Those are just tack welds using an industrial welder, 4 tack welds equally spaced means nothing will move but if its wrong they can be cut off, i suspect he's got a welding job where times a limit, turning the power and speed up means you can get a pipe fully seamed in a couple of seconds and when you learn to do that as a job its easier doing it on whatever welding your doing, should have put some triangular plates where the pipe met though