| 摘要 |
<p>A casing shut-in valve system (74) having a flapper valve assembly (34) and a shift head assembly (76); the flapper valve assembly (34) having an upper body member (36), lower body member (38), flow sleeve (40), valve seat sleeve member (42), flapper (54), flapper hinge assembly (56), and a plurality of spring strut assemblies (58) disposed on opposite sides of the flapper hinge assembly; the shift head assembly (76) having key housing (134) with bit sub (144) rotatably mounted in bearing (152), a plurality of outwardly biased shift keys (80), and a load equalizer plate (138) at each end of the key housing; the shift head assembly (76) being adapted to selectively open or close the valve by engaging and moving the flow sleeve (40) between defined upper and lower positions, thereby controlling the movement of flapper (54) through an angle (128) of rotation that is less than 90 degrees, and preferably about 45 degrees.</p> |
