Supraflow® under pressure tapping tees are indispensable when installing large-volume by-pass diversions, whether branching, networks or standard by-pass assemblies. Pipe perforation is made by means of a “zero chip” cutter, housed inside the tee and retaining the disc and all the chips produced. The ability to install 90 and 110 mm diameter PE pipe electrofusion derivations so reliably and easily makes the Supraflow® tapping tees a true novelty world-wide.