Paintball

[Horizon]

Not HPA, but I've had two 4 oz. Brass Eagle CO2 tanks split open and blow across the room.

[phaedin]

I have heard that during the hydro test the tanks deform slightly and return, but not exactly, to the same shape.
I maybe misinformed and havent verified this, so take this for what its worth. Some confirmation of this would be good.
If it doesnt fail during hydro, them it shouldnt fail under normal operating pressures

[Shane-O]

Originally Posted by RatFink

Hydro testing always scares me. Think of this: aluminum and carbon and resin have relatively low fatigue resistance: IE. they don't spring back real well. So to make sure your tank is safe for the next three to five years, they stress the s**t out of it and then return it to you. The tanks only have a 15 year life as it is and are very overbuilt. Just something to think about.

Keep this in mind, when you fill the tank to 4500psi, your doing the same thing. When they test the tank, they are checking to see how much it expands and how much it contracts back. If it does not contract back far enough it fails. Being that this happens on a regular basis, not to that extent though, I feel perfectly comfortable with the hydro testing process.

[alpha434]

Originally Posted by Shane-O

Keep this in mind, when you fill the tank to 4500psi, your doing the same thing. When they test the tank, they are checking to see how much it expands and how much it contracts back. If it does not contract back far enough it fails. Being that this happens on a regular basis, not to that extent though, I feel perfectly comfortable with the hydro testing process.

Yeah... But they are also putting 6750 into the tank for that test.

[RatFink]

Originally Posted by Shane-O

When they test the tank, they are checking to see how much it expands and how much it contracts back. If it does not contract back far enough it fails.

I was not aware of this, As I understood it, they would simply submerge the tank in a bath of water and over fill. I didn't realize there was any science involved. I feel a little better now, not much, but a little...

[ta2maki]

I've read that one of the reasons of the 15 year lifespan is the fact that the hydrotesting itself damages the tanks.

[jerryjjackson69]

Pretty sure hydro testing involves submerging the tank and overrunning it, and making sure it doesn't displace ANY amount of water due to change in shape or volume externally.

I've seen plenty of burst discs fail, regs and valves unthread and the tank starts leaking, I've seen pin valves fail in an ASA with no vent hole, so the tank kicks off the gun hard enough to bruise your ribs pretty badly. I've only seen video of the one time a tank failed at the field. It was in the proshop, so a security cam caught most of what happened. Guy was holding the tank and filling it, the the tank just disappeared and was bouncing around the shop so fast the camera couldn't record it, stuff was just getting dented and falling off the walls. When it stopped you could see the tank had failed at the neck and was peeled back like a banana (as others have described). The reg was still connected by the nipple to the fill station. Amazingly the employee was uninjured.

[gospeedgo1]

Only seen what looked like a reg failure, tank flew around the parking lot. I think it was an empire/pure energy tank.

[DarkStar]

Good Description of a hydro-test:
American Paintball hydrostatic

key point:

"The second burette from the right now reads 65ml. The water has been pushed up the burette by the tank expansion due to the pressure on it of 5000 PSI. This must be a stable reading. In other words, the water level in the burette cannot change for at least 30 seconds. This could be due to a continual expansion of the metal of the tank which would be reasonable cause to fail the cylinder.

After the burette level is recorded. The pressure is released from the cylinder. The cylinder will not return to the size it was before the pressure was applied because it was permanently stretched. The burette to the left reads 2.4 ml. That 2.4 ml represents the amount of permanent stretch. If the tank stretched and did not return close to its original size, it would mean the metal of the tank was not resilient enough to be safely used to contain high pressure. This SCUBA tank must return to at least 10% of the upper reading. SCBA bottles must return to 5% usually."

[beebs]

Never seen one, but a field in washington was closed down when a kid was killed. He was taking a tank off a gun, He had the gun between his legs and was doubled over unscrewing the tank, but it seperated from the reg and came off and popped him in the forehead.