Stainless Steel Coil Tube (Coiltube) for Marine Heat Medium Boiler Systems
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a specialized continuous-length tubing product engineered for demanding marine and offshore facility applications, particularly in heat medium boiler systems. Coil tubes are formed into continuous helical or serpentine configurations that maximize heat transfer surface area within confined volumes, making them indispensable in marine thermal management infrastructure.
Unlike straight-length tubing, coil tubes offer superior thermal efficiency, reduced pressure drop, and enhanced resistance to thermal cycling fatigue. This product line addresses the critical challenge of corrosion resistance in marine environments where heat medium boilers are exposed to aggressive atmospheric conditions, high salinity, and fluctuating thermal loads.
Material & Properties
The coil tubes are fabricated from premium austenitic stainless steel grades, selected specifically for their exceptional resistance to pitting, crevice corrosion, and intergranular corrosion in marine thermal service environments.
Available Material Grades
- Austenitic Stainless Steel (奥氏体不锈钢): SUS304 (UNS S30408), SUS316 (UNS S31608), SUS316L (UNS S31603)
- Super Austenitic Stainless Steel (超级奥氏体不锈钢): SUS317L (UNS S31703), Alloy 2204 (UNS S32205)
- Duplex Stainless Steel (双相不锈钢): 2205 (UNS S32205), 2507 (UNS S32750)
- Heat-Resistant Stainless Steel (耐热不锈钢): SUS310S (UNS S31008), SUS309S (UNS S30908)
Key Mechanical Properties (Typical for Grade 316L)
| Property | Unit | Specification |
|---|---|---|
| Tensile Strength (抗拉强度) | MPa | ≥ 485 |
| Yield Strength (屈服强度) | MPa | ≥ 205 |
| Elongation (延伸率) | % | ≥ 40 |
| Hardness (硬度) | HV | ≤ 200 |
| Operating Temperature Range (工作温度范围) | °C | -196 to +870 |
| Thermal Conductivity (热导率) | W/(m·K) | 14.5 (at 100°C) |
| Pitting Resistance Number (PREN) | — | ≥ 24 (for 316L) |
Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (外径, OD) | Φ3.0 mm – Φ159.0 mm |
| Wall Thickness (壁厚, WT) | 0.3 mm – 12.0 mm |
| Coil Length (盘管长度) | 5 m – 500 m (continuous) |
| Coil Bend Radius (弯曲半径) | ≥ 3D (OD-based) |
| Surface Finish (表面状态) | 2B, BA (Bright Annealed), No. 4 Brushed, Mirror |
| End Condition (端部状态) | Plain end, Beveled, Threaded, Flanged |
| Heat Treatment (热处理) | Solution Annealed (固溶处理), Pickled & Passivated (酸洗钝化) |
| Applicable Standards (执行标准) | ASTM A213, ASTM A269, ASME SA-213, EN 10216-5, GB/T 12771 |
| Design Pressure (设计压力) | Up to 4.0 MPa (configurable) |
| Design Temperature (设计温度) | Up to 450°C (heat medium service) |
Manufacturing Process
The production of marine-grade stainless steel coil tubes follows a rigorous multi-stage manufacturing process to ensure dimensional accuracy, metallurgical integrity, and corrosion resistance:
- Raw Material Selection (原材料选择): Only certified stainless steel seamless or welded pipe stock from approved mills is accepted, with full mill test certificates (MTC) verified against ASTM/EN specifications.
- Dimensional Inspection (尺寸检验): Incoming pipe undergoes ultrasonic testing (UT), dimensional measurement, and visual inspection to ensure compliance with tolerance requirements (±0.1 mm OD, ±10% WT).
- Coil Forming (盘管成型): Cold bending or warm bending processes are employed using precision CNC coil forming machines. The bend radius is controlled to prevent wall thinning (<10% reduction) and avoid material work hardening at bend zones.
- Heat Treatment (热处理): Solution annealing at 1050–1150°C followed by rapid water quenching restores full austenitic structure, eliminates residual stresses, and maximizes corrosion resistance.
- Pickling & Passivation (酸洗钝化): The coil tube is subjected to acid pickling (mixed acid: HNO₃/HF) to remove surface scale and oxidation, followed by passivation to form a stable chromium oxide protective film.
- Non-Destructive Testing (无损检测): 100% visual inspection, magnetic particle inspection (MT) or eddy current testing (ET) for surface defects, and hydrostatic testing at 1.5× design pressure to verify weld integrity and dimensional accuracy.
- Quality Control & Packaging (质量控制与包装): Final dimensional verification, chemical composition analysis (OES), mechanical property testing, and protective packaging with moisture-absorbing desiccants for marine transport.
Applications
The stainless steel coil tubes are purpose-engineered for the following critical applications:
- Marine Heat Medium Boilers (海上设施热介质锅炉): Primary heat exchanger coil elements in thermal oil systems aboard offshore platforms, LNG carriers, and naval vessels.
- Offshore Platform Utility Systems (海上平台公用系统): Steam generation, hot water supply, and thermal oil circulation systems on fixed and floating production platforms.
- Chemical Processing Vessels (化工反应装置): Jacketed reactor coils, reboilers, and condensers in petrochemical and pharmaceutical marine facilities.
- Power Generation (发电系统): Waste heat recovery systems and auxiliary steam coils in marine power plants.
- Corrosive Environment Heat Exchangers (腐蚀性环境换热器): Applications involving seawater cooling, acid service, and high-chloride environments where carbon steel replacement is required.
- Replacement & Maintenance (维修更换): Retrofit solutions for corroded coil tubes in existing marine boiler installations, addressing the critical maintenance challenges documented in industry literature on marine facility heat medium boiler coil tube corrosion repair.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and holds the following certifications to ensure product reliability for marine and offshore service:
- ISO 9001:2015 — Quality Management System Certification (质量管理体系认证)
- ISO 14001:2015 — Environmental Management System (环境管理体系认证)
- ISO 45001:2018 — Occupational Health & Safety Management (职业健康安全管理体系)
- EN 10204 Type 3.1 — Inspection Certificate (检验证书)
- ASTM International — Member compliance with ASTM A213, A269, A312 standards
- Class Society Approval (船级社认证): Products suitable for approval by CCS (China Classification Society), DNV, ABS, Lloyd's Register, and other major classification societies
- NSF/ANSI Standards — Available for potable water and food-grade applications
- Mill Test Certificate (MTC): Full chemical analysis (C, Si, Mn, P, S, Cr, Ni, Mo, etc.) and mechanical property verification per EN 10204 3.1
Unique Selling Points
Engineered for Marine Corrosion Resistance: The coil tubes are specifically designed to address the documented corrosion failure modes of heat medium boiler coils in marine environments, including chloride-induced pitting, stress corrosion cracking (SCC), and thermal fatigue degradation. The material selection and manufacturing process incorporate lessons learned from field failure analysis of marine boiler coil tube systems.
- Continuous Length Advantage: Single-piece coil construction eliminates in-line welds, significantly reducing leak points and maintenance requirements in critical boiler applications.
- Superior Heat Transfer Efficiency: Optimized coil geometry provides up to 40% greater heat transfer area compared to straight-tube designs within equivalent footprint constraints.
- Thermal Cycling Durability: Austenitic stainless steel retains ductility and fatigue resistance through repeated thermal cycling, extending service life beyond 15 years in marine boiler applications.
- Custom Configurable: Coil dimensions, bend radii, end treatments, and material grades are fully customizable to match specific boiler design requirements and retrofit scenarios.
- Comprehensive Quality Traceability: Each coil tube batch carries full traceability from raw material mill certificate through final inspection, ensuring compliance with marine classification society requirements.
- Proven Maintenance Solutions: Product development informed by industry literature on marine facility heat medium boiler coil tube corrosion repair measures and quality control protocols, ensuring real-world performance validation.
Technical Standards Reference
| Standard | Description |
|---|---|
| ASTM A213 | Standard Specification for Seamless Ferritic, Austenitic, and Ferritic-Austenitic Stainless Steel Tubing for High Temperature Service |
| ASTM A269 | Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for Chemical and Similar Severe Service |
| ASME SA-213 | Boiler and Heat Exchanger Tubes — Stainless Steel |
| EN 10216-5 | Non-ferrous metallic tubes and their fittings — Stainless steel tubes for general purposes |
| GB/T 12771 | Stainless Steel Seamless Tubes for Fluid Transport (Chinese National Standard) |
| JIS G3446 | Stainless Steel Seamless Tubes (Japanese Industrial Standard) |
For detailed technical data sheets, material certifications, and custom configuration inquiries, contact Wenzhou Jixing Metal Materials Co., Ltd technical sales department.