Abstract: The present invention relates to an arc-welding device for securing studs on metallic elements underwater, and comprising a head containing a chamber and of which the welding bead is obtained by means of a dielectric refractory ring placed around the base of the stud, wherein an annular space is provided between the stud and the ring and neutral gas is blown into the chamber through said space, to drive the water out of the chamber and keep up therein a gaseous atmosphere to facilitate the welding of the studs; the refractory ring is produced from borosilicate glass, rich in silica.

Abstract: The present invention relates to a process and an installation for purification of the helium contained in a mixture of gas, employing a pre-treatment unit to retain the impurities such as water, carbon dioxide gas and heavy organic compounds, and at least one reactor of the chromatographic type located downstream of said pre-treatment unit, said process comprising the following steps of:(a) adjusting the pressure of the mixture of gas until the working pressure of the phase of adsorption is obtained, this pressure being between 10 and 30 bars, and preferably 12 to 15 bars;(b) taking the temperature of the mixture of gas at the outlet of said pre-treatment unit until it is located in the range -15.degree. C./-35.degree. C., and preferably -25.degree. C.;(c) and sending the mixture of gas into the reactor and passing it through an absorbent, which is constituted by a microporous charcoal whose pores are of dimensions less than or equal to 20 .ANG..

Abstract: Apparatus for connecting a cylindrical first member to a second member which may comprise: a tubular body attachable to the second member and adapted to receive one end of the first member; a gripping assembly carried by the body and movable from a radially expanded position, in which one end of the first member may be axially received and displaced from the body, to a radially contracted position gripping the exterior of the first member and preventing its axial displacement from the body; an annular seal assembly carried by the body and movable from a relaxed position, in which one end of the first member may be axially received therein, to a compressed position, sealingly engaging the first member; and an actuating assembly carried by the body and operable to move the gripping and seal assemblies to their contracted and compressed positions, respectively.

Abstract: Apparatus for checking the bore and for plugging a pipe comprises a frame movable along the interior of the pipe, the frame carrying means for detecting a deviation in the bore of the pipe, means responsive to an overpressure of fluid in the pipe in a direction opposite to that in which the apparatus is intended to move, and a movable control part responsive to the detection of a deviation and of an overpressure for operating locking means for locking the apparatus relative to the pipe and sealing means for sealing the pipe.