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INPUT   DATA

Title

API Gravity Reading
Temperature Reading		°F

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OUTPUT   VARIABLES   &   GRAPHS

Variables	Values
♦  API Gravity Corrected to 60°F
♦  API Corrected (Rajan's Estimate)
♦  Volume Correction Factor

Corrected Oil Gravity & Volume Correction Factor

For the purpose of custody transfer of bulk petroleum oils and products, bulk volumes and contractual densities are stated at a fixed reference or base temperarure, usually 60°F. Volumes and API densities measured at temperatures other than base value are adjusted by correlations and factors developed and tabulated in ASTM Petroleum Measurement Tables.
This Peteng calculator is an internet implementation of the published subroutines from which the tables were generated.

The method of calculation consists of 2 sequential steps: API gravity correction and Volume correction. The calculator accepts as input the observed API and observed temperature, and output the API gravity at 60°F. This corrected API gravity along with observed temperature are then feed into the volume correction routine to obtain the Correction factor.

Some attempts had been to make the usage of the hardcopy ASTM Petroleum Measurement Tables less cumbersome. Keaves plotted directed from these tables and proposed a graphical interpolation method. Rajan extended this work by proposing a simple equation to approximate corrected API gravity for temperatures > 45°F:

Where:

   T = observed temperature, °F
   A_T = API gravity @ T
   A₆₀ = API gravity @ 60°F

BIBLIOGRAPHY

• American Society For Testing & Materials; Petroleum Measurement Tables, Volume Correction Factors, Volume X, ASTM D 1250-80, Tables 5A & 6A, 1980.
• Rajan V.S.V.; Discussion of new method to read and correct the API gravity of oil from observed temperatures to 60°F; paper SPE-28944, J. Petroleum Tech., 1994.
• Keaves S.V.; New method to read and correct the API gravity of oil from observed temperatures to 60°F; J. Petroleum Tech., Jan. 1994, p. 7.