CRC is a 4-head TIG machine that welds pipes on the outside. The heads rotate 90 degrees about the pipe joint for a complete weld. It is pretty much automatic. It is used on board ships to do continuous welding of undersea pipes. In other words, the ship carries pipe segments on board that have especially machined ends. They are fed to the machine one by one and are welded to the long pipeline trailing from the back of the ship and landing on the sea bed.