Stainless Steel Coil Tube (盘管) – GLC-60-Ⅱ Series for Steam Boiler Applications
1. Product Overview
The Stainless Steel Coil Tube (盘管Coiltube) is a precision-engineered coiled tubing product manufactured by Wenzhou Jixing Metal Materials Co., Ltd, specifically designed for steam vehicle boiler systems, including the GLC-60-Ⅱ Type Steam Vehicle Coil Tube Boiler. This product line addresses the critical engineering challenges associated with scale formation (水垢处理) in high-temperature, high-pressure steam environments. The coil tube is formed into a continuous helical or serpentine configuration, optimizing heat transfer surface area while minimizing volumetric footprint within boiler casings.
These coil tubes are integral to indirect heating systems where thermal medium circulation must be efficient, corrosion-resistant, and mechanically durable under cyclic thermal loading. The product has been extensively studied and documented in technical literature concerning boiler scale treatment and maintenance protocols for the GLC-60-Ⅱ steam vehicle platform.
2. Material & Properties
2.1 Base Material Composition
The primary material grade for this coil tube product is Austenitic Stainless Steel, with the following standard compositions:
- 304 (S30408) – General-purpose grade with excellent corrosion resistance and formability
- 316 (S31608) – Enhanced pitting and crevice corrosion resistance due to Molybdenum addition
- 321 (S32108) – Stabilized grade with Titanium addition for high-temperature service
2.2 Mechanical Properties
- Tensile Strength (抗拉强度): ≥ 520 MPa (minimum)
- Yield Strength (屈服强度): ≥ 205 MPa (0.2% offset)
- Elongation (延伸率): ≥ 40%
- Impact Toughness (冲击韧性): ≥ 27 J at –40°C (Charpy V-Notch)
- Thermal Conductivity (热导率): 16.3 W/(m·K) at 100°C
- Thermal Expansion Coefficient (热膨胀系数): 17.3 × 10⁻⁶ /°C (20–100°C)
- Maximum Service Temperature (最高使用温度): 870°C (oxidation limit)
2.3 Corrosion Resistance
The austenitic microstructure provides superior resistance to:
- General aqueous corrosion in boiler feedwater environments
- Scaling and deposit-induced localized attack (水垢腐蚀)
- Intergranular corrosion (晶间腐蚀) following stabilization heat treatment
- Oxidation and scaling at elevated steam temperatures
3. Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Product Designation | GLC-60-Ⅱ Coil Tube | — |
| Outer Diameter (外径) | Φ14 – Φ51 mm | ASTM A213 / GB/T 12771 |
| Wall Thickness (壁厚) | 0.8 – 4.0 mm | ASTM A213 / GB/T 12771 |
| Coil Diameter (盘管直径) | 150 – 600 mm (configurable) | Custom per application |
| Tube Length per Coil (单圈管长) | 5 – 50 m (continuous coil) | — |
| Material Grade (材质) | SUS304 / SUS316 / SUS321 | ASTM A213 TP304/316/321 |
| Surface Finish (表面状态) | BA (Bright Annealed) / No.4 / 2B | — |
| Pressure Rating (承压等级) | Up to 1.6 MPa (operating) | GB/T 150 |
| Steam Temperature Range (蒸汽温度范围) | 100 – 250°C | — |
| End Connection (端部连接) | Welded / Threaded / Flanged | ASME B16.5 |
| Applicable Boiler Type (适用锅炉型号) | GLC-60-Ⅱ Steam Vehicle Boiler | — |
| Coating / Passivation (涂层/钝化) | Passivated (钝化处理) – Cr₂O₃ film | ASTM A967 |
| Standards Compliance (标准符合性) | ASTM A213, GB/T 12771, EN 10216-5 | — |
4. Manufacturing Process
The production of the GLC-60-Ⅱ series coil tube involves a multi-stage manufacturing sequence designed to ensure dimensional accuracy, metallurgical integrity, and long-term service reliability:
- Strip Preparation (带材准备): Cold-rolled stainless steel strip (冷轧带钢) is inspected for surface quality, dimensional tolerance, and chemical composition verification via XRF (X-Ray Fluorescence) analysis.
- Spiral Forming (螺旋成型): The flat strip is wound through precision forming rollers to achieve the specified outer diameter and wall thickness. The forming process maintains controlled strain distribution to prevent work-hardening in localized zones.
- Seam Welding (焊缝焊接): High-frequency induction welding (高频感应焊接) or TIG (Tungsten Inert Gas) welding is applied to create the longitudinal seam. Weld parameters are optimized to achieve full penetration and a smooth internal weld profile (内焊道平整度).
- Coil Winding (盘管绕制): The formed tube is wound onto a precision mandrel to create the final coil geometry. Tension and curvature are controlled to prevent kinking or ovality exceeding ±2% of nominal OD.
- Solution Annealing (固溶退火): The welded coil tube is subjected to solution annealing at 1050–1100°C followed by rapid quenching to restore full austenitic microstructure, dissolve carbides, and achieve optimal corrosion resistance.
- Pickling & Passivation (酸洗钝化): The annealed coil is immersed in a mixed acid solution (HNO₃ + HF) to remove oxide scale, followed by passivation treatment to establish a protective chromium oxide (Cr₂O₃) surface film. This is critical for resistance against boiler scale adhesion.
- Hydrostatic Testing (水压试验): Each coil assembly undergoes hydrostatic pressure testing at 1.5× the maximum design pressure to verify weld integrity and dimensional soundness.
- Final Inspection & Packaging (终检与包装): Dimensional verification, surface inspection (目视检验), and protective packaging prior to dispatch.
5. Applications
The GLC-60-Ⅱ Stainless Steel Coil Tube serves in the following primary application domains:
- Steam Vehicle Boiler Systems (蒸汽机车锅炉系统): Primary heating element in GLC-60-Ⅱ type locomotive boilers, providing indirect heat exchange between combustion gases and boiler water.
- Industrial Process Heating (工业过程加热): Coil heat exchangers in chemical processing, food processing, and pharmaceutical manufacturing requiring sanitary-grade heat transfer surfaces.
- Boiler Scale Treatment Systems (锅炉水垢处理系统): The coil tube design facilitates effective chemical scale removal (除垢) through enhanced fluid dynamics and accessible geometry for cleaning agents.
- Marine Auxiliary Boilers (船用辅助锅炉): Corrosion-resistant heating coils in seawater-exposed marine environments where 316-grade material is specified.
- Energy Storage Systems (能量存储系统): Thermal energy storage vessels utilizing coil tubes for heat transfer medium circulation.
6. Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains the following quality management and product certifications:
- ISO 9001:2015 – Quality Management System (质量管理体系)
- ISO 14001:2015 – Environmental Management System (环境管理体系)
- ASME "S" Stamp – Pressure Vessel Code certification (where applicable)
- CE Marking – Conformity with European Pressure Equipment Directive (PED 2014/68/EU)
- NACE MR0175 – Compliance for sour service applications (where 316 grade is specified)
- Mill Test Certificates (MTC) – EN 10204 Type 3.1 / ASTM E997 material traceability documentation
- NDT Testing (无损检测): 100% eddy current testing (涡流检测) on weld seams; radiographic testing (RT, 射线检测) on sample lots per AQL protocol
7. Unique Selling Points
- Scale-Resistant Surface Engineering (抗垢表面工程): The passivated BA surface finish significantly reduces scale nucleation sites, extending cleaning intervals and reducing maintenance downtime in GLC-60-Ⅱ boiler operations.
- Precision Coil Geometry (精密盘管几何): Tolerance-controlled winding ensures uniform heat transfer distribution and predictable pressure drop characteristics across the coil assembly.
- Full Material Traceability (全材料可追溯性): Each coil tube is accompanied by complete mill test documentation, enabling lifecycle corrosion monitoring and maintenance planning.
- Custom Configuration Capability (定制配置能力): Coil diameter, tube dimensions, material grade, and end connections are customizable to specific boiler design requirements.
- Thermal Cycling Durability (热循环耐久性): The austenitic microstructure provides excellent resistance to thermal fatigue under repeated heating and cooling cycles inherent in steam boiler operations.
Technical Note: For GLC-60-Ⅱ steam vehicle boiler applications involving aggressive water chemistry or high scaling tendencies, a minimum wall thickness of 2.0 mm and 316L (low-carbon) grade are recommended to ensure a service life exceeding 10,000 operating hours with periodic scale treatment (水垢处理) intervals.