Stainless Steel Water-Cooled Wall Coil Tube — Industrial Furnace Application
Product Overview
The Stainless Steel Coil Tube (Model Reference: No. 606) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubular product specifically designed for water-cooled wall (Water-Cooled Wall, WCW) systems in industrial combustion furnaces. This coil tube serves as a critical thermal barrier component within combined burner assemblies (Combined Burner System), providing essential cooling protection to furnace refractory linings and structural steel while simultaneously facilitating efficient heat transfer through circulating coolant media.
The product is engineered to withstand extreme thermal cycling conditions, high-temperature radiative heat fluxes, and prolonged exposure to corrosive combustion byproducts. Its serpentine coil configuration maximizes the heat exchange surface area within a compact spatial envelope, making it an indispensable component in continuous industrial heating processes.
Material & Properties
Base Alloy Composition
The coil tube is fabricated from austenitic stainless steel grades conforming to international metallurgical standards. The primary material specifications include:
- Grade 304 (UNS S30400) — General corrosion resistance, suitable for moderate-temperature applications up to 870°C (1600°F)
- Grade 310S (UNS S31008) — Elevated temperature resistance, sustained service up to 1150°C (2100°F), enhanced oxidation resistance
- Grade 321 (UNS S32100) — Titanium-stabilized variant offering superior resistance to intergranular corrosion and thermal fatigue
- Grade 347 (UNS S34700) — Niobium-stabilized grade providing enhanced creep strength at elevated temperatures
Mechanical Properties (Typical — Grade 310S)
- Tensile Strength (Ultimate Tensile Strength, UTS): ≥ 515 MPa (75 ksi)
- Yield Strength (0.2% Proof Stress): ≥ 205 MPa (30 ksi)
- Elongation at Break: ≥ 40%
- Thermal Conductivity (at 100°C): 16.3 W/(m·K)
- Thermal Expansion Coefficient (20–100°C): 17.3 × 10⁻⁶ /°C
- Specific Heat Capacity: 0.50 J/(g·K)
- Maximum Service Temperature: 1150°C (2100°F) continuous; 1200°C (2192°F) intermittent
Corrosion Resistance Characteristics
- Outstanding resistance to oxidation and scaling in oxidizing atmospheres up to 1150°C
- Resistance to sulfidation under reducing conditions
- Immunity to general acid corrosion in non-oxidizing environments
- Excellent resistance to thermal cycling without loss of mechanical integrity
Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Product Type | Seamless / Welded Stainless Steel Coil Tube | — |
| Outer Diameter (OD) | 18 mm – 50 mm (customizable) | ASTM A213 / A269 |
| Wall Thickness | 1.5 mm – 4.0 mm | ASTM A213 / A269 |
| Coil Bend Radius | ≥ 5× OD (minimum) | Internal Design Specification |
| Coil Length (Developed) | Up to 120 m per assembly (customizable) | — |
| Surface Finish | Pickled & Passivated (2B) or Polished (No. 4) | ASTM A403 |
| Tolerance on OD | ±0.10 mm | ASTM A213 |
| Tolerance on Wall Thickness | ±10% of nominal | ASTM A213 |
| Operating Pressure (Design) | Up to 2.5 MPa (363 psi) | ASME BPV Section VIII |
| Coolant Flow Rate (Typical) | 0.8 – 3.0 m³/h depending on configuration | — |
| End Connections | Threaded (NPT/BSP), Flanged, or Butt-Weld (BW) | ASME B16.5 / B1.20.1 |
| Heat Treatment | Solution Annealing at 1010–1150°C followed by water quench | ASTM A213 |
Manufacturing Process
Process Flow
- Raw Material Selection & Inspection: Certified stainless steel bars or seamless tubes are sourced from approved mills with full traceability documentation (Mill Test Certificate, MTC). Incoming material undergoes spectrographic analysis to verify chemical composition within specified limits.
- Piercing & Seamless Tube Forming: For seamless variants, heated billets are pierced through a mandrel in a rotary piercing mill, followed by elongation and reduction passes to achieve the target OD and wall thickness dimensions.
- Cold Drawing / Cold Rolling: The tube blank is drawn through precision-die tooling to achieve tight dimensional tolerances, improved surface finish, and enhanced mechanical properties through work hardening.
- Intermediate Annealing: Periodic solution annealing is performed during cold working to relieve accumulated residual stresses and restore ductility for subsequent forming operations.
- Coil Forming (Tube Bending): Using CNC-controlled mandrel bending machines, the straight tube is precisely formed into the serpentine coil geometry. The bending process employs a hardened mandrel plug to prevent ovality and wall thinning at bend radii. Bend tolerance is maintained within ±1.5° per revolution.
- Final Solution Annealing & Pickling: The formed coil assembly undergoes final solution heat treatment in a controlled-atmosphere furnace to eliminate all residual stresses introduced during forming. Subsequent acid pickling removes surface oxide scale, followed by passivation to establish a protective chromium oxide layer.
- Hydrostatic Pressure Testing: Each coil tube assembly is subjected to hydrostatic pressure testing at 1.5× the design operating pressure for a minimum dwell time of 30 minutes to verify structural integrity and weld soundness.
- Non-Destructive Testing (NDT): Eddy current testing (ECT) and ultrasonic testing (UT) are performed to detect surface and subsurface defects. Radiographic testing (RT) may be applied to weld joints where applicable.
- Dimensional Inspection & Final Quality Assurance: Comprehensive dimensional verification including OD, wall thickness, bend radius, and overall developed length. Surface quality is inspected for scratches, dents, or discoloration.
Applications
The Stainless Steel Water-Cooled Wall Coil Tube is deployed across a wide range of high-temperature industrial processes where refractory protection and controlled heat extraction are critical:
- Industrial Furnace Water-Cooled Walls: Primary application in regenerative and recuperative furnaces, providing a sacrificial cooling barrier that protects furnace shell steel from radiant heat flux exceeding 100 kW/m².
- Combined Burner Assemblies: Integrated into burner throat cooling systems where the coil tube absorbs and dissipates flame impingement heat, extending burner refractory life by 3–5×.
- Heat Treatment Furnaces: Used in annealing, quenching, and tempering furnaces for continuous steel processing lines.
- Aluminum & Non-Ferrous Metal Melting Furnaces: Cooling walls in pot furnaces and channel furnaces operating at 650–750°C.
- Glass Industry Furnaces: Application in glass melting furnaces where thermal stability and resistance to alkali vapor corrosion are paramount.
- Cement Kiln Pre-Calcination Systems: Cooling panels in preheater towers and calcination zones.
- Power Generation: Water-cooled panels in waste heat recovery boilers and boiler furnace walls.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems and adheres to the following international standards and certifications:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control
- ISO 14001:2015 — Environmental Management System for sustainable manufacturing practices
- ASTM A213 — Standard Specification for Seamless and Welded Austenitic Cr-Ni Stainless Steel Tubing for High-Temperature Service
- ASTM A269 — Standard Specification for Seamless and Welded Austenitic Chromium-Chromium-Nickel Stainless Steel Tubes
- ASTM A403 — Standard Specification for Stainless Steel Bar and Shapes for General Application
- EN 10216-5 — European standard for non-ferrous metallic tubes for pressure purposes
- JIS G3459 — Japanese Industrial Standard for austenitic stainless steel tubes for general purposes
- ASME BPV Code Section VIII — Div. 1, pressure vessel and piping design compliance
- Mill Test Certificates (MTC) — EN 10204 Type 3.1 certified documentation provided with every shipment
Unique Selling Points
- Precision Coil Geometry: CNC-controlled bending ensures repeatable coil configurations with minimal variation, enabling seamless integration into existing furnace designs and reducing installation labor.
- Full Traceability: Each product batch carries complete metallurgical traceability from raw material mill through final inspection, supporting regulatory compliance in critical industrial applications.
- Custom Engineering Capability: Flexible design services accommodate non-standard OD, wall thickness, coil pitch, and total developed length requirements tailored to specific furnace thermal profiles.
- Extended Service Life: Solution-annealed microstructure provides superior resistance to thermal fatigue cracking and intergranular corrosion, significantly reducing maintenance intervals and unplanned downtime.
- Cost-Effective Total Ownership: While initial material cost is premium, the extended service life (typically 8–15 years vs. 2–4 years for carbon steel alternatives) and reduced maintenance frequency deliver superior life-cycle cost performance.
Technical Note: The maintenance and inspection protocols for water-cooled wall coil tubes in combined burner systems require periodic flow rate monitoring, pressure differential measurement across coil assemblies, and visual inspection of external surfaces for signs of scaling, oxidation spalling, or mechanical damage. Recommended inspection intervals are 6 months for active service and annually for standby units. Any deviation in pressure drop exceeding ±15% from baseline values warrants immediate investigation for internal scaling or blockage.