Best Cylinder
This command computes the best cylinder of the tank's shell. It also computes the plumbness of the tank, according to API 653 standard.
Requirements
To enter the command, a tank project must already exist. If several projects exist, first select the project in which you want to work.
Two methods are available:
Automatic method: the shell wall will be extracted automatically and a best cylinder will be computed from the shell.
Manual method: you will be required to click one or several seed points on the shell to initialize the cylinder extraction from it.
Constraints: the main axis and the diameter of the cylinder are computed. Nevertheless, you can force those values if necessary.
Tolerance for cylinder extraction:
When using the automatic method, you can eliminate the worst or the less significant points from computation. Here you choose a number of points in % of the total number of points in the shell.
When using the manual method, you can define an extraction tolerance (in the measurement unit of the document) to remove the less significant points from computation.
Tolerance for Plumbness: the default value is set to API 653 recommendation value.
Notes
A label is created in the 3D scene to display the plumbness value. If the display of labels is set to 'long', a note will be given to the plumbness value:
+ The plumbness is between 0 and 25% of the tolerance.
+ + The plumbness is between 25 and 50% of the tolerance.
+ + + The plumbness is between 50 and 75% of the tolerance.
+ + + + The plumbness is between 75 and 100% of the tolerance.
+ + + + ! The plumbness is out of the tolerance.
Technical information
Plumbness is defined by API 653 as the distance at the top of the tank between the vertical axis (Z axis) and the main axis of the tank (best cylinder axis). This value, represented by "A" should not exceed the height of the tank "h" divided by 100.
Fig. plumbness