APPARAT FOR BORRNING AV HAL I ROR, SOM STAR UNDER INRE OVERTRYCK

摘要

"DRILLING HOLES IN PRESSURIZED PIPES" An apparatus for drilling pipes or containers under pressure employing a drill support device attachable to a surface of the pipe or container and having peripheral sealing means between said device and said container. A seal across an aperture in said device has sectoral leaves normally closed by the pressure to seal the aperture but able to be opened inwards to pass a drill.