Making connections to pipes under pressure

摘要

This application describes methods and apparatus for making connections to pipes and pressure vessels while they are under pressure. The invention provides a first drive mechanism for delivering a cutting tool to the vessel wall and a second separate drive mechanism for powering the movement of the cutting tool through the wall. The long linear travel associated with the transit of the cutter to the wall is divorced from the short cutter travel required to perform the actual cutting operation. This allows the two long and short travel systems to be designed independently of one another, and engineering compromises between them can be avoided.