This would depend on what you are trying to accomplish with the tank. It would not be necessary to have the sump as a water draw off, but that would be true if the product was miscible with water as well. However, the sump could be used for silt control/removal or some other process purpose.
Dear Fegenbush,
Thank you for your early reply, the tank is for bitumen residue with density of 1.05 and design temperature is 210C.
could you please explain the sump usages in process.
regards.
One application would be if the intent is to drain the tank dry for out-of-service inspection or cleaning. The sump would permit the draining of the tank contents to below the level of the floor plate. I am sure there are a variety of other reasons for including a sump, but it is an optional feature and you should not feel obligated to include it unless there is a reason for it.
If you do not use a "sump", the the entire bottom of the tank becomes the sump. The usable storage capacity of the tank is reduced by this volume, which cannot be pumped out.