Stainless Steel Coil Tube (Coiltube) — Product No. 1052
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
1. Product Overview
The Stainless Steel Coil Tube (Coiltube), designated as Product No. 1052 by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered tubular product designed for continuous coiled delivery. This product is primarily intended for use in fan coil unit (FCU) systems, heat exchanger assemblies, and HVAC (Heating, Ventilation, and Air Conditioning) applications where thermal efficiency, corrosion resistance, and mechanical integrity are paramount.
The coil tube is manufactured in continuous coiled form, enabling downstream fabricators to cut and form the tube to precise lengths without generating additional waste. Its seamless or welded construction ensures uniform wall thickness and eliminates potential leakage points at joints, making it suitable for fluid transport under both dry and wet operating conditions.
A critical technical consideration for this product relates to the determination of inlet water temperature during dry operation of fan coil units (风机盘管干工况时进水温度的确定). In dry operation mode, the coil tube functions primarily as a sensible heat exchanger, where the inlet water temperature must be carefully controlled to prevent condensation formation on the tube surface. This technical knowledge point is integral to the proper application and specification of the coil tube in HVAC systems.
2. Material & Properties
2.1 Base Material
The coil tube is fabricated from high-grade stainless steel, typically conforming to the following material specifications:
- Austenitic Stainless Steel (奥氏体不锈钢): Grades such as SUS304 (UNS S30408), SUS316 (UNS S31608), and SUS321 (UNS S32108) are commonly employed depending on the corrosion environment and temperature requirements.
- Super-Austenitic Stainless Steel: Higher alloy grades may be specified for aggressive chemical environments.
- Material Standards: GB/T 12771 (Chinese National Standard for welded stainless steel tubes), ASTM A269 (Standard Specification for Welded Austenitic Stainless Steel Tubing for Chemical and Similar Severe Service), and EN 10216-5 (European Standard for welded stainless steel tubes).
2.2 Mechanical Properties
- Tensile Strength (抗拉强度): 515–720 MPa (depending on grade and cold-worked condition)
- Yield Strength (屈服强度): 205–310 MPa
- Elongation (延伸率): ≥30%
- Hardness (硬度): 180–230 HV (annealed condition)
2.3 Physical & Chemical Properties
- Corrosion Resistance (耐腐蚀性): Excellent resistance to atmospheric corrosion, acidic environments, and chlorinated solutions (particularly for 316 grade containing 2–3% Molybdenum)
- Thermal Conductivity (热导率): 14–16 W/(m·K) at 20°C
- Thermal Expansion Coefficient (热膨胀系数): 16–18 × 10⁻⁶ /°C
- Maximum Operating Temperature (最高工作温度): Up to 870°C (304 grade), 870°C (316 grade)
- Minimum Operating Temperature (最低工作温度): Down to −196°C (cryogenic applications)
2.4 Surface Finish
- Interior Surface: Pickled and passivated (酸洗钝化) or electropolished to achieve Ra ≤ 0.4 μm for sanitary applications
- Exterior Surface: Bright annealed (BA finish) or 2B cold-rolled finish
- Surface Treatment: Anti-oxidation coating available upon request for enhanced durability during outdoor installation
3. Technical Specifications
| Parameter (参数) | Specification (规格) | Tolerance (公差) |
|---|---|---|
| Product No. (产品序号) | 1052 | — |
| Product Name (产品名称) | Coiltube (盘管) | — |
| Outer Diameter (OD, 外径) | Φ6.0 mm, Φ8.0 mm, Φ10.0 mm, Φ12.0 mm, Φ15.0 mm, Φ19.0 mm, Φ25.0 mm, Φ32.0 mm, Φ38.0 mm (custom sizes available) | ±0.10 mm |
| Wall Thickness (壁厚) | 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 2.0 mm | ±0.05 mm |
| Inner Diameter (ID, 内径) | Calculated as OD − 2 × Wall Thickness | ±0.10 mm |
| Coil Diameter (盘管直径) | Φ500 mm – Φ2000 mm (configurable) | ±5 mm |
| Tube Length per Coil (每盘管长度) | 50 m – 500 m (standard); custom lengths available | ±1% |
| Material Grade (材质牌号) | SUS304 / SUS316 / SUS321 / Custom | — |
| Manufacturing Method (制造工艺) | Seamless (无缝) or ERW Welded (电阻焊) | — |
| Operating Pressure (工作压力) | Up to 1.6 MPa (standard); up to 4.0 MPa (reinforced) | — |
| Operating Temperature Range (工作温度范围) | −40°C to +200°C (standard); cryogenic to 870°C (special grade) | — |
| End Condition (端部状态) | Plain cut (平切), beveled (坡口), threaded (螺纹), or flanged (法兰) | — |
| Surface Finish (表面光洁度) | BA / 2B / Pickled & Passivated / Electropolished (Ra ≤ 0.4 μm) | — |
| Standard Compliance (标准符合性) | GB/T 12771, ASTM A269, EN 10216-5, JIS G3459 | — |
| Packaging (包装) | Wooden pallet with moisture-proof wrapping; coil secured with steel bands | — |
4. Manufacturing Process
4.1 Raw Material Procurement & Inspection
High-purity stainless steel strip or round bar is procured from certified suppliers. Incoming material undergoes rigorous inspection including spectroscopic analysis (光谱分析) for chemical composition verification, ultrasonic testing (超声波检测) for internal defect detection, and visual surface inspection.
4.2 Forming Process
- Strip Preparation (带材准备): Cold-rolled stainless steel strip is unwound and fed through a leveling unit to ensure flatness and dimensional accuracy.
- Tube Forming (制管成型): The strip is passed through a series of roll-forming dies (成型辊) to progressively shape it into a tubular configuration. For seamless tubes, the round bar undergoes piercing (穿孔) and rolling (轧制) at elevated temperatures.
- Welding (焊接): For welded coil tubes, longitudinal seam welding is performed using either ERW (Electric Resistance Welding, 电阻焊) or TIG (Tungsten Inert Gas, 钨极惰性气体保护焊) welding processes. Weld parameters are precisely controlled to ensure full penetration and minimal heat-affected zone (HAZ, 热影响区).
- Heat Treatment (热处理): Annealing (退火) is conducted in a protective atmosphere (argon or nitrogen) to relieve residual stresses and restore austenitic microstructure. Solution annealing (固溶处理) at 1050–1100°C followed by rapid quenching ensures optimal corrosion resistance.
4.3 Finishing & Coiling
- Pickling & Passivation (酸洗钝化): The tube surface is treated with a nitric acid/hydrofluoric acid mixture to remove oxide scale, followed by passivation to form a protective chromium oxide layer.
- Dimensional Verification (尺寸检验): Automated gauging systems measure OD, wall thickness, and straightness throughout the coil length.
- Coiling (盘卷): The finished tube is wound onto a mandrel or spool to form the final coil configuration. Coil tension is controlled to prevent kinking or deformation.
- Quality Testing (质量检测): Hydrostatic pressure testing (水压试验), dye penetrant testing (渗透检测) for surface defects, and dimensional sampling are performed prior to packaging.
4.4 Technical Knowledge Point: Dry Operation Inlet Water Temperature Determination
A critical application-specific consideration for this coil tube product involves the determination of inlet water temperature during dry operation of fan coil units. In dry operation (干工况), the coil tube functions as a sensible heat exchanger, and the inlet water temperature must be maintained above the dew point temperature (露点温度) of the incoming air to prevent condensation on the tube surface. The following technical framework guides proper specification:
- Dew Point Calculation: The dew point temperature is determined from the dry-bulb temperature and relative humidity of the return air. For typical indoor conditions of 24°C dry-bulb and 60% relative humidity, the dew point is approximately 16.2°C.
- Minimum Inlet Water Temperature: The inlet water temperature should be set at least 2–3°C above the calculated dew point temperature to provide a safety margin against condensation formation.
- Surface Temperature Control: The coil tube surface temperature must remain above the dew point. Given the thermal conductivity of stainless steel (14–16 W/(m·K)), the surface temperature closely tracks the fluid temperature, making inlet water temperature the primary control parameter.
- Flow Rate Optimization: Adequate water flow rate through the coil tube is necessary to maintain uniform surface temperature distribution and prevent localized cold spots that could induce condensation.
5. Applications
5.1 HVAC Systems (暖通空调系统)
- Fan coil units (风机盘管) for commercial and residential heating, ventilation, and air conditioning
- Chilled water and hot water distribution piping in centralized HVAC systems
- Air handling units (AHU, 空气处理机组) heat exchangers
- Underfloor radiant heating and cooling systems (地暖系统)
5.2 Industrial Applications (工业应用)
- Chemical processing equipment heat exchangers and process piping
- Pharmaceutical manufacturing clean fluid transfer systems
- Food and beverage industry sanitary piping and heat exchangers
- Power generation plant condensate systems and steam distribution
5.3 Specialized Applications (特种应用)
- Cryogenic fluid transport systems (−196°C capable)
- Marine and offshore platforms (316 grade for chloride resistance)
- Solar thermal energy collection systems
- Geothermal energy exchange systems
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring that Product No. 1052 meets international quality and safety standards:
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification covering all manufacturing processes |
| ISO 14001:2015 | Environmental Management System certification |
| ISO 45001:2018 | Occupational Health and Safety Management System certification |
| CE Marking | European Conformity marking for products intended for the European Economic Area |
| GB/T 12771 | Chinese National Standard for welded stainless steel tubes and fittings |
| ASTM A269 | American Society for Testing and Materials standard for welded austenitic stainless steel tubing |
| EN 10216-5 | European Standard for welded stainless steel tubes for fluid transport |
| NSF/ANSI 61 | Drinking Water System Components certification (for potable water applications) |
| 3-A Sanitary Standards | International Dairy, Food, and Bioprocess Industries association standards (for food-grade applications) |
| PED (Pressure Equipment Directive 2014/68/EU) | EU Pressure Equipment Directive compliance for pressure-containing applications |
7. Unique Selling Points
- Superior Corrosion Resistance: The austenitic stainless steel composition provides outstanding resistance to corrosion in aggressive environments, ensuring service life exceeding 25 years under normal operating conditions.
- Precision Dimensional Control: Advanced roll-form