To make the welding of circular joints easier, a motorised turntable is normally used. However, it's enough to rotate the workpiece by hand underneath the TIG torch. This results in a perfectly acceptable weld, and doesn't take too long to set up.
This is an example of welding a pipe fitting into a hole in a 1.6mm steel disc. The small drill chuck is mounted on a piece of ½" bar, which fits neatly into a corresponding ½" hole in the piece of wood held in the vice (the pulley is just something convenient to turn the shaft with). The ground lead is clamped to the lower end of the bar and hangs down, so it is free to rotate. The workpiece is held in the drill chuck. The TIG torch is clamped in a retort stand and adjusted to align with the seam. The torch is controlled with a foot switch.
The end result is very uniform, with the exception of a small crater at the end, because I forgot to turn on the post-weld current.