| 摘要 |
FIELD: devices adapted to case oil and gas wells, particularly to prevent reverse grout flow from hole annuity into string. ^ SUBSTANCE: valve has ball slide, which may be thrown down from surface, body provided with elastic member and expandable seat arranged inside it. Elastic member and expandable seat are formed so that through orifice defined in above members may expand up to value equal to ball slide diameter. The valve also has seat support. The seat consists of annular segments displaceable along inner converging downward conical surface formed on seat support by expanding the seat with ball slide. When the ball seat returns in its initial position the segments are pressed one to another due to elastic member flexibility. ^ EFFECT: increased reliability of casing pipe sealing and resistance to pressure directed from below. ^ 4 dwg
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