| 摘要 |
An apparatus for maintaining constant circulation of drilling fluid includes a valve section (5) at the top of each section of drill pipes to be connected to or removed from the drill string. The valve section (5) has a top inlet for axial circulation and a side inlet (5b) for radial circulation. Two separate valves (5c, 5d) within the valve section controls flow through the inlets. An external valve control device (4) has a circulation adapter (4b) for connecting drill fluid at operational pressure to the side inlet (5b) and separate activating adapters (4c, 4d) connecting to the couplings for opening or closing the valves (5c, 5d). |
