316L Electropolished Stainless Steel Coil Tube for Gas Chromatography (GC) Carrier Gas Lines
Product Overview
This high-precision stainless steel coil tube is specifically engineered for Gas Chromatography (GC) carrier gas delivery systems. Designed to transport high-purity helium (He), hydrogen (H₂), and nitrogen (N₂) carrier gases with exceptional flow stability, this product meets the demanding requirements of process analysis instrumentation where even trace-level contamination or pressure fluctuations can compromise analytical accuracy. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this coil tube represents the pinnacle of ultra-pure gas line technology for laboratory and industrial process analytical applications.
Material & Properties
The coil tube is fabricated from AISI 316L (UNS S31603) austenitic stainless steel, cold-worked (cold-drawn/re-drawn) to achieve superior dimensional precision and mechanical integrity. The "L" designation indicates a low-carbon variant (C ≤ 0.03%), which minimizes intergranular corrosion susceptibility during welding and high-temperature exposure.
- Base Material: 316L Cold-Worked Capillary Stainless Steel
- Chemical Composition: Cr 16–18%, Ni 10–14%, Mo 2–3%, C ≤ 0.03%
- Corrosion Resistance: Excellent resistance to pitting, crevice, and intergranular corrosion
- Surface Finish: Electropolished (EP) inner bore — Ra ≤ 0.05 μm
- Mechanical Properties: High tensile strength, excellent fatigue resistance from cold-drawing process
- Outgassing Rate: Ultra-low outgassing suitable for high-purity gas service
Specifications
| Parameter | Specification |
|---|---|
| Material Grade | AISI 316L (UNS S31603), Cold-Worked |
| Outer Diameter (OD) | ≤ 3 mm (Capillary configuration) |
| Inner Diameter (ID) | Standard capillary bore (typical: 0.1–0.53 mm ID) |
| Wall Thickness | As per capillary dimensional standards |
| Inner Surface Finish | Electropolished (EP), Ra ≤ 0.05 μm |
| Outer Surface Finish | Mechanical polished / Brushed |
| Form | Coil Tube (Continuous Coiled Configuration) |
| Carrier Gases Supported | Helium (He), Hydrogen (H₂), Nitrogen (N₂) — High Purity |
| Pressure Rating | High-pressure gas service (up to 40–60 bar typical) |
| Leak Tightness | Helium leak tested — ≤ 1 × 10⁻⁹ mbar·L/s |
| Coil Diameter | Customizable per application requirements |
| Length | Custom cut lengths or continuous coil supply |
Manufacturing Process
- Raw Material Selection: Premium-grade 316L stainless steel seamless capillary tube sourced from certified mill producers with full traceability.
- Cold Drawing (Re-Drawing): Multi-pass cold-drawing process through precision tungsten carbide dies to achieve tight dimensional tolerances (±0.005 mm) and enhanced mechanical strength. This re-drawing process aligns the grain structure, improving fatigue life and pressure resistance.
- Electropolishing (EP): The inner bore undergoes electrochemical polishing to achieve a mirror-like surface finish (Ra ≤ 0.05 μm). This process removes surface contaminants, eliminates dead legs, and prevents particle adhesion — critical for maintaining carrier gas purity in GC applications.
- Purification & Cleaning: Multi-stage cleaning including acid pickling, deionized water rinsing, and high-purity solvent flushing to eliminate residual contaminants and moisture.
- Coiling: Precision coiling at controlled bend radii to prevent wall-thinning, kinking, or deformation that could impair flow uniformity.
- Helium Leak Testing: Each coil assembly undergoes 100% helium mass spectrometry leak detection to ensure absolute leak-tightness at the 10⁻⁹ mbar·L/s level.
- End Capping & Packaging: Hermetic end-capping with inert gas purging and vacuum packaging to prevent re-contamination prior to shipment.
Applications
This coil tube is purpose-designed for process analysis instrumentation, specifically for the following applications:
- Gas Chromatography (GC) Carrier Gas Lines: Primary application — delivering high-purity He, H₂, or N₂ carrier gases from cylinder/bank to GC instrument with minimal pressure drop and zero contamination.
- Process Analytical Instruments (PAI): In-line gas delivery for continuous process monitoring in petrochemical, pharmaceutical, and semiconductor manufacturing.
- High-Purity Gas Distribution Systems: Laboratory and industrial gas panel-to-instrument connections requiring ultra-low outgassing.
- Mass Spectrometry (MS) Gas Lines: Compatible with GC-MS hyphenated systems requiring absolute purity.
- Environmental Monitoring: Carrier gas delivery for trace-level pollutant detection systems.
- Pharmaceutical Quality Control: GMP-compliant gas delivery for residual solvent analysis and impurity profiling.
Quality Certifications & Compliance
- Material Certification: Full mill test certificates (EN 10204 3.1) with chemical analysis and mechanical property verification
- Leak Testing: 100% helium mass spectrometer leak testing per ASTM F2373 / ISO 11114
- Surface Quality: Electropolishing per ASTM B910 / AMS 2700 standards
- Purity Assurance: Ultra-low particulate and metallic contamination — suitable for GC-grade gas service
- Dimensional Compliance: Tight tolerances per ASTM A269 / ASTM A213 seamless capillary tube standards
- Traceability: Full heat-number traceability from raw material through final product
Unique Selling Points
1. Ultra-Pure Electropolished Interior: Ra ≤ 0.05 μm EP finish eliminates gas adsorption sites and ensures zero particulate release into the carrier gas stream — preserving chromatographic resolution and baseline stability.
2. Cold-Worked 316L Construction: Re-drawing process provides superior pressure resistance, fatigue life, and dimensional consistency compared to annealed alternatives, ensuring long-term flow stability under cyclic operating conditions.
3. Helium Leak Tested at 10⁻⁹ mbar·L/s: Industry-leading leak-tightness guarantees no carrier gas loss or ambient air ingress that could introduce oxygen or moisture contaminants.
4. Capillary OD ≤ 3 mm Design: Minimizes dead volume and residence time, reducing peak broadening and improving chromatographic efficiency for quantitative analysis.
5. Multi-Gas Compatibility: Single product solution for He, H₂, and N₂ carrier gases — simplifying inventory management while maintaining consistent performance across different GC method requirements.
Technical Notes
Flow stability in GC carrier gas lines is governed by the combined effects of tube inner diameter uniformity, surface roughness, and leak-tightness. This product addresses all three factors simultaneously through its cold-drawn dimensional precision, electropolished surface, and helium-verified integrity. The result is a carrier gas delivery system that maintains constant flow rate (±0.1% stability) over extended analytical runs, ensuring reproducible retention times and accurate quantitative results.