Stainless Steel Coil Tube (盘管 Coiltube) — Inverted Drawing Process Specification
1. Product Overview
The Stainless Steel Coil Tube (盘管 Coiltube), product catalog number 458, is a precision-engineered continuous-length tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This coil tube is produced through the proprietary Inverted Coil Tube Drawing Machine (倒立式盘管拉拔机) process, which represents a significant advancement in tubular forming technology. Unlike conventional upright drawing machines, the inverted configuration provides superior material flow control, enhanced dimensional accuracy, and improved surface integrity throughout the drawing cycle.
The coil tube is supplied in continuous coil form, eliminating the need for butt welding during downstream processing and significantly reducing material waste. This product is categorized under the Literature Study (文献学习) classification, indicating its status as a technically validated and academically documented product line with well-established process parameters and quality benchmarks.
2. Material & Properties
The coil tube is fabricated from high-grade austenitic and/or duplex stainless steel grades, selected to meet the demanding requirements of corrosion resistance, mechanical strength, and formability. The following table outlines the typical material specifications:
| Parameter | Specification | Test Standard |
|---|---|---|
| Material Grades | SUS304, SUS316, SUS316L, SUS321, SUS310S, SUS2205 | ASTM A213 / GB/T 12771 |
| Tensile Strength (UTS) | ≥ 520 MPa (typical for 304 grade) | ASTM A376 / ISO 6892 |
| Yield Strength (0.2% Offset) | ≥ 205 MPa | ASTM A376 |
| Elongation at Break | ≥ 40% | ASTM A376 |
| Hardness (Rockwell B) | ≤ 95 HRB | ASTM A262 |
| Corrosion Resistance | PASS — Salt Spray Test 1000 hrs (316 grade) | ASTM B117 / GB/T 10125 |
| Surface Finish | Mirror (Ra ≤ 0.05 μm), Hairline, No.4 Brush, or Pickled & Passivated | ASTM A478 |
| Carbon Equivalent (CE) | ≤ 0.04% (low-carbon grades for welding applications) | ISO 8044 |
3. Specifications
The following table presents the dimensional and geometric specifications for the Coil Tube product line:
| Specification Parameter | Range / Value | Tolerance |
|---|---|---|
| Outer Diameter (OD) | Φ3.0 mm – Φ38.1 mm | ±0.05 mm |
| Wall Thickness | 0.3 mm – 3.0 mm | ±0.03 mm |
| Coil Length (per coil) | 50 m – 300 m (configurable) | ±2% |
| Coil Inner Diameter (ID) | Φ150 mm / Φ200 mm / Φ250 mm | ±5 mm |
| Coil Outer Diameter (OD) | ≤ Φ600 mm (standard) | — |
| Straightness Deviation | ≤ 0.5 mm/m (when uncoiled) | — |
| Roundness (Circularity) | ≤ 1.5% of OD | — |
| Wall Thickness Variation | ≤ ±10% of nominal thickness | — |
| End Condition | Clean cut, deburred, or custom-formed | — |
| Maximum Drawing Reduction per Pass | ≤ 25% (inverted machine configuration) | — |
4. Manufacturing Process
The production of the Stainless Steel Coil Tube employs a multi-stage manufacturing workflow centered around the Inverted Coil Tube Drawing Machine (倒立式盘管拉拔机). The inverted orientation of the drawing head — with the die assembly positioned below the tube feed — provides a number of process advantages including gravity-assisted tube alignment, reduced bending stresses, and improved lubricant retention within the die cavity.
4.1 Process Flow
- Raw Material Selection & Inspection: Stainless steel seamless or welded pipe blanks are received and subjected to incoming quality inspection (IQI), including chemical composition analysis (OES), dimensional verification, and surface defect screening.
- Preparation & Cutting: Pipe blanks are cut to specified drawing lengths using a high-precision plasma or laser cutting system, with deburring and chamfering to prepare end faces for die entry.
- Surface Preparation: Tubes are cleaned, degreased, and coated with a specialized drawing lubricant (typically a molybdenum disulfide-based or PTFE-enhanced compound) to reduce friction and prevent galling during the drawing operation.
- Inverted Drawing Operation: The tube is fed from above into the inverted die assembly. The drawing head pulls the tube through the die from top to bottom, applying compressive and tensile stresses that reduce the outer diameter and wall thickness to target specifications. Multiple passes may be required depending on the reduction ratio per pass.
- Intermediate Annealing (if required):strong> For multi-pass drawing sequences, intermediate annealing at 1050–1150°C followed by controlled cooling (air or furnace cool) restores ductility and relieves residual stresses accumulated during prior drawing passes.
- Pickling & Passivation: After the final drawing pass, the coil tube undergoes acid pickling (HNO₃/HF or HNO₃/HCl blend) to remove surface oxides, followed by passivation treatment to establish a protective chromium oxide layer.
- Surface Finishing: Depending on the application, the coil tube may receive additional surface treatments including mechanical polishing, electropolishing, or chemical brightening to achieve mirror or satin finishes.
- Coiling & Packaging: The finished tube is coiled onto a mandrel at controlled tension to prevent ovalization or springback. Coils are wrapped in protective film, placed in moisture-barrier packaging, and secured for shipment.
- Final Quality Inspection (FQI): Each coil undergoes dimensional measurement (OD, wall thickness, roundness), mechanical testing (tensile, hardness), corrosion testing (as applicable), and visual/eddy-current inspection prior to release.
4.2 Inverted Drawing Machine — Technical Advantages
The inverted coil tube drawing machine (倒立式盘管拉拔机) represents a process innovation that addresses several limitations of traditional upright drawing configurations:
- Reduced Bending Stress: The inverted geometry minimizes lateral bending moments on the tube during feed, resulting in superior dimensional consistency and reduced risk of ovalization.
- Enhanced Lubricant Retention: Gravity assists in maintaining lubricant film integrity within the die bore, reducing wear on both the tube surface and the die tooling.
- Improved Surface Quality: The downward drawing motion produces a more uniform material flow, yielding superior surface finish (typically Ra ≤ 0.1 μm achievable) and reduced surface defects.
- Higher Productivity: The inverted configuration enables higher drawing speeds with equivalent or superior product quality, increasing throughput by an estimated 15–25% compared to conventional setups.
- Tool Life Extension: Reduced friction and improved material flow extend die and plug tool life, reducing maintenance frequency and overall manufacturing cost.
5. Applications
The Stainless Steel Coil Tube (盘管 Coiltube) is widely utilized across multiple high-precision industries due to its continuous-length supply format, superior surface quality, and dimensional accuracy:
- Medical & Pharmaceutical Equipment: Surgical instrument tubing, endoscope sheaths, infusion device components, and pharmaceutical processing lines where biocompatibility (ISO 10993) and corrosion resistance are critical.
- Automotive Industry: Fuel system lines, exhaust system components, hydraulic brake lines, and sensor housings requiring high-temperature resistance and fatigue durability.
- Food & Beverage Processing: Sanitary piping, heat exchanger tubes, and processing equipment components requiring FDA-compliant, easily cleanable surfaces.
- Chemical Processing: Reactor internals, heat exchanger tubes, and process piping in aggressive chemical environments (particularly 316L and 2205 grades).
- Electronics & Optics: Precision instrument housings, optical fiber protection tubes, and sensor components requiring tight dimensional tolerances and high surface finish.
- Consumer Goods: High-end watch components, jewelry manufacturing, and premium appliance parts where aesthetic surface quality is paramount.
- Energy Sector: Solar thermal collector tubes, hydrogen fuel cell components, and nuclear-grade tubing applications.
6. Quality Certifications & Compliance
The Stainless Steel Coil Tube product line adheres to international quality management and industry-specific certification standards:
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification covering all manufacturing, inspection, and delivery processes. |
| ISO 14001:2015 | Environmental Management System certification demonstrating environmental responsibility in production. |
| ISO 45001:2018 | Occupational Health and Safety Management System certification. |
| ASTM / ASME | Compliance with ASTM A213 (seamless tubular), ASTM A269 (welded tubular), and ASME B36.19M dimensional standards. |
| EN 10216-5 / EN 10217-7 | European standards for welded stainless steel tubes for pressure and non-pressure applications. |
| GB/T 12771 | Chinese national standard for seamless stainless steel tubes for general use. |
| CE Marking | Conformity with European Economic Area (EEA) directives for market access. |
| Material Traceability | Full heat-number traceability from raw material mill certificate through final product delivery. |
7. Unique Selling Points
- Proprietary Inverted Drawing Technology: The inverted coil tube drawing machine (倒立式盘管拉拔机) provides a competitive advantage in surface quality, dimensional accuracy, and manufacturing efficiency that is difficult to replicate with conventional upright drawing setups.
- Superior Surface Finish: Achievable mirror finish (Ra ≤ 0.05 μm) directly from the drawing process, minimizing or eliminating the need for additional polishing operations.
- Continuous-Length Supply: Coil format eliminates butt welds, reducing material waste by up to 15% and eliminating potential leak paths in critical applications.
- Tight Dimensional Tolerances: OD tolerance of ±0.05 mm and wall thickness tolerance of ±0.03 mm enable direct use in precision applications without secondary machining.
- Multi-Grade Capability: Production flexibility across austenitic, duplex, and specialty stainless steel grades from a single manufacturing platform.
- Custom Configuration: Tailored coil dimensions, surface finishes, end conditions, and packaging to meet specific customer requirements.
8. Storage & Handling Recommendations
- Store coils in a dry, well-ventilated warehouse with ambient temperature between 5°C and 40°C and relative humidity below 60%.
- Protect coils from contact with carbon steel or other reactive metals to prevent galvanic corrosion.
- Do not stack coils vertically; store horizontally on purpose-designed coil saddles or racks.
- During uncoiling, maintain consistent tension and avoid sharp bends below the minimum recommended bend radius (typically ≥ 5× OD for austenitic grades).
- Handle with clean, dry gloves to prevent fingerprint-induced localized corrosion on passivated surfaces.
9. Conclusion
The Stainless Steel Coil Tube (盘管 Coiltube) product from Wenzhou Jixing Metal Materials Co., Ltd. exemplifies the convergence of advanced metallurgical engineering and precision manufacturing technology. The utilization of the inverted coil tube drawing machine (倒立式盘管拉拔机) as the core forming technology provides measurable improvements in product quality, process efficiency, and cost competitiveness. With comprehensive quality certification, multi-grade material capability, and full traceability, this product line serves as a reliable supply chain solution for demanding industrial applications worldwide.