GPA STD 8217
Temperature Correction for the Volume of NGL and LPG Tables 23E, 24E, 53E, 54E, 59E, and 60E
|Publication Date:||1 January 2019|
The actual standard represented by this report consists of the explicit implementation procedures. Sample tables, flow charts, and specific examples created from a computerized version of these implementation procedures are presented within. The examples are to provide guides and check points to those who wish to implement a computerized procedure to represent the Standard, however these are not a part of the actual Standard.
This standard covers a 60 °F relative density range of 0.3500 to 0.6880 which nominally equates to a density at 15 °C of 351.7 kg/m3 to 687.8 kg/m3 and a density at 20 °C of 331.7 kg/m3 to 683.6 kg/m3. The temperature range of this standard is -50.8 °F to 199.4 °F (-46 °C to 93 °C). At all conditions, the pressure is assumed to be at saturation conditions (also known as bubble point or saturation vapor pressure).
NOTE These are nominal ranges which are further refined within the standard by correlation limits to be the ranges bounded by the points in Table 1:
Input range-the box defined in the scope of the standard as a (60 °F/60 °F) relative density of 0.35 to 0.688 and -46 °C to 93 °C.
Correlation range-the polygon defined by line segments connecting the relative densities and critical temperatures of the reference fluids in Table 1 of the standard for the upper boundary, -46 °C for the lower temperature boundary, the relative density of EE (68/32) for the lower relative density boundary and the relative density of n-heptane for the upper relative density boundary. See Figure 1 in this document for an illustration.
The calculation method was developed from GPA RR-148 "Volume Correction Factors for Natural Gas Liquids- Phase II"  and API/ASTM/GPA Technical Publication, TP-25, September, 1998 . The implementation procedures for Tables 23E and 24E are entirely consistent with those presented in API/ASTM/GPA Technical Publication, TP-27. Supporting data can be found in GPA RR-147 "Density Measurements on Natural Gas Liquids" . GPA RR-133 "Volume Correction Factors for Natural Gas Liquids-Phase I"  should no longer be used, as GPA RR-148 completely replaced it.
The implementation procedures describe how to:
1) calculate the CTL given an appropriate density factor at the basis temperature and an observed temperature, and
2) calculate the appropriate density factor at basis temperature given a relative density at an observed temperature.
The implementation procedures are presented in pairs by base temperature. First the procedures for Tables 23E and 24E at a 60 °F base temperature are given. The procedure for Table 23E makes use of the procedure described in Table 24E thus Table 24E is presented first. These are followed by procedures for Tables 54E and 53E at a base temperature of 15 °C which themselves make use of procedures in described in Tables 23E and 24E; these in turn are followed by the procedures for Tables 60E and 59E at a base temperature of 20 °C which also make use of procedures in described in Tables 23E and 24E.