Who wants to tell me why I can't use standard oil tanks for pressurized storage? I would probably use 3 - 275gal tanks. I know very little (nothing) about plumbing and heating but I'm guessing that all the guys looking for used propane tanks would use oil tanks if it was feasible. And of course I am also looking for usesd propane tanks.
Oil Tanks for heat storage
- Thread starter Zeppy
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Zeppy said:
The issue is that they (oil tanks) are only rated for 1-2 psi up to 100F, so the odds of them being ok for up to 30psi at 200F are unlikely. Also, rust is an issue when they are used in an unpressurized system. They could be coated on the inside with gas tank lining but it would be pricey (several hundred dollars) and you would still be limited to using them for an unpressurized system.
Back 25 years ago, heating oil tanks were used as heat storage tanks on early gasifier boilers made by Madawaska and Dumont (they are also refered to as the University of Maine or Dick Hill boilers). More than a few of these boilers were taken out of service when the fuel oil tanks rusted through and dumped 550 gallons of stale black and rusty water on the basement floor. As noted fule oil tanks have to be used in a vented configuration as they are only rated to a low pressure. If you do try to use them under pressure they will "oil can" with the side pushing out until a seam fails, hopefully in a slow manner otherwise they can and have exploded. Propane tanks are a lot thicker and rated for pressure when they were built. Do note that generally a used propane tank has been taken out of service as it had deteriorated enough that it can no longer be rated for use with propane. Generally it has to have alterations made for use for storage which should in theory be done by a an ASME code shop. Some states require that if you do use a pressurized tank, it has to be rated and built and repaired to code so the used propane tank may not be adequate. Arguably if the tank fails and floods your house, the insurance company could elect not to pay any of the claim no matter what state it is installed in.
Dick Hill used oil tanks under no pressure until we started working together and he started using our tanks.
Since we were both basically cheap, we ran the boilers into one of my tanks and then ran the heating system unpressurized.
I have done this a lot and it works well in many installations.
Since we were both basically cheap, we ran the boilers into one of my tanks and then ran the heating system unpressurized.
I have done this a lot and it works well in many installations.
The shape of an oil tank is all wrong for pressure storage. A pressure tank has the heads pressed or spun to a certain shape & the welding is very carefully done even in a non ASME tank. If you do a rough calculation of an oil tank end or side & get square inches & multiply this by 30 which is max pressure if precharge is lost you will probably not be in a hurry to use one of these, Randy
Simply put, an oil tank is not designed for pressure and it will fail, sometimes slowly, sometimes in a very spectacular manner. I've seen more than a couple DIY jobs that have done so. There is a very good reason ASME storage tanks are so freakin expensive. Non pressurized would be fine if you have your boiler water tested regularly.
Just a thought, have any of you looking for storage considered buying a used oilfield storage/processing tank? I know we have plenty of them here probably the same in any oil producing region south of 49. Lots of tanks in the 400-500 barrel size & smaller ones too, some are rated for temps exceeding 400 °F & higher at insane pressures, some with 8" or more of spayed on high temp foam insulation, best of all price is usually less than .10 per gallon so real cheap real large storage. Worth looking into if they exist in your area IMO.
Zeppy said:
I think is says right on the side of the tank anything over 5 psig will void/ruin the tank. They're barely rated fo 2 psig, and new installations need a minimum of 2" vent (has to be 1 size larger than fill, and minimum fill is 1.5". Newer oil trucks with their increased pressure were bursting tanks that had smaller vents.
btuser said:
Here in Maine code is 1.5" fill, 1.5" vent. At least it was last fall when I did my research to replace my old tank.
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