دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a valve installed above the kelly that can be closed manually to protect the rotary hose from high pressure that may exist in the drill stem.

n: The two position and two way valve located between the sub of swivel and the upper of kelly,which can seal the pressure of drill pipe when well blowout.

a valve at the top of the kelly that can be closed in the event of a inside tubing kick or high pressures.