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Sch 160

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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Sch 160

Unread postAuthor: frankrede » Fri Jul 27, 2007 3:40 pm

I Found a local pipe supplier in my area and they have sch 160 steel available in most sizes.
I was wondering what I could do with it.
I was wondering if it could take the bang of DDT repeatedly and possibly use it for good?
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Unread postAuthor: DYI » Fri Jul 27, 2007 3:52 pm

I wouldn't trust it with repeated detonations, for the simple fact that it is steel. You could use it with unregulated CO2, or maybe HPA regulated to about 2000psi, but you would have to find some of those 3000psi forged steel fittings.
It could probably survive DDT once or twice, but steel doesn't have the impact resistance to survive it repeatedly.
Hope you can find something impressive to do with it. :)
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Unread postAuthor: Fnord » Fri Jul 27, 2007 4:33 pm

I think it kinda depends on the diameter of the pipe. I imagine 3/4" sch 160 would hold up fairly well, but obviously I wouldn't trust 34" sch 160.

The fittings would probably fail before the pipe, anyway. The shape of fittings probably won't be as strong as the perfect cylinder that the pipe creates.
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Unread postAuthor: DYI » Fri Jul 27, 2007 4:37 pm

Well, a DDT at 6x did significant damage to Sch80 steel pipe that was only 1/2" diameter, so I don't know how long even small diameter Sch 160 would hold up.
I agree though, that the fittings would likely be the biggest problem.
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Unread postAuthor: frankrede » Fri Jul 27, 2007 5:05 pm

Indeed, I suppose I'll ask if they have it in other materials.
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Unread postAuthor: DYI » Fri Jul 27, 2007 5:09 pm

IMHO, something with a bit more "give", like aluminum, would work well for this application, as long as the walls were thick enough. Brass could also be good, but it would be pretty expensive. Maybe ABS, but the walls would have to be about an inch thick on a 1" ID pipe to withstand the pressure.
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Unread postAuthor: frankrede » Fri Jul 27, 2007 5:12 pm

I am done with plastics in my guns.
Aluminum sounds good, does that come in pipe form?
Mcmaster has sch 80 aluminum, would that suffice in 1 1/2"?
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Unread postAuthor: DYI » Fri Jul 27, 2007 5:24 pm

In my upcoming oxy-MAPP hybrid, I'm getting a 12" long piece of 3" diameter Alloy 2024 aluminum and machining it into a cylinder with a 1.5" ID. All attached fittings will be precision machined yellow brass rated for >3000psi. I think that the setup I just described should be sufficient if DDT does occur, although I will be a long way away when it fires (2x mixes of pure Oxygen and MAPP will be pretty scary).
I don't know if I would trust the alu. pipe and fittings, considering that they are only rated for about 500psi, but they may work. DDT in a propane/air mix can produce about 750psi, and I don't like exceeding pressure ratings.
I only use plastics in guns if they are absolutely necessary (and with the supply of gavanised steel pipe and fittings around here they rarely are).
Building something to withstand detonations can be challenging and costly, best of luck with it.
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Unread postAuthor: joannaardway » Fri Jul 27, 2007 5:29 pm

DYI wrote:It could probably survive DDT once or twice, but steel doesn't have the impact resistance to survive it repeatedly.

That leaves me wondering why the hell firearms made of steel (which make up a very large percentage) aren't exploding all over the place.

It depends on the bore, but DDT is no where near the pressures generated by a firearm cartridge, so within reason, it could be done.
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Unread postAuthor: frankrede » Fri Jul 27, 2007 6:07 pm

What will get you is that even aluminum framed firearms have steel lined barrels.


DYI!
Thats a monster setup, those yellow brass fittings aren't cheap either.
What are you using as a union?
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Unread postAuthor: DYI » Fri Jul 27, 2007 6:33 pm

Joanna: I don't mean to be insulting, but firearms do not utilise detonations. This is the reason that using flash powder in a firearm will make it explode, because the flash powder detonates, whereas normal smokeless powder burns very rapidly and, although capable of producing immense pressures, it does not detonate, at least under normal conditions. Gun barrels are also made of a special type of steel, far stronger than that used in pipe fittings. The reason therefore, that aluminum firearms have steel lined barrels is because, for a given thickness, steel is always stronger than aluminum, and, since detonations don't come into play, aluminum's extra impact resistance is not needed.

Frankrede: No, those yellow brass fittings aren't cheap. I will be using a 3/4" yellow brass union rated for 1200psi, at least until I decide to make my own. The setup is probably overkill, but a little bit of overkill on safety is always a good idea when making something like this.
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Unread postAuthor: frankrede » Fri Jul 27, 2007 6:49 pm

hmm, sounds nice, and there is no such thing as overkill. Especially when something capable of turning you into a vegetable is involved.
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Unread postAuthor: Matheusilla » Sat Jul 28, 2007 10:50 am

I like all the ideas I've heard here so far. You guys seem to be on the path to something great.
DYI: is 2024 alumminum stronger than the hardened 60 or 70 series alumminum?? As a suggestion for overkilling safety, how about bolting everything together, as opposed to threading?
Does anyone know the difference in velocity of an oxy/maap detonation compared to that of "exploding" smokeless powder? (I appologise beforehand if that type of discussion is against the rules)
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Unread postAuthor: DYI » Sat Jul 28, 2007 11:12 am

2024 alloy is an aircraft grade aluminum designed specifically for strength, so it likely stronger than 60 or 70 series alloys, such as the very common 6061. Hardened alloys would not be a good idea for a material used to contain a detonation, as they would be more brittle, defeating the original purpose of using aluminum because of it's softness, and therefore its increased impact resistance. Bolting everything together would be very difficult in the case of my design, and probably wouldn't help safety very much, and, short of welding, sealing it would be impossible.
An oxy-MAPP mixture detonation would have a higher flamefront velocity than that of smokeless powder burning (obviously), but I don't know exact numbers on either. I don't think that this type of discussion is against the rules, seeing as we are not discussing it as a fuel, but using it as a comparison against the intended gaseous fuel.
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Unread postAuthor: SpudBlaster15 » Sat Jul 28, 2007 2:00 pm

so it likely stronger than 60 or 70 series alloys


7075 aluminum alloy is much stronger overall than 2024, but 2024 has a greater fatigue strength, meaning it is probably more likely to survive a detonation.
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