i am new to the industry, so i am really hoping to get some feedback from the professionals here in this forum.
ok, here’s the situation, we are designing a new upgrader refinery, i am asked to size the tank farm.
i have the following questions hoping someone can clarify for me, pls forgive me if they seem dump to u…
what are the dikes for, if you have berm, i mean if it’s the case that tanks sit on dikes and are surrounded by berms?
which tank need berm? following the general rule that only oil tanks need them or if there’s more specific rules? we have feed tanks(coke and diluent), intermediate feed/product tanks(diesel, gasoil, residue,naptha) and product tanks (gasoline, fuel oil, kereosen…)
I are now trying to find out the max size of this tank farm, so in stead of grouping some tanks together and estimating the berm size, i am sizing the berm individually (one berm for one tank), what is the typical dimension of a berm say for a tank 76m (d) 22 (h) or 2918?? anywhere i can find these kind info?
these are the questions i have so far, many thanks for answering my questions~~~
I can’t say I know the answers definitively, and I also don’t know that I accept that the tanks sit on “dikes”. I think that what they are is reinforced pads, or footings, because the tanks concentrate a lot of weight on a comparatively small footprint. Also, they are meant to drain via gravity. So, they are on reinforced ground or pads, and those pads are elevated so that the contents continue to drain relatively quickly when the level inside the tank has dropped to about 5-10% of its normal capacity/volume.
The berm would be high enough to capture and hold the contents of one or two tanks, depending on local, state, and federal ordinances/laws. The only time all tanks might fail would be in times of war or sabotage. In that respect, the berm would have to be huge. So the berm probably needs to be sufficiently high to deal with the most likely failure event, and that would be a ruptured sidewall or broken and leaking valve on one tank.
If you accept that for figuring purposes, then the volume formed by the berm’s dimensions can be computed: lengths of two sides times the height of the berm. Once that matches and exceeds the volume of the largest tank, or if the berms surround each tank, those volumes, you are where you need to be.
and i got the idea that the capacity of the berm has to be at least equal to the tank(s) it surrounds, but the thing i dont get is how to define the length, width and the height of the berm, as there are three parameters…i mean if one looks at the length&width first (and get the height by diving the capacity by the berm area), then how far away from the edge of the tank is acceptable, are there any rules to follow? or any rules of thumb?
or is there any limit to the height of the berm? if so, then the area of the berm can be easily figured…
I don’t know the area you are describing…could it be that the requirement is to have two “layers” of retention…a primary berm and a secondary? Otherwise, I have no way of explaining what you refer to as a dike.
BTW, when calculating the volume of the berms, don’t forget to subtract the part of that greater volume that is taken up by the pad and tank that are below the top of the berm(s). The greater volume of the berm is easily calculated, but the tank takes up some of that volume already, and so does the pad upon which it sits. Those two will have to be taken into account to get the berm up to its proper volume, and thus its dimensions.
So, tank volume is X cu meters or liters…whatever. But when it empties catastrophically, it will only fill the berm until the contents can equalize across the entire surface area afforded by the berm. Presumably, some of the contents of the tank won’t have to leak at all because the level in the berm will have risen to meet the descending columm in the tank. Begin a series of ballpark estimates of the berm height and side dimensions until you equal the volume of the tank.
My advice is to forget about the tank and pad. Why make the calculations harder than necessary? For example, a 10,000 gallon tank requires an enclosed volume of 10,000. Some will remain inside the tank and some not. Leave enough room around the tank(s) for piping and pumps. Flammable liquid tanks require fuse activated gravity shut off valves in addition to the regular shut off valve between tank and pump.
Normal retaining wall height is about 3 feet or 1 meter so that personnel can easily get to the tank, pump and piping. If constrained by available space for the tank farm, the walls might be higher but then add a ladder on both sides of the wall.
Don’t forget to add a sewer for draining rain water from the enclosure but include a shut off valve outside the enclosure (which is normally in the off position) to prevent spills from going to waste tratment. Actually, if the enclosure filled with water, partially filled tanks could easily float off the pad and rupture lines or tank. For that reason tank farm permits aren’t issued in areas below the 100 year flood plain.
You probably need to model pipe racks too. The liquids have to get to and from rail unloading platforms and process units.
ok, i have a couple of storage tanks that are 76 m(d) 21m(h) with a capacity of 550kbbl, if using the 1m height rule, then berm size could go up to 313 m313 m assuming it’s squared, i am thinking about go with 100100 10(h), but does the number make sense?
i have no idea in terms of scale as havent been to any refinery site…should pay a visit once i have a chance.
one more thing, what about the spacing between berm and berm? i understand that the best thing to do is to group the tanks and surround them with one berm, but what if you have to have tank groups side by side? is it possible in reality? is so, then again what we do with the spacing between berm and berm? is it important? is there a rule of thumb or where i can look up for this kind info?
Wow, 76 m diameter tank. You must be modeling a complete modern refinery! To put it into perspective for all, 76 m is about 6 plus or minus one tank car in any scale ! Are you sure you have room on your layout for a tank of that size, and then adding a “berm”? If you really need to have such large tanks, then I suggest you paint them on the backdrop!
Anyway, your calculations are roughly correct. For those needing a conversion factor,
1 barrel (petroleum) = 42 gallons or 5.6 cu.ft. or .16 cu. m.
Todo is talking about a tank that will hold roughly 600,000 barrels, and yes, I think they are that large at a real refinery, but they have a lot of smaller tanks too.
I am by no means an authority on petroleum refinery tank farms but extending my knowlege of much smaller tank farms with 8-15 foot diameter, 20 foot high tanks, I would think that refinery and insurance codes would require berms be separated by at least enough room for fire fighting equipment to pass between them, and each tank probably would be equipped with external water cooling systems in case of fire at an adjacent tank, and having "berm wall lengths 3 or 4 times the tank diameter of such large tanks seems to fit casual glances at refinery tank farms I’ve had while driving past them on rare occasions.
You might google The Petroleum Institute for contact information as to where you might get more specific information. Good luck to you.
I don’t see that all these calculations are necessary,since you only want to represent a tank farm and not replicate exactly the whole thing,uses up too much room. Just google earth a tank farm and model the general layout. I’m a firm believer in the KIS principle. Maybe one or two tanks and paint the rst on the backdrop. BILL
You’ve got the basic idea at this point - the volume contained by the berm has to be large enough to contain the tank within it. If there are multiple tanks (which is very common), then the berm has to be large enough to contain the volume of the largest tank within it. If you’re trying to do it accuractly, you have to subtract out of the volume of the other tanks - the design is based on the assumption that only one tank leaks at a time. However, you also have to include enough additional volume to account for rainfall - for a model, leave some freeboard. In the case of very large tanks, the berms are anywhere from 8-12 feet tall (2.5 - 4m).
In modern facilities, it is also possible that the tanks themselves are double-walled, so no external secondary containtment is required. This reduces the fire hazard associated with a leaking tank.