Introduction on Three Techniques/Patents for Improving Performance of Oil Casing Thread Connection

Introduced here in the paper are three thread connection-related techniques / patents,namely,the "Non-thread Sticking Coupling with Round Thread Connection",the "Oil Field Service Casing with High Strength Round Thread Connection" (HS-RTC) and the "High Airtight Buttress Threaded Casing" (HT-BTC).The patent of "Non-thread Sticking Coupling with Round Thread Connection" involves such a technique to eliminate thread sticking with bigger pitch circle of the initial threads of the coupling and a small transitional section of "lead-in threads".The patent of the HS-RTC is of a solution to enhance connection strength with the black threads of the round threaded casing.And the technique of the HT-BTC provides a solution to enhance the airtight performance of the API buttress threaded casing(BTC) by means of machining the casing end face into a curved axial shrink metal-tight surface and reducing the coupling length so as to ensure that when each two casings are coupled at site the end faces of them are strongly pressing against each other to form a metal seal ring.