Stainless Steel Coiled Tube (Coiltube) — W27Y-219 Medium Frequency Induction Heating Hydraulic Coiling Process
1. Product Overview
The Stainless Steel Coiled Tube (Coiltube) is a precision-engineered continuous tube product manufactured through advanced medium frequency induction heating and hydraulic coiling technology. Produced by Wenzhou Jixing Metal Materials Co., Ltd., this product is designed using the proprietary W27Y-219 Medium Frequency Induction Heating Hydraulic Coil Bending Machine (中频加热液压盘管机). The coiling process enables the formation of long, uninterrupted stainless steel tubes into compact, spiral-wound configurations without introducing weld seams, thereby preserving the metallurgical integrity and mechanical properties of the base material. This product category falls under the technical literature and process engineering domain, representing a state-of-the-art method for producing seamless coiled tubing suitable for demanding industrial applications.
2. Material & Properties
The stainless steel coiled tube is fabricated from high-grade austenitic stainless steel grades, with the most commonly utilized materials including:
- 304 (A2-D / 06Cr19Ni10): General-purpose austenitic grade offering excellent corrosion resistance, weldability, and formability. Suitable for a wide range of chemical, food, and pharmaceutical environments.
- 316 (A4-D / 06Cr17Ni12Mo2): Enhanced corrosion resistance grade with molybdenum addition, providing superior resistance to chlorides and aggressive chemical media.
- 321 (06Cr18Ni11Ti): Titanium-stabilized grade with improved resistance to intergranular corrosion at elevated temperatures.
- 316L (022Cr17Ni12Mo2): Low-carbon variant of 316 with enhanced weldability and resistance to sensitization during welding operations.
Key mechanical and physical properties of the coiled tube include:
- Yield Strength (屈服强度): Typically ≥ 205 MPa for Grade 304, ≥ 170 MPa for Grade 316L
- Tensile Strength (抗拉强度): Typically 515–730 MPa depending on grade and wall thickness
- Hardness (硬度): ≤ 220 HV (Rockwell B ≤ 95) in the annealed condition
- Corrosion Resistance (耐腐蚀性): Excellent resistance to atmospheric, aqueous, and mild chemical environments
- Temperature Range (使用温度范围): −196 °C to +870 °C (Grade 304), −196 °C to +870 °C (Grade 316L)
- Surface Finish (表面光洁度): Available in No.1 pickled, 2B, BA (Bright Annealed), or polished (Ra ≤ 0.4 μm) finishes
3. Specifications
| Parameter (参数) | Specification / Range (规格范围) | Standard / Reference (标准参考) |
|---|---|---|
| Tube Outer Diameter (管外径) | 6 mm – 219 mm (0.24" – 8.62") | ASTM A213, ASTM A269, GB/T 14976 |
| Tube Wall Thickness (管壁厚) | 0.5 mm – 12 mm (0.02" – 0.47") | ASTM A213, GB/T 12771 |
| Coil Inner Diameter (盘管内径) | Adaptable per W27Y-219 machine configuration | Custom / OEM Specification |
| Coil Length (盘管长度) | Continuous — limited only by supply coil length (typically 50 m – 500 m per coil) | Project-specific |
| Induction Heating Frequency (中频加热频率) | Medium Frequency (中频): 250 Hz – 2,000 Hz | W27Y-219 Process Standard |
| Heating Temperature (加热温度) | Controlled within ±15 °C of target bending temperature | W27Y-219 Process Standard |
| Hydraulic Bending Force (液压弯曲力) | Up to 219 kN (as indicated by model designation) | W27Y-219 Machine Rating |
| Bending Radius (弯曲半径) | ≥ 3D (D = tube outer diameter) — optimized by induction pre-heating | ASTM A213, ISO 15492 |
| Material Grade (材质牌号) | 304, 304L, 316, 316L, 321, 310S, 2205 Duplex | ASTM A213 / A269 / GB/T 14976 |
| Surface Treatment (表面处理) | No.1 Pickled, 2B, BA, Mirror Polish (Ra ≤ 0.2 μm) | ASTM A479 |
| End Form (管端形式) | Plain cut, beveled, or threaded per customer specification | ASME B1.20.1 |
| Coil Packaging (盘管包装) | Wooden drum / steel frame with moisture-proof wrapping | ISO 4180 |
4. Manufacturing Process
The production of stainless steel coiled tubes utilizing the W27Y-219 Medium Frequency Induction Heating Hydraulic Coil Bending Machine follows a rigorously controlled multi-stage process:
4.1 Raw Material Preparation (原材料准备)
- Selection of certified seamless stainless steel tube stock meeting ASTM A213 / A269 or equivalent GB/T standards.
- Incoming inspection including dimensional verification, chemical composition analysis (spectrometry), and mechanical property testing.
- Surface preparation: pickling and passivation to remove oxide scale and ensure a clean, corrosion-resistant surface.
4.2 Medium Frequency Induction Heating (中频感应加热)
The core differentiating technology of the W27Y-219 process is the application of medium frequency induction heating to the tube section immediately preceding the bending operation. An alternating electromagnetic field at frequencies between 250 Hz and 2,000 Hz induces eddy currents within the tube wall, generating localized Joule heating. This technique offers several critical advantages:
- Localized Heating (局部加热): Only the bending zone is heated, minimizing thermal distortion to the remainder of the tube.
- Reduced Bending Force (降低弯曲力): Elevated temperature reduces the yield strength locally, decreasing the required hydraulic force by approximately 40–60% compared to cold bending.
- Prevention of Wall Thinning (防止壁厚减薄): Uniform heating prevents asymmetric plastic deformation and localized wall thinning at the outer bend radius.
- Elimination of Surface Cracking (消除表面裂纹): Controlled heating temperatures prevent intergranular cracking, particularly in sensitized austenitic grades.
- Energy Efficiency (节能效率): Induction heating achieves thermal conversion efficiencies of 60–80%, significantly superior to gas flame or resistance heating methods.
4.3 Hydraulic Coiling / Bending (液压盘管弯曲)
The W27Y-219 hydraulic system applies precisely controlled bending forces to form the heated tube section into the desired coil geometry. The process involves:
- Feeding (送料): The tube is fed continuously through the induction heating coil and into the hydraulic bending head.
- Heating Zone (加热区): The tube passes through the induction coil, reaching the target bending temperature (typically 600–850 °C depending on grade).
- Bending Operation (弯曲操作): The hydraulic bending head, rated at up to 219 kN, applies radial force to form the tube into a controlled spiral path.
- Cooling (冷却): The bent section is cooled — either air-cooled or water-quenched — to restore full mechanical properties while maintaining the formed geometry.
- Continuous Coiling (连续盘卷): The process repeats in a continuous cycle, producing an unbroken coiled tube of the desired length.
4.4 Post-Processing (后处理)
- Stress Relief Annealing (去应力退火): Optional annealing at 1050 °C followed by water quenching to eliminate residual stresses from the bending process.
- Pickling & Passivation (酸洗钝化): Removal of any heat tint or oxide scale formed during induction heating, followed by passivation to restore the passive chromium oxide layer.
- Surface Finishing (表面精加工): Optional electropolishing or mechanical polishing to achieve specified surface roughness values.
- Dimensional Inspection (尺寸检验): Verification of coil diameter, tube diameter, wall thickness, and straightness tolerances.
5. Applications
Stainless steel coiled tubes produced via the W27Y-219 medium frequency induction heating process find extensive application across multiple high-value industries:
5.1 Heat Exchangers & Boiler Systems (热交换器与锅炉系统)
- Condenser tubes, evaporator tubes, and heat exchanger bundles requiring long, continuous tube lengths without butt welds.
- Fire-tube and water-tube boilers where corrosion-resistant tubing is essential for longevity.
5.2 Chemical & Petrochemical Processing (化工与石油化工)
- Reactors, distillation columns, and heat transfer systems handling corrosive chemical media.
- Piping systems for acid, alkali, and halide-containing process streams.
5.3 Food & Beverage Industry (食品与饮料行业)
- Sterilization systems, pasteurizers, and CIP (Clean-in-Place) piping networks.
- Heat exchangers in dairy, brewing, and pharmaceutical processing where hygienic surface finishes (Ra ≤ 0.4 μm) are mandated.
5.4 Pharmaceutical & Medical Devices (制药与医疗器械)
- Bioreactor heating/cooling coils, autoclave tubing, and pharmaceutical heat transfer systems.
- Medical instrument tubing requiring high purity and corrosion resistance.
5.5 Energy & Power Generation (能源与发电)
- Solar thermal energy systems, geothermal heat exchangers, and nuclear auxiliary cooling loops.
- Supercritical and ultra-supercritical power plant components requiring high-temperature stainless steel tubing.
5.6 Aerospace & Defense (航空航天与国防)
- Fuel lines, hydraulic systems, and heat management circuits in aircraft and spacecraft.
- Specialty applications requiring high strength-to-weight ratios and corrosion resistance.
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and adheres to internationally recognized standards for stainless steel tube production:
6.1 Quality Management System (质量管理体系)
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management System certification.
6.2 Product Standards (产品标准)
- ASTM A213: Standard Specification for Seamless and Welded 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 Applications.
- ASTM A312: Standard Specification for Seamless and Welded Austenitic Chromium-Chromium-Nickel Stainless Steel Pipes and Tubes.
- GB/T 14976: Chinese National Standard for Seamless Stainless Steel Tubes for Fluid Transport.
- GB/T 12771: Chinese National Standard for Welded Stainless Steel Tubes for Fluid Transport.
- EN 10216-5: European Standard for Seamless Stainless Steel Tubes — General Requirements.
- ISO 15492: International Standard for Seamless and Welded Steel and Nickel Alloy Tubes for Heat Exchangers and Heat Sinks.
6.3 Testing & Inspection (测试与检验)
- Chemical Analysis (化学成分分析): Optical emission spectrometry (OES) for bulk composition verification.
- Mechanical Testing (力学性能测试): Tensile testing, hardness testing (HV, HRB), and impact testing per ASTM E8/E8M and ASTM E10/E10M.
- Hydrostatic Testing (水压试验): Each coil subjected to hydrostatic pressure testing at 1.5× maximum working pressure per ASTM A530.
- Non-Destructive Testing (无损检测): Eddy current testing (ECT) per ASTM E309 and ultrasonic testing (UT) per ASTM E308 for detection of internal and surface defects.
- Corrosion Testing (腐蚀测试): Salt spray testing per ASTM B117, intergranular corrosion testing per ASTM A262 (Practice No. 1E / 1A), and crevice corrosion testing.
- Dimensional Inspection (尺寸检验): Coordinate measuring machine (CMM) and laser scanning for coil geometry verification.
6.4 Industry-Specific Certifications (行业专项认证)
- EN 10204 3.1 Certificate: Third-party inspection certificate for material traceability and conformity.
- ASME Stamp (U/U1/U2): Available for pressure vessel components where applicable.
- NACE MR0175 / ISO 15156: Compliance for sour service applications (H₂S-containing environments).
- NSF/ANSI 61: Certification for potable water applications where food-grade tubing is required.
- 3-A Sanitary Standards: Compliance for food, dairy, and pharmaceutical processing applications.