Stainless Steel Coil Tube for Waste Heat Boiler Retrofit Systems
Product Overview
The Stainless Steel Coil Tube (盘管, Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered continuous coiled tube product specifically designed for high-temperature waste heat recovery applications, including gasification waste heat boilers (Gasification Waste Heat Boiler Retrofit). This product serves as a critical heat exchange element in industrial thermal systems where extreme temperatures, corrosive flue gas environments, and sustained mechanical stress demand superior material performance and geometric consistency.
Unlike standard straight tubes, coil tubes offer significantly greater heat transfer surface area per unit volume, making them ideal for compact waste heat recovery units (WHRU), radiant sections of waste heat boilers, and gasification process heat exchangers. The continuous coil geometry eliminates weld joints along the tube length, thereby minimizing potential failure points under thermal cycling conditions.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel grades selected to withstand the harsh conditions encountered in gasification and waste heat recovery environments. Key material specifications include:
- Primary Grades: SUS310S (UNS S31008), SUS309S (UNS S30908), SUS321 (UNS S32100), and custom alloy compositions tailored to specific service conditions
- Chemical Composition: High chromium (Cr ≥ 25%) and nickel (Ni ≥ 19%) content ensuring excellent oxidation resistance and thermal stability at elevated temperatures
- Heat Resistance: Capable of sustained service temperatures up to 1,150°C (SUS310S) and intermittent exposure up to 1,200°C
- Corrosion Resistance: Superior resistance to sulfur-containing flue gases, molten ash deposition, and hot alkali corrosion
- Mechanical Properties: High tensile strength retention at elevated temperatures with excellent creep resistance and thermal fatigue endurance
- Thermal Conductivity: Optimized for efficient heat transfer between hot gas streams and working fluid (water/steam)
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管, Coiltube) |
| Product Code | 1644 |
| Material Grade | SUS310S / SUS309S / SUS321 / Custom Alloy |
| Outer Diameter (OD) | Φ25 mm – Φ108 mm (customizable) |
| Wall Thickness | 1.0 mm – 6.0 mm (customizable) |
| Coil Diameter | Φ0.5 m – Φ5.0 m (as per design requirement) |
| Coil Length | Continuous, up to 200 m per coil (seamless) |
| Surface Finish | Mill finish / Polished / Passivated |
| Maximum Service Temperature | 1,150°C (SUS310S) |
| Minimum Service Temperature | -196°C (cryogenic compatible) |
| Pressure Rating | Up to 4.0 MPa (design dependent) |
| Manufacturing Standard | ASTM A213 / ASTM A312 / GB/T 14976 / EN 10216 |
| Testing Standards | GB/T 246 / ASTM A269 / Hydrostatic Test / Spectroscopic Analysis |
| Applicable Standards | GB/T 13296 / ASME B36.19M / DIN 17457 |
Manufacturing Process
The production of high-performance stainless steel coil tubes follows a rigorous multi-stage manufacturing process to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection & Inspection: High-purity stainless steel billets or seamless pipe blanks are sourced from certified suppliers. Incoming material undergoes spectroscopic analysis (OES) to verify chemical composition compliance with the specified grade.
- Seamless Tube Formation: The parent tube is manufactured via the hot-rolling or cold-drawing process from seamless steel blanks, ensuring uniform wall thickness and the absence of longitudinal weld seams that could compromise structural integrity under thermal cycling.
- Hot Coiling / Spiral Bending: The seamless tube is heated to the optimal plastic deformation temperature range (typically 900–1,100°C for austenitic grades) and coiled onto a precision mandrel using a controlled spiral bending process. This ensures uniform curvature without wall thinning, distortion, or surface cracking.
- Cooling & Stress Relief: Post-coiling annealing (stress relief) is performed at controlled temperatures (typically 1,050–1,100°C for SUS310S) followed by controlled cooling to eliminate residual stresses introduced during the coiling process.
- Surface Treatment: The finished coil tube undergoes pickling and passivation treatment to remove scale, decarburization layers, and surface contaminants, restoring the full corrosion resistance of the stainless steel alloy.
- Quality Inspection & Testing: Comprehensive non-destructive testing (NDT) including eddy current testing, hydrostatic pressure testing, dimensional measurement (OD, wall thickness, coil diameter tolerance), and surface defect inspection is performed on every batch.
Applications
The stainless steel coil tube finds extensive application in high-temperature industrial thermal systems, with the following primary use cases:
- Gasification Waste Heat Boiler Retrofit: As demonstrated in the Guangzhou Nitrogen (Guangdan) gasification waste heat boiler retrofit project (广氮油气化盘管式废热锅炉改造), coil tubes serve as the primary heat exchange elements in retrofitting existing boiler systems to improve thermal efficiency and recover waste heat from gasification processes. The coil geometry enables compact installation within constrained retrofit spaces while maximizing heat absorption surface area.
- Gasification Process Heat Recovery: Used in integrated gasification combined cycle (IGCC) plants and coal gasification systems where waste heat from syngas must be recovered for steam generation.
- Petrochemical & Refinery Applications: Employed in furnace radiant sections, waste heat boilers, and fired heater coil systems in petroleum refining and petrochemical processing.
- Power Generation: Applied in waste heat recovery units (WHRU) of combined cycle power plants and industrial steam generation systems.
- Metal Smelting & Foundry: Used in heat exchangers for molten metal processing, aluminum smelting, and steel mill waste heat recovery.
- Chemical Processing: Deployed in high-temperature reactors, distillation columns, and process heat exchangers handling corrosive chemical media.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and holds the following certifications to ensure product reliability and compliance with international standards:
- 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 Q2 — Quality Management System for Petroleum, Petrochemical, and Natural Gas Industries
- EN 10204 — Material Test Certificates (Type 2.1 and 3.1 available upon request)
- Mill Test Certificates (MTC) — Full chemical analysis, mechanical test data, and dimensional verification provided with each shipment
- Third-Party Inspection — Available upon customer request (SGS, BV, DNV, Lloyd's Register)
Unique Selling Points
Seamless Continuous Coil Design: The absence of longitudinal weld seams provides superior mechanical integrity and eliminates potential leak paths in high-temperature, high-pressure waste heat recovery applications.
Retrofit-Optimized Geometry: Coil diameter and pitch are engineered to fit within existing boiler structural frameworks, enabling efficient retrofit projects without major structural modifications—directly addressing the challenges encountered in gasification waste heat boiler retrofit scenarios such as the Guangdan project.
Superior High-Temperature Performance: SUS310S/SUS309S grades provide exceptional oxidation resistance and strength retention at temperatures exceeding 1,000°C, ensuring long service life in gasification environments with thermal cycling.
Custom Engineering Capability: Full customization of coil diameter, tube dimensions, material grade, and surface finish to meet specific project requirements, supported by technical consultation and design assistance.
Comprehensive Quality Assurance: End-to-end traceability from raw material to finished product with full documentation including material certifications, dimensional reports, and NDT results.