A process of manufacturing a well closure apparatus and using it downhole by releasing components contained within the apparatus. The well closure apparatus is an internal bidirectional tubing plug that is adapted for insertion into a tubing string for sealing the tubing string internally while running the tubing into a fluid filled well. The tubing plug is comprised of a body having an inner surface with a recess or passage extending through the body from one end to the other. The recess holds petals and a keystone petal that are held within the recess by a cork and the cork is held in place by a nut. At depth, the tubing is filled with well fluid, the tubing plug is released at a predetermined hydraulic pressure, and the pieces of the releasing components are pumped to the bottom of the well or are circulated out of the well.