A fluid pressure entry tap valve for use with pressurized pipes comprising a Wye device with an on-off valve of the ball type in each of two forks of the Wye. Preferably, one fork is in-line with the stem of the Wye while the other fork is at an angle thereto. The Wye stem is externally threaded for complementary engagement with a pipe saddle structure. The saddle structure is designed for either clamping to the pipe, or for being welded thereto.During use the Wye fork which is straight in-line with the stem has it's ball valve opened so a wet tap drill can be inserted to make an opening into the pipe under pressure. Then after removal of the drill the associated valve is closed. A curved guide directional shoe then is mounted upon the Wye, the valve opened again, and the guide inserted through the Wye into the pressurized pipe. Then the ball valve in the angled other fork of the Wye can be opened and a detector head of leak detector apparatus inserted therethrough into the pipe while still under pressure.The method of installing a Wye device with a pressurized pipe, tapping the pipe while under pressure, inserting a directional guide structure, and then inserting a detector head into the pressurized pipe while still under pressure in the desired direction for detecting leaks therein is also part of this invention.