Abstract: The invention relates to a welding torch comprising a torch body that is elongate along a longitudinal direction and that presents a working end, an electrode having a portion that projects longitudinally from the working end, and a channel for a flow of protective gas formed inside the body and terminating at the working end via at least one opening for ejecting gas in the form of a jet towards the projecting portion of the electrode. According to the invention, the torch includes jet-enlarger means for enlarging the jet of gas, which jet-enlarger means are in the form of a convex open-work grid covering the gas ejection opening(s).

Abstract: An end portion of each of two parts is machined and the machined end portion of the parts are arranged in facing positions to form a welding bevel extending in a longitudinal direction between the parts, whereafter a filler metal is deposited into the welding bevel. The welding bevel is a narrow bevel with side walls at an aperture angle of no more than 5° relative to the longitudinal central plane of the bevel. A nickel alloy comprising 18-32% of chromium is deposited into the welding bevel. The method is particularly suitable for joining a pressurized water nuclear reactor vessel tubing and an austenitic stainless steel primary circuit pipe.

Abstract: The machined ends of two parts (2, 4) are arranged in facing positions to form a welding bevel (6) between the parts (2, 4). A series of layers of filler metal are deposited one on top of the other in the welding bevel (6) in a direction thereof corresponding to the width of the parts (2, 4), by melting a wire (14) supplied at a predetermined feed rate to an electric arc between the parts to be welded and an electrode (13) supplied with a predetermined welding current and voltage. Each layer of filler metal essentially consists of a single weld bead across the full width of the bevel (6). The electric welding current and voltage and the feed rate of the wire (14) are predetermined in accordance with the width of the bevel (6).

Abstract: The welding electrode rotates at variable speed about the axis of the cylindrical part so as to lay down successive superposed layers, each covering the entire width of the bevel. The electrode is moved translationally in the direction of the axis of the cylindrical part. The device includes arrangements for adjusting the speed of rotation of the electrode and for moving it in the direction of the axis. The method may be used for welding a replacement adaptor onto the vessel head of a nuclear reactor.