when scrappin a tube to lightly crack the neck as you know to let air in otherwise when the dump truck empties your can you get an explosion or implosion rather lol.
Also you can use a long phillips and where the suction cup for the high voltage wire goes into the outer section of the tube, put the screwdriver into the hole. You should be able to hit the screwdriver with the heel of your hand and drive it thru the inner layer of tube to vent it.