A purge dam assembly confines a volume within an assembly of pipes, including a distal pipe and a proximal pipe together arranged for butt welding at a seam. A distal disk is covered at its periphery with a distal sock including gasketing material. A proximal disk is covered at its periphery with a proximal sock including the gasketing material. Each disk is sized such that the sock contacts but does not completely seal against an inner surface of one of the tubes or pipes permitting a purging flow of gas from the volume and past each disk. A cross-member having a proximal and a distal end, the proximal end is affixed to the proximal disk and the distal end is affixed to the distal disk to preserve the spatial separation between the proximal disk and distal disks and to maintain the proximal and distal disks in coaxial alignment.

A purge dam assembly confines a volume within an assembly of pipes, including a distal pipe and a proximal pipe together arranged for butt welding at a seam. A distal disk is covered at its periphery with a distal bootie including gasketing material. A proximal disk is covered at its periphery with a proximal bootie including the gasketing material. The each disk is sized such that the bootie contacts but does not completely seal against an inner surface of one of the tubes or pipes permitting a purging flow of gas from the volume and past each disk. A cross-member having a proximal and a distal end, the proximal end is affixed to the proximal disk and the distal end is affixed to the distal disk to preserve the spatial separation between the proximal disk and distal disks and to maintain the proximal and distal disks in coaxial alignment.

A robotic crawler for back purging a weld location in a piping circuit includes a body, one or more conveyors coupled to the body for transporting the robotic crawler within the piping circuit, first and second seal assemblies configured to generate an interference seal with an interior of the piping circuit, a pair of extendable arms, each extendable arm supporting a respective one of the first and second seal assemblies on an opposite side of the body, each respective extendable arm selectively extendable and retractable with respect to the body to adjust a position of the respective seal assembly with respect to the body, and an inert gas flow valve for providing an inert gas into a sealed area defined between the first and second seal assemblies.

A method of providing an inert atmosphere to the inside of a piping assembly prior to and during welding, including introducing a canister, and a deflated bladder which surrounds the canister, into a piping assembly to be welded. Introducing purge gas, thereby inflating the deflated bladder and sealing the canister against the inside of the piping assembly to be welded. Introducing excess purge gas from the bladder into a primary purge gas diffuser, thereby producing a first diffused purge gas stream. Introducing the first diffused purge gas stream into a secondary purge gas diffuser, thereby producing a secondary diffused purge gas stream. Introducing the secondary diffused purge gas stream into a tertiary purge gas diffuser, thereby producing a third purge gas stream. And introducing the third purge gas stream into the inside of the piping assembly to be welded.

An orbital welding device (1), having a welding current source (10) in a welding current source housing (11) and an orbital welding head (20), which is separate from the welding current source housing (11) and is connected to the welding current source (10) by a cable (2), the orbital welding head (20) having a pipe mount (21) and a welding electrode holder (22) for holding a welding electrode (23). An electric motor (31) is designed to drive the welding electrode holder (22) and thus turn it with respect to the pipe mount (21). The orbital welding head (20) has a chamber (50) for shielding gas. An optical oxygen sensor (40) is designed to measure an oxygen concentration in a measuring region (51) in the chamber (50). The oxygen sensor (40) is arranged outside the chamber (50) and is optically coupled to the measuring region (51) by an optical coupling.

An orbital welding device (1) for welding two pieces of pipe, the orbital welding device (1) having a welding current source (10) in a welding current source housing (11) and an orbital welding head (20), which is separate from the welding current source housing (11) and is connected to the welding current source (10) by a cable (2), the orbital welding head (20) having a chamber (50) for the use of shielding gas (50) and/or the orbital welding device (1) having a purging device (90) for the use of shielding gas, preferably back-up shielding gas or purge gas, the orbital welding device (1) having an oxygen sensor (40), wherein the oxygen sensor (40) is arranged in or on the welding current source housing (11).

A robotic crawler for back purging a weld location in a piping circuit includes a body, one or more conveyors coupled to the body for transporting the robotic crawler within the piping circuit, first and second seal assemblies configured to generate an interference seal with an interior of the piping circuit, a pair of extendable arms, each extendable arm supporting a respective one of the first and second seal assemblies on an opposite side of the body, each respective extendable arm selectively extendable and retractable with respect to the body to adjust a position of the respective seal assembly with respect to the body, and an inert gas flow valve for providing an inert gas into a sealed area defined between the first and second seal assemblies.

An orbital welding device (1), having a welding current source (10) in a welding current source housing (11) and an orbital welding head (20), which is separate from the welding current source housing (11) and is connected to the welding current source (10) by a cable (2), the orbital welding head (20) having a pipe mount (21) and a welding electrode holder (22) for holding a welding electrode (23). An electric motor (31) is designed to drive the welding electrode holder (22) and thus turn it with respect to the pipe mount (21). The orbital welding head (20) has a chamber (50) for shielding gas. An optical oxygen sensor (40) is designed to measure an oxygen concentration in a measuring region (51) in the chamber (50). The oxygen sensor (40) is arranged outside the chamber (50) and is optically coupled to the measuring region (51) by an optical coupling.

An orbital welding system is disclosed for joining a riser to a pulled collar on a manifold runner with a circumferential weld bead, which includes a multi-axis welding platform, a weld head assembly supported on the welding platform and including a shaft housing, an electrode drive shaft mounted for axial rotation within the shaft housing, a drive motor connected to the electrode drive shaft for axially rotating the electrode drive shaft, and a torch assembly that rotates with the electrode drive shaft and includes a vertical torch shaft having an electrode holder at an upper end thereof for retaining a tungsten electrode.