304/316L Stainless Steel Coil Tube for Tank Heating & Cooling Systems
Product Overview
The 304/316L Stainless Steel Coil Tube is a purpose-engineered solution designed for temperature maintenance and cooling applications within storage tanks in the petroleum and chemical industries. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., these coil tubes are specifically formulated to withstand the demanding conditions of intermittent operation cycles, ensuring reliable thermal regulation of stored media while maintaining long-term structural integrity in aggressive chemical environments.
These coil tubes serve as critical heat transfer elements in tank heating and cooling systems, enabling precise control of medium temperatures during both active operation and shutdown periods. The product addresses a key industry challenge—corrosion caused by residual water accumulation during non-operational intervals—through strategic material selection and manufacturing optimization.
Material & Properties
Available in two premium austenitic stainless steel grades, these coil tubes offer exceptional corrosion resistance and thermal performance:
- Grade 304 (UNS S30408): The standard choice for moderate corrosive environments. Offers excellent weldability, formability, and resistance to atmospheric and mild chemical corrosion. Ideal for hydrocarbon storage applications where chloride exposure is limited.
- Grade 316L (UNS S31603): The enhanced option featuring 2–3% molybdenum content, providing superior resistance to pitting and crevice corrosion. Particularly recommended for applications involving chlorinated media, acidic compounds, or environments where residual water accumulation during shutdown periods poses elevated corrosion risk.
Key Material Properties
| Property | Grade 304 | Grade 316L |
|---|---|---|
| Carbon (max) | 0.08% | 0.03% |
| Chromium | 18.0–20.0% | 16.5–18.5% |
| Nickel | 8.0–10.5% | 10.0–14.0% |
| Molybdenum | — | 2.0–3.0% |
| Tensile Strength (min) | 515 MPa | 485 MPa |
| Yield Strength (min) | 205 MPa | 170 MPa |
| Operating Temperature Range | -196°C to 870°C | -196°C to 870°C |
| Thermal Conductivity | 16.3 W/(m·K) | 16.3 W/(m·K) |
Specifications
| Parameter | Specification |
|---|---|
| Tube Type | Welded Coil Tube (盘管) |
| Available Grades | SUS 304, SUS 316L |
| Outer Diameter | 12.7 mm – 108 mm (custom sizes available) |
| Wall Thickness | 0.8 mm – 6.0 mm |
| Coil Diameter | 300 mm – 5000 mm (customizable per tank geometry) |
| Coil Length | Up to 5000 m per coil (continuous) |
| Surface Finish | No. 4 Brushed / 2B Annealed / Custom |
| Welding Process | Automatic Argon Arc (TIG) / Laser Welding |
| Standard Compliance | ASTM A213 / ASME SA-213 / EN 10216-5 |
| Operation Mode | Intermittent / Continuous |
| Pressure Rating | Up to 4.0 MPa (depending on dimensions) |
Manufacturing Process
Wenzhou Jixing Metal Materials Co., Ltd. employs a rigorous multi-stage manufacturing process to ensure coil tube quality and performance:
- Raw Material Selection: Only certified mill-fresh stainless steel strip from accredited suppliers is used, with full traceability documentation and incoming chemical/spectroscopic verification.
- Slitting & Edge Preparation: Precision slitting to exact coil tube dimensions with burr-free edge treatment to prevent stress concentration points.
- Coiling & Forming: High-precision coiling equipment forms the strip into seamless helical coils with controlled coil diameter and pitch, ensuring uniform geometry.
- Welding: Automatic longitudinal welding using inert-gas-shielded processes (TIG or laser) with real-time weld monitoring, producing strong, leak-tight weld seams.
- Solution Annealing: Post-weld annealing at 1050–1100°C followed by controlled cooling to restore full austenitic structure, eliminate residual stresses, and maximize corrosion resistance.
- Pickling & Passivation: Chemical pickling removes oxide scale, followed by passivation treatment to establish a protective chromium oxide layer—critical for resisting shutdown-period water corrosion.
- Quality Inspection: 100% dimensional inspection, hydrostatic pressure testing, and visual/spectroscopic verification of material grade compliance.
Applications
These coil tubes are specifically engineered for the following storage and transportation facility applications within the petroleum and chemical industry:
- Storage Tank Heating Coils: Maintaining the temperature of viscous hydrocarbons, polymers, and specialty chemicals to ensure flowability and prevent solidification during storage.
- Storage Tank Cooling Coils: Regulating temperatures of exothermic or temperature-sensitive stored media to prevent degradation, vapor pressure buildup, or thermal runaway.
- Intermittent Operation Systems: Designed for tanks that experience regular start-stop cycles, where thermal cycling and wet-dry alternation impose additional material demands.
- Process Vessel Auxiliary Heating/Cooling: Supplementary thermal management for reactors, mixing vessels, and intermediate storage units.
Unique Selling Points
- Shutdown Corrosion Mitigation: The passivation treatment and low-carbon composition of 316L grade specifically address the critical industry pain point of residual water corrosion during tank shutdown periods, extending service life significantly.
- Intermittent Operation Durability: Engineered to withstand repeated thermal cycling without fatigue degradation, making these coils ideal for facilities with variable operating schedules.
- Continuous Coil Supply: Delivered as continuous coils up to 5000 meters, minimizing field splices and reducing potential leak points in the final installation.
- Customizable Geometry: Coil diameter, tube dimensions, and pitch are tailored to specific tank configurations, optimizing heat transfer efficiency for each application.
- Full Traceability: Every coil is accompanied by mill certificates, chemical analysis reports, and test documentation ensuring complete supply chain transparency.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management and certification frameworks:
- ISO 9001:2015 Quality Management System Certification
- ISO 14001:2015 Environmental Management System Certification
- Product compliance with ASTM, ASME, EN, and GB standards
- Third-party inspection available (SGS, BV, Lloyd's)
- Full material traceability with EN 10204 3.1 mill test certificates
- Hydrostatic pressure test reports provided per coil
- Corrosion resistance testing (ASTM A967 passivation verification)
Recommendation: For applications where tanks experience frequent shutdown periods with potential water ingress, Grade 316L is strongly recommended over Grade 304 to maximize resistance against chloride-induced pitting and crevice corrosion during idle intervals. Both grades should be supplied with factory-applied passivation treatment and stored in dry conditions prior to installation.