API 2000 Venting requirements

[carlostech]

Hello all,

Currently lookin at API 2000 4.3.3.3.3 and having trouble understanding the method of determining wetted surface area. The calculation states (for vertical tanks):

"For vertical tanks, the wetted area is equal to the total surface area of the vertical shell to a height of 9.14 m above grade. For a vertical tank setting on the ground, the area of ground paltes.."

Does this mean the maximum height to use is 9.14 m irrespective of the actual tank height? And the term "above grade", is this in term to the ground/sea level of the tank?
Feedback would be much appreciated.

Cheers

[CarlosBatista]

yes 9.14 x pi x d wet area

[CarlosBatista]

9.14 m from the bottom

[CarlosBatista]

pi = 3.14159

[CarlosBatista]

max area: pi x 9.14 x D