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View Full Version : Might be a bad idea.


FU Toolbag
12-31-2009, 07:06 PM
I don't sleep much. As a result, I think too much. Lately I've had an idea going through my head. Not sure if it's genius or retarded yet, the jury is still out, but this is it.

I have a set of torpedoe propane tanks. They're about 8" dia and 8' long. I'm thinking they would make a good set of frame rails. I'm not talking clamping them to a set of frame rails, but to build a frame around them. I am certified to weld presure vessels so that's not a problem. I also know about the doubler aspects, but I just can't think of a real reason why not to do it?

It does scare me, but I can't come up with an actuall reason why. I've never seen it done. That doesn't bother me, but it does cause me to pause.

Just wundering. Flame on

redman
12-31-2009, 07:22 PM
im confused, would you fill them with propane?

FU Toolbag
12-31-2009, 07:32 PM
yes...

barracuda
12-31-2009, 08:58 PM
i am thinking cyclic stresses could be an issue:)

FU Toolbag
12-31-2009, 09:15 PM
Would it be any different if I had a peice of tube there holding stuff together? So many 4x4's are built with 1.75 tube with only .125 wall? I'm planning in putting doublers where all the mounts will be, and probably a doubler under the whole thing as a skid plate/mounting surface.

D-Ass
12-31-2009, 09:44 PM
the tanks would not be the greatest idea I would be scared shitless if It hit any sharp object or slid across a rock any minor rub could be enough to split the tank and with that much fuel be it propane or gas would not be a happy situation

also welding on the tank would make one hell of a stress point (as you would know) if you were to join them as frame rails the constant flexing of the welded area would weaken the metal and shear it off causing a BIG problem

if you take a look at any "production" frame made the rails are joined by bolts, riviting or spot welds (not full seam welds) the reason is to allow the rails and the stringers to flex if it was fully welded the welded portion would crack in no time by the shear stress

last thing is I wouldn't want to get caught by DOT. could put your ass in a sling for a verry long time

[cheers]

FU Toolbag
12-31-2009, 10:13 PM
This is not for the street, so dot can go hang out at timmies, or hell, their choice. I know production frames are made to flex, but that's not what I'm going for. How many tube buggies have frame flex? The idea would be to have a all tube type buggy with intigrated rollbar. frame flex is irrelevent. Stress points from the link mounts are a potential problem, thus the doublers.

The potential problems are there I know. How many guy's have dragged there rig ovedr something sharp and it split their tubing? I know if I drive it off a cliff I'm fucked, but I'll probably have other problems to be worried about.

barracuda
12-31-2009, 10:22 PM
as long as it is stiff enough in design and welded well i dont see much of a problem . those tanks are extremley strong and i dont think punturing them would ever happen unless onpurpose. Granted i have a belly full of cuttle fish and beer but it seems like it would work[cheers]

D-Ass
01-01-2010, 12:28 AM
propane tanks are not that strong they are not made like high pressure tanks! a propane tank has a psi rating of 250lbs the average gas cylinder has a rating of 4000psi (safety margin of 4 ) so a propane tank can take on average 1000lbs while a compressed gas cylinder is 16000 lbs now take a look at what DOM. can take now you see the differance not to be a dick just saying some one would have done it all ready if it was a good idea :dontknow:

why not just mount them to the frame instead of making them part of it with what you have said about building up around them making them part of the frame dosn't make that much scense to me it gust sounds like adding a lot of very dangerous unknowns with no real benefit :confused:

if you do decide to build it I would love to see some pix or a sketch of what you have planed [cheers]

mus-Tard
01-01-2010, 02:51 AM
give'r bud [cheers]

Trooper
01-01-2010, 03:28 AM
Why not turn your frame into a pressure vessel? LPG is really really low pressure as you should know having your astm pv certs

FU Toolbag
01-01-2010, 09:56 AM
I know of several rock buggies where the frame is used as an airtank. My tanks aren't the old uncertifyable 250psi from the 80's. Mine are the proper 312psi tanks and they are only a couple years old. I'm thinking that if my mounts are fully boxed which will reduce the specific stress points on the tanks. I've also thought about using a saddle system where the tanks are actually removable, but that would include a fair amout more weight, and yes, this is an attempt tp be light.

InteriorZR2
01-01-2010, 12:57 PM
...and yes, this is an attempt tp be light.

This coming from the guy who built the 8000lb LC? lol

FU Toolbag
01-01-2010, 02:29 PM
This coming from the guy who built the 8000lb LC? lol

and you point is?? Goal is 2500lbs.

DirtyComanche
01-01-2010, 08:18 PM
If you main hangup for the weight is the actual fuel tanks, you could get one of those composite (they're either fiberglass or carbonfiber, I forget) tanks they sell for the marine and RV world. Light, visible fuel level, etc. Capacity is not great, it's in the range of the aluminum lift truck tanks (about 30lbs).

Otherwise, like I said before, go for it. I doubt it will ever present any problems given your capabilities as a welder and your knowledge on the subject. The tanks are stupid overkill anyways... Build the rest of the structure to help things out (I'm assuming that you'll have a cage).

Propane tanks can take some pretty massive hits. People think they're fragile. Look at some of the shit in the scrappers that got all fawked up, normally the tanks are still peachy.

Zibi
01-01-2010, 10:37 PM
I think this is one of those things where yeah, it miiight work, but do you really want to be the person who finds out it doesn't?

skyjacker
01-01-2010, 11:19 PM
sounds like an interesting ideia , only way you'll know if it will work is to try it right

strokenit
01-02-2010, 08:21 PM
This is where my built in hatered of blowing myself up would kickin and say maybe not the best idea.

Troy
01-02-2010, 08:40 PM
i was thinkin about this on the way home today... what if you used a higher pressure cylinder like an argon or oxygen tank.. working pressure of 2200 psi usually and they are thicker than most propane tanks... although you would have to adapt your fittings and bleeder bungs...

importcrusher
01-02-2010, 10:22 PM
i was thinkin about this on the way home today... what if you used a higher pressure cylinder like an argon or oxygen tank.. working pressure of 2200 psi usually and they are thicker than most propane tanks... although you would have to adapt your fittings and bleeder bungs...
i think this fellow has the rite idea(you should fill 1 tank with gasoline and the other with propane that way when you roll up to an event everybody will know about you )i will cheer for you (from a distance) hey but really when is this little project going to start?or are you likin that ranger?food

epic3
01-03-2010, 01:29 AM
gonna name it the challenger when your done?

Troy
01-03-2010, 01:38 AM
i think this fellow has the rite idea(you should fill 1 tank with gasoline and the other with propane that way when you roll up to an event everybody will know about you )i will cheer for you (from a distance) hey but really when is this little project going to start?or are you likin that ranger?food
are you high?

im just adding advice im not the one building the bomb

D-Ass
01-03-2010, 03:24 AM
think real hard bout it!:confused0006:

http://msnbcmedia1.msn.com/j/msnbc/Components/Photos/050709/050609_columbia_hmed_6p.hmedium.jpg

ROBO
01-03-2010, 09:59 AM
this i can tell you .. i have prop tanks in my rig bounced them a few time off rocks.. tough as nails .. the valves on the othe r hand... sheared one off one time.. i stood there askin why are all those people runnin away fast? other than that.. no problums but i shurs as hell would not weld too one or us it in a frame construciton ting.. way too much chance of problums.

m j
01-03-2010, 10:09 AM
I had a 20' hose on my loose LPG tanks
it was spooky the first few times the tailgate popped open and the tanks ended up on the ground
after a few times it just becomes comedy
they are heavy SOBs when full

no way would I use them as a structural member

FU Toolbag
01-03-2010, 01:05 PM
I had a 20' hose on my loose LPG tanks
it was spooky the first few times the tailgate popped open and the tanks ended up on the ground
after a few times it just becomes comedy
they are heavy SOBs when full

Now that's just fucked up. And you say I'm nuts????

Punk in Drublic
01-03-2010, 04:47 PM
I had a 20' hose on my loose LPG tanks
it was spooky the first few times the tailgate popped open and the tanks ended up on the ground
after a few times it just becomes comedy
they are heavy SOBs when full

no way would I use them as a structural member

[36] [36] [36] laughin my ass off[cheers]

digger
01-03-2010, 09:38 PM
go back to sleep

Trooper
01-03-2010, 09:38 PM
i was thinkin about this on the way home today... what if you used a higher pressure cylinder like an argon or oxygen tank.. working pressure of 2200 psi usually and they are thicker than most propane tanks... although you would have to adapt your fittings and bleeder bungs...

Thats a decent idea. You cannot pressurize LPG to 2200 but most XPR tanks have about 20 meters squared capacity. Would be totally over kill for propane. I tossed a empty oxygen tank off a overpass with the valve gaurd on and it didnt do shit to the bottle. When they are under pressure they are even stronger. Think of a pop can weak as shit empty but full they are strong as shit.

Troy
01-04-2010, 01:18 AM
Thats a decent idea. You cannot pressurize LPG to 2200 but most XPR tanks have about 20 meters squared capacity. Would be totally over kill for propane. I tossed a empty oxygen tank off a overpass with the valve gaurd on and it didnt do shit to the bottle. When they are under pressure they are even stronger. Think of a pop can weak as shit empty but full they are strong as shit.

ya this is what i was thinking...

of course you wouldnt pressurize the lpg to 2200 but the safe working ratio would be way overkill which is good

throwing the cylinder off an overpass sounds like fun:)

barracuda
01-04-2010, 02:01 AM
as much as this is interesting there is apoint of diminishing returns. I think that as a weight shaveing measure it might in the end prove fruitless .

conventional frame and aluminum tank would be simpler and probably lighter but admitidlly less Challenging .oh yeah

m j
01-04-2010, 05:51 AM
Now that's just fucked up. And you say I'm nuts????

I dont recall saying you were nuts, or saying that I am even a little bit sane, but now that you mention it...

a guy that doesnt even bother to attach tanks to the vehicle at all is saying welding them in as a structural member sounds sketchy

FU Toolbag
01-05-2010, 12:41 AM
The one point that seams to be being missed is that I have the tanks. I don't want to go get some alu tanks if I don't have to. I already know of a couple steel forklift tanks that I can get cheap, but where to put them? I was just figuring this could do a multipurpose job.

It has been interesting seeing who jumped on the "it's a bomb" bandwagon. I've been working with propane for years, and the sheer terror that some people get when you mention propane never stops to amaze me. You have to do something extremeeely wrong to cause a leak when positioned right let alone blow up, which has certain laws of physics that will prevent that from happening. There are enough safety devices in place that if used correctly make it way safer than gas, which by the way, is way mose dangerouse than gas. If you puncture your propane line and it does catch fire, turn the tank off. You light your gas car on fire, you can watch my ass cheeks as I run in faster than you.

Today a guy at work swaped out the tank on the forklift and had a liquid leak when he opened it up. I woudn't say he was scared, but there was definite panic in his face. I had to go fix it for him.

About 10 yrs ago I needed a tank for a specific purpose. It didn't exist. Noone made one, so I did. Yes, I took a 20" tank from a box style tank, cut both ends off of it, and rewellded it back together. It's still out there.

Basicly, know your shit. If you don't know propane, that's fine, but don't have a panic attack just because something scares you. A lack of understanding is nothing to be ashamed of. Speaking out of your lack of understanding is.

m j
01-05-2010, 06:03 AM
I am not afraid of the stuff, and know exactly what you mean
breaking a line can be different then venting the entire tank contents
I think the flash freeze part would suck if it got someone you like
I dont think a tank is a particularly strong item, and to make it structural strong it would be heavier then normal tubing with a normal tank mounted in it

strokenit
01-05-2010, 08:25 AM
I don't think anyone really thinks they will "blow up" just two 8' long tanks used as part of a frame sounds dangerous. You have to realise the picture that pops into your head when someone says they are thinking of using propane tanks as part of a frame. I don't dought it can be done. Yes tanks are strong when new but I've also had one puncture under my old work van. Yes it was an old tank and rotted out. Lazics said it wasn't uncommon when they replaced it.[cheers]

bakelite
01-05-2010, 09:22 AM
If people never thought outside the box nothing would ever change. I'd like to see you try it and see how it turns out. [cheers]

longhorn
01-05-2010, 05:25 PM
If people never thought outside the box nothing would ever change. I'd like to see you try it and see how it turns out. [cheers]

We will know it didnt work when you see a big splash out in front of your house Joe..................

barracuda
01-05-2010, 05:34 PM
all i can add is make sure your o rings are in good shape :)

Little Bandit
01-12-2010, 12:49 AM
Here are a couple pics to show an alternative idea for mounting the tanks.

In this configuration the tanks would provide all the rigidity to the chassis, but the loads are fed into bulkhead or subframe structures and not the tanks themselves. Obviously using steel tube or plate. This layout is waayyy stiffer than a spaceframe type chassis.

You could almost build your "cage" as a separate entity from main chassis.

Think of a pop can weak as shit empty but full they are strong as shit.

That is true for a compressed liquid, not a compressed gas or liquid/gas mixture. Which is why a pneumatic tank is much more dangerous than a hydraulic cylinder when it blows, you have to compress 1000000000xxx times the volume to build the pressure in an air tank, but only 1.01xxx times in a hydraulic cylinder.

Your wall thickness wouldn't have to be that much to provide the rigidity assuming you fed the loads in properly, 1/8" would be overkill.

I have no idea how it would behave as a tank as well, but my biggest concern would be the new structural welds cracking on the tank.

121708

121709

121710

Troy
01-12-2010, 08:16 PM
thats a cool frame

85chevy
01-12-2010, 11:08 PM
I always thought the tanks were designed not to explode when shot at by firearms or smashed into by other vehicles instead to disipate there contents thus the reason we aren't driving around with bombs but then again I could be wrong. Hell just build it if it doesn't work can always blow it up:confused0006:

Broncoo
02-09-2010, 11:00 PM
cenerfire riifle has enough jam to puncture but not centerfire pistol. unless you takin magnum pistol rounds.

otherwise interesting idea if i were to do such a thing i would make the tank removable