Abstract: A valve housing is composed of a pair of shell sections each of which has an open side surrounded by an edge face, and a semi-circular rib located within the open side and having a face slightly downwardly recessed from the associated edge face. The shell sections are placed together so that their edge faces abut, and these edge faces are welded to one another. The ribs are semi-circular in mutually opposite directions and thus form a circumferentially complete annular portion. Opposite this portion the housing is provided with an opening having a larger diameter than the portion, and after the shell sections have been welded together a material-removing tool is inserted through this opening and forms on the tubular portion a circumferentially complete annular welding face which is in part of stepped configuration.