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Sump pit in the crude tank

Sump pit in the crude tank

Sump pit in the crude tank

Our crude tank do not have sump pit that can remove water from the crude tank.

Now we encounter water carried with crude oil problem during crude switch in our crude distillation unit.

We think it is because water drainage is not enough in our crude tank.

We check with the designer of our crude tank.

The designer mention that the sump pit is easy to crack when there is an earthquake, so new crude tank usually do not have the sump pit.

Is it right?

RE: Sump pit in the crude tank


The answer to your question is yes and no,..... if the sump is designed with a little bit of a gap and if the tank bottom is thick enough, an earthquake resistant design is possible. The sump, of course, makes the tank design and construction more difficult.

The typical "water sump" for a crude oil tank was, at one time, a standard detail included in API-650.

Some crude oil tank designers do not include this "water sump" in the tank. They simply use an "apex-up" bottom and drain the water at the shell/floor joint. Large tanks require multiple drainage points. This approach should be combined with a special corrosion resistant interior coating up to the first three feet of the shell.

"Protectoseal" (www.protectoseal.com)makes a water drain valve (series 660) that may be of interest to you.

Let us know about your final decision.....

My thoughts only.....


RE: Sump pit in the crude tank

Water draining may pose problems at times due to emulsion formation. Emulsion itself may be about a foot high. Heating the tank bottom by providing steam coils may help to break the emulsion. Try to get an idea of emulsion height and assuming most of it is water, try operating at a safe ( very little emulsion entrainment) height. Sometimes, the interface muck collects at interface and along with sludge  may make water float above oil. Try draining this muck carefully or clean the tank if possible. Study the problem in some more detail by checking for sludge, interface muck, etc, by gauging from top of the floating roof at different points.Best of Luck

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