摘要 |
<p>A ball valve (10) has a ball valve member (34) mounted for floating movement in a valve chamber (32) between an upstream metal seat (102) and a downstream metal seat (104). Each metal seat (102, 104) fits within a recess (100) and has a body portion (110) of a generally uniform thickness adjacent an opposed shoulder (108) with a lip (114) about its inner circumference for sealing against spherical surface (40) of ball valve member (34) at all times. Body portion (110) acts as a Belleville spring and spaces lip (114) from adjacent shoulder (108) at low fluid pressures. A bearing portion (118) has an arcuate seat (120) spaced from spherical surface (40) at low fluid pressures but contacting spherical surface (40) at high fluid pressures. A flexible connector (128) of a relatively thin uniform thickness extends between bearing portion (118) and body portion (110). The stem (36) has a Belleville spring (86) exerting a compressive loading against a packing (82) and a thrust bearing (88) is mounted outwardly of the packing (82) between stem shoulder (52) and the outer clamping plate (72).</p> |