Edge Settlement. 1

[bhekkema]

What is the correct formula to calculate the maximum allowable edge settlement. (Or what is the PRACTICAL formula to use)

These are a few a know (the most conservative first

API uses B=0,37R. But this is not realistic.
There is also a method used by AEC B=0.41R^2
EEMUA uses B=2R.

Table B10 and B11 is only used for lapwelded plates. So this isnot used for tanks with a annular ring. Is this correct?

And what does ASME say about settlement? I have not found anything about.

Bron Hekkema

 

[JoeTank]

See API-653, B.3.4.3... For butt-welded annular rings apply the API -653 criteria for the case when the bottom lap joints are essentially perpendicular to the shell. Use Figure B-11 in this case.

Don't bother looking in ASME, stay in the tank Codes and Standards.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[bhekkema]

Thanks.
But should I ignore the formula B=0.37R. and only use the figure. As for I understand is this formula based on the
tank diameter and useless for edge settlement. (B=D/64).
And what is your experience with the API criteria.? Is it realistic?
In the Netherlands the soil is very soft. And the limit is allready reached with new tanks.

Bron Hekkema

 

[JoeTank]

The B = 0.37R is the original criteria in API-653, but was later revised to the use of Figures B-10 and B-11. Therefore, I recommend that you do not use B = 0.37R. If you have more edge settlement than is permitted by API-653, then you are given the option to perform a more rigorous analysis to justify the excessive settlement.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com