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    The kelly valve , which is a manually operated ball valve in the drill string , is one of effective tool for preventation from blowout . The kelly valve 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 drillpipe and lower end of kelly or connected between lower end of kelly saver subs. The kelly valve features a simple operation, the kelly valve can be opened on or closed off by only turning the special operating spanner at 90 degrees according to indicating direction . During drilling operation, in order to avoid serious well kick or blowout accident , the kelly valve shall be connected at upper end and lower end of kelly.

Technical parameters and specifications for the upper kelly valve

Technical parameters and specifications for the lower kelly valve