Threaded connections

Claim 1

A THREADED COAXIAL TUBULAR CONNECTION FOR TWO TUBULAR MEMBERS SUITABLE FOR CONNECTING MINE RAISE DRILL PIPE, E.G. OF THE ORDER OF TWELVE INCHES IN DIAMETER, COMPRISISNG A BOX ON ONE END OF ONE OF SAID TUBULAR MEMBERS, SAID BOX HAVING AN INTERNALLY TAPERED BORE FLARING TOWARD THE MOUTH OF THE BOX AND MERGING AT ITS SMALLER DIAMETER END WITH THE CYLINDRICAL INNER PERIPHERY OF SAID ONE TUBULAR MEMBER, SAID BOX HAVING A TRANSVERSE END FACE ADJACENT THE LARGER DIAMETER END OF SAID BORE, THE INNER PERIPHERY OF SAID BOX BEING UNTHREADED OVER A PORTION OF ITS AREA EXTENDING FROM SAID END FACE TOWARD THE JUNCTURE OF THE TAPERED BORE OF THE BOX WITH THE CYLINDRICAL INNER PERIPHERY OF SAID ONE MEMBER, SAID UNTHREADED PORTION FORMING THE MOUTH OF THE BOX, SAID BOX HAVING DOUBLE, MODIFIED BUTTRESS, HELICAL THREADS PROJECTING INWARDLY FROM SAID BORE TOWARD THE AXIS OF THE MEMBERS AND EXTENDING FROM THE MOUTH OF THE BOX TOWARD SAID JUNCTURE OF THE TAPERED BORE OF THE BOX AND THE CYLINDRICAL INNER PERIPHERY OF SAID ONE MEMBER, SAID THREADS PROJECTING INWARDLY NO FARTHER THAN THE CYLINDRICAL SURFACE DEFINED BY SAID INNER PERIPHERY OF SAID ONE MEMBER SO THAT THE THREADS GRADUALLY REDUCE IN HEIGHT AS THEY APPROACH SAID JUNCTION UNTIL THEY VANISH ALTOGETHER AT SAID JUCTION, SAID THREADS HAVING A LEAD BETWEEN 3/4 INCH PER FOOT AND 1 1/4 INCHES AND HAVING A HEIGHT IN THE RANGE OF 1/8 INCH TO 3/16" AND AN AVERAGE WIDTH OF THE SAME ORDER OF MAGNITUDE AS THE HEIGHT, THE PRESSURE THREAD FLANK ANGLE BEING OF THE ORDER OF 10 TO 20 DEGREES, THE OTHER THREAD FLANK ANGLE BEING OF THE ORDER OF 30 TO 60 DEGREES, A PIN ON AN INTERNAL UPSET END OF THE OTHER OF SAID TUBULAR MEMBERS, TAPERING DOWN TOWARD THE END OF THE PIN, THE LARGE DIAMETER END OF SAID PIN HAVING A SMALLER DIAMETER THAN THE DIAMETER OF THE OUTER PERIPHERY OF SAID OTHER TUBULAR MEMBER FORMING A TRANSVERSE SHOULDER ADJACENT THE LARGE DIAMETER END OF SAID PIN ADAPTED FOR ENGAGEMENT WITH SAID END FACE OF THE BOX, SAID PIN HAVING DOUBLE, MODIFIED BUTTRESS, HELICAL THREADS SIMILAR TO THE THREADS ON THE BOX PROJECTING OUTWARDLY FROM SAID PIN AWAY FROM THE AXIS OF THE MEMBERS AND EXTENDING FROM A PLANE SPACED AXIALLY FROM SAID SHOULDER TOWARD THE END OF THE PIN, SAID PIN AND BOX THREADS BEING NARROWER THAN THE SPACES BETWEEN THE THREADS LEAVING SPACE BETWEEN THE NONPRESSURE THREAD FLANKS WHEN THE CONNECTION IS MADE UP