# Cost Estimation Of Fixed Roof (Cone) Carbon Steel Storage Tanks

Estimating Cost for process equipment has always been an achilles heel for process engineers including yours truly. Everytime when I was asked to provide budgetary cost for equipment mentioned in a Front End Engineering Design report I used to be red-faced because I just had no idea of how equipment was costed. Fortunately in one or two organizations where I worked there was a procurement and inspection group who knew quite a lot about equipment cost and could provide the data. But there were also occasions where I struggled to find cost data since I had no support of a costing or procurement engineer. Some research on the subject allowed me to find empirical methods of costing some common type of process equipment using empirical correlations. Todays blog entry is related to costing of "Fixed Cone Roof Carbon Steel Storage Tanks". I am presenting the equations below which can be programmed in an excel sheet and which I have already programmed as one. I believe that the cost calculated from the equations described below should be good enough for a +/- 25% budgetary cost. It would be appropriate to mention the references for these equations beforehand and they are as follows:

"Estimate Costs of Heat Exchangers and Storage Tanks via Correlations" by Armando B. Corripio, Katherine S. Chrien, and Lawrence B. Evans, Chemical Engineering magazine January 25, 1982.

Base Cost for CS Shop Fabricated tanks

SI Units

CB = EXP(7.994 + 0.6637*lnV - 0.063088*(lnV)2)

where:

CB = Base Cost of the tank, USD

V = Volume in m3, Lower Limit: 5 m3, Upper Limit: 80 m3

USC Units

CB = EXP(2.331 + 1.3673*lnV - 0.063088*(lnV)2)

where:

CB = Base Cost of the tank, USD

V = Volume in US Gallons, Lower Limit: 1,300 gallon, Upper Limit: 21,000 gallon

Base Cost for CS Field-Erected tanks

SI Units

CB = EXP(9.369 - 0.1045*lnV + 0.045355*(lnV)2)

where:

CB = Base Cost of the tank, USD

V = Volume in m3, Lower Limit: 80 m3, Upper Limit: 45,000 m3

USC Units

CB = EXP(11.362 - 0.6104*lnV + 0.045355*(lnV)2)

where:

CB = Base Cost of the tank, USD

V = Volume in US Gallons, Lower Limit: 21,000 gallon, Upper Limit: 11,000,000 gallon

Updated Cost

CB(updated) = CB*(CICY / CIBY)

where:

CB(updated) = Updated Cost of the Tank, USD

CICY = Cost Index, Current Year

CIBY = Cost Index, Base Year

Note: Cost Index (CI) for any year can be obtained form the Chemical Engineering Plant Cost Index (CEPCI) data.

General Notes:

1. Cost of field-erected tanks includes the costs of platforms and ladders but not of foundations and other installation materials (piping, electrical, instrumentation etc.)

2. Cost of shop-fabricated tanks does not include any installation materials including platforms / ladders.

I also plan to put the correlations for costing "Shell & Tube" Heat Exchangers, which are somewhat complex considering the type of head and the tube metallurgy, in my next blog entry. Let me have comments from the members of "Cheresources". Happy reading.

Regards,
Ankur.

AYACHI DHAFER
Dear M ANKUR;

Thank you for the information, i just want to add that the process engineer must know a little about the civil engineering and the metal structural in order to know the cost of the investissemnt that we want to do (in order to convice our boss to do or not to do).

Thank you M ANKUR
Best Regards
AYCHI Dhafer
martin_h
Thank you Ankur,

Can you confirm the base year for the escalation calculation please? Is it the 1982 refered to in the reference?

If so, have you validated the estimates at all recently, the conventional approach taken by most cost estimators is to ignore any data more than 5, but possibly up to 10 years old.

Regards

Martin_h
ankur2061
Martin,

Considering 1982 as a base year would be impractical as suggested by you.

I agree with your contention for considering 5 years as a practical period for the cost index ratio. As an example, if I want to calculate the updated cost for the year 2012, then the ratio for the "Cost Index-Current" to the "Cost Index-Base" would be based on the cost index for the year 2012 divided by the cost index for the year 2007. This I believe should give a +/- 25% cost estimation from the actual cost.

As far as doing any validation for the cost calculated based on the method mentioned above, no, I haven't done so till date.

Whenever I get some actual cost data related to various tank sizes I will do the validation exercise and share it on my blog. Meanwhile, if somebody else can help validating the equations above, I would be very grateful.

Regards,
Ankur.
Dear Ankur,
What about big storage tanks, can i apply this equation for big storage tanks also.
thanks
Toor
ankur2061
Toor,

The above equations hold goood for site fabricated tanks up to 45,000 m3 which is clearly mentioned in the blog entry.

Regards,
Ankur.
SahayaEugine

Dear Mr Ankur,

Could you please advice how to calculate the repair cost for API Storage Tanks,

Kind Regards,

Eugine.

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