Kelly cock is also called drill pipe safety valve.It is one of the effective tools to prevent blowout. The Kelly plug valve is divided into upper Kelly plug valve and lower Kelly plug valve. The upper Kelly plug valve is used between the lower end of faucet joint and Kelly. The lower Kelly plug valve is used between the lower end of the Kelly and the upper end of the Kelly or the lower end of the Kelly protective joint. It can be opened and closed by turning 90 ° with a special wrench according to the instructions. In drilling operation, in order to avoid the occurrence of malignant accidents, the Kelly plug valves should be assembled at the upper and lower ends of the Kelly to prevent drilling fluid loss and blowout.Our company can produce sulfur proof kelly cock with high quality imported sulfur proof material.