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PostPosted: October 27, 2015, 9:10 pm 
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a.moore wrote:
Quick fuel tank update...

Everything is pressure tested and the hand full of pin holes are filled. I filled the tank with water, sealed all of the openings, and applied ~5 psi of air pressure to force the water out.

Attachment:
DSC04422.JPG



The mounting straps are also done and awaiting some rubber padding to prevent chafing.

Attachment:
DSC04432.JPG

Attachment:
DSC04428.JPG



So I'm down to an idler pulley or two to reroute the accessory belt (and an accessory belt), some cooling lines, a fuel tank filler neck, some fuel tank manhole cover gaskets, transmission oil/brake fluid/coolant, some seat belts, and some 87 octane until I will be ready to attempt the first start and the first drive.

The list is getting shorter. :D


Reading threw your build log. Came across this post. We test tanks at work using a similar method. 2 lbs of air and spray soapy water over them to check for air leaks. We had a guy put too much air in a tank and blew a head off one.

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PostPosted: October 27, 2015, 9:26 pm 
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Also, do you have any more pics of your oil pan? Great looking build btw. Not sure how I missed this one.

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PostPosted: October 28, 2015, 8:56 pm 
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Thanks.

Unfortunately those pics are all that I have. I didn't take very many of the chopped pan - it was literally a stock pan that had been chucked in the mill and the bottom was trimmed flush with the bell housing. I never had oil pressure issues in hard turns so I never bothered to get fancy with baffling.

Funny you mention that story - I once suggested that same method to someone that was trying to find an oil leak in a tank but failed to mention using only a few psi. After not being able to find the leak the first few tries, he cranked it up to 100 psi. We later found out that the tank was designed to 1/3 of that. On the plus side it was over designed but the manufacturer was less than amused.

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PostPosted: October 28, 2015, 9:42 pm 
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a.moore wrote:
Thanks.

Unfortunately those pics are all that I have. I didn't take very many of the chopped pan - it was literally a stock pan that had been chucked in the mill and the bottom was trimmed flush with the bell housing. I never had oil pressure issues in hard turns so I never bothered to get fancy with baffling.

Funny you mention that story - I once suggested that same method to someone that was trying to find an oil leak in a tank but failed to mention using only a few psi. After not being able to find the leak the first few tries, he cranked it up to 100 psi. We later found out that the tank was designed to 1/3 of that. On the plus side it was over designed but the manufacturer was less than amused.


Wow, Im shocked he didn't destroy that tank. We test no more then 5 psi unless its a pressure vessel and those can go up to 900psi. They are also 1-1/2 to 3 inches thick.

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PostPosted: October 29, 2015, 8:12 am 
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People generally don't understand that psi is pounds per square inch.
A little story about an industrial accident from early in my career.

We had these HUGE autoclaves at work. The doors were about 8 feet in diameter, weighed a couple of tons and hung on hinges with pins bigger than my wrist, and closed using multiple bolts like a submarine hatch.

One day a fairly new operator got in a rush to get it unloaded. Valves were opened and it was bleeding down. At about 5 psi he tried spinning the wheel to open the door and it wouldn't budge. He thought it was stuck, so he attached the hook from the gantry crane and hit the up button....

End result the autoclave slid back a few FEET through the wall of the building and the door went flying across the shop with the gantry crane in tow.
Thankfully no one was killed.

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PostPosted: October 31, 2015, 12:26 am 
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We had a close call at work with a big heating unit. It was a steel tube about 6 or 7' in diameter and 40' long and not rated for anything more than atmospheric pressure. It's made of approx. 1/4" steel with just flats plate bolted to flanges for end caps. A valve somewhere in the system stuck open and the relief valve didn't work properly, and the whole thing ended up somewhere around 200 psi, while filled about 3/4's or a bit better with oil at 400 degrees. Just sheer luck that it didn't burst. The gaskets at both ends leaked a bit and the flat end caps are no longer flat. Pressure can do some scary things when large areas are involved.
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PostPosted: October 31, 2015, 12:31 am 
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Pressurized fluid is worlds better than pressurized gas. The energy in compressed gas is exponentially larger. Had the tank been empty when it was pressurized, it would have been more likely to cause serious damage.


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PostPosted: October 31, 2015, 12:56 am 
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esp42089 wrote:
Pressurized fluid is worlds better than pressurized gas. The energy in compressed gas is exponentially larger. Had the tank been empty when it was pressurized, it would have been more likely to cause serious damage.

Most of the time that's true, but not in the case of steam. BLEVE's (Boiling Liquid, Expanding Vapour Explosion) are really scary stuff. Water expands about 1700 times it's original volume when it turns to steam, so basically the same as a pressure vessel at 25,000 psi.
The close call we had was with heat medium oil, so wouldn't vapourize, just would have been a hell of a mess. But the vessel was only about 3/4s full of oil though, and was pressured up with natural gas, with a giant burner and fire tu e going through the middle of the works. I still wouldn't want to be anywhere nearby if it let go.
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PostPosted: October 31, 2015, 12:23 pm 
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turbo_bird wrote:
We had a close call at work with a big heating unit. It was a steel tube about 6 or 7' in diameter and 40' long and not rated for anything more than atmospheric pressure. It's made of approx. 1/4" steel with just flats plate bolted to flanges for end caps. A valve somewhere in the system stuck open and the relief valve didn't work properly, and the whole thing ended up somewhere around 200 psi, while filled about 3/4's or a bit better with oil at 400 degrees. Just sheer luck that it didn't burst. The gaskets at both ends leaked a bit and the flat end caps are no longer flat. Pressure can do some scary things when large areas are involved.
Kristian


I'm thinking the oil inside kept it from busting. 1/4" metal isn't thick at all and engineers don't call for much more then a 1/4" weld for that thickness of material. At 50psi I think was when that tanks welds couldn't hold anymore. That's crazy to think that tank held 200psi.

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PostPosted: April 11, 2016, 9:58 pm 
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TooBusy wrote:
People generally don't understand that psi is pounds per square inch.
A little story about an industrial accident from early in my career.

We had these HUGE autoclaves at work. The doors were about 8 feet in diameter, weighed a couple of tons and hung on hinges with pins bigger than my wrist, and closed using multiple bolts like a submarine hatch.

One day a fairly new operator got in a rush to get it unloaded. Valves were opened and it was bleeding down. At about 5 psi he tried spinning the wheel to open the door and it wouldn't budge. He thought it was stuck, so he attached the hook from the gantry crane and hit the up button....

End result the autoclave slid back a few FEET through the wall of the building and the door went flying across the shop with the gantry crane in tow.
Thankfully no one was killed.


To take that one step further, this example equates to the door having 7,234 square inches of surface area, x 5psi=36,172 pound of force available to do what it did!
We have a fab shop, and for years we worked on Fuel Oil and Gasoline delivery trucks. They got steam cleaned professionally, and never tested at over 2psig. We had one incident because of a lack of a secondary safety rupture disk, and the regulator was creeping up. I think it hit 20 psig with water filling about 3/4 of the tank as a hydrotest, when the bulkhead reversed itself and tore off of the bottom of the floor. Needless to say, it was fortunate that is all that happened, but it was one EXPENSIVE screw up! We made sure to use secondary and tertiary safety's after that...

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PostPosted: April 12, 2016, 12:22 am 
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This example is virtually the same one I use when explaining how the astronaut in The Martian taped up the door opening with plastic sheet and tape, and why it would fail.
A 6-ft diameter opening and atmospheric pressure difference would present a 62,000 lb force on his sheeting and tape. I'm amazed the othewise-excellent movie missed that goof.

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PostPosted: April 12, 2016, 3:54 am 
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KB58 wrote:
This example is virtually the same one I use when explaining how the astronaut in The Martian taped up the door opening with plastic sheet and tape, and why it would fail.
A 6-ft diameter opening and atmospheric pressure difference would present a 62,000 lb force on his sheeting and tape. I'm amazed the othewise-excellent movie missed that goof.


Must have been some REALLY good duct tape... :shock:

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PostPosted: April 12, 2016, 10:15 am 
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It is amazing how the area that the pressure is applied can make all the difference. One of my favorite Mythbuster episodes with a mere atmospheric pressure causing this much damage:

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PostPosted: April 12, 2016, 12:00 pm 
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Dismantalus wrote:
KB58 wrote:
This example is virtually the same one I use when explaining how the astronaut in The Martian taped up the door opening with plastic sheet and tape, and why it would fail.
A 6-ft diameter opening and atmospheric pressure difference would present a 62,000 lb force on his sheeting and tape. I'm amazed the othewise-excellent movie missed that goof.


Must have been some REALLY good duct tape... :shock:

Well, it's a bit of a stretch at first glance, but not totally outrageous.
A person could easily live at 15000+ ft pressure altitude (there are settlements on earth higher than that), which corresponds to 8.3 psi in standard conditions. This means a 6 ft diameter opening (4071 sq in) would need a force of 33800 lb to keep it closed. The circumference of the opening is 226", so a tensile strength of 150 lb/in would be the minimum for a taped joint. While hardware store duct tape isn't generally more than 50 lb/in for the heavy duty stuff (3M cloth backed gaffer tape is listed at 60 lb/in), some of the high strength tapes available today exceed that by a large margin. 3M glass yarn backed tape, for example, has a tensile strength of 380 lb/in. The bigger problem would be adhesion, but if you do a multiwrap joint and there's a bit of a flange on the opening then it acts more like a clamping mechanism and doesn't rely on adhesion as much. The tarp could also be made to handle the pressure. HDPE has a tensile strength of 4000 psi, so an 80 mil tarp would withstand 72000 lb around its circumference.


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PostPosted: April 12, 2016, 4:29 pm 
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rx7locost wrote:
It is amazing how the area that the pressure is applied can make all the difference. One of my favorite Mythbuster episodes with a mere atmospheric pressure causing this much damage:


It would be even more impressive to see a full one explode. There was a train wreck at my family's farm in the 70's, and there were 6 propane cars in it. One was leaking and on fire so they couldn't begin the cleanup, and because it's the CN mainline, they wanted to get the tracks clear asap. Someone decided to use explosives to vent the leaking propane a bit quicker. They used a bit too much though, and the fire was so hot that the rest of the cars blew up one after the other. The house I grew up in is about 1/2 mile from where they blew. My grandpa was watching from the yard, but said the flames got so hot that he went around to the back of the house. He saw the flames directly overhead when the tanks started popping off, and there's still about 3-4' from one end of a tank car in a neighbor's field, 3/4 mille from where it blew up.
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