Abstract: This invention relates to a welding carriage operable to drive across a surface of a work piece having a joint to be welded. The welding carriage comprises a number of wheels, where each wheel is pivotal around an axle and where each wheel is a magnetic wheel; the welding carriage further comprises means for supporting a welding device wherein at least one of the wheels can be flexed inwardly or outwardly so that the welding carriage can travel over curved surfaces. The welding carriage can travel over magnetizable surfaces having any direction, e.g. orientation in space. The welding carriage can carry a laser sensor arrangement arranged to detect the position as well as the direction of a joint to be welded, so that the welding carriage is applicable for performing fully automated welding.