Re-Rating Tank

[mecheng1818]

i am currently doing a study where i need to verify the calculations done to re-rate a tank due to annular plate corrosion.

i have found a section pertaining to this in API 650 - section 5.5.

the formula seems a bit difficult to understand, or am i not looking at the correct section?

it should deal with a calculation relating the re-rated liquid level and the annular plate corrosion.

Thanks in advance.

 

[mecheng1818]

so i just reviewed API 579 as well and there is a section in there for Storage Tanks.

it is section A.6.

anyone can confirm?

 

[JStephen]

Have you determined why the annular plate was used in the first place?

Annular plates are required on certain large tanks (5.5), are sometimes used for seismic resistance (App. E), are sometimes used to lower stresses in heated tanks (App. M), and are sometimes used simply due to customer requirements.

You might also check if API-653 has specific requirements for annular plate design or re-design.

 

[mecheng1818]

to be honest the data i have so far is limited. i am just arranging what formulas i will have to use. in addition the initial design data from the tank may be difficult to obtain.

it is for a large tank. API 653 did not go into any detailed calculation or explanation. it provided guidance on what should be done if a repair is required but nothing in depth.

sorry for the questions but i am junior engineer.