Lined and sealed tubing joint

Claim 1

AN OIL WELL PIPE STRING JOINT COMPRISING COAXIAL PIN AND BOX MEMBERS RESPECTIVELY INCLUDING EXTERNAL AND INTERNAL THREADS, SAID PIN MEMBER BEING SCREWED LONGITUDINALLY FORWARDLY INTO THE BOX MEMBER TO INTERENGAGE SAID THREADS FOR HOLDING THE PIPES AGAINST SEPARATION, SAID PIN MEMBER HAVING AT ITS FORWARD TERMINAL A FORWARDLY FACING ANNULAR SHOULDER, SAID BOX MEMBER HAVING AN ANNULAR SHOULDER FACING REARWARDLY TOWARD SAID PIN SHOULDER BUT SPACED FORWARDLY THEREOF, CORROSION RESISTANT ABRASIVE MATERIAL COATING SAID PIN AND BOX MEMBER BORES PROXIMATE SAID SHOULDERS, AND MEANS INCLUDING A PAIR OF ANNULARLY CONTINUOUS RINGS OF CORROSION RESISTANT MATERIAL COMPRESSED BETWEEN SAID SHOULDERS, ONE RING CONTACTING THE PIN SHOULDER AND THE OTHER RING CONTACTING THE BOX SHOULDDER, SAID RINGS BEING RELATIVELY ROTATABLE IN RESPONSE TO SCREWING AND UNSCREWING OF THE PIN MEMBER IN THE BOX MEMBER, THE BOX MEMBER FORMING AN ANNULAR RECESS OPENING INWARDLY TO BE BOUNDED BY SAID PIN AND BOX MEMBER SHOULDERS, BOTH RINGS BEING RETAINED IN SAID RECESS AGAINST DISLODGEMENT THEREFROM UPON UNSCREWING OF THE PIN MEMBER AND THE ABRASIVE COATING THEREON TO SEPARATE FROM SAID ONE RING, AND SAID MEANS AND COATING MATERIAL FORMING A CORROSION RESISTANT BARRIER PREVENTING CORROSIVE FLUID ACCESS TO SAID THREADS.