Product Description
Kelly valve is a manually operated ball type drill stem valve; it
is divided into upper Kelly valve and lower Kelly valve. The upper
Kelly valve is connected between lower end of swivel and upper end
of Kelly; the lower Kelly valve is connected between upper end of
drill pipe and lower end of Kelly or connected between lower end of
Kelly saver subs. The Kelly valve can be opened on or closed off by
only turning the special operating wrench at 90° according to
indicating direction. During drilling operation, the Kelly valve
shall be connected at upper end and lower end of Kelly.
The sealing principle for Kelly valve is that the ball is
positioned and provided with proceeding stress by the lower seat
supported by spring load and a close seal between ball and ball
seat is provided. During normal drilling operation, the hole is
kept unblocked by turning the stem to be “on” position; In case of
kick or blowout, turn the operating stem to be “off” position to
close off the internal bore of drill string, the kick or blowout
accident is avoided due to a high pressure sealing situation
between ball and ball seat.
