Abstract: Internal pipe welding apparatus, including a pair of internal pipe clamps between which is disposed a rotative welding head support. The welding wire and gas feed conduits are disposed through passages through the central hub of one of the clamps. The welding head support is rotated by a ring gear engaged by a gear carried by a shaft disposed through a passage of the central hub of the other clamp. The gear engagement with the ring gear is adjustable to minimize vibration and chatter. The welding wire feeders are mounted on a block support at the front of the first mentioned central hub.