Floating Roof Adjustment - Method 1
Use the Floating Roof Adjustment - Method 1 when the strapping table has no floating roof correction incorporated into the table and the level gauge is greater than or equal to the critical high. The roof deduction is then calculated by dividing the weight of the floating roof by the observed density. The density and weight units must be consistent. The applicable equation is the following.
Where:
Weightroof = Floating roof weight in mass units.
VCF = Volume correction factor based on reference temperature.
DensityRef.T = Density of material at the reference temperature in mass/volume units.
Vroof = Floating roof correction in volume units
The Vroof quantity is then subtracted from the gross volume.
For calculation of the Volume displacement due to a floating roof based on volume change per unit density, seeFloating Roof Adjustment - Method 2.
EXAMPLE: Floating Roof Adjustment - Method 1
The tables below list the example data.
Input Data
| Attribute | Value |
|---|---|
| Product | Crude Oil |
| Reference Temperature | 60 F |
| API Gravity @ 60F | 40.0 |
| Liquid Temperature | 84.0 F |
| Gauge | 10 ft 5 in |
Strapping Table Data
| Attribute | Value |
|---|---|
| Roof Weight | 1,215,000 lb |
| Strapping API @ Strap. Temp. | 35.0 |
| Adjustment | 24.59 bbl / API |
| Critical Zone Height | 5 ft 0 in |
If the level gauge is greater than or equal to the critical high, then start by calculating the material density at reference temperature in mass/volume units. For this example, the density units are lb/bbl. The density of water at 60°F is 350.161 lb/bbl. If the level gauge is less than the critical high, then the correction is zero.
DensityRef.T = 40.0 API = 0.82507 specific gravity
DensityRef.T = (0.82507 x 350.161) = 288.907 lb/bbl
The floating roof adjustment is then calculated as follows.
Vroof = 4257.02 bbl
See Configuring - Floating Roof Adjustment (Method 1) for details on how to configure this method.