Fluid-packed drill pipe

Claim 1

A DEVICE OF THE CLASS DESCRIBED, COMPRISING AN INNER STEEL TUBE AND AN OUTER STEEL TUBE ARRANGED ONE WITHIN THE OTHER WITH THEIR RESPECTIVE OPPOSITE ENDS PROXIMATE EACH OTHER, EXCEPT FOR A PROTRUDING END PORTION OF THE INNER STEEL TUBE BEYOND EACH END OF THE OUTER STEEL TUBE AND INNER SURFACE OF EACH END OF THE OUTER STEEL TUBE BEING TAPERED IN SHAPE TOWARDS THE LONGITUDINAL CENTER OF THE OUTER STEEL TUBE, SAID INNER STEEL TUBE AND OUTER STEEL TUBE FORMING A CYLINDRICAL SPACE BETWEEN THE OUTER SURFACE OF THE INNER STEL TUBE AND THE INNER SURFACE OF THE OUTER STEEL TUBE, A BUSHING AFFIXED TO EACH END OF THE INNER STEEL TUBE AT THE END PORTION OF THE OUTER STEEL TUBE AND HAVING A TAPERED OUTER SURFACE IN SLIDABLE CONTACT WITH THE INNER SURFACE OF THE OUTER STEEL TUBE SO AS TO SEAL THE CYLINDRICAL SPACE BETWEEN THE OUTER SURFACE OF THE INNER STEEL TUBE AND THE INNER SURFACE OF THE OUTER STEEL TUBE IN A FLUID-TIGHT MANNER, EACH BUSHING HAVING A LONGITUDINAL OPENING PARTIALLY THREADED AND CLOSED BY A SCREW PLUG FACILITATING THE FILLING OF THE CYLINDRICAL SPACE WITH A FLUID OF PRE-SELECTED GRAVITY, A TOOL JOINT SHRUNK FIT ABOUT THE OUTER SURFACE OF THE INNER STEEL TUBE AND THE OUTER SURFACE OF THE OUTER STEEL TUBE AND AFFIXED THERETO BY AN ANNULAR WELD, A TOOL JOINT PIN SHRUNK FIT ABOUT THE OTHER PROTRUDING END OF THE INNER STEEL TUBE AND ABOUT THE END OF THE OUTER STEEL TUBE AND AFFIXED THERETO BY ANNULAR WELD, AND FLUID OF PRE-SELECTED DENSITY AND QUANTITY STORED IN THE CYLINDRICAL SPACE HEREINABOVE DESCRIBED.