The kelly cock, which is a manually operated ball valve connected in the bore of drill string, is one of effective tool for preventation from blowout. The kelly cock is divided into upper kelly cock 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 drillpipe and lower end of kelly or connected between lower end of kelly saver subs. The kelly cock valve features a simple operation, the kelly cock 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 cock shall be connected at upper end and lower end of kelly.Type OD. mm Thread API I.D. mm Max. rated working pressure (psi) CS146 146 41/2REG LH 57 68.6 CS200 200 65/8 REG LH 75 68.6 Type O.D mm Thread API I.D. mm Max.Sealing Pressure Mpa XS105 105 NC31 40 68.6 XS121 121 NC38 51 68.6 XS127 127 NC38 57 68.6 XS178 178 NC50 70 68.6
