Tubing isolation disc valve

Claim 1

A full-bore well tool adapted to be tandemly coupled in a pipe string suspended in a well bore, comprising: a tubular housing having an axial bore with a portion thereof defining an enlarged chamber; closure means in said housing including a rupturable disc of a ductile material having a central portion extended transversely across said enlarged chamber, and means sealingly securing the peripheral portion of said disc to said housing for closing said housing bore so long as said disc is intact; means adapted for severing a major part of said central disc portion from said peripheral disc portion and displacing said major part outwardly against one wall of said enlarged chamber, including a tubular mandrel having an unobstructed axial bore movably arranged within said housing bore and including a skewed forward end defining a slanted annular cutting edge having a forwardly-opening longitudinal notch in one segment thereof; actuating means including piston means on said mandrel operable in response to fluid pressure exterior of said housing to advance said mandrel from an initial position where its said forward end is adjacent to said disc to a final position where its said forward end has passed through said disc for progressively severing those parts of said central disc portion successively contacted by said annular cutting edge from said peripheral disc portion and progressively bending that part of said central disc portion disposed within said notch outwardly to confine said central disc portion between said chamber wall and the exterior of said mandrel; and retaining means cooperatively arranged on said mandrel and said housing and operable upon advancement of said mandrel to its said final position for securing said mandrel in its said final position to block said central disc portion from subsequently moving inwardly across said unobstructed axial bore of said mandrel.