The barrel was the weekest part

[tghhs]

So i was out testing this launcher:
http://www.spudfiles.com/forums/tghhs-a ... 20207.html

After i'd just given it a new chamber and barrel, because it had a tinny leak through the front bushing that was annoying me. I used pn9 for the barrel this time though.

I took it up to 100 psi, like i always did and.... POP! hu????? looked at the pressure gauge; 60psi, hmm????? took a step back and looked at it; no problem there. pulled the trigger; all good, actuated just dandy. Looked inside the barrel, Oh F**K!

Has this happened to others? Here at SF, the common belief is that pipe can take more pressure if it's on the out side. Well, im not sure this is true, at least when a piston is pushed against it.

Was i a fool? should i have expected this? What do you guys think?

[deathbyDWV]

Well, that hasn't happened to me...

It seems like the outside would take less pressure than the inside since it has more surface area... But it also seems that the pipe, when pressure is on the outside, would try to compact together like an arch in a building, making it stronger... As long as there aren't any imperfections...

[psycix]

Weird. PN9 should be able to hold 131 psi (from the inside).


Common belief is that a pipe is able to hold at least the same pressure from the outside as the inside.
But I guess that is not the case if it is deformed and became somewhat epileptic.

Any experts with a mathematical explanation nearby?

[tghhs]

Yeah, that would make sense. I'm sorta thinking that maybe the barrel support could have slightly bent it out of shape, because it was quite a tight fit.

Also, because of the pretty extreme valve seat to diameter ratio, the piston would have been putting much more force on the barrel than most cannons.

[absinthe]

i don't see how a pipe could handle the same pressure on the outside as the inside, as this demonstrates, you only need to crush the pipe on the inside on the outside it needs to rupture

[ONEWING]

True abinthe, difference between crushing and exploding. Its like the ,pvie of the gas truck that imploded or a 44 gal drum that will implode when pulled to a vacuum, less then 1bar (14.5psi) pressure on outside.