دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a special valve normally installed below the kelly. Usually, the valve is open so that drilling fluid can flow out of the kelly and down the drill stem. It can, however, be manually closed with a special wrench when necessary. In one case, the valve is closed and broken out, still attached to the kelly to prevent drilling mud in the kelly from draining onto the rig floor. In another case, when kick pressure inside the drill stem exists, the drill stem safety valve is closed to prevent the pressure from escaping up the drill stem. Also called lower kelly cock, mud saver valve.

n: a special valve normally installed below the kelly. Usually, the valve is open so that drilling fluid can flow out of the kelly and down the drill stem. When the mud pump is stopped, the valve can be manually closed with a special wrench to prevent pressurised fluids in the drill string from flowing into the kelly. When closed, the valve also prevents mud in the kelly from spilling onto the rig floor when the kelly is broken out of the drill string. Also called a drill stem safety valve, mud saver valve.

n: see drill stem safety valve. lower kelly cock.

a near full-opening valve installed just below the kelly. It has the same outside diameter as the tool joints.

n: a lower kelly cock. See drill stem safety valve, lower kelly cock.