"riverman" wrote in message
oups.com...
Umm, lots of outside pressure on something like a cylinder compresses
it evenly, like squeezing an egg in your hand without it breaking. But
if you compromise ths struture of the the tube, it can implode. Just
wondering how the tube keeps from imploding when they cut into it.

Did I miss something?

Again?

The list of suitable materials for a pipeline at that kind of depth and
pressure is going to be a very short one. It's safe to assume, I think,
that it's some sort of steel. Can't tell much for sure about the size of
the pipe but assuming the crab is neither a giant nor a pygmy species, and
judging by the hint of curvature in the cut, I'd guess we're looking at
something in the range of several inches to a couple of feet in diameter.
Even at ground level and low pressures pipe that size would have a wall
thickness of 1/4 inch or more. I haven't looked it up, but I'm pretty sure
that 2700 psi is well within the strength limits of just about any steel at
that thickness.

What I find curious is the assertion that pressure inside the pipe is 0
psi. Why (and how, for that matter) would someone generate and maintain a
vacuum in a pipeline at that depth and pressure? Then too, if you pause the
video at just the right point, it looks very much like about half of the
crab gets across the cut with no apparent difficulty before the whole thing
gets sucked in. And then it disappears in large chunks. If the suction is
great enough to make big chunks of crab disappear in a small fraction of a
second, how did it manage to get so far? Shouldn't it have gone in feet
first?

Wolfgang