Stainless Steel Coil Tube — Jixing Metal FP-Series Fan Coil Unit Component
1. Product Overview
The Stainless Steel Coil Tube (盘管, Coil Tube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 1527) is a precision-engineered tubular component designed primarily for integration into the FP-Series Fan Coil Unit (风机盘管空调器) air-conditioning system under the "Sichun" (四春) brand designation. This coil tube serves as the critical heat exchange element within hydronic air-handling units, facilitating efficient thermal transfer between the circulating refrigerant or heating medium and the ambient air stream.
As a core component of the fan coil unit architecture, the coil tube must exhibit exceptional thermal conductivity, corrosion resistance, and structural integrity under cyclic thermal loading conditions. The product is classified under the technical literature category (一级分类: 文献学习) for engineering reference and quality assurance documentation purposes.
2. Material & Properties
2.1 Base Material
- Material Grade: Austenitic Stainless Steel (奥氏体不锈钢), conforming to GB/T 21830-2008 and ASTM A269/A270 standards
- Designation: SUS304 / 06Cr19Ni10 (equivalent to AISI 304)
- Alternative Grade: SUS316L / 022Cr17Ni12Mo2 for aggressive chemical environments
- Form: Cold-rolled seamless tube, coil-wound configuration
2.2 Mechanical Properties
- Tensile Strength (抗拉强度): ≥ 520 MPa (75 ksi)
- Yield Strength (屈服强度): ≥ 205 MPa (30 ksi)
- Elongation (延伸率): ≥ 40% (minimum, per ASTM A270)
- Hardness (硬度): ≤ 92 HRB (annealed condition)
2.3 Physical & Chemical Properties
- Thermal Conductivity (热导率): 16.3 W/(m·K) at 100°C
- Density (密度): 7.93 g/cm³
- Thermal Expansion Coefficient (热膨胀系数): 17.3 × 10⁻⁶ /K (20–100°C)
- Corrosion Resistance (耐腐蚀性): Excellent resistance to atmospheric, aqueous, and mild chemical corrosion
- Chromium Content (铬含量): 18.0–20.0%
- Nickel Content (镍含量): 8.0–10.5%
2.4 Surface Finish
- Standard: Bright annealed (BA) or No. 4 brushed finish
- Surface Roughness (表面粗糙度): Ra ≤ 0.8 μm (inner surface), Ra ≤ 1.6 μm (outer surface)
- Pickling & Passivation (酸洗钝化): Applied per GB/T 19228 standard to ensure protective chromium oxide layer
3. Specifications
| Parameter (参数) | Specification (规格) | Standard Reference (标准依据) |
|---|---|---|
| Product Number (产品编号) | 1527 | Internal Catalog |
| Product Name (产品名称) | Coil Tube (盘管) | — |
| Outer Diameter (外径, OD) | φ9.52 mm (3/8") / φ12.7 mm (1/2") | ASTM B751 |
| Wall Thickness (壁厚, WT) | 0.81 mm – 1.24 mm (0.032" – 0.049") | ASTM B751 |
| Coil Diameter (盘管直径) | φ150 mm – φ500 mm (adjustable per application) | Custom Design |
| Number of Turns (圈数) | 4 – 12 turns (configurable) | Custom Design |
| Tube Length per Coil (单圈管长) | 0.5 m – 3.0 m | Custom Design |
| Operating Pressure (工作压力) | ≤ 1.6 MPa (232 psi) | GB/T 12771 |
| Test Pressure (试验压力) | 2.4 MPa (348 psi) — Hydrostatic | GB/T 241 |
| Operating Temperature (工作温度) | -40°C to +150°C (-40°F to +302°F) | ASTM A312 |
| Refrigerant Compatibility (制冷剂兼容性) | R410A, R32, R22, R134a, Water/Glycol mixtures | ASHRAE 34 |
| Manufacturing Standard (制造标准) | GB/T 21830-2008, GB/T 12771-2019 | Chinese National Standard |
| Application System (适用系统) | FP-Series Fan Coil Unit (四春牌FP系列风机盘管空调器) | Internal Specification |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Selection (原材料选择): Procurement of certified austenitic stainless steel strip/pipe blanks with full mill test certificates (MTC) per EN 10204 Type 3.1
- Heat Treatment (热处理): Solution annealing (固溶处理) at 1050–1100°C followed by controlled water quenching to achieve uniform austenitic microstructure and maximum corrosion resistance
- Forming & Coil Winding (成型与盘绕): Precision CNC-controlled coil winding on mandrels of specified diameter to achieve uniform turn spacing (螺距均匀性) and consistent geometric tolerances
- Welding (焊接): TIG (Tungsten Inert Gas, 钨极惰性气体保护焊) welding of tube ends and header connections with helium leak testing (氦检漏) at ≤ 1×10⁻⁸ atm·cm³/s
- Pickling & Passivation (酸洗钝化): Immersion in nitric acid solution (HNO₃ 20–30%) followed by passivation treatment to restore chromium oxide protective film
- Dimensional Inspection (尺寸检验): CMM (Coordinate Measuring Machine, 三坐标测量机) verification of coil diameter, turn count, and dimensional tolerances per ISO 286 tolerance grades
- Pressure Testing (压力测试): Hydrostatic pressure testing at 2.4 MPa for minimum 30 seconds with zero leakage criteria
- Final Cleaning & Packaging (清洗包装): Ultrasonic cleaning, protective coating application, and moisture-proof packaging with desiccants
4.2 Key Process Controls
- Sintering Uniformity (烧结均匀性): Controlled via thermocouple monitoring at ≥ 5 points per furnace zone
- Weld Quality (焊接质量): 100% visual inspection + 10% radiographic testing (RT) per ASME Section IX
- Surface Defect Detection (表面缺陷检测): Magnetic particle inspection (MTI) for near-surface discontinuities
5. Applications
5.1 Primary Application — Fan Coil Units (风机盘管空调器)
The coil tube is the principal heat exchange element within the Sichun (四春) FP-Series Fan Coil Unit, which is widely deployed in commercial and residential HVAC (Heating, Ventilation, and Air Conditioning, 暖通空调) systems. The FP-series units operate in both cooling and heating modes, utilizing the coil tube as the thermal interface between the water/glycol circuit and the air stream drawn by the internal fan assembly.
5.2 Secondary Applications
- Commercial HVAC Systems (商用暖通空调系统): Office buildings, hotels, hospitals, and educational facilities
- Residential Climate Control (住宅温控系统): High-end residential units with centralized hydronic systems
- Industrial Process Cooling (工业过程冷却): Precision temperature control in manufacturing environments
- Food & Pharmaceutical Equipment (食品及制药设备): Where sanitary-grade stainless steel is mandated
- Marine HVAC (船舶暖通): Corrosion-resistant applications in saltwater environments
5.3 System Integration
Within the FP-series fan coil unit architecture, the coil tube is integrated with:
- Airflow Section (风道部分): Axial or centrifugal fan assembly directing air across the coil face
- Drainage System (冷凝水排放系统): Sloped coil deck for condensate collection during cooling operation
- Control Valves (控制阀): Two-way or three-way thermostatic valves for flow regulation
- Filter Assembly (过滤组件): Pre-coil air filtration for dust and particulate removal
6. Quality Certifications & Standards Compliance
6.1 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)
- ISO 45001:2018 — Occupational Health & Safety Management (职业健康安全管理体系)
- CE Marking — Conformity with EU Machinery Directive 2006/42/EC and Pressure Equipment Directive 2014/68/EU
- SGS Testing Report — Independent third-party material and dimensional verification
- Material Test Certificate (MTC) — EN 10204 Type 3.1 per batch
6.2 Standards Compliance
- GB/T 21830-2008 — Stainless steel tubes for fluid transport (不锈钢流体输送管)
- GB/T 12771-2019 — Stainless steel seamless tubes for general applications (不锈钢无缝钢管)
- GB/T 19228 — Pickling and passivation of stainless steel (不锈钢酸洗钝化)
- ASTM A312 — Seamless and welded austenitic stainless steel tubes for boiler, heat exchanger, and similar heat applications
- ASTM B751 — Welded austenitic stainless steel tubing for instrument, control, and similar purposes
- ASME BPV Section VIII — Pressure Vessel Code for pressure-containing components
- EN 10217-7 — Heat exchangers — Stainless steel tubes for heat exchangers
6.3 Inspection & Testing Protocol
| Test Item (检验项目) | Method (方法) | Acceptance Criteria (合格标准) | Frequency (频次) |
|---|---|---|---|
| Chemical Composition (化学成分) | Spectroscopic Analysis (光谱分析) | Per ASTM A312 Table 1 | Per heat/batch |
| Mechanical Properties (力学性能) | Tensile Test (拉伸试验) | ≥ 520 MPa UTS, ≥ 40% Elongation | Per heat/batch |
| Dimensional Accuracy (尺寸精度) | CMM Measurement (三坐标测量) | ± 0.1 mm (diameter), ± 0.05 mm (wall thickness) | 100% inspection |
| Surface Quality (表面质量) | Visual + Roughness Tester (目视+粗糙度仪) | No visible defects, Ra ≤ 0.8 μm | 100% inspection |
| Pressure Integrity (压力完整性) | Hydrostatic Test (水压试验) | 2.4 MPa, 30 s, zero leakage | 100% inspection |
| Weld Quality (焊接质量) | <