LOW STRESS STEM CONNECTION STRUCTURE FOR A NON-RISING STEM TYPE GATE VALVE

摘要

A low stress stem connection structure (77) for connecting the rotatable stem (43) and the gate member (33) of a non-rising stem type gate valve (1). The stem (43) has an externally threaded end section (47) and the gate member (33) has an externally threaded extension (79) with a longitudinal bore (83) in which the end section (47) of the stem (43) is received. A stem nut (87) is threadably received on the end (47) of the stem (43) and engages the gate member extension (79) to reciprocally move the gate member (33) in response to rotation of the stem (43). The gate member (33) may move relative to the longitudinal axis of the stem (43) in the direction of flow of a fluid through the gate valve (1). A gate nut (97) is threadably received on the gate member extension (79) to hold the stem nut (87) in position on the stem (433 and limit movement of the gate member (33). The structure facilitates movement of the gate member (33) to open and close the gate valve (1) even though the gate member (38) is subjected to high fluid pressures.