A method of welding in which an inert gaseous shield at a welding zone is provided by a mixture of gases of different densities. The proportions of the individual gases in the mixture are controlled to ensure that the density of the gas mixture is about the same as the density of the surrounding atmospheric air. Cryogenic means may be used to form a condensed gas plug in a pipe or the like to be welded.

Method of welding and a system therefor

For use in helium or other gas reclamation, a diver gas safety valve adapted for attachment to a diver's helmet and to an exhaust gas recovery system, the safety valve including a collapsible tube for expanding to transfer exhaust gas having a pressure greater than ambient water pressure surrounding the diver and for collapsing to prevent such exhaust gas transfer at exhaust gas pressure below the ambient water pressure in order to prevent dangerous, sudden outflows of the exhaust gas from the diver's helmet.

Diver gas safety valve

An improved diving habitat for providing breathing gas to a diver in which expired breathing gas is recovered from the habitat utilizing an indirect fluid coupling which is in fluid communication with the interior of the habitat and with a recovery line adapted for connection to a diving gas reconditioning system, the coupling providing for the transfer of the expired breathing gas from the habitat to the recovery line under normal conditions and further providing for a flow of water to the recovery line from the water environment in the event of a dangerous change in pressure in the recovery line.

Jr. Hilbert Joseph Savoie

Papers

Diving gas recovery apparatus