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Cleaning propane tanks

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by waterflea, Jul 26, 2008.

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  1. DaveBP

    DaveBP Minister of Fire

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    No, Chuck, I don't think it will end up looking like a hot dog. But it will have nearly 15 tons of force pushing that flat end out and it will dish (I don't know how much) and that will put forces on the welds that they aren't designed to take. They wouldn't need to fail explosively to ruin your whole week. A leak is as bad as a flood in January. Rereading your post I realize you don't need to shorten the tank. Cleaning the inside of the tank is a great idea and I would like to pressure wash mine as well before I use them. Looks like Locust Loco cut a hole in the end and used a long wand guessing from the photo. Being you're experienced with heavy welding why not just remove and replace the round head. With spherical ends these things will tip up within vertical clearance about their overall length. With a 4ft. square end it might not clear your ceiling before it gets vertical. The shells on some modern 500 gallon tanks are about 1/4" thick if they are about 36" dia. The heads are 1/32" or so thinner. Old ones are made of thicker plate, I think; at least mine are (40 years old). I'm limited to available equipment. My tractor won't quite pick them up vertically and I only have gas welding gear so I'm not confident to do it myself. I have access to the welding shop and welder at work (he welds the housings of some the biggest gear boxes in the world). I envy you guys with real tools. How do you plan to add a 2nd tank later? Drain the system and weld them together with some kind of pipe or just threaded pipe fittings? I keep tossing back and forth on this one. I have two 500gal tanks now and am expecting that's all I need.

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  2. chuck172

    chuck172 Minister of Fire

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    After giving it more thought I'll do the job the right way. I'll remove a piece . and reweld the dome. I'll then fabricate some type of legs for it. Thanks for all the good advice.
  3. pybyr

    pybyr Minister of Fire

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    I'm neither an engineer nor a welder, just someone who wishes I was and has dabbled in both on a DIY level... if vertical space is a constraint, what if you cut one end's dome off, and inverted it into the open end of the tank, so as to get a flat bottom, but the strength that goes with the curve; as I understand it, an inverted dome is nearly as strong as a regular dome, and I recall seeing old "range boiler" tanks built in such a manner (inverted dome on bottom)
  4. chuck172

    chuck172 Minister of Fire

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    That's exactly the advice I was given on a welding forum recently.
    I must say that this whole storage concept has been a royal P.I.T.A
    I have never changed my mind, or had my mind changed by good advice so many times before. I hope I have the good sense to wait till next winter and burn without storage one year. Like I had originally planned.
    I was told that this September, Tarm will begin selling storage tanks. I have also heard that they will be very expensive. I think the indoor swimming pools with the golden coils that STSS sells are just unbelievably high priced.
  5. pybyr

    pybyr Minister of Fire

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    Chuck-well, glad I inadvertently offered something confirmed useful :)

    Yep, storage is the hard nut to crack; I went to Tarm USA in early June, and saw the prototype pressure vessels, and they'd never fit in my sub-7 foot 1830 house basement- looked like they'd need an 8 foot+++ headroom cellar clearance. Good thing for stratification, bad thing if you can't fit it in the home you already own and want to stay in. I am definitely going to go with a 6 x6 horizontal x 5 foot high 409 stainless bolted sectional tank + plate HX, because (A) I can get it into the cellar to install; and (B) it won't cost any more than an STSS + coils and will be a heckuvalot more bulletproof over the long run. it'll take more careful planning for stratification than a tall vertically-oriented propane cylinder, but still oughta work. I am working closely with a MFR on the basic layout and am more than happy to share details, as this is all to the good, for all of us, in the long run.
  6. jebatty

    jebatty Minister of Fire

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    I can understand the anxiety, confusion, and excitement over storage, space requirements, engineering, plumbing, and operation. Two things stand out for me:

    1) Buffer/storage to allow a gasifier to burn full-out at maximum efficiency when heat demand is less than boiler capacity, or to store heat for future use.

    Tank configuration to achieve maximum stratification is not automatically high on the list to meet this objective. A BTU stored is a BTU stored. Water volume as opposed to stratification is the prime concern. Space requirements, tank capacity, maximum tank heat based on tank material, open/pressurized tank, and insulation based on heated/unheated space seem to be the main issues.

    As others have said, a heating system designed to extract useful heat down to 120F or so might be the ideal, as the system can deliver more usable stored BTU's per tank capacity the lower the design temperature of the system. Radiant systems can function down to this low temperature. My system is radiant, the tank itself is the radiator for the heated space (can't get more simple than this). Last winter it was uncommon for me to load the tank to higher than 150 at the top (130-140 was more common), bottom would be about 100-120.

    2) Stratification to provide stored, usable heat for systems not designed for low temperature radiation, for dhw, or other uses requiring high temperature stored water. Vertical height and plumbing to minimize mixing of stored water would be key considerations, along with physical constraints of available space.

    With an installed baseboard or water to air heat exchanger, there may not be many options here. For dwh though, I am perplexed by a general "need" for temps higher than 120. Most dhw recommendations are not more than 125, and some recommend less.

    As this forum draws lots of comments aimed toward achieving maximum stratification, with the resulting problems, maybe we need more comments on system designs or modifications that are not so dependent upon maximum stratification. This might provide options to relieve some of the stratification angst.

    In the end, we want BTU's, and the lower the usable temp the more BTU's we can store per tank capacity, and the simpler all of the issues become.
  7. Willman

    Willman Minister of Fire

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    Jim
    DHW not hot enough can be a source of legionella. Google the term for more info.

    Below from ASHRAE Journal, October 2007

    Many guidelines recommend that the hot water temperature at the tank be 140°F (60°C) and the circulating hot water temperature be 124°F (51°C).16 Will this eliminate Legionella from distal outlets (faucets and showers)? The aforementioned study12 showed that peripheral sites remained heavily colonized despite elevated recirculation temperatures (>140°F [>60°C]). Legionella colonization was ultimately reduced in a Swedish hospital after it raised the temperatures even higher, to 149°F (65°C) at the tank and 133°F – 142°F (56°C – 61°C) at the outlets.17

    Full article here. http://www.legionella.org/stout ashrae 2007.pdf

    Will
  8. Willman

    Willman Minister of Fire

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    This is where the mixing valve comes into use, hot water to prevent legionella with mix valve for safety.


    Will
  9. jebatty

    jebatty Minister of Fire

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    No dispute that dhw can be a source of legionella. I need to consider this with a dose of salt, however, as home dhw systems through modern times likely have not met high temps and incidence of legionella is uncommon, to say the least. Our dhw never has been as high as 140.

    I have no concern about door knobs, toilet seats wherever they may be, my kitchen counter at home, the common towel we use, the dish cloth for washing dishes, the shared water glass, taking care of snotty noses, kisses and hugs all the way around, and even not always washing hands every time after the bathroom stop. We don't use disinfectants or alcohol, no anti-bacterial soap, and stay as far away from antibiotics as we can. I'm for playing outside, healthy doses of dirt and crud, being around lots of people, getting the proper immunizations, eating good food, and building good immune systems.
  10. solarvt

    solarvt New Member

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    Hello Everyone , lots of smart (experienced) people sharing ideas. Im about to pull the trigger on a EKO25. I have my sights on a 500 gallon LP Currently we have BB DHW and the EKO will be our back , primary in the winter. Need help in understanding if the water in the storage tank is only intended to go through a closed loop for my BB heat. Or will this also be used for my DHW. Seems like we don't want our drinking water going through the storage tank (please overlook my newbee questions. I just need to get it straight.
  11. solarvt

    solarvt New Member

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    Hello Everyone , lots of smart (experienced) people sharing ideas. Im about to pull the trigger on a EKO25. I have my sights on a 500 gallon LP Currently we have BB DHW and the EKO will be our back , primary in the winter. Need help in understanding if the water in the storage tank is only intended to go through a closed loop for my BB heat. Or will this also be used for my DHW. Seems like we don't want our drinking water going through the storage tank (please overlook my newbee questions. I just need to get it straight.
  12. solarvt

    solarvt New Member

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    Hello Everyone , lots of smart (experienced) people sharing ideas. Im about to pull the trigger on a EKO25. I have my sights on a 500 gallon LP Currently we have BB DHW and the EKO will be our primary in the winter. Need help in understanding if the water in the storage tank is only intended to go through a closed loop for my BB heat. Or will this also be used for my DHW. Seems like we don't want our drinking water going through the storage tank (please overlook my newbee questions. I just need to get it straight.
  13. jebatty

    jebatty Minister of Fire

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    Your heating water (tank and boiler) should be separate from your DHW. Use a heat exchanger to extract heat from the boiler/tank to provide heat for your potable DHW. Sidearms, plate and coil hx's all may be used and each has +'s and -'s.
  14. DenaliChuck

    DenaliChuck Member

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    I just picked up my two 500 gallon propane tanks, they're a tad rusty, but in excellent shape overall.

    A friend's dad who is a chemist just told me not to use bleach to clean the propane tanks because it will start a rapid rust reaction. He suggested 2 gallons of denatured alcohol to clean the mercaptan out of a 500 gallon tank.

    Also, remember that most landfills have a free collection day for household chemicals so don't dump the stuff or burn it off.
  15. bernard

    bernard Member

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    Question on using the denatured alcohol to clean a 500 gallon tank>>
    Must the tank be full of water and how long should the alcohol stay in?
    Thank you
  16. DenaliChuck

    DenaliChuck Member

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    The alcohol goes into the empty tank. I drove around some bumpy roads with the tanks on my trailer to mix it well and soften any stuck on stuff. They've been soaking for a week and this weekend I'll roll the tanks and drain the alcohol and mercaptan into a 5-gallon bucket. Then I'll fill the tanks with water which displaces the remaining propane (which is heavier than air). Then the fun begins with my 3.5" hole saw and lots of lubricating fluid!
  17. chuck172

    chuck172 Minister of Fire

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    I just finished drilling and welding my tank. I used a 2" hole saw for 1 1/4" couplings. It went well. The tank wall thickness is 5/16".
  18. DenaliChuck

    DenaliChuck Member

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    Chuck,

    How long did it take per hole? I assumed you used lubricating oil...and that the propane that seeped into the metal didn't explode ;-)
  19. chuck172

    chuck172 Minister of Fire

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    The drilling went well. It took a while, broke a few pilot drill bits that are still in the tank. I'd say about 20 min. per hole.

    I must admit I was scared. I flushed the tank 3 times. Welded with the tank just about full of water. I lucked out with this tank. There was no mercaptan, or propane odor to begin with. Very clean.
    Before I struck the arc, I set off a bottle rocket with a delayed fuse into the tank. If the tank would have exploded I'd be history now, the delayed fuse part didn't work.
  20. RJP Electric

    RJP Electric Member

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    I did the same thing as chuck with the hole saw, but I had a professional welder mig welded the pipes for me. I have two 1 1/4 dip tubes on either side to pull up the return cold water evenly 3 inches off the bottom and I used the existing 1 1/4 in the center for my supply.

    I brought it in yesterday and my plummer started to pipe it in. We love pictures here.
    Oh make sure you have enough rear weight on your tractor, that tank is heavy. It is a 1963 model, it held gas all these years but it looked like brand new inside.

    Attached Files:

  21. DenaliChuck

    DenaliChuck Member

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    Glad you made it! The bottle rocket is a good idea, except for the bad fuse. And no mercaptan is great, hope I luck out too. I'm going to drill with the tanks full of water but I'm not too worried. Going to get a local guy to do the welding for me - all I have is a little wire feed and he's got a big stick welder (and a lot more experience!). He told me that anything above 15psi needs to be done by a certified welder, so it is good that my system will run at 14.5 psi ;-)
  22. DenaliChuck

    DenaliChuck Member

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    Drained 2 gallons of denatured alcohol out of each of my 500 gallon tanks with no mercaptan noticeable, the liquid was a little rusty in color. Filled with water to force out the remaining propane and drained. The water definitely smells like propane (mercaptan) but the tanks appear clean inside. They'll be welded and set in place tomorrow if all goes well.
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