Abstract: An apparatus for providing access to pressurized pipes includes a body member configured to be attached to a pipe or vessel or a fitting coupled to a pipe or vessel. The body member has an internal barrel in fluid communication with the pipe or vessel or fitting when the body member is attached to the pipe or vessel or fitting. A hollow piston is slidable axially within the internal barrel, and the apparatus is configured such that when an internal volume of the piston is pressurized by a fluid from the pipe or vessel, a force exerted by pressurized fluid on the piston in an axial direction is opposed by a force exerted by pressurized fluid on a counter-pressure portion of the piston. The apparatus includes a conduit orifice that allows a conduit to be disposed therethrough so as to pass into the apparatus to an interior of the piston.