Draw off Sump for effluent tank as per API 650

[AkhilKumar]

Dears
my client wants to install/construct draw off sump for above ground effluent tanks and what should be the dimensions for this tank as per API 650. anyone with vast experience in construction of above ground storage tanks your help is appriciated.

 

[MJCronin]

Sweetie,

The best design of a draw-down or draw-off sump depends on the size of tank, tank floor and foundation design.

There is no one single "API-650" sump design. This choice is left to the storage tank engineer.

For some very large tanks, multiple draw-off sumps are a good choice.

Give us more details and we may be able to help

MJCronin
Sr. Process Engineer

 

[AkhilKumar]

Sir,

Thank you for your response as per preliminary design it is supposed to have 2 draw off sumps for this tank the diameter of the tank is 98.5' and the foundation is a concrete ring wall, It would be very helpful to know the dimensions of the draw off sump required.

 

[IFRs]

What is the size of the draw-off pipe, what is the flow rate out of the sump?

 

[AkhilKumar]

Mr. MJ Cronin,

​

The Tank Bottom you have provided is conical but my foundation detail is flat and the draw off sump outlets are provided in the two opposite sides of the tank.

 

[IFRs]

API 650 table 5.16 associates sump size with draw-off pipe size. This can be a starting point for sizing the sump.

 

[MJCronin]

Akhil..

I only provided that detail to prompt you for more information.

Like most newbies to these fora, we often only get a few details such as... "Urgent, Need pump for water"

... and then only after a series of time wasting back-and-forth questions, do we ever get to a point where the question can be answered.

Secondly, we also get questions from the terminally lazy such as "Explain all of fluid dynamics to me, I have a flow problem"

Reasonable questions, of course, come from reasonable people ....

Sooooo..... you say you want two sumps on this tank ?.... Hmmmmmmmmmm

Tell us more ...

MJCronin
Sr. Process Engineer

 

[AkhilKumar]

Dear Mr.Cronin and IFRs,

​

In actuality I did a research on the forum and web for any typical draw off sump detail for API 650 storage tanks but all i could find was the details is available in 5.16 b Fig. of API 650 and I am not familiar nor have this API 650 drawing accessible with me that is why i opted to gain the help from experts in this forum. The storage tank requires detailed design and only preliminary design is available the Diameter of tank is as mentioned 96'5" feet and height of tank is 39'4" The tank has a RCC ring wall foundation and the base of tank or top of foundation is flat with cement sand mix grouted layer followed by 2 layers of sweet sand followed by 1 layer of HDPE membrane and finally Soil sub-grade compacted to 90% MDD it requires 2 draw off sumps as per the preliminary design at opposite edges of the circumference of the tank. This is the total detail i could share from my side if any solution can be provided from the the respected members and forum handlers with these detail it would be really helpful for me.

PS: If i wasted any of your time I regret for doing such please accept my apologies.

Good Day! and Happy new Year

Thank you.

Regards

Akhil Kumar.

 

[MJCronin]

Mr. Kumar ...

Thank you for these details, it appears that you have a robust foundation design that would be suitable for draw off sumps, but a structural engineer should still be consulted.

I suggest discussions with an experienced tank fabricator .... there are many possible acceptable designs... There are probably "typical" sump designs that have been developed by engineering firms and repeatedly used. I cannot give you these ...

As you probably know, the volume of the sump depends on the draw-down needs of the tank and the nature of the liquid stored and the impurities (water?) that needs to be removed.

See page 25 from this presentation ...

https://www.slideshare.net/ledzung/storage-tanks-basic-training-rev-2

MJCronin
Sr. Process Engineer

 

[MJCronin]

Suggest that you consider reposting in the "Storage Tank" forum ...


MJCronin
Sr. Process Engineer

 

[IFRs]

Why is this so hard?
Just use API 650.
Start with your draw-off pipe size, then use the table for the sump size, material thickness, distance from the tank shell.
Done, move on.