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PVC Failures
Posted: Sun Oct 17, 2010 1:09 am
by HunterT
I found this article and it really demonstrates the how PVC fails. A must for any spud cannon maker.
http://www.crazybuilders.com/item.php?i ... =blast_box
Posted: Sun Oct 17, 2010 5:42 am
by jrrdw
That's pretty cool and all, but I don't for see any spudder doing this while out shooting their cannon. Nice scatter of shrapnel...
There has been a few PVC test posted here, and by far my favorite is the static pressure test with a 2" X 10' piece of SCH40 pressure rated pipe. Filled with water the PVC pipe held to 1029PSI then split the side open in the middle.
Posted: Sun Oct 17, 2010 3:30 pm
by HunterT
jrrdw wrote:
Filled with water the PVC pipe held to 1029PSI then split the side open in the middle.
WHOA
That's a lot of pressure. When I first began spudding I didn't believe that PVC was that tough.
Posted: Sun Oct 17, 2010 3:33 pm
by Gun Freak
Many people underestimate it's strength. While I am cautious when using PVC, I still know that when properly put together and handled, it is perfectly safe for a spudder's application.
Posted: Sun Oct 17, 2010 5:02 pm
by saefroch
hunterT wrote:
jrrdw wrote:
Filled with water the PVC pipe held to 1029PSI then split the side open in the middle.
WHOA That's a lot of pressure. When I first began spudding I didn't believe that PVC was that tough.
Yeah, PVC can hold a considerable amount of pressure, I have some 2" that's rated to 240psi. It's because of the failure mode that people avoid pushing it.
Posted: Sun Oct 17, 2010 5:44 pm
by Gun Freak
The pipe is rated with a high safety factor. My 2" is rated to 280 psi. As the diameter goes up, the pressure rating goes down. I believe my 1/2" is rated to 680, and I would trust it at like 300 psi. At these pressures though, failure decomes even more dangerous because the higher pressure can send the shrapnel even faster.
Posted: Sun Oct 17, 2010 7:22 pm
by metalmeltr
I had a PWC DWV cleanout blow out the back of my advanced combustion the other day, deystroyed the fan, what i found of the cap was shattered.
Posted: Sun Oct 17, 2010 8:55 pm
by c11man
Gun Freak wrote:The pipe is rated with a high safety factor.
i dont know any acual numbers but to be legal to sell the pipe has to have a pretty good saftey factor. due to PVC's less than favorable failure properties i would assume that it is made with an even higher saftey factor than say a copper pipe.
remember that its not the pressure that causes most failures, its the recoil, piston impact, and barrel flex that put exessive forces on the pipe/fittings and causes the failure. build a launcher than can has the can handle these forces and you will have lots of fun with your pvc
also you MUST weld the joints correctly and wait for it to cure fully