Inert gas shielded arc welding torches

Claim 2

A welding torch for making circumferential butt-welds between two tubular members comprising: a. at least two trolleys arranged to be spaced around the periphery of one of the said tubular members and arranged to run around the outside of one of said tubular members. b. a length of wire for linking said trolleys so that they are spaced around the periphery of said one tubular member, said length of wire extending around said trolleys to clam them against said tubular member. c. drive means being provided on at least one of said trolleys for driving all of said linked trolleys around the periphery of said tubular member. d. a welding head carried by at least one of said trolleys, said welding head including an electrode between which and the joint between said tubular members an electric arc can be struck for making said butt-weld. e. means for supplying welding current to said electrode. f. a track fitted around one of said tubular members adapted to constrain said trolleys to follow a desired path around said one tubular member such that said electrode is positioned for welding.

Claim 3

A welding torch according to claim 1 further comprising a tensionary device in which the ends of said length of wire are held, said tension device being capable of clamping said trolleys against said tubular member with sufficient force to enable said trolley provided with said drive to rotate the said torch by friction between itself and said surface of said tubular member.

Claim 4

A welding torch for making circumferential butt-welds between two tubular members comprising: a. three trolleys arranged to be spaced around the periphery of one of said tubular members, each of said trolleys comprising a platform provided with wheels by which it is able to roll around the outside of one of said tubular members; b. a length of wire extending tightly around said trolleys so that they are spaced around the said periphery of said tubular member and are clamped against said tubular member; c. drive means provided on one of said trolleys, said drive means being arranged to rotate the wheels of that trolley and said length of wire clamping said trolleys against said surface such that rotation of said wheels by said drive means causes said linked trolleys to run around said surface of said tubular member; d. a welding head carried by another of said trolleys, said welding head including a non-consumable electrode between which and said join between said tubular members an electric arc can be struck for making said butt-weld; e. means for supplying welding current to said electrode, and; f. a chain fitted around one of said tubular members, grooves being provided in said platforms of said trolleys and said chain fitting within said grooves, said fitting of said chain within said grooves constraining said trolleys to follow a path around said tubular member such that said electrode is correctly positioned for welding.

Claim 5

A welding torch for making circumferential butt-welds between two tubular members comprising: a. three trolleys arranged to be spaced around the periphery of one of said tubular members, each of said trolleys comprising a platform provided with wheels by which it is able to roll around the outside of one of said tubular members; b. a length of wire extending tightly around said trolleys so that they are spaced around the said periphery of said tubular member and are clamped against said tubular member; c. drive means provided on one of said trolleys, said drive means being arranged to rotate the wheels of that trolley and said length of wire clamping said trolleys against said surface such that rotation of said wheels by said drive means causes said linked trolleys to run around said surface of said tubular member; d. a welding head carried by another of said trolleys, said welding head including a non-consumable electrode between which and said join between said tubular members an electric arc can be struck for making said butt-weld; e. means for supplying welding current to said electrode, and; f. a chain fitted around one of said tubular members, grooves being provided in said platforms of said trolleys and said chain fitting within said grooves, said fitting of said chain within said grooves constraining said trolleys to follow a path around said tubular member such that said electrode is correctly positioned for welding.