A check valve that is dropped from the surface and pumped to a seat located in a special landing sub placed at the bottom of the drill string. It allows drilling fluids to be pumped down the well but to prevent fluids from flowing up the inside of the drillstring.
IS-A back-pressure valve latches into mating groove in TC Series tubing hangers or couplings to seal the wellbore while the BOP´s are removed and the Christmas tree is installed.