API 2519 : 3ED 83(R1996)

EVAPORATION LOSS FROM INTERNAL FLOATING-ROOF TANKS

American Petroleum Institute

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Scope
Section 1 - Loss/emission calculation procedures
1.1 Loss equations
1.1.1 Standing storage loss
1.1.2 Withdrawal loss
1.1.3 Total loss
1.2 Discussion of variables
1.2.1 Standing storage loss factors
1.2.1.1 Rim seal loss factor
1.2.1.2 Total deck fitting loss factor
1.2.1.3 Deck seam loss factor
1.2.1.4 Vapor pressure function
1.2.1.5 Vapor molecular weight
1.2.1.6 Product factor
1.2.1.7 Density of condensed vapor
1.2.2 Withdrawal loss factors
1.2.2.1 Annual net throughput
1.2.2.2 Clingage factor
1.2.2.3 Average liquid stock density
1.2.2.4 Number of columns
1.2.2.5 Effective column diameter
1.3 Summary of calculation procedures and sample
         problem
1.3.1 Calculation procedure summary
1.3.2 Sample problem
1.3.3 Solution
1.3.3.1 Standing storage loss
1.3.3.2 Withdrawal loss
1.3.3.3 Total loss
Section 2 - Description of internal floating-roof tank
            components
2.1 Internal floating-roof tanks
2.2 Floating decks
2.2.1 Noncontact decks with bolted seams
2.2.2 Contact decks with bolted seams
2.2.3 Welded contact decks
2.2.4 Other deck designs
2.3 Rim seals
2.3.1 Flexible wiper seals (vapor-mounted)
2.3.2 Resilient filled seals (vapor- or liquid-
         mounted)
2.3.3 Secondary seals
2.4 Deck fittings
2.4.1 Access hatches
2.4.2 Column wells
2.4.3 Deck legs or hanger wells
2.4.4 Gauge float wells
2.4.5 Ladder wells
2.4.6 Sample pipes or wells
2.4.7 Stub drains
2.4.8 Vacuum breakers
Section 3 - Details of loss analysis
3.1 Introduction
3.2 Loss mechanisms
3.2.1 Rim seal area loss mechanisms
3.2.2 Deck fitting loss mechanisms
3.2.3 Deck seam loss mechanisms
3.2.4 Withdrawal loss mechanisms
3.3 Data base for loss correlations
3.3.1 Standing storage loss data
3.3.2 Withdrawal loss data
3.4 Development of standing storage loss
         correlation
3.4.1 Rim seal loss factor
3.4.2 Tank diameter
3.4.3 Deck fitting factors
3.4.4 Deck seam factors
3.4.5 Vapor pressure function
3.4.6 Product factor
3.5 Development of withdrawal loss correlation
References
Membership committee on evaporation loss measurement
(1982)
Contents of documentation records
Tables
1 Summary of standing storage loss calculation
    procedure
2 Summary of withdrawal loss calculation procedure
3 Rim seal loss factors (Kr)
4 Deck fitting loss factors (Kf) and typical number of
    deck fittings (Nf)
5 Typical number of columns (Nc) for tanks with
    column-supported fixed roofs
6 Deck seam length factors (Sd) for typical deck
    constructions
7 Physical properties of seleted petrochemicals
8 Average annual ambient temperature (Ta) for
    selected U.S. locations
9 Average annual stock storage temperature (Ts) as a
    function of tank paint color
10 Average clingage factors (C)
11 Floating deck and rim seal system types tested
Figures
1 Total deck fitting loss factors (Ff) for typical
    deck fittings in tanks with column-supported fixed
    roofs
2 Total deck fitting loss factors (Ff) for typical
    deck fittings in tanks with self-supporting fixed
    roofs
3 Vapor pressure function (P*)
4 True vapor pressure (P) of refined petroleum stocks
    (1 psi to 20 psi RVP)
5 True vapor pressure (P) of crude oils (2 psi to 15
    psi RVP)
6 Typical internal floating decks and typical rim
    seal systems

Abstract

Provides improved method for estimating total evaporative losses and/or the equivalent atmospheric hydrocarbon emissions from freely vented internal floating-roof tanks containing multi-component hydrocarbon mixtures as well as single component stocks. Coverage includes standing storage loss, withdrawal loss, total loss, rim seal loss factor, total deck fitting loss factor, product factor, clingage factor, noncontact decks with bolted seams, welded contact decks, secondary seals, ladder wells, stub drains, tank diameter, and development of withdrawal loss correlation.