Zero clearance anti-extrusion rings for containment of PTFE packing

摘要

A packing containment (10) assembly for sealing an operating member such as a shaft (12) or stem in a fluid control valve (14), particularly where PTFE packing (16) is used. A pair of zero clearance anti-extrusion rings (18) of PEEK material are mounted in the shaft with the PTFE packing (16) therebetween. Each ring (18) has an inner diameter slightly less than the shaft (12) outer diameter to form an interference fit. The rings (18) are split with a scarf cut (24) to provide an overlapping joint and enable mounting of the rings (18) on the operating member (12). A male adapter PEEK ring (64) matches a V-type female packing ring (16a) which significantly reduces the amount of PTFE packing (16) needed for a reliable seal. A step cut PEEK zero clearance anti-extrusion ring (18) could be used as well as a fractured carbon ring (50). IMAGE