A fusion weld made without the addition of filler metal.

The control of a process with equipment that requires little or no observation of the welding and no manual adjustment of the equipment controls.

The removal of weld metal and base metal from the other side of a partially welded joint to assure complete penetration upon subsequent welding from that side.

The momentary recession of the flame into the welding or cutting tip followed by reappearance or complete extinction of the flame.