Stainless Steel Coil Tube for Waste Heat Boiler 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 waste heat recovery systems and waste heat boiler (Waste Heat Boiler, WHB) applications. These coil tubes are formed from high-quality stainless steel strip through cold-rolling, welding, and coiling processes, delivering the thermal efficiency, corrosion resistance, and mechanical integrity required in high-temperature exhaust gas environments.
Coil tubes serve as the core heat exchange elements in waste heat boilers, where they absorb thermal energy from high-temperature flue gases (typically ranging from 300°C to 900°C) and transfer it to a working fluid (water or steam). The serpentine coiled configuration maximizes the heat transfer surface area within a compact footprint, making these tubes indispensable in industrial energy recovery systems.
Material & Properties
Coil tubes for waste heat boiler applications are fabricated from austenitic and duplex stainless steel grades selected for their exceptional resistance to thermal cycling, oxidation, and corrosion under harsh industrial conditions.
- Common Grades: AISI 304 (S30408), AISI 316L (S31603), AISI 321 (S32101), AISI 347 (S34701), AISI 310S (S31008), and Duplex 2205 (S31803)
- Tensile Strength: Typically 505–720 MPa, depending on grade and heat treatment
- Yield Strength: Minimum 205 MPa (for annealed austenitic grades)
- Maximum Service Temperature: Up to 870°C (AISI 310S); up to 450°C (AISI 304/316L)
- Corrosion Resistance: Excellent resistance to intergranular corrosion, pitting, and stress corrosion cracking (SCC) in chloride-containing environments
- Thermal Conductivity: 14.6–22.9 W/(m·K), optimized for efficient heat transfer
- Carbon Equivalent (CE): < 0.04% for low-carbon grades (304L, 316L), ensuring weldability and resistance to sensitization
- Surface Finish: 2B, BA (Bright Annealed), or No. 4 finish, depending on application requirements
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product Code | 1530 |
| Material Grades | AISI 304, 304L, 316L, 321, 347, 310S, 2205 |
| Outer Diameter (OD) | 12 mm – 108 mm (customizable) |
| Wall Thickness | 0.5 mm – 4.0 mm |
| Coil Diameter | Min. 200 mm – Max. 2000 mm (customizable) |
| Coil Length | Up to 2000 m per coil (continuous production) |
| Welding Process | TIG (Tungsten Inert Gas) Welding / Laser Welding |
| Weld Seam Finish | Smooth, burr-free; internal/external grinding available |
| Temperature Range | -196°C to +870°C (grade-dependent) |
| Pressure Rating | Up to 4.0 MPa (design dependent) |
| Standards Compliance | ASTM A213, ASTM A269, EN 10216-5, GB/T 12771 |
| Surface Treatment | Pickling & Passivation; optional electropolishing |
| Customization | Coil pitch, diameter, tube layout, and end fittings customizable per engineering drawings |
Manufacturing Process
The manufacturing of stainless steel coil tubes for waste heat boilers follows a rigorous multi-stage process to ensure dimensional accuracy, metallurgical integrity, and long-term service reliability:
- Raw Material Selection & Inspection: Stainless steel strip is sourced from certified mills and subjected to spectroscopic analysis, visual inspection, and mechanical testing to verify compliance with specified grade requirements.
- Slitting & Leveling: The strip is slit to the required width and leveled to eliminate residual stresses and ensure flatness prior to forming.
- Forming (Rolling): The leveled strip is fed through a series of precision rolls to form a circular tube profile. Multi-stand roll forming ensures uniform wall thickness and dimensional consistency.
- Welding: The formed tube is longitudinally welded using TIG welding with argon shielding gas, or via high-precision laser welding for superior weld quality. The welding parameters are carefully controlled to minimize heat-affected zone (HAZ) distortion and maintain metallurgical homogeneity.
- Weld Seam Finishing: The longitudinal weld seam is ground and polished to achieve a smooth, burr-free finish on both the internal and external surfaces, critical for fluid flow and heat transfer efficiency.
- Coiling: The continuous welded tube is coiled at a controlled speed and diameter using a hydraulic coil winder. The coiling process is designed to prevent tube deformation, ovality, or kinking.
- Heat Treatment (if required): Solution annealing (1050°C–1150°C with water quench) may be performed to relieve residual stresses and restore full austenitic microstructure for grades requiring enhanced corrosion resistance.
- Pickling & Passivation: The coil tube is treated with a mixed acid solution (HNO₃/HF) to remove oxide scale, followed by passivation to form a stable chromium oxide protective layer.
- Quality Control & Testing: Each coil undergoes dimensional inspection, hydrostatic pressure testing, chemical composition verification, and visual/non-destructive testing (NDT) including dye penetrant inspection (DPI) or eddy current testing (ECT) of weld seams.
- Coil Layout & Fabrication (for boiler integration): The coil tube is laid out according to engineering drawings in serpentine or helical configurations, with support structures and connection headers fabricated and welded as required.
The coil tube manufacturing process for waste heat boilers demands particular attention to weld quality, dimensional tolerance, and thermal stability. Unlike standard process tubes, coil tubes must maintain their geometric integrity under repeated thermal cycling, making weld integrity and material selection paramount.
Applications
Stainless steel coil tubes from Wenzhou Jixing Metal Materials Co., Ltd. are deployed across a broad spectrum of industrial waste heat recovery applications:
- Waste Heat Boilers (WHB): Primary heat exchange elements for recovering thermal energy from industrial furnace exhaust gases, generating process steam for power generation or heating.
- Cement Kiln Systems: Coil tubes used in preheater towers and waste heat recovery units to capture heat from kiln exhaust gases (typically 300°C–400°C).
- Steel Mill Applications: Heat recovery from blast furnace gas (BFG), basic oxygen furnace (BOF) off-gas, and coke oven gas (COG) systems.
- Petrochemical & Refinery Plants: Waste heat recovery from catalytic cracker units, reformers, and flaring systems.
- Power Generation: Auxiliary waste heat recovery systems in combined cycle power plants and industrial cogeneration (CHP) facilities.
- Food & Pharmaceutical Processing: Steam generation for process heating where high purity and corrosion resistance are required.
- Marine & Offshore: Waste heat recovery from marine engine exhaust systems and offshore platform gas processing.
- Glass & Ceramic Industry: Heat recovery from furnace off-gases in continuous production lines.
Quality Certifications & Standards
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system to ensure product reliability and regulatory compliance:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO 45001:2018 — Occupational Health & Safety Management System
- EN 10204 — Type 3.1 Mill Test Certificates (MTC) provided with every shipment
- ASTM A213 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for High Temperature Service
- ASTM A269 — Standard Specification for Seamless, Welded, and Heavy-Walled Austenitic Stainless Steel Pipes
- ASME Section VIII — Compliance for pressure vessel applications
- CE Marking — European Conformity for products supplied to EU markets
- NB Inspection — National Supervision Bureau certification for pressure equipment in China
Unique Selling Points
- Customizable Coil Geometry: Coil diameter, pitch, tube layout, and total length can be tailored to specific boiler designs, enabling optimized heat transfer surface area within constrained installation spaces.
- Superior Weld Integrity: TIG and laser welding processes with controlled shielding gas coverage ensure weld seams that match or exceed the mechanical and corrosion properties of the base metal.
- Wide Grade Selection: From standard austenitic (304/316L) to high-temperature (310S) and duplex (2205) grades, accommodating service temperatures from cryogenic to 870°C.
- Continuous Production Capability: Up to 2000 m per coil, reducing field welding joints and minimizing potential leak points in waste heat boiler installations.
- End-to-End Engineering Support: From material selection consultation through coil layout design, manufacturing, and on-site installation guidance.
- Rigorous Quality Assurance: Multi-stage inspection protocols including hydrostatic testing, NDT of welds, dimensional verification, and full traceability documentation.
Wenzhou Jixing Metal Materials Co., Ltd. leverages decades of expertise in stainless steel tubing manufacturing to deliver coil tube solutions that maximize energy recovery efficiency, minimize maintenance costs, and extend service life in demanding waste heat boiler environments. For detailed engineering specifications and custom quotations, please contact our technical sales team directly.