Wofly Technology Ensures Quality and Safety in Laboratory Gas Piping Systems

Empowering Laboratory Gas Piping Systems

Quality and Safety Assurance

Summary

Laboratory gas piping systems are an essential part of the infrastructure for scientific research, testing, and precision manufacturing. The pressure, purity, and flow stability of gases transported through these systems—including hydrogen (H₂), oxygen (O₂), nitrogen (N₂), argon (Ar), helium (He), ammonia (NH₃), and silane (SiH₄)—directly affect the reproducibility of experimental data and the safe operation of equipment.

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Classification and Hazardous Properties of Laboratory Gases

Laboratory gases are classified into four categories based on their chemical properties, and each category has specific requirements for piping materials and safety precautions:

• Inert gases (N₂, Ar, He): These gases are chemically stable and are used for purging, as protective gases, and as carrier gases. High concentrations can cause asphyxiation, so adequate ventilation must be maintained.
• Oxidizing gases (O₂, compressed air): These gases are oxidizing; piping must be strictly oil-free, and seals must be made of flame-retardant materials.
• Flammable gases (H₂, SiH₄): H₂ has an explosive limit of 4%–75%; SiH₄ is spontaneously combustible; requires a dedicated cylinder cabinet and exhaust gas treatment equipment.
• Corrosive gases (NH₃, Cl₂): Corrosive to piping materials; requires the use of corrosion-resistant alloys and the installation of gas detection and alarm systems.

Core Safety Risks in Gas Piping Systems

Gas leaks most commonly occur at valve packing, VCR fittings, welds, and flanges; flammable gases can accumulate to explosive concentrations, while toxic gases pose a direct threat to personnel safety.

Purity contamination stems from particles, moisture, and metal ion precipitation on the inner walls of piping, which can lead to reduced device yield and instrument baseline drift; high-purity piping requires an inner surface roughness (Ra) of ≤0.4 μm.

Pressure abnormalities include overpressure caused by pressure-reducing valve failure and pipeline blockages, as well as pressure fluctuations resulting from gas source switching, all of which affect equipment safety and experimental stability.

Material corrosion is common in environments with corrosive gases. 316L stainless steel is resistant to alkaline gases such as NH₃, while strong oxidizing gases such as Cl₂ require the use of Hastelloy or Monel alloys.

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Quality Requirements for Laboratory Gas Piping

• Material Selection: For high-purity gases, use 316L stainless steel electropolished (EP) tubing to reduce particle adsorption and gas outgassing; for general-purpose gases, 304 stainless steel seamless tubing may be used.
• Joining Process: The high-purity system employs fully automated rail-guided tungsten inert gas (GTAW) welding; removable joints use VCR metal-to-metal seals with a leakage rate of ≤1×10⁻⁹ Pa·m³/s.
• Inspection and Acceptance: Hydrostatic testing (1.5 times the design pressure), pneumatic testing (1.15 times the design pressure), and helium mass spectrometer leak detection are performed in sequence.
• Standards: Complies with domestic and international standards such as SEMI F20, GB 50177, and GB 50029.

Wofly Technology's System Solutions and Core Technologies

Shenzhen Wofly Technology Special Gas Engineering Design Showcase (For Reference Only)

End-to-End Engineering Service System

Shenzhen Wo Fei Technology provides end-to-end services ranging from solution design to final acceptance and delivery, with clear technical standards and quality control points established for each stage:

• Solution Design: The layout is determined based on gas type, consumption, pressure rating, and terminal distribution. Separate piping is used for flammable gases (H₂, SiH₄); a safe distance is maintained between oxidizing gases and flammable gases; and corrosion-resistant materials are selected for corrosive gases (NH₃, Cl₂).
• Material Selection: 316L EP tubing is used for high-purity systems; diaphragm valves and bellows valves are selected to prevent packing leaks; pressure-reducing valves are selected based on inlet pressure and outlet flow rate.
• Construction and Installation: Pipes are cut using planetary pipe cutters and welded with fully automatic rail-mounted welding machines; parameters are confirmed through process qualification (PQR). During construction, pipes are purged with argon to prevent oxidation.
• Inspection and Acceptance: Pressure testing, leak detection, purging and cleaning, and purity verification are completed, and an inspection report and as-built documentation are issued.

                        Laboratory Design Concepts (For Reference Only)

Core Equipment and Key Components

Special Gas Cabinet (GC): Designed to store high-pressure gas cylinders, equipped with automatic ventilation, leak alarms, and low-pressure alarms; the cabinet door is explosion-proof, and the ventilation system meets the required air change rate.

Pressure Reducing Valves (WR1200 Series, etc.): Reduce cylinder pressure (15–20 MPa) to operating pressure (0.1–0.8 MPa). These valves feature a two-stage pressure reduction design with a pressure regulation accuracy of ±2% or better, and their inner walls are electrolytically polished.

Diaphragm Valves (MV4/MVH4 Series, etc.): Metal diaphragm seals with no stuffing box, ensuring zero leakage. The MV4 is suitable for general high-purity gases, while the MVH4 is designed for high-temperature or corrosive gases; both have a cycle life of over 100,000 operations.

Special Gas Control Panel (GSP): Integrates pressure regulators, pressure gauges, diaphragm valves, and flow meters to enable centralized regulation and monitoring of pressure and flow; its modular design facilitates maintenance and expansion.

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Key Technical Features

Electropolished Piping: The inner surface of 316L stainless steel has a surface roughness (Ra) of ≤0.4 μm, forming a chromium-enriched passivation layer that reduces particle adsorption and metal ion leaching.

Fully Automated Rail Welding: Programmable control of welding current, rotation speed, and wire feed rate ensures uniform, defect-free welds; parameter records are retained for each weld, enabling full traceability.

VCR metal-to-metal seals: Sealing is achieved through the plastic deformation of metal gaskets, with a leakage rate of ≤1×10⁻⁹ Pa·m³/s; suitable for high-purity and vacuum systems.

Piping purging and passivation: High-purity N₂ or Ar is used for high-flow purging to remove particles and moisture; for oxygen-sensitive systems, further passivation is performed to form a stable oxide film.

Quality and Safety Assurance System and Service Value

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Multi-level Testing and Verification System

Laboratory gas piping must undergo multi-stage testing prior to delivery, with clear acceptance criteria for each stage:

1. Pressure Testing: The hydrostatic test is conducted at 1.5 times the design pressure, with pressure maintained for 30 minutes without leakage; the pneumatic test is conducted at 1.15 times the design pressure, using a foaming agent to inspect joints and welds, and a specialized safety plan must be developed.

2. Helium Mass Spectrometry Leak Detection: Using He as the tracer gas with a sensitivity of 1×10⁻¹² Pa·m³/s, all welds, valves, and joints are inspected individually; the total system leakage rate must be ≤1×10⁻⁹ Pa·m³/s, and a formal report must be issued.

3. Purge and Purity Verification: After purging with high-purity N₂ or Ar, test the dew point (≤ -70°C), oxygen content (≤ 1 ppm), and particle count to confirm the cleanliness of the piping.

4. Functional Testing: Verify the pressure-regulating accuracy of the pressure-reducing valve, the sealing performance of valves during opening and closing, and the response time of the alarm system.

Standard Adherence and Compliance Delivery

The project complies with international standards such as SEMI F20, SEMI S2, and CGA G-4.1, as well as national standards and industry specifications including GB 50177, GB 50029, GB 50235, GB/T 20801, GB 50591, and other national standards and industry specifications. The delivery documentation includes as-built drawings, material quality certificates, welding records, pressure test reports, helium leak test reports, purity test reports, and operation and maintenance manuals, ensuring the project’s traceability.

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Service Value and Operational Support

1. Safe Operation: Multi-level leak detection and alarm interlocks, combined with the gas cylinder cabinet’s exhaust system, gas detectors, and emergency shut-off valves, provide triple protection; in the event of a leak, the system automatically triggers an alarm and shuts off the gas supply.

2. Reliable Data: Pressure regulators maintain stability within ±2%, and gas purity reaches 99.9999% (6N) after purging and passivation, minimizing experimental errors caused by fluctuations in gas quality.

3. Easy Operation and Maintenance: The modular design facilitates online replacement of valves and filters. Piping is clearly labeled, and recommended maintenance schedules and spare parts lists are provided with the delivery documentation.

4. Flexible Expansion: The system includes reserved interfaces and branch lines, allowing for the addition of new gas outlets without interrupting operations. The layout is designed with future expansion needs in mind. The quality and safety of laboratory gas piping depend on every stage of the process—from design and materials to installation and testing. Shenzhen Wo Fei Technology provides end-to-end quality and safety assurance for laboratory gas piping through professional system solutions, strict installation standards, and a comprehensive testing system.

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