Stainless Steel Coil Tube — Helium Mass Spectrometry Leak Detection Specification
Product Overview
The Stainless Steel Coil Tube (Product No. 226) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tubing product designed for demanding industrial applications requiring ultra-low permeability and exceptional leak integrity. This coil tube is engineered specifically for high-purity piping systems and vacuum applications where even trace-level leakage can compromise system performance, product purity, or safety compliance.
A defining characteristic of this product is its rigorous Helium Mass Spectrometry (HMS) Leak Detection and Bubble Test Method verification protocol, achieving a detection sensitivity of 10⁻⁹ mbar·L/s. This represents industry-leading micro-leak localization capability, ensuring that every coil tube unit meets the stringent quality thresholds required for critical process environments.
Material & Properties
Base Material
- Material Grade: Austenitic stainless steel (typical grades: 304 / 304L / 316L / 316LN)
- Chemical Composition: Low-carbon austenitic formulation optimized for weldability, corrosion resistance, and cryogenic toughness
- Surface Finish: Electropolished or passivated interior surface (Ra ≤ 0.4 μm for high-purity applications)
- Wall Construction: Seamless or welded with full-penetration butt welds; coil-formed to specified bending radius
Mechanical & Physical Properties
- Tensile Strength: ≥ 520 MPa (minimum)
- Yield Strength: ≥ 205 MPa (minimum, at 0.2% offset)
- Elongation: ≥ 40% (minimum, at rupture)
- Operating Temperature Range: −196 °C (LN₂) to +600 °C
- Maximum Working Pressure: Up to 40 bar (gauge), depending on wall thickness and diameter
- Permeability Rate: < 10⁻⁹ mbar·L/s (verified by helium mass spectrometry)
Specifications
| Parameter | Specification / Value | Test Method / Standard |
|---|---|---|
| Product Category | Coil Tube (盘管) | — |
| Application Classification | Installation & Maintenance — Leak Detection | — |
| Leak Detection Method | Helium Mass Spectrometry (HMS) / Bubble Test | ASTM F2685 / EN ISO 16617 / GB/T 13927 |
| Detection Sensitivity | 10⁻⁹ mbar·L/s | Helium mass spectrometer calibration |
| Leak Localization | Micro-leak pinpointing (sub-millimeter resolution) | Sniffer probe technique |
| Coil Diameter Range | OD 6 mm – 159 mm | Dimensional inspection |
| Wall Thickness Range | 0.5 mm – 6.0 mm | Ultrasonic thickness gauge |
| Coil Length | Up to 500 m per coil (custom lengths available) | Length measurement |
| Minimum Bend Radius | 3D (three times outer diameter) | Bend radius verification |
| Pressure Test Level | 1.5× maximum working pressure | Hydrostatic / pneumatic test |
| Verification Frequency | Periodic verification for high-purity piping and vacuum systems | Scheduled QA protocol |
Manufacturing Process
- Material Selection & Incoming Inspection: Raw steel coil/sheet sourced from certified mills; verified for chemical composition (OES spectroscopy), mechanical properties, and surface quality.
- Forming & Welding: Precision roll-forming or cold-bending into coil geometry; seamless tubes are drawn and cold-formed. Welded variants employ orbital TIG (GTAW) welding with inert gas shielding (argon/helium mix).
- Heat Treatment: Solution annealing at 1050–1150 °C followed by controlled cooling to achieve uniform austenitic microstructure and stress relief.
- Surface Treatment: Interior electropolishing or chemical passivation to remove free iron, contaminants, and achieve ultra-low surface roughness for high-purity service.
- Coil Winding: Careful coiling at controlled tension to avoid deformation, kinking, or micro-cracking; maintained within minimum bend radius specifications.
- Leak Detection & Quality Assurance: Every production lot undergoes helium mass spectrometry leak testing. Suspect areas are further verified using the bubble test method for visual confirmation. Results are documented with sensitivity traceable to 10⁻⁹ mbar·L/s standard.
- Packaging & Protection: Coils are wrapped in protective film, placed in wooden crates or custom packaging, and stored in controlled environments to prevent contamination prior to shipment.
Leak Detection Methodology — Technical Detail
Helium Mass Spectrometry (HMS)
The Helium Mass Spectrometer is the primary instrument for micro-leak detection. The system is evacuated to base pressure, and helium is introduced as a tracer gas either by pressurizing the coil tube from the inside (internal pressurization method) or by sweeping the exterior surface with a sniffer probe (external sniffing method). The mass spectrometer detects helium molecules (m/z = 4) with extraordinary sensitivity, capable of identifying leak rates as low as 10⁻⁹ mbar·L/s.
Key advantages of HMS for coil tube inspection include:
- Non-destructive testing capability
- Quantitative leak rate measurement
- High selectivity — helium is rare in ambient air (0.000527%), minimizing false positives
- Applicable to complex geometries typical of coiled tubing
Bubble Test Method
The Bubble Test serves as a complementary verification technique, particularly for confirming and localizing leaks identified by the mass spectrometer. The coil tube is pressurized with an inert gas (nitrogen or helium) and submerged in or coated with a surfactant solution. Visible bubble formation indicates the presence and location of a leak. While less sensitive than HMS (typically limited to ~10⁻⁴ mbar·L/s), the bubble test provides immediate visual confirmation and is ideal for rapid field screening.
Applications
Primary Application Domains
- Semiconductor Manufacturing: Ultra-high-purity (UHP) gas delivery systems requiring leak rates below 10⁻⁹ mbar·L/s for chemical vapor deposition (CVD), physical vapor deposition (PVD), and etching processes.
- Pharmaceutical & Biotechnology: GMP-compliant piping for sterile gas transfer, cleanroom ventilation, and bioreactor systems.
- Cryogenic Systems: Liquid nitrogen (LN₂), liquid natural gas (LNG), and hydrogen liquefaction plants operating at cryogenic temperatures.
- Vacuum Technology: Components for vacuum chambers, particle accelerators, and research instrumentation requiring ultra-high vacuum (UHV) integrity.
- Food & Beverage Industry: Hygienic process piping for carbonation, CO₂ injection, and nitrogen blanket systems.
- Energy & Petrochemical: High-pressure gas distribution, hydrogen pipelines, and hydrogen fuel cell supply systems.
Periodic Verification Protocol
For high-purity piping and vacuum systems, the helium mass spectrometry leak test is designated as the standard periodic verification method. Recommended verification intervals include:
- Post-installation commissioning (mandatory)
- Every 12 months for high-purity systems
- Every 6 months for UHV applications
- After any mechanical shock, repair, or maintenance intervention
Quality Certifications & Standards Compliance
Product Certifications
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- CE Marking — European Conformity (where applicable)
- EN 10204 3.1 — Material Test Certificates
- ASME B31.3 — Process Piping compliance
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes
- ASTM A213 / A269 / A554 — Material and product standards
Testing & Inspection Standards
- ASTM F2685 — Standard Practice for Helium Leak Detection of Welded Joints
- EN ISO 16617 — Helium leak detection of welded joints
- GB/T 13927 — Chinese standard for pressure piping leak testing
- ASTM A999 — Standard specification for seamless austenitic stainless steel pipe for high-temperature service
- ASME BPV Section VIII — Pressure vessel and piping code compliance
Traceability & Documentation
Each coil tube lot is accompanied by a comprehensive Quality Assurance Dossier including:
- Mill test certificates (MTC) with full chemical and mechanical analysis
- Helium mass spectrometry leak test report with calibrated instrument traceability
- Dimensional inspection records
- Surface finish verification (interferometry or profilometry data)
- Heat treatment records and microstructure verification
- Welding procedure qualifications (WPS/PQR) for welded variants
Unique Selling Points
Industry-Leading Leak Detection Sensitivity: At 10⁻⁹ mbar·L/s, Wenzhou Jixing Metal Materials delivers helium mass spectrometry verification at a sensitivity level that exceeds most competitors' standard offering, ensuring coil tubes meet the most demanding UHP and UHV specifications.
- Dual-Method Verification: The combination of helium mass spectrometry (quantitative, high-sensitivity) and bubble testing (qualitative, visual confirmation) provides a redundant, high-confidence quality assurance approach.
- Full Traceability: From raw material to finished coil, every lot carries complete documentation traceable to international standards, enabling seamless integration into regulated supply chains.
- Customization Capability: Coil dimensions, lengths, material grades, and surface finishes are tailored to specific application requirements, reducing downstream fabrication costs and installation complexity.
- Critical Application Focus: The product is specifically engineered and validated for high-purity piping and vacuum system applications where leak integrity is non-negotiable.
Conclusion
The Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd. represents a benchmark product in the precision tubing industry. Its integration of state-of-the-art helium mass spectrometry leak detection at 10⁻⁹ mbar·L/s sensitivity, combined with rigorous manufacturing controls and full standards compliance, positions it as the preferred choice for engineers and procurement professionals responsible for high-purity and vacuum system integrity. The periodic verification protocol ensures sustained performance throughout the service life of critical process installations.