Method for producing a ball valve for conditioning a fluid, ball valve and welding tool for holding and actuating a valve element

A method for producing a valve (1) for regulating a fluid is disclosed. The valve comprises a valve housing (2) with a central part (3) and with a connecting end (4). The ball (5) is arranged in the central part (3) relative to one or more valve seats (7). The method for producing a valve housing (2) comprises at least arranging at least a first and a second housing part (2a, 2b) in a rotatable manner and with the ends (3a) of the central part facing each other, and arranging a ball (5) in a fixed position within the inner space (3b) of the central part (3). Then, the first and second housing parts (2a, 2b) are welded from outside the central part (3) while rotating the first and second housing parts (2a, 2b) and while holding the ball (5) in a fixed and non-rotating position within the central part (3). During the welding step, a shielding gas is supplied to the inner space (3b) of the central part (3). The result is a valve housing with a single weld seam arranged at the central part (3) of the valve housing (2). A valve and a welding tool for holding a valve component during a welding step are also disclosed.