Old PVC cannon, still safe?

dippert · Sat May 28, 2011 11:40 am

I built a cannon a few years ago. The chamber is 4" sch40 PVC from McMaster. It's been sitting in my garage at my apartment for the last 2 years. Should I be worried about the PVC becoming brittle? It's been exposed to temps over 100* and below 0* in the garage (Indiana weather). No direct sunlight.

Technician1002 · Sat May 28, 2011 2:47 pm

Sunlight is the killer. Protected in the garage should be fine. If it received any major bumps and bangs, then don't trust it. That is what finally killed my Mouse Musket.

dippert · Sun May 29, 2011 10:14 am

I see. I'm don't remember if it got banged around. I'll build another one just to be on the safe side.

I wonder if it would be worth getting the next gun's chamber and barrel sprayed with line-X. They have some stuff that can keep a wall standing after an explosion.

I might be getting a job at a machine shop in the next few weeks. I may have to learn up on hybrids. Larda has me inspired with that stainless steel beast.

jimmy101 · Sun May 29, 2011 3:42 pm

What tech said. Besides, you house probably has PVC water lines in it that are much older than the cannon. A PWS may occasionally hit 100 PSI (or much higher in water hammer situations) but you don't hear about decades old PVC failing.

Sunlight will degrade PVC but age alone doesn't do much.

warhead052 · Sun May 29, 2011 6:48 pm

Dippert, its plastic. Does plastic break up over time? Not that anyone has heard of. I think your fine. But if you want to test it, bury it, then fire it. If its pneumatic, put pressure in until you hit the pressure you want, then done. Leave it for a few hours, and then come back. If it has not blown up, its safe to use.

Doctore · Sun May 29, 2011 7:16 pm

Well,PVC does not readily degrade when exposed to sunlight (ultraviolet radiation) due to natural UV inhibitors present in the material. Short-term exposure to sunlight, such as during construction, is typically not a problem for PVC pipe. PVC piping may be used in outodoor applications when the piping system is painted with a light-colored water based acrylic or latex paint(Do not use oil based paints) that is chemically compatible with PVC. When painted, the effects of UV exposure are significantly reduced.

jimmy101 · Mon May 30, 2011 10:24 am

Doctore wrote:Well,PVC does not readily degrade when exposed to sunlight (ultraviolet radiation) due to natural UV inhibitors present in the material. Short-term exposure to sunlight, such as during construction, is typically not a problem for PVC pipe. PVC piping may be used in outodoor applications when the piping system is painted with a light-colored water based acrylic or latex paint(Do not use oil based paints) that is chemically compatible with PVC. When painted, the effects of UV exposure are significantly reduced.

Depends on what "readily" means and whether of not the particular PVC actually has the UV inhibitors . Several years in the sun, unpainted, and the PVC will be severely pitted. Even PVC used for exterior trims will pit in full sun within a few years if unpainted.