Stainless Steel Spiral Coil Tube — Product Technical Specification
Product Overview
The Stainless Steel Spiral Coil Tube (hereinafter referred to as "Coil Tube") is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is produced through the helical bending of stainless steel flat strip material on a dedicated roll bending machine (Roll Bending Machine, RBM), forming a continuous spiral coil geometry with uniform pitch, consistent cross-section, and superior surface finish. The resulting coil tube is widely utilized in heat exchangers, evaporators, condensers, and other process engineering applications where high thermal efficiency, corrosion resistance, and mechanical durability are critical requirements.
Unlike conventional round tubes that are mechanically drawn or extruded, the spiral coil tube is formed from flat stainless steel strip through a cold-forming process, enabling customized inner diameters, wall thicknesses, and coil geometries tailored to specific application requirements. This manufacturing approach provides distinct advantages in terms of material utilization efficiency, dimensional flexibility, and production cost-effectiveness.
Material & Properties
Available Grades
- AISI 304 (UNS S30408) — General-purpose austenitic stainless steel with excellent corrosion resistance and formability.
- AISI 316 (UNS S31608) — Molybdenum-enhanced austenitic grade offering superior resistance to pitting and crevice corrosion in chloride-containing environments.
- AISI 321 (UNS S32108) — Titanium-stabilized austenitic grade suitable for high-temperature service up to 870°C.
- AISI 316L (UNS S31603) — Low-carbon variant of 316 for enhanced weldability and resistance to intergranular corrosion.
- Other custom grades upon request (e.g., 310S, 904L, duplex 2205).
Mechanical Properties (Typical — Grade 304, Annealed Condition)
| Property | Symbol | Value | Unit |
|---|---|---|---|
| Tensile Strength (抗拉强度) | σb | ≥ 520 | MPa |
| Yield Strength (屈服强度) | σ0.2 | ≥ 205 | MPa |
| Elongation (延伸率) | A50mm | ≥ 40 | % |
| Hardness (硬度) | — | ≤ 217 | HBW |
| Density (密度) | ρ | 7.93 | g/cm³ |
| Thermal Conductivity (热导率, at 100°C) | λ | 16.3 | W/(m·K) |
| Thermal Expansion Coefficient (热膨胀系数, 100–200°C) | α | 16.8 | ×10⁻⁶/°C |
| Maximum Service Temperature (最高使用温度) | — | 870 | °C |
Chemical Composition (AISI 304, wt%)
| C | S | P | Cr | Ni | Mn | Si | N | Fe |
|---|---|---|---|---|---|---|---|---|
| ≤ 0.08 | ≤ 0.030 | ≤ 0.045 | 18.0–20.0 | 8.0–10.5 | ≤ 2.0 | ≤ 0.75 | ≤ 0.10 | Balance |
Specifications
Dimensional Parameters
| Parameter | Symbol | Range / Value | Unit |
|---|---|---|---|
| Inner Diameter (内径) | Di | 3 – 50 | mm |
| Wall Thickness (壁厚) | t | 0.3 – 2.0 | mm |
| Coil Outer Diameter (盘管外径) | Dc | 50 – 2000 | mm |
| Coil Length (盘管展开长度) | L | Custom (up to 5000) | mm |
| Pitch / Turn Spacing (螺距) | p | 1.5 – 30 | mm |
| Number of Turns (圈数) | n | Custom | — |
| Surface Finish (表面光洁度) | Ra | 0.2 – 1.6 | μm |
| Surface Treatment (表面处理) | — | Pickled & Passivated / Polished / Matte | — |
| End Form (端部形式) | — | Flat / Beveled / Welded Closed / Flanged | — |
| Dimensional Tolerance (尺寸公差) | — | ± 0.1 mm (diameter); ± 0.2 mm (pitch) | mm |
Standard References
- ASTM A213 / A269 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing.
- ASTM A240 — Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip.
- EN 10216-5 — Steel Tubes for Technical Purposes — Heat-Exchanger Tubes.
- GB/T 12771 — Seamless and Welded Stainless Steel Tubes for General Purposes (Chinese National Standard).
- JIS G3459 — Stainless Steel Tubes for Pressure Vessels.
Manufacturing Process
The production of spiral coil tubes is a multi-stage cold-forming process that demands precise control over material flow, geometric accuracy, and surface integrity. The following outlines the complete manufacturing workflow:
- Raw Material Inspection (原材料检验) — Incoming stainless steel flat strip is inspected for chemical composition (via Optical Emission Spectrometry, OES), mechanical properties, surface quality, and dimensional conformity. Mill certificates (Mill Test Reports, MTRs) are verified against applicable standards.
- Edge Preparation & Surface Cleaning (边缘处理与表面清洁) — Strip edges are deburred and cleaned to remove scale, oils, and contaminants that could compromise forming quality or subsequent welding integrity.
- Coil Winding on Roll Bending Machine (卷板机弯制螺旋盘管) — The core forming operation involves feeding the flat strip through a multi-roller bending system. Key process parameters include:
- Roll Configuration: Typically a three-roll or four-roll arrangement with programmable roll positions to define the coil diameter and helical pitch.
- Forming Speed: Controlled at 10–60 m/min to prevent work-hardening-induced cracking and ensure uniform plastic deformation.
- Pitch Control: Achieved through synchronized feed rate and roll spacing adjustments, ensuring consistent turn-to-turn spacing throughout the coil length.
- Springback Compensation: Pre-calculated over-bending angles are applied to compensate for elastic recovery (springback) inherent in cold-formed austenitic stainless steel, ensuring final geometry accuracy.
- Tension Monitoring: Real-time tension control prevents slippage, edge waviness, and dimensional deviation during the winding operation.
- Welding of Helical Seam (螺旋焊缝焊接) — Where a continuous tubular channel is required, the helical seam formed by the overlapping strip edges is welded using one of the following methods:
- TIG Welding (Gas Tungsten Arc Welding, GTAW) — Preferred for high-purity welds in food-grade and pharmaceutical applications.
- Laser Welding — Employed for high-speed production with narrow, deep weld penetration and minimal heat-affected zone (HAZ).
- Orbital TIG Welding — Used for automated, consistent circumferential welds on closed-end coil configurations.
- Heat Treatment (if required) (热处理) — Annealing at 1050–1100°C followed by rapid quenching may be applied to relieve residual stresses introduced during cold forming, restore full annealed mechanical properties, and improve corrosion resistance. Solution annealing (Solution Heat Treatment) is particularly important for grades susceptible to sensitization.
- Pickling & Passivation (酸洗钝化) — The coil tube is subjected to acid pickling (typically nitric-hydrofluoric acid solution) to remove oxide scale, followed by passivation treatment to restore and enhance the chromium oxide passive film, ensuring optimal corrosion resistance.
- End Processing (端部加工) — Coil ends are trimmed, beveled, or fitted with flanges, threaded connectors, or welding ends according to customer specifications. End closures may be achieved by welding or mechanical crimping.
- Final Inspection & Quality Control (最终检验与质量控制) — Comprehensive quality assurance includes:
- Dimensional verification via Coordinate Measuring Machine (CMM) or laser scanning.
- Visual inspection of weld seams and surface finish.
- Helium leak testing or pressure testing (typically at 1.5× working pressure) for weld integrity.
- Magnetic particle inspection (MPI) or penetrant testing (PT) for surface defect detection.
- Chemical composition verification via X-ray Fluorescence (XRF) spectroscopy.
- Packaging & Dispatch (包装与发货) — Finished coil tubes are individually wrapped in protective film or paper, packed in wooden crates or steel containers, and labeled with product identification, material grade, heat number, and compliance certificates.
Applications
The stainless steel spiral coil tube is engineered for demanding industrial and commercial applications across multiple sectors:
- Heat Exchangers (热交换器) — Spiral coil tubes serve as the primary heat transfer elements in shell-and-coil heat exchangers, providing high surface-area-to-volume ratios for efficient thermal exchange in liquid-liquid and liquid-gas systems.
- Evaporators & Condensers (蒸发器与冷凝器) — Utilized in refrigeration, air conditioning, and industrial process cooling systems where the helical geometry enhances turbulent flow and heat transfer coefficients.
- Chemical Processing (化工处理) — Deployed in reactors, condensers, and heat recovery systems handling aggressive chemicals, acids, and alkalis, leveraging the corrosion resistance of austenitic stainless steels.
- Food & Beverage Industry (食品饮料行业) — Applied in pasteurization systems, brewing equipment, and dairy processing where hygienic surface finish and compliance with food-grade standards (e.g., 3-A Sanitary Standards) are mandatory.
- Pharmaceutical Manufacturing (制药行业) — Used in sterile processing equipment, clean steam systems, and pharmaceutical heat exchangers requiring polished (Ra ≤ 0.4 μm) or electropolished surfaces.
- Power Generation (发电) — Employed in waste heat recovery (WHR) systems, boiler economizers, and superheater coils in thermal and nuclear power plants.
- Oil & Gas (石油与天然气) — Applied in offshore platform heat exchangers, subsea heating systems, and process cooling circuits where resistance to chloride-induced stress corrosion cracking (SCC) is essential (Grade 316L recommended).
- Marine Engineering (海洋工程) — Used in shipboard cooling systems, condensers, and heat exchangers exposed to seawater environments.
- Aerospace (航空航天) — Deployed in aircraft environmental control systems, fuel cooling loops, and hydraulic fluid heat exchangers requiring lightweight, high-performance tubular components.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems and holds the following certifications and complies with the following standards:
- ISO 9001:2015 — Quality Management Systems (质量管理体系认证)
- ISO 14001:2015 — Environmental Management Systems (环境管理体系认证)
- ISO 45001:2018 — Occupational Health and Safety Management Systems (职业健康安全管理体系认证)
- EN 10204 Type 3.1 — Test Reports with declared values verified by inspection (材料测试报告)
- PED (Pressure Equipment Directive) 2014/68/EU — Compliance for pressure vessel components (欧盟压力设备指令)
- ASME Section VIII — Compliance for pressure vessel components (美国机械工程师协会标准)
- NSF/ANSI 61 — Drinking Water System Components (饮用水系统组件认证, where applicable)
- 3-A Sanitary Standards — For food and dairy processing applications (3-A卫生标准)
- CE Marking — Conformity with European health, safety, and environmental protection standards
- Material Traceability — Full heat-number traceability from raw material mill through manufacturing to final delivery, supported by comprehensive documentation packages including MTRs, dimensional reports, NDT reports, and pressure test records.
Unique Selling Points
1. Precision Helical Geometry: Advanced roll bending technology with CNC-controlled roll positioning ensures dimensional accuracy of ±0.2 mm in pitch and ±0.1 mm in diameter, guaranteeing optimal heat transfer performance and seamless integration into engineered assemblies.