Abstract: An at least one spherical valve stem seat and a method for manufacturing the at least one spherical valve stem seat. The at least one spherical valve stem seat has a finished valve stem seat blank and a shell in retained communication therewith. The method for manufacturing the at least one spherical valve stem seat includes a molding process and an accompanying sintering, and machining process.

Abstract: A clutch mechanism for a slurry valve, wherein the slurry valve has a valve seat for seating a valve closure member carried on a valve stem, a drive member threadably engaged with the valve stem, the drive member being rotatable relative to the valve stem to axially move the valve stem and closure member relative to the valve seat to open and close the slurry valve, and a driving means for rotating the drive member, the clutch mechanism comprising: a clutch body having an internally threaded bore for threadably receiving the valve stem; and clamping means actuable with the clutch body for clamping the clutch body to the driving means so as to lock the valve stem and drive member together and allow them to rotate in unison to grind scale from the valve seat and valve closure member when they are positioned against each other.