steel pipe

[pat123]

I went in Homedepot today to look at pipe to use on my hybrid. they have black pipe and galvanized pipe. thats all it says on the box they were in. I bought two coupling to see if a spark plug will fit in it. It doesn't says what sch it is or anything. has any one bought this pipe from homedepot and is it safe to use?

thanks in advance.

[bigbob12345]

Use the galvanised pipe the black pipe will corrode.
and yes it is safe to use at mixes up to 6x. more and it most likley wont fail but will be getting closer to the burst pressure.

[judgment_arms]

I’ve got an uncle that works for the gas company; he says that it’s designed for less-than 100psi propane, not high pressure pneumatics.

On the other hand the guy at the Fergusson plumbing supply store says that it 150psi WSP (working steam pressure) and that garages run HPA, Liquid Oxygen, and Acetylene through it.
And I’ve also seen it filled with unregulated Co2 on a regular occasion.

I‘ll let you decide.

[DYI]

The black pipe is designed for use with fuel gases like propane, and will corrode if it is used for air or water. The galvanised pipe will only corrode on the uncoated threads. Both are SCH 40, and are of roughly equivalent strength. The fittings are rated for 150 psi WP, and the pipe is rated depending on size, but even the 2" size has a working pressure of over 700 psi. The fittings aren't rated for much, but I have been using them at 500psig constant pressure for about half a year (which isn't by any means saying that it is safe). I wouldn't trust the fittings as high as I trust the pipe, simply because they are malleable iron, not steel, and seem to be of relatively low quality manufacture. The black and fittings are cheaper though...

[pat123]

so what type of pipe do you use for hybrids?

[bigbob12345]

Galvanised because there is air in the application and black will corrode.

[judgment_arms]

...The fittings are rated for 150 psi WP...

Ah, that’s what my uncle meant; it’s not the pipe that won’t take the pressure, but the fittings! He was saying something about the threads weakening the pipe… there was other people talking and I couldn’t hear all that he said.

What if one were to case harden the fittings, would that help?

[pat123]

I mean is it strong enough to hold the pressure. is this what most people use.

edit: this is what I was planning on using for the chamber.
http://www.homedepot.com/webapp/wcs/sto ... 026+502123

[bigbob12345]

Yes it is strong enough to hold the pressure and is what most people use.

[DYI]

Case hardening the fittings:
1) It wouldn't work, because they aren't even steel
2) Messing with steel fittings probably isn't a good idea, it would make them brittle and could cause cracking.

As I said, I've used the pipe and fittings at 500 psig, and I wouldn't trust them much higher with constant pressure. They have been tried in 2" size with an 11x hybrid mix and held up fine.

[judgment_arms]

Case hardening the fittings:
1) It wouldn't work, because they aren't even steel
2) Messing with steel fittings probably isn't a good idea, it would make them brittle and could cause cracking.

Case hardening is the process of carbonizing iron forming a layer of steel on the surface of the iron object.
What you’re thinking of is different, I'm not talking about the process used by Myth Busters to harden the hammers, that’s just hardening.

This involves the use of a “pot”, traditionally made of clay, filled with leather, bones, charcoal and/or hair. The “pot” is sealed, although there might be a small hole in the lid I can’t remember, and placed in the forge were it is then heated to… uh, chary red to yellow (the steel in the pot, not the pot itself) and allowed to cook.

[SpudMonster]

I’ve got an uncle that works for the gas company; he says that it’s designed for less-than 100psi propane, not high pressure pneumatics.

On the other hand the guy at the Fergusson plumbing supply store says that it 150psi WSP (working steam pressure) and that garages run HPA, Liquid Oxygen, and Acetylene through it.
And I’ve also seen it filled with unregulated Co2 on a regular occasion.

I‘ll let you decide.

The guy at fergusson must be on crack. 150 WSP fittings/valves are rated at 600 PSI WOG (water, oil, INERT gas).

HPA is between 3 and 5 times the rated pressure. Fittings are only designed with a safety factor of 4 (I think) so that's idiotic.

Acetylene and oxygen however are beyond retarded. I can't even begin to comprehend the idiocy of anyone who would run those through galvanized line... Acetylene is the second most flammable gas in existence and decomposes over 15 PSI. Oxygen is even worse. Any system running oxygen gas has to be specially cleaned and kept sealed until the moment it's put into the line. If it will burn, it'll explode spontaneously in oxygen. Oils and other contaminants will detonate. And I have seen some pretty fucking oily galvanized pipe at the stores.

Unregulated CO2 is stupid, but safe enough, as it's only around 800 PSI, not too far above the working pressure of the pipe.

[judgment_arms]

yeah, galvanized pipe is rated for 150psi working steam pressure, so are most brass/copper ball valves, which gives them a WOG pressure of about 600psi.

I’ve not seen the welding gases run through it though, but he didn’t seem high, I think he honestly believed that and probably doesn’t know enough about the subject to know otherwise

I don’t know much beyond that, other than I’ve seen it used with HPA, with out detonation, at a scuba shop when the Myth Busters visited one, but that could have bean the high pressure gas pipe my uncle told me to get (rated to ~500-700WSP I believe).

[pat123]

Ok thanks,
so i just have to buy the parts. how would you attach a spark plug. It fits in the 1/4in coulpling, but the threads don't match up.

[SpudMonster]

Spark plug threads are typically 14 MM. Damn close to 1/4" NPT but not quite. You can find some if you look around that are designed for small engines that have 1/4" pipe threads.