|This FIoat Valve is normally installed in a standard bore?back of the blt sub, to provide fluid flow control at the bottom of the driII stem. It also prevents backflow of cuttings from plugging the driII bit Jets while making connections. Its 70Mpa(10 000psi)working pressure complements today?ós high pressure BOP stacks.
When the flapper is held open by the built?in latch. the drill pipe fills from the bottom.This eliminates the mess and lost time of filling operations. Runing in with the flapper open also reduces the potential of formation damage from pressure surges caused by the bit acting as a piston or ram as it is lowered into the hole. The flapper latch is automatically released by initial circulation of drilling fluid through the valve. During normal circulation, the flapper is fully open and out of the way. The large bore of the Valve provides minimum flow restriction.
When circulation is stopped. the flapper is closed by the flapper spring. preventing backflow through the bit.
When run in the closed position, the Valve allows the drill pipe to be-floated in while only partially filled with drilling fluid. This lowers the effective weight of the drilI string and reduces strain on rig equipment.
The FIoat Valve Sub is a bit sub in which a fIoat valve is be installed.Its connection is ordered by user. The Supplier put a Float Valve into the bore of the sub according to specification of standard API. Mechanical property of material of sub cenfoms to the requirement of standard SY5200 2002 and API.