API-653 Tank settlement 2

[Ganotec]

Hi,
I recently got issues concerning a settlement status concerning a API-653 renovated tank. The data was collected by a surveyor and was sent out to two different firms. The results came back and both had different answers:
-The first one said everything was fine (This one was comparing Ui for each and every point collected, and comparing it to S[sub]max,in[/sub] as per Art. B.3.2.2)
-The second one said that the tank was not within the standard of API-653 (This on was comparing the Si for each and every point collected and comparing it to S[sub]max,in[/sub] as per Art. B.3.2.2)

Now after reading the chapter on tank settlement on my own, and making a speadsheet of my own I came to the following conclusion:
-API-653 B.3.2.2 Smax,in and API-653 B.3.2.1 both only give limits to the out-of-plane settlement (Ui)
-Out of plane deflections (S[sub]i[/sub]=U[sub]i[/sub]-(1/2U[sub]i-2[/sub]+1/2U[sub]i+2[/sub])) are not used in the calculations of tank settlement validation.
-According to me the first study would be right.
-The figures B.4 & B.5 are in fact indicating out of plane settlement (Ui) and not deflection (Si)

Can anyone confirm this?

Thanks!

 

[JStephen]

I don't have the standard here in front of me, but believe you are right- the limitation is on out-of=plane deflection and stresses.

 

[Ganotec]

Did you mean that S[sub]max,in[/sub] limits out of plane settlement (Ui) or deflection (Si)? Because as stated in my post, the way API is wording it, it seems to be out of plane settlement(Ui).

 

[InspAPI653]

Ganotec,

When you have a survey company conduct your settlement survey's, chances are extremely likely that they do not API-653 Code well nor do they follow set guidelines. I have a simple excel spreadsheet, that if followed, will allow for the measurements and simplicity of the code to be satisfied.