering Capability: Tailored design solutions for specific tank dimensions, product viscosities, and ambient conditions, enabling optimal performance across a wide range of operational scenarios.
- Corrosion-Resistant Durability: Premium stainless steel alloys combined with controlled manufacturing processes ensure long-term reliability in aggressive hydrocarbon environments without the need for additional protective linings.
- Compact Footprint: The coiled configuration delivers maximum heat exchange surface area within minimal spatial volume, a critical advantage for retrofit applications and space-constrained installations.
- Traceable Quality: Full material traceability from mill certificate through final product, with comprehensive documentation supporting regulatory compliance and asset integrity management.