Helium Technical grade 4.6 (99.996%). An inert gas, technical Helium is used for lifting (airships and balloons), as well as for leak detection, optical fibre production, and as a shielding gas for welding. It is the preferred shielding gas for high power laser welding. Its high thermal conductivity produces welds with an excellent aspect ratio. Its high ionisation potential results in good plasma suppression and high weld speeds. Supplied in a 47 litre steel cylinder at 300 bar.