A method for producing a ball valve for regulating a fluid, the ball valve including a valve housing with a central part and with two connection ends, the connection ends extending away from the central part, wherein internally of the central part there is arranged a valve element, wherein the valve element is arranged relative to one or more valve seats in the central part of the valve housing, and wherein the method of producing the valve housing at least includes the following steps: - providing at least a first housing part and a second housing part, said first and second housing parts (2a, 2b) each comprising at least a central housing part and a connection end (4a, 4b), and - providing a valve element shaped as a ball with at least one through-going aperture, - arranging the first and second housing parts (2a, 2b) at a position with the central part ends facing towards each other, and further arranging the ball at a position inside an inner space of the central part, - welding the first and second housing parts (2a, 2b) together using a welding tool to provide the valve housing, characterized in that the welding is performed while performing a relative rotation in a rotating direction about a rotation axis between the position of the first and second housing parts (2a, 2b) and the positions of the ball and the welding tool to provide a valve housing with a single welding seam arranged at the central part of the valve housing, the rotation axis coinciding with a central longitudinal axis of the valve housing and ball, wherein the welding is performed either from the inner space or an outer side of the central part and that the relative rotation is performed by: - rotating the first and second housing parts (2a, 2b) relative to the positions of the ball and the welding tool, and/or - rotating the ball and the welding tool relative to the position of the first and second housing parts (2a, 2b). - providing at least a first housing part and a second housing part, said first and second housing parts (2a, 2b) each comprising at least a central housing part and a connection end (4a, 4b), and - providing a valve element shaped as a ball with at least one through-going aperture, - arranging the first and second housing parts (2a, 2b) at a position with the central part ends facing towards each other, and further arranging the ball at a position inside an inner space of the central part, - welding the first and second housing parts (2a, 2b) together using a welding tool to provide the valve housing, characterized in that the welding is performed while performing a relative rotation in a rotating direction about a rotation axis between the position of the first and second housing parts (2a, 2b) and the positions of the ball and the welding tool to provide a valve housing with a single welding seam arranged at the central part of the valve housing, the rotation axis coinciding with a central longitudinal axis of the valve housing and ball, wherein the welding is performed either from the inner space or an outer side of the central part and that the relative rotation is performed by: - rotating the first and second housing parts (2a, 2b) relative to the positions of the ball and the welding tool, and/or - rotating the ball and the welding tool relative to the position of the first and second housing parts (2a, 2b). - rotating the first and second housing parts (2a, 2b) relative to the positions of the ball and the welding tool, and/or - rotating the ball and the welding tool relative to the position of the first and second housing parts (2a, 2b).