Back purging robotic crawler

A method, comprising:

• conveying a robotic crawler, via conveyors of the robotic crawler, longitudinally through a piping circuit and towards a weld location;
• extending, via one or more arm actuators, a pair of extendable arms of the robotic crawler longitudinally away from a body of the robotic crawler, each extendable arm supporting a respective one of first and second seal assemblies spaced longitudinally away from the body on an opposite side of the body of the robotic crawler;
• generating an interference seal within an interior of the piping circuit, via the first and second seal assemblies of the robotic crawler;
• introducing, via an inert gas flow valve, an inert gas into a sealed area defined between the first and second seal assemblies;
• releasing, via an oxygen release valve, oxygenated air from the sealed area into a remainder of the piping circuit;
• and
• welding an exterior of the piping circuit while the interior of the piping circuit at the weld location is shielded by the inert gas.

A robotic crawler for back purging a weld location in a piping circuit, the robotic crawler comprising:

• a body;
• one or more conveyors coupled to the body for transporting the robotic crawler longitudinally 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 spaced longitudinally away from the body on an opposite side of the body, each respective extendable arm selectively extendable away from the body and retractable toward the body in a longitudinal direction 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.