Comprehensive Explanation of Helium Used in High-Precision Welding

Helium is a colorless, odorless, non-flammable gas that exists in the atmosphere at a concentration of about 5.2 parts per million. It is chemically inert and does not react with other elements or compounds under normal conditions.

In theory, helium can be extracted from the air, but due to its extremely low concentration, industrial helium is primarily separated and refined from natural gas that contains approximately 0.5% helium.

Helium (symbol: He), derived from the Greek word “helios” meaning “sun”, was discovered in 1868. It is lighter than air and is widely used in airships and balloons as a safer alternative to the highly flammable hydrogen. Liquid helium, with its exceptionally low boiling point, is invaluable in cryogenics.

  • English Name: Helium
  • EINECS Number: 275-187-7
  • Chemical Formula: He
  • Category: Noble gas
  • Molecular Weight: 4.003
  • Gas Density: 0.1786 g/L (at 0°C, 1 atm)
  • Liquid Density: 125.2 g/L (at 4.2 K, 100.312 kPa)
  • Specific Gravity: 0.14 (Air = 1)
  • Boiling Point: 4.3 K (1 atm)
  • Melting Point: 1.0 K (26 atm)
  • Critical Temperature: -268.95°C
  • Critical Pressure: 0.228 MPa
  • Latent Heat of Vaporization: 5.50 cal/g or 20.4 kJ/kg (at boiling point)
  • Gas-Liquid Volume Ratio: 699:1 (0°C, 1 atm, based on liquid volume = 1)

Properties:
Helium is a colorless, odorless, tasteless inert gas under ambient conditions. It has the lowest critical temperature of all elements, making it the most difficult gas to liquefy. It does not burn or support combustion. It emits a deep yellow glow during low-pressure discharge. Due to its unique physical characteristics, helium does not solidify under its own vapor pressure even at absolute zero. It usually does not form compounds, though under specific conditions it can form some compounds with certain metals.

Quality Standards:

  1. National Industrial Helium Standard: GB/T 4844.1—1995

In 1868, French astronomer Janssen observed a yellow spectral line D during a total solar eclipse, which differed from the known sodium D1 and D2 lines. Around the same time, British astronomer Lockyer also observed this line and hypothesized it to be a new metallic element present only in the sun. He named it Helium — “helio” from the Greek for sun god, and “-ium” as a suffix for metallic elements. The Chinese name for Helium is derived from this.

In 1895, British chemists Ramsay and Travers successfully identified helium on Earth as a rare, non-metallic gas while treating pitchblende with sulfuric acid.

Helium Purity Grades:

Industrial Helium

  • Purity ≥ 99%
  • Total impurities (Neon, Hydrogen, Oxygen, Argon, Nitrogen, Methane) ≤ 1%
  • Moisture (dew point) ≤ -43°C

Pure Helium

Purity (%)Ne (ppm)H₂ (ppm)O₂/Ar (ppm)N₂ (ppm)CO (ppm)CO₂ (ppm)CH₄ (ppm)H₂O (ppm)
99.995≤15≤3≤3≤10≤1≤1≤1≤10
99.993≤25≤5≤5≤17≤1≤1≤1≤15
99.99≤40≤7≤5≤25≤1≤1≤1≤20

Applications:
Thanks to its ultra-low boiling point (-268.9°C), liquid helium is essential for cryogenic cooling, especially in superconducting applications like magnetic levitation trains. Due to its inert nature and lightness, helium is commonly used in airships and advertising balloons. It also plays a critical role in mixed-gas breathing systems for deep-sea diving, and in MRI superconducting magnet cooling in medical applications.

Helium is widely used in:

  • Military and scientific research
  • Petrochemical and refrigeration industries
  • Semiconductor and photonics manufacturing
  • Precision welding
  • Leak detection in pipelines and high-vacuum systems
  • Superconducting experiments
  • Deep-sea diving gas mixtures
  • Rocket propulsion systems for pressurizing liquid hydrogen/oxygen tanks
  • Carrier gas in gas chromatography
  • Arc welding shielding gas
  • Gas thermometers
  • Vacuum leak detection (e.g., helium mass spectrometers)

Helium Content Analysis:
Analyzed using gas chromatography with a 6 m stainless steel column (inner diameter 4 mm) packed with PoraPak Q or equivalent. Carrier gas: 99.99% helium at 40 ml/min flow rate. Detector: thermal conductivity detector (TCD). Column temperature: 60°C; Detector temperature: 130°C.
The sample’s retention time should match that of a standard containing 1.0% air in helium, confirming helium content ≥99.0% (by volume).

Production Methods:

  1. Condensation Method: Helium is extracted from natural gas using cryogenic techniques, including gas purification, crude helium recovery, and helium refinement, to produce 99.99% pure helium.
  2. Air Separation Method: Helium-neon mixtures are extracted from air separation units and then purified to produce 99.99% helium.
  3. Hydrogen Liquefaction Method: Helium is recovered from synthetic ammonia tail gas using low-temperature adsorption, distillation, catalytic hydrogen removal, and purification.
  4. High-Purity Method: 99.99% helium is further purified with activated carbon to achieve 99.9999% ultra-high-purity helium.

Helium does not solidify simply by cooling to absolute zero—it requires pressure. At 2.173 K, helium transforms from a normal liquid (Helium I) to a superfluid (Helium II), which has zero entropy, extremely high thermal conductivity, and near-zero viscosity.

Because sound travels in helium about three times faster than in air, inhaling helium changes the timbre of one’s voice, making it sound high-pitched and cartoonish. This phenomenon is due to helium altering the resonance frequencies of the vocal tract, increasing high-frequency components and reducing mid-to-low frequencies.

Helium Toxicity:

Inhaling a large amount of helium can displace oxygen in the lungs, causing hypoxia. Since the body reacts primarily to excess CO₂ rather than lack of O₂, symptoms can go unnoticed until severe — including dizziness, nausea, loss of consciousness, and potentially death. Inhaling directly from a high-pressure cylinder can cause serious lung damage due to the high flow rate. Although high-pressure oxygen and helium mixtures can cause High Pressure Nervous Syndrome (HPNS), small amounts of nitrogen can mitigate this effect. Since air naturally contains 78% nitrogen, short-term exposure is generally safe. Some snack bags contain trace helium, which poses no health risk.

Safety Precautions:

  1. Helium is typically stored at 15 MPa pressure. Use regulators like YQY-12 or 152IN-125 to reduce pressure before use. Check all piping with soapy water to ensure no leaks.
  2. Ensure good ventilation. If helium concentration increases and oxygen drops below 19.5%, symptoms may include rapid breathing, lack of focus, fatigue, nausea, and ultimately coma or death. Gas cylinders must be inspected regularly for safety certification.
  3. When nearly empty, helium cylinders should retain a residual pressure of at least 0.5 MPa (minimum 0.25 MPa) and the valve must be closed to maintain gas quality and ensure safe use.
  4. During transport, storage, and use, helium cylinders should be stored separately from heat sources and open flames. Avoid oil contamination, sunlight, impact, or mishandling. Do not arc-weld or spark near cylinders. Use designated cylinder trolleys for short distances and hazardous materials transport vehicles for long distances. Liquid helium is -268.9°C and can cause severe frostbite upon skin contact.

Explosion and Fire Hazards:

  • Helium is non-flammable.
  • In case of fire, move containers to open areas if safe. Spray containers with water to cool until the fire is extinguished.

Helium Price Trends:

In recent years, global helium prices have fluctuated due to limited supply sources, increased demand, and geopolitical constraints affecting major helium-producing regions. Prices are often impacted by supply disruptions from countries like the U.S., Qatar, and Algeria. As of 2025, helium prices have remained relatively high, driven by continued growth in demand from the semiconductor, aerospace, and medical imaging sectors. For large-volume users or long-term contracts, prices may be more stable, while spot-market prices can vary significantly.

Purchasing helium through trusted suppliers ensures not only competitive pricing but also consistency in purity and delivery.


About JinHong Gas – Your Trusted Industrial Gas Supplier:

JinHong Gas is a leading provider of industrial gases, including helium for high-precision welding, medical imaging, electronics manufacturing, and scientific research. We offer a full range of gas products—helium, argon, nitrogen, hydrogen, and specialty gas mixtures—with various purity levels to meet your exact specifications.

Our production facilities are equipped with advanced purification and quality control systems to ensure the highest standards of gas purity and safety. We support industries across welding, semiconductors, cryogenics, healthcare, and aerospace, providing reliable supply and tailored gas solutions.

Contact us to learn how JinHong Gas can support your industrial applications with premium helium and a complete range of specialty gases.

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