C&M SURVEYORS COMPANY, S.A.

PETROLEUM LOSS CONTROL, CARGO AND MARINE SURVEYORS SERVICE

Inspections carry Out by Engineers, Marine Surveyors, Ship’s Officers & ISPS Security Officers

Our role is to be a professional partner to make your import/export a success. We either perform jobs at any Off-Shore or On-Shore port or oilfield or factory. We are always as per specifications in all aspects protecting the interest of all parts involved: seller, buyer, ship’s owner, insurance company.

SEE BELOW DATA AND FORMULAS

Mathematic Data, Formulas and Definitions

Vessel Experience Factor (VEF)

At the end of a ship loading or discharge operation, it is customary to compare quantity measured on shore with the quantity measured on board the ship. The shore figures and ship figures will be subject to the effects of random errors and systematic errors so they are unlikely to agree exactly.

The question is: “How closely should they agree?” In a perfect world, for any given vessel, a constant ratio between the ship’s figure and shore figures should be achievable (even if the ship’s tanks are over or under-calibrated). In reality, this ratio is not constant but varies about a mean valué which is known as the vessel’s experience factor. Such factors are often used at loading ports to provide a convenient means of checking the accuracy of B/L and ship’s figures.

Standard Temperature for Oit Trading

An oil volume can only be measured at its prevailing temperature and it, therefore, follows that the standard volume must usually be calculated. Unfortunately, different countries nave different standard (reference) temperatures. Generally, the reference temperatures are:
In Eastern Block, Brazil 20°C; in Western Europe 15°C; in the USA 60°F.

On Board Quantity (OBQ), Quantity Remaining On Board (ROB) and Water:

OBQ: All the oil, water, sludge and sediment in the cargo tanks and associated lines and pumps on
a ship before loading commences.

ROB: All the measurable oil, water, sludge and sediment in the cargo tanks and associated lines &
pumps on a ship after discharging a cargo has been completed, excluding vapours.

DISSOLVED WATER: is the water contained within the oil forming a solution at the temperature.

SUSPENDED WATER: is the water within the oil which is finely dispersed as small droplets.

FREE WATER: is the water that exists in a separated layer in the bottom of the tank.

VOLUMES

  1. Total Observed Volume (TOV) is the volume of oil including total water (dissolved water +
    suspended water + free water) and total sediment (suspended sediment + bottom sediment)
    measured at the observed oil temperature and pressure prevailing.
  2. Gross Observed Volume (GOV) is the volume of oil including dissolved water, suspended water
    and suspended sediment but excluding free water and bottom sediment, measured at the observed
    oil temperature and pressure prevailing.
  3. Gross Standard Volume (GSV) is the volume of oil including dissolved water, suspended water and
    suspended sediment but excluding free water and bottom sediment, calculated at standard condition,
    e.g. 15°Cor 20°C or 60°F.
  4. Net Observed Volume (NOV) is the volume of oil excluding total water and total sediment at the
    observed oil temperature and pressure prevailing.
  5. Net Standard Volume (NSV) is the volume of oil excluding total water and total sediment, calculated
    at standard conditions e.g. 15°C or 20°C or 60°F.
  6. Total Calculated Volume (TCV) is the gross standard volume plus the free water measured at the
    temperature and pressure prevailing.
  7. The Volume Correction Factor (VCF) is the volume factor depending on the oil type, density or its
    equivalent, and the temperature which corrects oil volumes to the Standard Reference Temperatures.
    (See ASTM Tables 54A. 54B, 54C, 54D or 6A, 6B).

Temperature Conversión Math formulas /ASTM TABLE 2

Degrees Celsius from Fahrenheit
C = 5/9 * (°F – 32)

Degrees Fahrenheit from Celsius
°F = [°C*9/5 + 32]

Specific Gravity @ 60°F against API @ 60F/ASTM TABLE 3

API @ 60°F = [141.5 / (SG @60°F)] – 131.5
SG @ 60°F = [141.5 /(API @60°F + 131.5)]

Volume Equivalencies

1 cubic meter (m3) = 1000 liters

1 cubic meter (m3) = 6.28981 US Barrels

1 cubic meter (m3) = 264.17 US Gallons

1 cubic meter (m3) = 1000 liters

1 cubic meter (m3) = 35.315 cubic feet

1 cubic meter (m3) = 219.97 Imp. Gallons

1 US Barrel = 42 US Gallons

1 US Barrel = 34.9726 Imp. Gallons
1 US Barrel = 158.984 liters

1 US Barrel = 0.15899 cubic meter (m3)

1 US Gallón = 3.78533 liters

Volume CALCULATIONS

TOV = Total Water + Total Sediment.

GOV = TOV – FW Water – bottom Sediment.

GST = GOV * Volume Correction Factor

NOV = GOV – (Vol. %Water) – (Vol.% Sediment)

NSV = NOV * Volume Correction Factor

SEDIMENTS

The Suspended sediment are non-hydrocarbon solids present in the oil but not in solution.

The Bottom sediment are non-hydrocarbon solids present in a tank as a separate layer at the bottom.

The Total sediment is the sum of the suspended and the bottom sediment.