CUT-OFF DEVICE FOR STRING OF PIPES Russian patent published in 2004 - IPC

FIELD: equipment shutting off tubing string fitted with sucker-rod pump. SUBSTANCE: cut-off device for string of pipes has body with seat and spring-loaded lock with pusher. There are also mobile tail part with groove in side surface and immobile bushing with key interacting with groove in tail part. Cut-off device is supplemented with mobile bushing with keys that is mounted butt to butt above immobile bushing. Tail part is of inserted type. Groove of tail part includes annular grooves open downwards for entrance of keys of mobile bushing and of key of immobile bushing. Contacting butts of bushings have stepped form. Recess in butt of upper bushing corresponds to protrusion on butt of lower bushing to ensure entrance of one to another with turn of mobile bushing. Butt tongues are made on protrusions to limit unauthorized turn of mobile bushing. Cut-off device is sunk into hole on string of pipes as assembly with pump from which tail part hangs. Upper part of body carries locking support to locate inserted sucker-rod pump. Lock can be opened and closed by manipulations with pump with tail part by lifting and lowering it with the aid of pump rods. Pump is replaced, rods are adjusted and well head is sealed when lock is closed. EFFECT: cut-off device ensures closure of string of pipes by manipulation with pump rods during adjustment of their length, for instance, while installing polished rod into casing-head stuffing box. 7 dwg