Cleaning propane tanks
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I just picked my tanks up from the welding shop. I also have three 500 gallon tanks. I’m not sure if it will work or not but I intend to use a high pressure washer. I may even see if I can purchase a long extension for the wand to reach in further. I have holes in each end and some holes in the center so I may be able to reach everything without an extension. I will probably pick them up from the end with my tractor and loader so that the debris will run out the other end as I spray. This is all just theory. I’ll let you know how it works out.
Ron
Ron
Be very aware that waste water from your tank cleaning may be ripe with mercaptan and oily residue, and that anything it gets on (ANYTHING) will smell very bad for a very long time. Clean far away from anything. You also might inquire of a local LP company as to the hazardous waste possibility of this water. The sewer or ground may be a very poor place to dispose of this water, especially if there is much oily residue in your tank.
I spilled water from my "new" tank on the floor of my shop, that was 4 months ago, and the smell is still strong, although less than initially. Maybe in a year or two (not kidding) it will be gone.
That said, my tank was quite clean from a visual inspection. I installed an in-line hot water filter on the return side from the tank to the boiler, and I let the hot water clean the tank with the filter catching the crud. After a couple of filter changes, the filter now remains essentially clear. The hot water also seems to have broken down the mercaptan, as water samples (to test for pH) have no odor at all.
I spilled water from my "new" tank on the floor of my shop, that was 4 months ago, and the smell is still strong, although less than initially. Maybe in a year or two (not kidding) it will be gone.
That said, my tank was quite clean from a visual inspection. I installed an in-line hot water filter on the return side from the tank to the boiler, and I let the hot water clean the tank with the filter catching the crud. After a couple of filter changes, the filter now remains essentially clear. The hot water also seems to have broken down the mercaptan, as water samples (to test for pH) have no odor at all.
I was thinking of used propane tanks for a while- and googled around for the health and hazmat characteristics of mercaptan, and the results were sufficiently un-pretty (central nervous system depressant that in significant exposure can mess up your breathing & other vital functions, and seemingly almost certain to be significantly toxic to anything that ingests it when it's dissolved in or carried by water) that I concluded, as jebatty said "The sewer or ground may be a very poor place to dispose of this water, especially if there is much oily residue in your tank"
In fact, I decided that for me, I did not want to deal with the health or liability aspects of having a bunch of mercaptan released on my property from cleaning out a used tank;
Everyone's got their own individual set of risk tolerance and living/neighbor situations, so I am not saying that my conclusion should be the same conclusion for everyone- just some factors to consider in making your decision.
In fact, I decided that for me, I did not want to deal with the health or liability aspects of having a bunch of mercaptan released on my property from cleaning out a used tank;
Everyone's got their own individual set of risk tolerance and living/neighbor situations, so I am not saying that my conclusion should be the same conclusion for everyone- just some factors to consider in making your decision.
Everyone needs to decide for themselves what they are willing to be exposed to, but all of those symptoms you mention are probably much more likely to occur just by pumping your own gas at a gas station.
Here is a link to the CDC sheet on it - they don't make it sound all that bad - especially in the minute amounts you are likely to encounter when cleaning a tank.
http://www.atsdr.cdc.gov/tfacts139.html
As a comparison, here is one for gasoline:
http://www.atsdr.cdc.gov/tfacts72.html
Between the two, gasoline sounds worse - if I spilled a pint of gasoline on my property, I wouldn't think much of it. I did my best to capture any dregs that came out of my propane tank, but if a bit got spilled, I am not going to worry about that either. The smell was the bigger concern and it didn't take long for that to dissipate.
Not trying to talk anyone into a tank if they don't want one...but nor would I want to scare people off from using one when chances are the average person brings home a larger quantity of dangerous chemicals just by doing the grocery shopping at Walmart.
Here is a link to the CDC sheet on it - they don't make it sound all that bad - especially in the minute amounts you are likely to encounter when cleaning a tank.
http://www.atsdr.cdc.gov/tfacts139.html
As a comparison, here is one for gasoline:
http://www.atsdr.cdc.gov/tfacts72.html
Between the two, gasoline sounds worse - if I spilled a pint of gasoline on my property, I wouldn't think much of it. I did my best to capture any dregs that came out of my propane tank, but if a bit got spilled, I am not going to worry about that either. The smell was the bigger concern and it didn't take long for that to dissipate.
Not trying to talk anyone into a tank if they don't want one...but nor would I want to scare people off from using one when chances are the average person brings home a larger quantity of dangerous chemicals just by doing the grocery shopping at Walmart.
I was talking with my propane supplier about cleaning out a tank
of mine and using it for water storage, when he made a comment
that was interesting.
Apparently mercaptan will break down very fast and easily
by common soil enzimes/microbes.
While doing propane deliverys one day,
his (the propane guy) coveralls got sprayed badly while hooking up the hose
and he was not able to wash out the odor,
even after repeated washings (don't use your home washing machine).
He was advised by his boss at the time,
to bury them in the ground for a few days, then wash them. He claims
that complety got rid of the mercaptan odor.
Sounds possible. I know for a fact that skunk odor can be completly
removed with a solution of hydrogen peroxide and baking soda.
I've also heard that bleach will do the same for mercaptan as will
hydrogen peroxide.
I'd be interested in hearing from someone qualified about
neutralizing mercaptan odor..dig a pit in the ground and run
the wash water into it? Repeated chem treatments? MM
of mine and using it for water storage, when he made a comment
that was interesting.
Apparently mercaptan will break down very fast and easily
by common soil enzimes/microbes.
While doing propane deliverys one day,
his (the propane guy) coveralls got sprayed badly while hooking up the hose
and he was not able to wash out the odor,
even after repeated washings (don't use your home washing machine).
He was advised by his boss at the time,
to bury them in the ground for a few days, then wash them. He claims
that complety got rid of the mercaptan odor.
Sounds possible. I know for a fact that skunk odor can be completly
removed with a solution of hydrogen peroxide and baking soda.
I've also heard that bleach will do the same for mercaptan as will
hydrogen peroxide.
I'd be interested in hearing from someone qualified about
neutralizing mercaptan odor..dig a pit in the ground and run
the wash water into it? Repeated chem treatments? MM
rreihart said:
Rob,
Here are a couple of previous threads concerning places to buy used propane tanks in the south central Pennsylvania area.
https://www.hearth.com/talk/threads/18711/
https://www.hearth.com/talk/threads/19547/
The three tanks that I got from Mr. King had very little smell to them and once the welder was done with his work there is no smell at all. No oily residue either. The tanks are far from clean inside which is why I want to use a high pressure washer on them. I don't know if all of Mr. King's tanks are odor free to the same degree. Some of them look much newer and probably have more odor. After hearing some of the stories about mercaptan I'm very glad I don't have to deal with it. I paid $200.00 each for the ones I got. I don't know if he would sell just one that cheap or if he was giving me a discount for buying three.
Ron
I used the high pressure washer on the inside of one of my tanks yesterday afternoon. It worked well and I was surprised at how much gunk came out. I’ll bet I could have filled a quart jar with it. The tank looks good inside now but I will still install some kind of filter in the system. It was no problem standing the tank on end outside but I have yet to figure out exactly how I’m going to stand it up once it’s in the building. They won’t go through the door vertically. A combination of chain hoist, block and tackle and a comealong I guess. Any tips would be appreciated. The picture on the right is the gunk. That’s a quarter lying on the 4 x 4 for size reference. I’m guessing I’ll get that much out of the other two tanks also.
Ron
Ron
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What is your ceiling height where tanks are going? I'm with you on vertical install. Space saving as well as stratification performance. All the euros seem to go vertical.
Grab the tank dead center in the horizontal position, raise up and then counterweight the end going down. Have another come along for the lowering. What will hold it upright ?
Will
Grab the tank dead center in the horizontal position, raise up and then counterweight the end going down. Have another come along for the lowering. What will hold it upright ?
Will
Will,
I have a full 12’ ceiling height in the section of the building that the tanks will be in. The tanks are approaching 11’ with the truck rims welded on one end. You can’t see the truck rim very well in the picture above because it’s in a shadow. The truck rims will be the primary thing keeping the tanks upright but I may also anchor them to the wall using the set of feet that end up at the top. Some sort of pivot arrangement might work for getting the tanks upright inside the building. I’ll have to give that some thought.
Ron
I have a full 12’ ceiling height in the section of the building that the tanks will be in. The tanks are approaching 11’ with the truck rims welded on one end. You can’t see the truck rim very well in the picture above because it’s in a shadow. The truck rims will be the primary thing keeping the tanks upright but I may also anchor them to the wall using the set of feet that end up at the top. Some sort of pivot arrangement might work for getting the tanks upright inside the building. I’ll have to give that some thought.
Ron
You guys might think I'm nuts but I have an Idea. I'm thinking of getting a 500 gallon propane tank. Only 1 for this year. I'll cut the dome off of one end and weld a 3/8- 4'X4 plate on it. I'll be able to pressure wash the inside. No mercaptan. End to end measurement will be about 9'. My basement ceiling joists are 9'6". I'll weld in couplings. Plenty of extra that I can always plug.
I'll have an auto-vent, anode tapping, plenty of gauges etc.
The advantages are:
better stratification
No smell
It will only take up a small corner space.
I'll be able to insulate the bottom, the plate will extend so I can anchor it down to the slab if I need to.
I can be smart and get one 1,000 gallon tank and cut it in half and have two tanks and be done with it.
I'll have an auto-vent, anode tapping, plenty of gauges etc.
The advantages are:
better stratification
No smell
It will only take up a small corner space.
I'll be able to insulate the bottom, the plate will extend so I can anchor it down to the slab if I need to.
I can be smart and get one 1,000 gallon tank and cut it in half and have two tanks and be done with it.
I'm sure you've figured this out, but I gotta point out you'll have 4,000lbs+/- of weight in just water. :gulp: Wouldn't be pretty if the base of these tanks fail. We're they designed to stand on end?
Pressure is pressure. The tanks are pressure tested to many times what they will be put through. I'm more afraid of 2 1/2 tons of weight on a 4X4' section of a 4" concrete slab.
Anybody know what the metal thickness is on theses tanks ? Does it vary from the dome ends to the cylinder itself ?
Will
Flat ends are not a good idea on a pressure vessel. The ends are dished for a reason. You may want to ask around before pursuing that route.
chuck172 said:
A flat plate on the end is not a good idea for a pressurized tank.At 15 psi a 30" dia tank will see about 10,000 pounds of force against the end.
A flat plate will bow outward even if it was 1/2" thick.
Ron,
Not a lot of wiggle room. You might have to get out the grease
Any chance of cutting off rim and re weld when tank is upright, to give you a little more room ? You will definitely have to do some vertical bracing to floor joists if you are gonna use them for chain fall. I would build a steel lifting rig, but then you will lose some height, unless you can put the cross beam up into joist bay. Any way your in for a challenge. It will be worth it though.Will
Area of a 30" dia circle is 706.5 sq inches(pi x radius squared=3.14x(15x15)=706.5)
At 15 psi that comes to 10,597.5 pounds(706.5 x 15 psi)
I do underground utilities and when we test water lines most are required to hold 200 psi.On a 24 inch line thats about 90,000 pounds trying to push the cap
off the end.I have seen them fail, It will make you a believer.
At 15 psi that comes to 10,597.5 pounds(706.5 x 15 psi)
I do underground utilities and when we test water lines most are required to hold 200 psi.On a 24 inch line thats about 90,000 pounds trying to push the cap
off the end.I have seen them fail, It will make you a believer.
I have worked on 36" and 42" cooling tower lines. I have welded hundreds of these joints. That's the biggest pipe I've worked on. I never had a problem.
I just don't understand how cutting the dome off and replacing it with flat plate, pressurizing it to 30#'s is gonna create the astronomical pressures that your talking about.
I just don't understand how cutting the dome off and replacing it with flat plate, pressurizing it to 30#'s is gonna create the astronomical pressures that your talking about.
Many conversations have been roadblocked by confusing the terms "force" and "pressure". Force is just "push". If you're talking vertically just think of it as weight. Imagine holding a 5 pound steel bar in the palm of your hand. One end of the bar is flat and the other end is sharpened to a pencil point. Either way, it puts 5 pounds of "force" on your palm. Flat end down is comfortable enough but with the pointed end down and you'll wince a bit. When you spread that force over a larger area the same force creates a lower "pressure"; pointed end down that force makes a very high "pressure".
Fluids and gases crammed into a tank equalize their push against the all the walls. Take a hydraulic bottle jack as an example. You push down the long handle on a small cylinder. Say for simplicity, the leverage in the handle pushes down with 100 pounds of "force" on that little cylinder that has a surface of 1 square inch area. The fluid will go into the larger cylinder and push with that same 100 pounds of force on each square inch of of enclosing wall (100 PSI). If the larger piston has an area of 10 square inches there will be 1000 pounds of force on the cylinder face. Now you have 1000 pounds of "force" lifting up, not 1000 PSI of "pressure".
That propane tank is the same thing. If you're pushing water into it with 30 lbs. of force per square inch (30 PSI) there is 30 pounds of force on every square inch of the tank wall. Do the arithmetic on a 1000 gallon tank. About 172 sq. ft. area (for a 42" dia. tank) is about 25,000 sq. inches times 30 PSI makes about 3/4 millions pounds of force trying make that tank bigger than it started. The beauty of cylindrical and spherical shapes is that they turn those forces into stretching forces with no bending. That's why tanks are round shaped. Steel is way stronger in stretch than it is in bend. Flat ends will try to bend into a spherical shape. When you weld a flange onto tanks and pipes the flat cap on the flange is always much thicker steel than the cylindrical walls are for that same reason.
Picture a 1" wide section of the proposed 1/2" flat end of this tank. If it's 42" dia. you'll have a 1/2 x 1 x 42 long bar of steel laying flat. Now support it on the ends. 42 sq. in. x 30 PSI is 1260 pounds of force (weight) across the bar. That bar is going to bend. A round flat plate is more complicated than a rectangular bar but you can see how it is likely that that tank is going to lift right up off the floor. The fun part is imagining the leverage this kind of force has pushing against that large area across the narrow width of even a large weld bead.
I think the safest thing to do is to cut out a band of the cylinder and reweld the spherical head back on to make it the required length.
Fluids and gases crammed into a tank equalize their push against the all the walls. Take a hydraulic bottle jack as an example. You push down the long handle on a small cylinder. Say for simplicity, the leverage in the handle pushes down with 100 pounds of "force" on that little cylinder that has a surface of 1 square inch area. The fluid will go into the larger cylinder and push with that same 100 pounds of force on each square inch of of enclosing wall (100 PSI). If the larger piston has an area of 10 square inches there will be 1000 pounds of force on the cylinder face. Now you have 1000 pounds of "force" lifting up, not 1000 PSI of "pressure".
That propane tank is the same thing. If you're pushing water into it with 30 lbs. of force per square inch (30 PSI) there is 30 pounds of force on every square inch of the tank wall. Do the arithmetic on a 1000 gallon tank. About 172 sq. ft. area (for a 42" dia. tank) is about 25,000 sq. inches times 30 PSI makes about 3/4 millions pounds of force trying make that tank bigger than it started. The beauty of cylindrical and spherical shapes is that they turn those forces into stretching forces with no bending. That's why tanks are round shaped. Steel is way stronger in stretch than it is in bend. Flat ends will try to bend into a spherical shape. When you weld a flange onto tanks and pipes the flat cap on the flange is always much thicker steel than the cylindrical walls are for that same reason.
Picture a 1" wide section of the proposed 1/2" flat end of this tank. If it's 42" dia. you'll have a 1/2 x 1 x 42 long bar of steel laying flat. Now support it on the ends. 42 sq. in. x 30 PSI is 1260 pounds of force (weight) across the bar. That bar is going to bend. A round flat plate is more complicated than a rectangular bar but you can see how it is likely that that tank is going to lift right up off the floor. The fun part is imagining the leverage this kind of force has pushing against that large area across the narrow width of even a large weld bead.
I think the safest thing to do is to cut out a band of the cylinder and reweld the spherical head back on to make it the required length.
So you're telling me that if I weld 3/8" plate on the bottom of a tank 9'high, although I'll only have 20psi from the system, and .433 pounds of water weight per foot, using 70,000 pounds of tensile strength welding rod, the tank will end up looking like a hot dog!
about all the bad stuff in propane tanks. does anyone cook with propane? i know its being burnt but its still there. not trying to change the topic just my thought.
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