Is this safe?

[Snowshoe]

years back i got a chunk of steam pipe the size of a tennis ballwith a 5/16 wall thickness from a friend who is a wlder at a sugar plant. i turned a plug that extended in the pipe about 2 inches and welded it to the brech with my heliarc welder. i have shot it with newspaper and tenis balls and golf balls with about 300 gr 2f. i have also shot 4oz solo cups filled with wet sand that work quite well. should i continue this or am i flurting with disaster?
shoe

 

[Darkgael]

I wish that I could give you a complete answer with the pressure statistics for the kind of pipe that you have been using. I can't but I'm sure that someone else on this forum can.
My gut reaction is "stop"; that kind of pipe is the basis for a "pipe bomb", which is basically what you have been playing with. Glad that you have had fun and no one has gotten hurt but, y'know, you only have to be wrong once with this kind of thing.
Pete

 

[guncobbler]

300 grains seems like a lot. You can have a lot of fun with just 50 grains of black powder. My golf ball mortar shots a ball faster than sight with just 50. We can't see it until the ball is almost 100 feet from the muzzle. One thing you can do is measure the outside diameter of the pipe at the breech face and compare it with the diameter at the muzzle. If you have any measurable swelling at the breech weld the vent shut and put it on the shelf. Be safe out there, GC

 

[TheDoubleD]

Pipe bomb!!

Walls are to thin, breech plug needs sweated in place, it's made from pipe which is probably seamed.

My chart doesn't go that low but by extension it appears in a cannon with 5/16 wall thicness maximum safe load is around 10 to 15 grs of Fg.

 

[BigDave]

If what you're shooting is light like a tennis ball, and there is a loose fit with no wad, then this is more of a fireworks mortar instead of a artillery mortar.

^ note proviso's on weight and loose fit above ^

The 300 grain charge = 19.44 grams

If you're lifting a tennis ball then you have something close to a 3" mortar which has a standard lift charge ~ 17 grams BP.

The fireworks industry has given up on steel tubes for standard shells for safely reasons, they use HDPE(plastic sewer pipe) or fiberglass now.
(Note HDPE is not PVC, PVC or other types of plastic pipes would actually be much more dangerous than steel)
When they do use one for extremely heavy shells, or for salutes they bury them in the ground.
They also have double layer welded bottoms.

A loose fit and light projectile would mean you're probably safe, but do you want to risk your life on probably?

Note that packing a wad to increase pressure and send the ball further greatly increases the risk.

 

[Will Bison]

Normally I and others like to see a wall thickness of one bore diameter at the breech end of the gun. So a gun with a two inch bore would be six inches in diameter at the breech. The outside taper should start well ahead of the projectile when loaded.

Welded anything on a cannon tube is a no-no in my book. Any tube should be made from DOM, no welded seams, or machined from solid stock. Breech plugs should be threaded in and at least 1.5 times bore diameter in depth.

 

[juancho]

Has anybody ever made such a type of "cannon" for the sole purpose of blowing it up?
No mithbuster :bull: ,just to see what it takes?
Not something full scale,I'm not talking bombs here.But something to give an idea for all those out there playing russian rulette with pipes.

 

[Will Bison]

juancho;

Kinda sorta did it once with a piece of EMT electrical conduit. I had one of my guys put together a Bazooka looking thing as a theatrical prop. It fired a small charge of BP as a blank for some shows we did. As I recall it was 2.5 inch diameter conduit.

Some years later we wanted to get more back blast but thought it a good idea to test it first. At around 20 ounces of BP it bulged. Remember that both ends were open so it was not the best test. I know it didn't rupture the tube just caused a bulge.

 

[Dphar]

years back i got a chunk of steam pipe the size of a tennis ballwith a 5/16 wall thickness from a friend who is a wlder at a sugar plant. i turned a plug that extended in the pipe about 2 inches and welded it to the brech with my heliarc welder. i have shot it with newspaper and tenis balls and golf balls with about 300 gr 2f. i have also shot 4oz solo cups filled with wet sand that work quite well. should i continue this or am i flurting with disaster?
shoe

This is not safe. Steam pipes, hydraulic pipes etc. May not tolerate the "pulse" of firing very well. Its not necessarily the pressure level but the speed of the pressure rise that can cause bursting.
FFG is very fine powder to use in this bore size especially with a heavy projectile. It has a burn rate several times faster than Cannon powder. FFG is twice as fast as FG and Cannon is much slower than FG.
In heavy charges Fg is too fine in bores much over 1-1.5".
I think that the use of FG or finer powder and/or over tamping of blank charges is a cause of unfortunate "events".
A couple of years ago I attended a rifle match that started with a blank fired from a home brewed cannon. After glancing at the loading process, heavy pounding with an iron rammer, I took my son to the parking lot. I met a friend out there who was also allergic to such foolishness. We returned to the firing line after the "cannon" was again safe to be around.

Dan

 

[Dphar]

Has anybody ever made such a type of "cannon" for the sole purpose of blowing it up?
No mithbuster :bull: ,just to see what it takes?
Not something full scale,I'm not talking bombs here.But something to give an idea for all those out there playing russian rulette with pipes.

This would prove little. Proving a barrel made of improper material will not prove its safe only that it did not fail at that firing. Could fail later with a much lighter charge. The only safe approach is proven materials, adequate wall thickness with proper powder granulation and charges for the bore size.
Still iron cannons used in combat had a rather frightening failure rate in the Civil War era.

The following was apparently more common in the mid-19th century than generally reported by the military.
[url] http://wfls.com/News/FLS/2005/092005/09242005/104850/index_html?page=1[/url]
Details the bursting of a gun on the USS Princeton in 1844 that killed the Secretary of State and the Secretary of the Navy and several others.
The technology was less than safe. Though I am sure the gun was proved and was loaded with the service charge.
Heavy charges of powder heating bores and wet mops down the bore for a fast reload were contributing factors.
IIRC the only guns that had no record of failure were the bronze smooth bores. Better heat conductivity of the bronze was thought to make them safer.

Dan

 

First basic rule of cannoneering, :nono: a pipe is not a cannon :shake: .

Claypipe
Gonnemeister

 

[Bullmoose]

It's a wonder it didn't blow up the first day.
God must be holding that thing together. Somebody loves up there.
300gr. with thin pipe!!! :surrender:

OH man OH man!!!! :nono:
watch out it is a loaded PIPE BOMB :shake:
It's time to buy a real cannon