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 each comprising at least a central housing part and a connection end , and - providing a valve element shaped as a ball with at least one through-going aperture , - arranging the first and second housing parts 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 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 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 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 . - providing at least a first housing part and a second housing part , said first and second housing parts each comprising at least a central housing part and a connection end , and - providing a valve element shaped as a ball with at least one through-going aperture , - arranging the first and second housing parts 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 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 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 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 . - rotating the first and second housing parts 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 . <EOS>