VALVES HAVING CERAMIC TRIM WITH PROTECTED SHUT-OFF SURFACES

摘要

Valve trim apparatus having ceramic trim with protected shut-off surfaces are described. An example valve trim apparatus includes a valve seat composed of a non-ceramic material and having a sleeve insert composed of a ceramic material. A closure member has a primary flow control member and a secondary flow control member. The secondary flow control member is composed of the ceramic material and fitted within a cavity of the closure member. The primary flow control member sealingly engages the non-ceramic material of the valve seat and the secondary flow control member moves within an aperture of the sleeve insert to modulate a fluid flow through the valve seat as the primary flow control member disengages from the non-ceramic material of the valve seat.