A method and guidance system for accurately positioning a welding torch relative to a desired weld path. The method and system are based on ultrasonic sensing of information relating to the distance between the welding torch and surfaces on one or more components being welded, and then using this information to move the welding torch to a specific point in space relative to the desired weld path. The method and system maintain the welding torch over the weld path and at a predetermined distance from the weld path during movement of the torch along the weld path.