316LVM Vacuum Melted Stainless Steel Capillary Coil Tube for Interventional Catheter Sheaths and Balloon Dilation Devices
Product Overview
The 316LVM Vacuum Melted Stainless Steel Capillary Coil Tube is a precision-engineered medical-grade tubing product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. specifically designed for the fabrication of interventional medical devices, including catheter sheaths and balloon dilation tubes. These devices are implanted or temporarily inserted into the human body, demanding the highest levels of biocompatibility, corrosion resistance, and mechanical integrity.
Conforming to ASTM F138 standard for passive implant-grade stainless steel, this coil tube represents the gold standard in minimally invasive intervention device manufacturing. The vacuum melting process eliminates harmful inclusions and impurities that could compromise biocompatibility, ensuring patient safety in critical clinical procedures.
Unique Selling Points: Vacuum melted purity for superior biocompatibility | ASTM F138 implant-grade compliance | Ultra-fine capillary dimensions enabling true miniaturization | Consistent coil form for seamless downstream processing | Full traceability from raw material to finished product
Material & Properties
The tubing is manufactured from SAE 316LVM (Vacuum Melted) austenitic stainless steel, a specialized variant of 316L stainless steel produced through vacuum induction melting (VIM). The vacuum melting process significantly reduces gas content (oxygen, nitrogen) and trace element inclusions (such as copper, tin, and lead), which are critical factors in determining biocompatibility and long-term implant safety.
Key Material Characteristics
- Biocompatibility: Certified for prolonged contact with human tissue and blood; non-cytotoxic, non-genotoxic, and non-sensitizing
- Corrosion Resistance: Exceptional resistance to physiological fluids, including blood, serum, and interstitial fluid, preventing ion release and tissue degradation
- Low Nickel Release: Vacuum melting minimizes free nickel content, reducing risk of allergic reactions and hypersensitivity
- Mechanical Strength: Maintains high tensile strength and fatigue resistance even at ultra-thin wall thicknesses required for miniaturized devices
- Formability: Excellent deep-drawability and cold-work hardening response for precise shaping during catheter component fabrication
- Radiopacity: Sufficient X-ray visibility to allow real-time fluoroscopic guidance during interventional procedures
Specifications
| Parameter | Specification |
|---|---|
| Material Grade | SAE 316LVM (Vacuum Melted) |
| Standard Compliance | ASTM F138 / ASTM F138M |
| Outer Diameter (OD) | 0.15 mm – 3.0 mm (0.006" – 0.118") |
| Wall Thickness | 0.02 mm – 0.50 mm (0.0008" – 0.020") |
| Coil Length | 50 m – 500 m per coil (customizable) |
| Surface Finish | Pickled & Passivated (Ra ≤ 0.4 μm); Electro-polished available |
| Manufacturing Process | Seamless cold drawing |
| Delivery Form | Coiled (Coiltube) |
| Maximum Oxygen Content | ≤ 0.008% (by weight) |
| Maximum Nitrogen Content | ≤ 0.030% (by weight) |
| Tensile Strength (Annealed) | ≥ 450 MPa (≥ 65 ksi) |
| Hardness (Annealed) | ≤ 200 HV |
| Crystallization Test | Pass (ASTM A240) |
| Pitting Resistance Test | Pass (ASTM A262 Practice E) |
Chemical Composition (ASTM F138 Requirements)
| Element | Maximum (%) | Element | Maximum (%) |
|---|---|---|---|
| Carbon (C) | 0.030 | Molybdenum (Mo) | 3.00 |
| Manganese (Mn) | 2.00 | Phosphorus (P) | 0.035 |
| Silicon (Si) | 1.00 | Sulfur (S) | 0.030 |
| Chromium (Cr) | 13.00 – 17.00 | Nickel (Ni) | 10.00 – 14.00 |
| Niobium (Nb) | 10 × C (min 0.030) | Titanium (Ti) | — |
Manufacturing Process
The production of 316LVM medical-grade coil tube involves a multi-stage precision manufacturing process, each step rigorously controlled to ensure product consistency and biocompatibility:
- Vacuum Induction Melting (VIM): Raw materials are melted under ultra-high vacuum conditions (≤ 10⁻³ Pa) to minimize dissolved gases and inclusions. The vacuum environment prevents oxidation and contamination from the atmosphere.
- Remelting (Optional VAR/ESR): For ultra-purity requirements, a secondary remelting step via Vacuum Arc Remelting (VAR) or Electro-Slag Remelting (ESR) further refines the microstructure and eliminates residual inclusions.
- Hot Rolling & Extrusion: The refined ingot is hot-rolled into intermediate wire rod or extruded into seamless tubing blanks with controlled dimensional tolerances.
- Pickling & Decapping: Surface oxides and scale are removed through controlled acid pickling to achieve a clean, uniform surface condition.
- Cold Drawing: Seamless capillary tubing is progressively cold-drawn through precision tungsten carbide dies to achieve final OD and wall thickness dimensions with tight tolerances (± 0.01 mm).
- Intermediate Annealing: Periodic solution annealing at 1050°C – 1150°C restores ductility and prevents work-hardening during multi-draw operations.
- Final Pickling & Passivation: The finished tubing undergoes final acid pickling and nitric/citric acid passivation to form a stable chromium oxide protective layer and remove any residual contaminants.
- Coiling: The finished tubing is wound into coils of specified length and diameter for convenient downstream processing by catheter manufacturers.
- Inspection & Testing: Every coil undergoes comprehensive dimensional inspection, chemical analysis (spectrometry), mechanical testing, and biocompatibility screening.
Applications
Interventional Medical Devices
- Catheter Sheaths: Used as the structural backbone or marker band material in vascular catheter sheaths for guiding interventional devices through blood vessels with minimal trauma
- Balloon Dilation Tubes: Serve as the reinforcing layer or radiopaque marker in balloon catheters used for angioplasty, stent delivery, and vessel dilation procedures
- Guide Wire Cores: Ultra-fine capillary tubing used as the central core of vascular guide wires requiring high pushability and kink resistance
- Valve Frame Components: Precision tubing segments for transcatheter heart valve (TAVR/TAVI) frame construction
- Embolic Protection Devices: Structural elements in devices used to capture embolic debris during carotid artery interventions
- Peripheral Vascular Devices: Components in devices for treating peripheral arterial disease, including angioplasty balloons and atherectomy catheters
Key Application Advantages
- In-Body Implantation Safety: Vacuum melted purity ensures no harmful leachables or degradation products are released into surrounding tissue
- Miniaturization Capability: Ultra-thin wall thicknesses (as low as 0.02 mm) enable device profiles below 0.5 mm, facilitating access to distal vessels and minimally invasive procedures
- Long-Term Stability: Superior corrosion resistance ensures device integrity throughout the intended clinical service life
- Processing Compatibility: Coiled delivery format enables seamless integration into automated catheter assembly lines, reducing waste and improving manufacturing efficiency
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and holds the following certifications to ensure medical-grade product compliance:
- ASTM F138 / F138M: Standard Specification for Passive Implant-Grade Stainless Steels — Full chemical, mechanical, and metallurgical compliance
- ISO 13485: Quality Management Systems for Medical Devices — Certified manufacturing and quality control processes
- ISO 9001: General Quality Management System certification
- ISO 14971: Risk Management for Medical Devices
- EU MDR (2017/745): Material documentation and declaration of compliance for European Union medical device regulations
- US FDA 21 CFR Part 820: Quality System Regulation compliance for US market supply
- RoHS / REACH: Compliance with hazardous substance restrictions and chemical registration requirements
- Biocompatibility Testing: ISO 10993 series testing (cytotoxicity, sensitization, irritation, hemocompatibility, systemic toxicity)
- Full Material Traceability: Heat number traceability from vacuum melt through all processing stages to final product delivery
Summary
The 316LVM Vacuum Melted Stainless Steel Capillary Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. is purpose-built for the demanding requirements of interventional medical device manufacturing. By combining vacuum melting purity, ASTM F138 implant-grade compliance, and ultra-fine capillary dimensions, this product enables the miniaturization and biocompatibility essential for next-generation catheter sheaths, balloon dilation devices, and other minimally invasive intervention tools. The coiled delivery format optimizes downstream processing efficiency while maintaining dimensional precision and surface quality throughout the manufacturing chain.