<p>A hermetic threaded joint includes female threads on a collar and male threads on the end of a pipe. They are matched with each other, the structures of female threads on the both ends of the collar are arranged symmetrically, and the female threads on each end are formed from buttress threads. A right-angle torque shoulder is arranged in front of the buttress threads, and the female threads on each end are connected with the said right-angle torque shoulder by a tool escape. A protruding threaded section that can prevent the leakage of the high-pressure gas is arranged on one tooth of the fourth to the seventh thread teeth of the female threads on the collar, thereby the sealing effection is achieved.</p>
