Stainless Steel Spiral Coil Tube (Coiltube) — Technical Specification
1. Product Overview
The Stainless Steel Spiral Coil Tube (Coiltube) is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. through advanced cold-drawing and continuous coiling processes. Unlike conventional straight stainless steel tubes, spiral coil tubes are formed into a continuous helical geometry, offering superior surface-area-to-volume ratios, enhanced heat transfer efficiency, and structural flexibility. This product is the result of rigorous process research and numerical simulation (工艺研究及数值模拟), ensuring dimensional accuracy, mechanical integrity, and consistent performance across production batches.
The spiral coil tube is designed for applications where compact heat exchange, fluid distribution, and stress-resistant coiled configurations are required. Its continuous helical form eliminates the need for secondary bending operations, reducing residual stresses and improving fatigue life compared to post-formed coil products.
2. Material & Properties
2.1 Material Grades
- Austenitic Stainless Steels: 304 (S30400), 304L (S30403), 316 (S31600), 316L (S31603), 321 (S32100), 310S (S31008)
- Duplex Stainless Steels: 2205 (S31803), 2507 (S32750)
- Super Austenitic: 904L (S31503)
2.2 Key Mechanical Properties
| Property | Typical Value (Grade 316L) | Test Standard |
|---|---|---|
| Tensile Strength (抗拉强度) | ≥ 485 MPa | ASTM A270 / GB/T 12771 |
| Yield Strength (屈服强度) | ≥ 170 MPa | ASTM A270 / GB/T 12771 |
| Elongation (伸长率) | ≥ 40% | ASTM A270 / GB/T 12771 |
| Hardness (硬度, HBW) | ≤ 210 | ASTM A262 |
| Corrosion Resistance (耐蚀性) | Excellent (pitting resistance equivalent number PREN ≥ 24) | ASTM A262 Practice E |
2.3 Surface Finish
- Internal Surface: Electropolished or acid pickled, surface roughness Ra ≤ 0.4 μm (for sanitary/chemical applications)
- External Surface: Mill finish, polished (2B), or custom brushed finish
3. Specifications
| Parameter | Specification Range | Unit | Standard Reference |
|---|---|---|---|
| Outer Diameter (OD, 外径) | 6 – 114.3 | mm | ASTM A270 / EN 10216-5 |
| Wall Thickness (壁厚) | 0.5 – 6.0 | mm | ASTM A270 / EN 10216-5 |
| Coil Diameter (盘管直径) | 100 – 2000 | mm | Custom (客户定制) |
| Coil Length (盘管长度) | 3 – 200 | m | Custom (客户定制) |
| Number of Coils (圈数) | 2 – 500 | turns | Custom (客户定制) |
| Dimensional Tolerance (尺寸公差) | ±0.05 mm (OD); ±0.1 mm (wall thickness) | mm | EN 10216-5 Class A |
| Forming Angle (螺旋角) | 0° – 45° | degrees | Custom (客户定制) |
4. Manufacturing Process
The production of the stainless steel spiral coil tube follows a rigorously controlled process validated through numerical simulation (数值模拟) and finite element analysis (FEA) to ensure process reliability and product consistency:
- Raw Material Inspection (原材料检验): Incoming stainless steel seamless tubes are verified for chemical composition (spectroscopic analysis), mechanical properties, and surface condition in accordance with ASTM A270 / GB/T 12771.
- Cutting & Straightening (切割与矫直): Straight tubes are cut to specified lengths and mechanically straightened to eliminate residual curvature.
- End Preparation (端部处理): Tube ends are chamfered and prepared for coiling to prevent material damage and ensure smooth coil formation.
- Spiral Coiling (螺旋盘绕): The straight tube is fed through a precision coiling machine (盘管机) with programmable coil diameter and pitch control. Numerical simulation models the forming forces, springback, and residual stress distribution to optimize machine parameters.
- Welding (焊接) — where applicable: For coil-to-coil connections, orbital TIG welding (Tungsten Inert Gas Welding) is employed to maintain metallurgical integrity and achieve leak-tight joints.
- Stress Relief Annealing (去应力退火): The coiled product undergoes controlled heat treatment (typically 300–400°C for austenitic grades) to relieve residual stresses induced during forming, as predicted by FEA models.
- Pickling & Passivation (酸洗钝化): The coil tube is subjected to acid pickling (HNO₃/HF mixture) and passivation to remove scale, restore chromium oxide passive layer, and ensure corrosion resistance.
- Final Inspection (最终检验): Dimensional verification, surface quality assessment, hydrostatic pressure testing, and non-destructive testing (NDT) including eddy current (ET) and visual examination.
Process Innovation: The integration of numerical simulation into the coiling process allows Wenzhou Jixing Metal Materials Co., Ltd. to predict and control springback, minimize ovality distortion, and optimize the coil pitch and diameter tolerances — resulting in a product with superior geometric accuracy and mechanical performance compared to conventional trial-and-error manufacturing.
5. Applications
- Heat Exchangers (热交换器): Spiral coil tubes provide high surface-area-to-volume ratios ideal for compact heat exchangers in chemical processing, power generation, and HVAC systems.
- Refrigeration & Air Conditioning (制冷与空调): Used as evaporator and condenser coils in industrial refrigeration units and chillers.
- Chemical Processing (化工处理): Reactor internals, distillation columns, and heat recovery systems where corrosion resistance and thermal efficiency are critical.
- Petroleum & Natural Gas (石油与天然气): Subsea umbilicals, wellhead heating coils, and process piping requiring durability in harsh environments.
- Food & Pharmaceutical (食品与制药): Sanitary-grade coil tubes for pasteurization, sterilization, and fluid transfer systems (Ra ≤ 0.4 μm electropolished finish).
- Power Generation (发电): Boiler tubes, economizers, and superheaters in steam turbine systems.
- Automotive & Aerospace (汽车与航空航天): Compact thermal management systems and fluid distribution networks.
6. Quality Certifications & Standards
| Standard / Certification | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification for manufacturing processes |
| ISO 3834 | Quality requirements for welding of metallic products |
| EN 10204 3.1 | Inspection documentation and material traceability |
| ASTM A270 | Standard specification for austenitic stainless steel tubing |
| EN 10216-5 | European standard for austenitic stainless steel tubes |
| GB/T 12771 | Chinese national standard for austenitic stainless steel seamless tubes |
| CE Marking | Compliance with European health, safety, and environmental protection standards |
| PED (Pressure Equipment Directive 2014/68/EU) | Compliance for pressure equipment applications |
7. Unique Selling Points
- Simulation-Driven Manufacturing: The coil forming process is validated through numerical simulation and FEA, ensuring predictable dimensional accuracy, minimized residual stress, and consistent batch-to-batch quality.
- One-Piece Continuous Form: The spiral coil tube is formed as a single continuous helix, eliminating weld joints and reducing points of failure in high-pressure or high-cycle applications.
- Superior Thermal Performance: The helical geometry maximizes surface area within a compact footprint, delivering up to 30% higher heat transfer efficiency compared to straight-tube alternatives of equivalent volume.
- Wide Material Range: Available in austenitic, duplex, and super-austenitic stainless steel grades to address diverse corrosion and mechanical requirements.
- Custom Engineering Capability: Coil diameter, pitch, length, and number of turns are fully customizable to meet specific design requirements, supported by engineering consultation and prototype development.