so the burst pressure would be roughly 8000 psi. These were conservative ratings, since systems were often pushed beyond the stated limits. Over pressurised tubing usually swells along it's entire length, and dosen't usually push out a dent.
With a setup like this, the rubber plug will usually push out first, at a surprisingly low pressure. There are test stands with this sort of connection, but all the pieces are held in place so no part can move.
I have no practical experience with this hydraulic technique, but my gut fe
eling is that it will do as proposed above: leak out the plug before you ca
n build enough pressure at the dent to pop it out...and a messy leak too, s
ays my gut. Here's another completely untested idea: Eastman sells a couple
different pneumatic "pillows" that seem to be made of polyurethane or heav
y guage polyethelene with an air line attached. These are use to pop out au
to sheetmetal dents in inacessable spots in unibody cars. If you could make
yourself a small version of this to the correct internal dimension of the
tube, you might be able to feed it into the exact area of the dent and then
inflate with a compressor. Sort of a bicycle version of the medical proced
ure used on arteries...with a lot less blood, we hope. My gut says that if
one can pop out auto sheetmetal dents, it probably needs less air pressure
(since it's directed right on the dent) then the hydraulic pressure require
d to fill the entire tube...you just have to be handy at "pillow constructi
on", and the weak spot will be where the air tubing line attaches to the pi
llow.
Just a thought...good luck!
-Alan Goldsworthy
San Francisco, CA