API 6A Kelly valve / kelly cock / Drill Pipe Safety Valve

Kelly valve also named Kelly cock or drill pipe safety valve. It is a hand control valve in drill string circulating system and it is one of the effective tools to prevent blowout. Kelly valve is divided into Upper Kelly Valve and Lower Kelly Valve. Upper Kelly Valve is connected between swivel sub and Kelly. Lower Kelly valve is connected between lower end of Kelly and top of drill pipe or lower end of Kelly save sub. Rotating the wrench of full opening safety valve 90° to realize on and off. In the drilling operation, in order to avoid malignant accidents, Kelly valves should be connected to both end of Kelly to prevent loss of drilling flid and blowout.
Kelly cock valve, which is a manually operated ball valve run in I.D of drill string, is one of effective tool for preventation from blowout.

The kelly cock is divided into upper kelly cock valve and lower kelly cock .

The upper kelly cock is connected between lower end of swivel and upper end of kelly. The lower kelly cock is connected between upper end of drill pipe and lower end of kelly or connected between lower end of kelly saver subs.

The kelly cock features a simple operation,the kelly cock can be opened on or closed off by only turning the special operationg spanner at 90 degrees according to indicating direction. During drilling operation the kelly cock shall be connected at upper end and lower end of kelly.