Freezing a large pipe to repair it - GIF

[hemmjo]

They could easily suffocate with all of the nitrogen purging the oxygen out of that pit.

[desbromilow]

They could easily suffocate with all of the nitrogen purging the oxygen out of that pit.

yeah, I was worrying about that too - later in the video you can see the flexi tube being used to control the atmosphere in the pit, but early in the video that's not evident.