Stainless Steel Coil Tube — W27Y-219 Medium Frequency Induction Heating Hydraulic Coiling Process
Product Overview
The Stainless Steel Coil Tube (Coiltube) produced by Wenzhou Jixing Metal Materials Co., Ltd. represents a premium category of seamless stainless steel tubing formed through a precision medium frequency induction heating hydraulic coiling process. Designated under the model series W27Y-219, this manufacturing system integrates medium frequency induction heating (Medium Frequency Induction Heating) with hydraulic-driven coiling to produce continuous stainless steel coil tubes with exceptional dimensional accuracy, metallurgical integrity, and surface finish quality.
Unlike conventional cold-rolling or hot-rolling coil tube production methods, the medium frequency induction heating approach enables precise thermal control at the tube surface, resulting in superior grain structure uniformity and reduced residual stress. The hydraulic coiling mechanism ensures consistent coiling tension and geometry, minimizing the risk of deformation or buckling during the winding process. The resulting coil tubes are delivered in continuous helical form, offering significant advantages in downstream processing efficiency, material utilization, and supply chain logistics.
Material & Properties
The coil tubes are fabricated from high-grade austenitic and duplex stainless steel grades, conforming to international material standards including ASTM (American Society for Testing and Materials), EN (European Norms), GB (Guobiao — Chinese National Standard), and JIS (Japanese Industrial Standards).
Commonly Available Grades
- 304 / 304L (UNS S30400 / S30403) — General purpose austenitic stainless steel with excellent corrosion resistance and formability
- 316 / 316L (UNS S31600 / S31603) — Enhanced molybdenum content for superior resistance to pitting and crevice corrosion
- 321 (UNS S32100) — Titanium-stabilized grade for high-temperature applications
- 310S (UNS S31008) — High-temperature austenitic grade with outstanding oxidation resistance
- 2205 (UNS S31803) — Duplex stainless steel offering twice the yield strength of 304 at comparable corrosion resistance
Mechanical Properties (Typical — Grade 304L, Annealed Condition)
| Property | Specification | Test Method |
|---|---|---|
| Tensile Strength (Rm) | ≥ 515 MPa (75 ksi) | ASTM A376 / GB/T 249 |
| Yield Strength (Rp0.2) | ≥ 205 MPa (30 ksi) | ASTM A376 / GB/T 249 |
| Elongation (A) | ≥ 35% (minimum, 50 mm gauge length) | ASTM A376 / GB/T 249 |
| Hardness (HB) | ≤ 217 (annealed condition) | ASTM A376 / GB/T 231 |
| Impact Energy (Charpy V-Notch, 25°C) | ≥ 47 J (typical) | ASTM A376 / GB/T 229 |
Chemical Composition (Typical — Grade 304L)
| Element | Maximum (%) | Element | Range (%) |
|---|---|---|---|
| Carbon (C) | 0.030 | Chromium (Cr) | 18.00 – 20.00 |
| Niobium (Nb) | 10 × C | Nickel (Ni) | 8.00 – 10.50 |
| Sulfur (S) | 0.030 | Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | 0.045 | Silicon (Si) | ≤ 1.00 |
Specifications
| Parameter | Specification / Range |
|---|---|
| Product Type | Seamless Stainless Steel Coil Tube (Continuous Helical Form) |
| Manufacturing Equipment | W27Y-219 Medium Frequency Induction Heating Hydraulic Coil Tube Machine |
| Outer Diameter (OD) | 6.0 mm – 108.0 mm (expandable upon request) |
| Wall Thickness | 0.5 mm – 4.0 mm |
| Coil Length (Continuous) | Up to 5,000 m (adjustable per customer requirement) |
| Coil Inner Diameter (ID) | 219 mm (standard, per W27Y-219 machine specification) |
| Surface Finish | Pickled & Passivated (2B), No. 4 Brushed, Mirror (8K), Custom |
| Heat Treatment Condition | Solution Annealed (Solution Annealing), Stress Relieved |
| Medium Frequency Heating Frequency | 100 – 200 Hz (Medium Frequency Induction Heating) |
| Hydraulic Coiling Force | Programmable, with closed-loop tension control |
| Dimensional Tolerance (OD) | ± 0.15 mm (per ASTM A376 / GB/T 14976) |
| Dimensional Tolerance (Wall Thickness) | ± 10% of nominal |
| Standards Compliance | ASTM A376, ASTM A269, GB/T 14976, GB/T 12771, EN 10216-5 |
| Packaging | Wooden crate / steel frame with moisture-proof wrapping; seaworthy export packaging |
Manufacturing Process
The production of Wenzhou Jixing's stainless steel coil tubes follows a rigorously controlled multi-stage process, centered around the W27Y-219 Medium Frequency Induction Heating Hydraulic Coil Tube Machine. Each stage is designed to maximize material integrity, dimensional precision, and surface quality.
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Raw Material Preparation & Inspection
Virgin stainless steel wire rod or pre-drawn tubing is sourced from certified mills. Incoming materials undergo spectroscopic analysis (Spectroscopic Composition Analysis) to verify chemical composition against the specified grade requirements. Physical inspection and dimensional measurement are performed prior to entering the production line.
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Wire Rod Drawing / Tube Pre-Forming
Depending on the target specification, the raw material is processed through multi-pass wire drawing (Wire Drawing) or tube pre-forming stations to achieve the desired pre-coiling dimensions. This stage establishes the initial geometry and surface condition for subsequent processing.
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Medium Frequency Induction Heating
The pre-formed tube passes through a medium frequency induction heating coil operating at 100–200 Hz. This electromagnetic heating method provides rapid, localized, and precisely controlled thermal treatment to the tube surface. The advantages of medium frequency induction heating include:
- Minimal thermal distortion compared to conventional furnace heating
- Superb grain boundary control due to short heating cycle
- Energy efficiency and environmental compliance
- Inline process integration, enabling continuous production
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Hydraulic Coiling Formation
The heated tube enters the hydraulic coiling head, where programmable hydraulic actuators wind the tube into a continuous helical coil with a standard inner diameter of 219 mm. The hydraulic system provides closed-loop tension control, ensuring uniform coiling force throughout the entire coil length. This eliminates the common defects of over-tensioning (which can cause thinning) and under-tensioning (which can lead to coil buckling or ovality).
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Solution Annealing & Pickling
After coiling, the tubes undergo solution annealing (Solution Annealing / Solution Heat Treatment) to relieve residual stresses introduced during forming and to restore full austenitic microstructure. The subsequent pickling (Pickling) process removes any surface oxide scale, followed by passivation (Passivation Treatment) to form a protective chromium oxide layer, ensuring optimal corrosion resistance.
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Non-Destructive Testing (NDT) & Quality Inspection
Every coil tube batch undergoes comprehensive quality assurance testing:
- Eddy Current Testing (ECT) — Detects surface and near-surface defects, wall thickness variations
- Ultrasonic Testing (UT) — Identifies internal volumetric defects and verifies wall thickness uniformity
- Visual Inspection — Surface condition, dimensional accuracy, and coil geometry verification
- Dimensional Measurement — Outer diameter, wall thickness, and coil dimensions per applicable standards
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Packaging & Dispatch
Finished coil tubes are secured in protective packaging designed for both domestic and international shipment. Each coil is clearly labeled with material grade, heat number, dimensions, and certification documentation.
Applications
The versatility of Wenzhou Jixing's stainless steel coil tubes — combined with the precision of the W27Y-219 manufacturing process — renders them suitable for a broad spectrum of industrial applications:
- Petroleum, Petrochemical & Natural Gas Industry — Heat exchanger tubes, process piping, refinery heat transfer systems, and corrosion-resistant structural tubing. The continuous coil form significantly reduces field welding and installation time.
- Food & Beverage Processing — Sanitary-grade tubing for dairy processing, brewing, pharmaceutical manufacturing, and food-grade conveyance systems. Available in electropolished or mirror-finish configurations for hygienic compliance.
- Chemical Processing & Pharmaceutical Manufacturing — Reactor piping, distillation columns, and process lines handling aggressive chemical media. Grades 316L and 2205 offer exceptional resistance to chloride-induced corrosion.
- Power Generation — Boiler tubes, superheater elements, and condenser tubing in thermal and nuclear power plants. The 310S grade is particularly suited for ultra-high-temperature environments.
- Automotive & Aerospace — Exhaust system components, fuel lines, hydraulic tubing, and structural tubing where high strength-to-weight ratios and corrosion resistance are critical.
- Construction & Architectural — Decorative tubing, structural components, and architectural features requiring both aesthetic quality and long-term durability.
- Medical Equipment — Surgical instrument tubing, MRI/NMR equipment components, and medical device fabrication requiring biocompatible, non-magnetic stainless steel.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and holds the following certifications, ensuring that every coil tube product meets international standards of quality, safety, and environmental responsibility:
| Certification | Scope / Description |
|---|---|
| ISO 9001:2015 | Quality Management System — Covers all production, inspection, and delivery processes |
| ISO 14001:2015 | Environmental Management System — Demonstrates commitment to sustainable manufacturing practices |
| ISO 45001:2018 | Occupational Health & Safety Management System — Ensures workplace safety standards |
| CE Marking | European Conformity — Certifies compliance with European health, safety, and environmental protection standards |
| EN 10204 3.1 | Material Test Certificate (Material Test Report) — Third-party verified product quality documentation for each heat lot |
| NACE MR0175 / ISO 15156 | Materials for Use in Hydrogen Sulfide (H2S) Containing Environments in Oil and Gas Production — Available for applicable grades |
| Mill Test Reports (MTR) | Comprehensive chemical and mechanical property documentation provided with every shipment, traceable to individual heat numbers |
Unique Selling Points
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