API 2518 : 62(R1987)

Section 1 - Evaporative loss from fixed-roof tanks
19.1.1 General
19.1.1.1 Scope
19.1.1.2 Referenced publications
19.1.2 Procedures for calculating losses
19.1.2.1 Loss equations
19.1.2.1.1 General
19.1.2.1.2 Standing storage loss, LS
19.1.2.1.3 Working loss, LW
19.1.2.1.4 Total loss, LT
19.1.2.2 Discussion of variables
19.1.2.2.1 General
19.1.2.2.2 Standing storage loss variables
19.1.2.2.2.1 Vapor space outage, HVO
19.1.2.2.2.2 Meteorological data, TAX, TAN, I
19.1.2.2.2.3 Tank paint solar absorptance, alpha
19.1.2.2.2.4 Liquid bulk temperature, TB
19.1.2.2.2.5 Daily average liquid surface temperature,
               TLA
19.1.2.2.2.6 Daily vapor temperature range, Delta TV
19.1.2.2.2.7 Daily maximum and minimum liquid surface
               temperatures, TLX, TLN
19.1.2.2.2.8 Vapor molecular weight, MV
19.1.2.2.2.9 Daily maximum, average, and minimum vapor
               pressures, PVX, PVA, PVN
19.1.2.2.2.10 Daily vapor pressure range, Delta PV
19.1.2.2.2.11 Breather vent pressure setting range,
               Delta PB
19.1.2.2.2.12 Vented vapor saturation factor, KS
19.1.2.2.2.13 Condensed vapor density, WVC
19.1.2.2.3 Working loss variables
19.1.2.2.3.1 Annual net throughput, Q
19.1.2.2.3.2 Turnover factor, KN
19.1.2.2.3.3 Product factor, KP
19.1.2.3 Summary of calculation procedure
19.1.2.4 Sample problem
19.1.2.4.1 Problem
19.1.2.4.2 Solution
19.1.2.4.2.1 Standing storage loss, LS
19.1.2.4.2.2 Working loss, LW
19.1.2.4.2.3 Total loss, LT
19.1.3 Description of fixed-roof tanks
19.1.3.1 General
19.1.3.2 Fixed-roof tanks
19.1.3.3 Roof fittings
19.1.3.3.1 Pressure-vacuum vents
19.1.3.3.2 Gauge-hatch/sample wells
19.1.3.3.3 Float gauges
19.1.3.3.4 Roof manholes
19.1.3.4 Insulation
19.1.3.5 Paint
19.1.4 Details of loss analysis
19.1.4.1 Introduction
19.1.4.2 Loss mechanisms
19.1.4.2.1 General
19.1.4.2.2 Evaporative loss
19.1.4.2.2.1 Standing storage loss
19.1.4.2.2.2 Working loss
19.1.4.2.3 Standing storage loss mechanisms
19.1.4.2.4 Working loss mechanisms
19.1.4.2.4.1 Filling loss mechanisms
19.1.4.2.4.2 Emptying loss mechanisms
19.1.4.3 Database for loss analysis
19.1.4.3.1 Standing storage loss data
19.1.4.3.2 Working loss data
19.1.4.4 Development of standing storage loss
               equation
19.1.4.4.1 General
19.1.4.4.2 Vapor space expansion factor
19.1.4.4.3 Vented vapor saturation factor
19.1.4.4.4 Vapor space temperature range
19.1.4.4.5 Paint solar absorptance
19.1.4.4.6 Liquid surface temperature
19.1.4.5 Development of working loss equation
19.1.4.5.1 General
19.1.4.5.2 Turnover factor
19.1.4.5.3 Product factor
Appendix A - Contents of documentation records
Appendix B - API committee on evaporation loss
             measurement (1991)
Figures
1 Fixed-roof tank geometry
2 Dome roof outage (HRO)
3 Vapor pressure function coefficient (A) of refined
    petroleum stocks with a Reid vapor pressure of 1 to
    20 pounds per square inch, extrapolated to 0.1
    pounds per square inch
4 Vapor pressure function coefficient (B) of refined
    petroleum stocks with a Reid vapor pressure of 1 to
    20 pounds per square inch, extrapolated to 0.1
    pounds per square inch
5 True vapor pressure (PV) of refined petroleum stocks
    with a Reid vapor pressure of 1 to 20 pounds per
    square inch
6 Vapor pressure function coefficient (A) of crude oil
    stocks with a Reid vapor pressure of 2 to 15 pounds
    per square inch, extrapolated to 0.1 pounds per
    square inch
7 Vapor pressure function coefficient (B) of crude oil
    stocks with a Reid vapor pressure of 2 to 15 pounds
    per square inch, extrapolated to 0.1 pounds per
    square inch
8 True vapor pressure (PV) of crude oil stocks with a
    Reid vapor pressure to 2 to 15 pounds per square
    inch
9 Vented vapor saturation factor (KS)
10 Working loss turnover factor (KN)
11 Typical fixed-roof tank
Tables
1 Nomenclature
2 Summary of procedure for calculating standing
    storage loss (LS)
3 Summary of procedure for calculating working loss
    (LW)
4 Meteorological data (TAX, TAN, I) for selected U.S.
    locations
5 Solar absorptance (alpha) for selected tank paints
6 Properties (MV, WVC, PV, A, B) of selected petroleum
    liquids
7 Properties (MV, WVC, PV, A, B) of selected
    petrochemicals
8 ASTM distillation slope (S) for selected refined
    petroleum stocks
9 Annual stock turnover rate (N) for 123 test tanks

Gives results of a study of test data on evaporation loss from cone roof tanks. Data did not include crude oil containing significant amounts of ethane and methane and the equations may or may not apply to production lease tanks. Limited to tanks with vertical cylindrical shells and fixed roofs, substantially liquid and vapor tight.