Pipe tapping method and apparatus

A method of tapping a main pipe for connection of a branch pipe thereto, comprising the steps:

• (a) presenting a drill to one side of the main pipe from within a tubular enclosure including a valving means, the tubular enclosure having a closed outer end portion and having its inner end constituted by and sealed against the wall of the main pipe to be drilled, the drill including guide means in sealed engagement within said tubular enclosure, and a structural cooperation being provided within the tubular enclosure between the valving means and the drill guide means that maintains said tubular enclosure as a sealed chamber as well as retaining the drill and its guide means within the tubular enclosure after drilling the pipe and until a longitudinal extension can be added to the tubular enclosure,
• (b) rotating the drill and applying endwise pressure to it from outside the enclosure thereby to drill a hole in and through one side of the main pipe,
• (c) after drilling, adding a longitudinal closed end extension to the outer end of the enclosure,
• (d) releasing the structural retaining cooperation between the valving means and the drill and its guide means and retracting the drill and its guide means away from the main pipe, through said outer end portion and at least partly into said extension,
• (e) using the valving means to apply a transverse valve closure across the tubular enclosure and between the retracted drill and the main pipe, and
• (f) removing the longitudinal extension and the drill from the tubular enclosure.