of the spherical body 12 and this is closed by a dome 66 reinforced by a disc 68 and bolted at 70 to a vertical cylindrical flange 72 since the fixed hinge 52 is welded directly to the seat hub 26 it is not necessary to handle the complete valve body 12 while the clapper is being mounted in fact the clapper 12 may be mounted and the fixed hinge 52 welded to the hub 26 entirely apart from the valve body 12 and then the hub 26 and clapper 38 may be inserted through the opening 64 as a unit and welded in place after checking to ensure that the seat clapper assembly and shaft fit nicely together they are disassembled and the seat hub 26 is welded into the body shell 12 where the shaft 50 is provided merely to suspend the clapper and does not extend outside of the body 12 for selective operation it may also be practical to assemble the seat clapper and shaft after the seat hub has been welded in place but before the body shells 12 have been welded together at 14 in describing this embodiment components which are substantially unchanged from the.