SIST ISO 91:2018
Petroleum and related products - Temperature and pressure volume correction factors (petroleum measurement tables) and standard reference conditions
Petroleum and related products - Temperature and pressure volume correction factors (petroleum measurement tables) and standard reference conditions
This document refers to temperature volume correction factors, which allow users to convert volumes,
measured at ambient conditions, to those at reference conditions for transactional purposes. This
document also refers to compressibility factors required to correct hydrocarbon volumes measured
under pressure to the corresponding volumes at the equilibrium pressure for the measured
temperature.
Table 1 shows the defining limits and their associated units of correction factors referenced in this
document for crude oil, refined products and lubricating oils. These values are shown in bold italics.
Also shown in the table are the limits converted to their equivalent units (and, in the case of the densities,
other base temperatures). Table 2 shows defining limits of correction factors for light hydrocarbons
(natural gas liquids and liquefied petroleum gases).
Pétrole et produits connexes - Facteurs de correction de volume par rapport à la température et à la pression (tables de mesure du pétrole) et conditions de référence standard
ISO 91:2017 fait r�f�rence aux facteurs de correction de volume par rapport � la temp�rature, qui permettent � l'utilisateur de convertir des volumes, mesur�s � des conditions ambiantes, en volumes qui auraient �t� relev�s aux conditions de r�f�rence � des fins commerciales. Le pr�sent document fait �galement r�f�rence aux facteurs de compressibilit� requis pour corriger des volumes d'hydrocarbures mesur�s sous une certaine pression afin de les convertir en volumes correspondants � la pression d'�quilibre pour la temp�rature mesur�e.
Naftni in sorodni proizvodi - Volumenski korekcijski faktorji temperature in tlaka (merilne tabele za naftne proizvode) in standardni referenčni pogoji
Ta dokument se nanaša na volumenske korekcijske faktorje temperature, ki uporabnikom omogočajo pretvorbo prostornine,
izmerjene pri običajnih okoljskih pogojih, v prostornino, izmerjeno pri referenčnih pogojih, za namene transakcije. Ta dokument se nanaša tudi na kompresijske faktorje, ki so potrebni za korekcijo prostornine ogljikovodikov, izmerjene pod tlakom, na ustrezno prostornino pri uravnoteženem tlaku za izmerjeno temperaturo.
Preglednica 1 prikazuje opredeljene mejne vrednosti in z njimi povezane enote korekcijskih faktorjev, ki so v tem dokumentu omenjene za surovo nafto, rafinirane proizvode in mazivna olja. Te vrednosti so prikazane v krepki, poševni pisavi.
V tabeli so prikazane tudi mejne vrednosti, pretvorjene v ustrezne enote (in v primeru gostote tudi ostale osnovne temperature). Preglednica 2 prikazuje opredeljene mejne vrednosti korekcijskih faktorjev za lahke ogljikovodike (utekočinjeni zemeljski plin in utekočinjeni naftni plin).
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INTERNATIONAL ISO
STANDARD 91
First edition
2017-05
Petroleum and related products —
Temperature and pressure volume
correction factors (petroleum
measurement tables) and standard
reference conditions
Pétrole et produits connexes — Facteurs de correction de volume
par rapport à la température et à la pression (tables de mesure du
pétrole) et conditions de référence standard
Reference number
ISO 91:2017(E)
©
ISO 2017
---------------------- Page: 1 ----------------------
ISO 91:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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ii © ISO 2017 – All rights reserved
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ISO 91:2017(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Sources and usage guidelines for volume correction factors . 2
4.1 Source of volume correction factors . 2
4.2 Usage guidelines . 3
Annex A (informative) Changes to previous standards . 5
Annex B (normative) Standard reference conditions . 7
Annex C (informative) Titles of petroleum measurement tables given in the API-ASTM-IP-
GPA standards for volume correction factors. 8
Annex D (informative) Other volume corrections factors standards .14
Bibliography .15
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ISO 91:2017(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical committee ISO/TC 28, Petroleum products and lubricants,
Subcommittee SC 2, Measurement of petroleum and related products.
This first edition cancels and replaces ISO 91-1:1992, ISO 91-2:1991, ISO 9770:1989, and ISO 5024:1999,
which have been technically revised.
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ISO 91:2017(E)
Introduction
Custody transfer of crude petroleum and its products are generally transacted in volumetric quantities.
Since crude oils and petroleum products have relatively high coefficients of thermal expansion and
compressibility, volumes are corrected to standard conditions of temperature and pressure in order
to provide a meaningful and consistent basis for measurement. The definition of standard reference
conditions is therefore of fundamental importance in measurement, calculation and accounting of
petroleum quantities.
Volume correction factors are used to account for the thermal expansion of liquid hydrocarbons
and convert observed volumes to volumes at standard temperature and pressure. Tables of volume
correction factors were originally developed by collecting empirical data relating to the volumetric
change of hydrocarbons over a range of temperatures and pressures. Cooperative international work
on volume correction factors dates from 1932. The temperature volume correction factor tables
[1]
(petroleum measurement tables) referenced in ISO Recommendation (R) 91:1959 were developed
during the late 1940s and published jointly by the American Society of Testing Materials (ASTM) in
[9]
1952 and the Institute of Petroleum (IP) (metric edition) in 1953 . These tables corrected to standard
temperatures of 15 °C and 60 °F only, and were based on data for crude petroleum and petroleum
fractions published in 1916 by the (United States) National Bureau of Standards (NBS) and some later
data on natural gasoline reported in 1942. These 1952 tables were referenced in API/Standard 2540-
[10]
1966 (also designated ASTM D1250-56). A few amendments to ISO/R 91 resulted in the publication
[2] [3]
of a second edition in 1970 . ISO/R 91:1970/Amd 1:1975 was published in 1975 for tables based on a
reference temperature of 20 °C.
In the early 1970s, it was demonstrated that the previously published tables were not satisfactorily
applicable to many crude oils of current economic importance. A revised standard was published
in 1980 by the American Petroleum Institute as the API Manual of Petroleum Measurement
Standards (MPMS) Chapter 11.1 (also designated API/Standard 2540, ASTM D1250-80 and IP 200/80)
following the development of a new database by API in cooperation with the US NBS. This study
included the examination of 463 samples of crude oil and refined products. The crude oil samples
represented 67 % of world production in 1974. The 1980 standard also constituted a major conceptual
departure from previous versions in the recognition of the use of computers in the petroleum industry.
The actual standard represented by API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 was
neither the hardcopy printed tables nor the set of equations used to represent the density data, but
was an explicit implementation procedure used to develop computer subroutines. The standardization
of an implementation procedure implied the standardization of the set of mathematical expressions,
including calculational sequence and round-off procedures, used within the computer code. Adherence
to the procedures given in API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 was an attempt to
ensure that all computers and computer codes meeting the stated specifications and restrictions would
be able to produce identical results. Hence, the published implementation procedures were the primary
standard, the distributed subroutines the secondary standard, and the published tables produced for
convenience.
[4]
API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 was referenced in ISO 91-1:1982 .
[5]
Corrections to the 1980 standard were listed in ISO 91-1:1992 .
Computer implementation procedures developed by the IP for corrections to 20 °C were published
in 1988. These implementation procedures were prepared as standard procedures to enable users
to produce their own computer programmes either for the generation of 20 °C tables or for use in
[8]
calculations without the generation of tables. IP Petroleum Measurement Paper No. 3 was referenced
[6]
in ISO 91-2:1991 , superseding Addendum 1:1975 to ISO/R 91.
Compressibility factors for hydrocarbons in the 0° to 100° API gravity range were developed in 1945
[12]
and published in 1960 as API/Standard 1101 , Appendix B, Table II. This table was superseded by
[13] [14]
API MPMS Chapters 11.2.1 and 11.2.1M published in 1984. API MPMS Chapter 11.2.1M-1984 was
[13]
adopted by ISO/TC 28 and published as ISO 9770:1989 .
Compressibility factors for hydrocarbons in the 0,500 to 0,611 relative density range and 20 °F to 128 °F
[15]
were published in 1984 as API MPMS Chapter 11.2.2 . A second edition of API MPMS Chapter 11.2.2
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ISO 91:2017(E)
was published in 1986 with an expanded relative density range of 0,350 to 0,637. A metric version of this
3 3
standard (350 kg/m to 637 kg/m range) was also published in 1986 as API MPMS Chapter 11.2.2M.
Unlike the 1980 temperature correction factor tables (API MPMS Chapter 11.1-1980), the compressibility
table values given in API MPMS Chapters 11.2.1 and 11.2.2 were the standard, not the implementation
procedure for the underlying equations.
In 2004, a revision to API MPMS Chapter 11.1 (also designated as an adjunct to ASTM D1250-04 and
IP 200/04) was published and established procedures for generalized crude oils, liquid refined products,
lubricating oils and individual and special applications, by which volume measurements taken at any
temperature and pressure (within the range of the standard) can be corrected to an equivalent volume
at 15 °C, 60 °F or 20 °C (or other reference temperature) and standard pressure, by use of a correction
factor for temperature and pressure of the liquid (CTPL). API MPMS Chapter 11.1-2004/Adjunct to
ASTM D1250-04/Adjunct to IP 200/04 superseded API MPMS Chapters 11.1-1980, 11.2.1-1984 and
11.2.1M-1984.
In 2007, Addendum 1 to API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04/Adjunct to IP 200/04
was published in order to include some minor updates to the standard.
Previously, most natural gas liquid (NGL) and liquefied petroleum gas (LPG) temperature correction
factors were obtained from a variety of sources.
[9] [4]
— ASTM-IP Petroleum Measurement Tables, 1952 , as referenced in ISO/R 91:1970 . This publication
is limited to a 60 °F relative density range of 0,500 and higher.
[16]
— GPA Standard 2142, published in 1957 .
[17]
— GPA Technical Publication TP-16, published in 1988 . It is limited to the following products: HD 5
propane with relative densities of 0,501, 0,505, and 0,510; iso-butane at a relative density of 0,565;
normal butane at a relative density of 0,585, and natural gasoline (12 psia to 14 psia Reid vapour
pressure) at a relative density of 0,664.
— API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 Volume XII, Table 33 “Specific
Gravity Reduction to 60 °F For Liquefied Petroleum Gases and Natural Gasoline”, as referenced in
[5]
ISO 91-1:1992 .
— API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 Volume XII, Table 34 “Reduction of Volume
to 60 °F Against Specific Gravity 60/60 °F For Liquefied Petroleum Gases and Natural Gasoline”, as
[5]
referenced in ISO 91-1:1992 .
[18]
— API/ASTM/GPA Technical Publication TP-25, published in 1988 .
In 2007, these documents were superseded by API MPMS Chapter 11.2.4/GPA Technical Publication TP-27.
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INTERNATIONAL STANDARD ISO 91:2017(E)
Petroleum and related products — Temperature
and pressure volume correction factors (petroleum
measurement tables) and standard reference conditions
1 Scope
This document refers to temperature volume correction factors, which allow users to convert volumes,
measured at ambient conditions, to those at reference conditions for transactional purposes. This
document also refers to compressibility factors required to correct hydrocarbon volumes measured
under pressure to the corresponding volumes at the equilibrium pressure for the measured
temperature.
Table 1 shows the defining limits and their associated units of correction factors referenced in this
document for crude oil, refined products and lubricating oils. These values are shown in bold italics.
Also shown in the table are the limits converted to their equivalent units (and, in the case of the densities,
other base temperatures). Table 2 shows defining limits of correction factors for light hydrocarbons
(natural gas liquids and liquefied petroleum gases).
Table 1 — Defining limits of correction factors for crude oil, refined products and lubricating oils
Crude oil Refined products Lubricating oils
3
Density, kg/m @ 60 °F 610,6 to 1 163,5 800,9 to 1 163,5
Relative density @ 60 °F 0,611 2 to 1,164 64 0,801 68 to 1,164 6
API gravity @ 60 °F 100 to –10 45 to –10
3
Density, kg/m @ 15 °C 611,16 to 1 163,79 611,16 to 1 163,86 801,25 to 1 163,85
3
Density, kg/m @ 20 °C 606,12 to 1 161,15 606,12 to 1 160,62 798,11 to 1 160,71
Temperature, °C –50,00 to 150
Temperature, °F –58,0 to 302
Pressure, psig 0 to 1 500
4
Pressure, kPa (gauge) 0 to 1,034 × 10
Pressure, bar (gauge) 0 to 103,4
60 °F thermal expansion
−6 −6
factor (α60), per °F 230,3 × 10 to 930,0 × 10
−6 −6
α60, Per °C 414,0 × 10 to 1 674,0 × 10
Table 2 — Defining limits of correction factors for light hydrocarbons (natural gas liquids and
liquefied petroleum gases)
3
Density, kg/m @ 60 °F 350,0 to 688,0
3
Density, kg/m @ 15 °C 351,7 to 687,8
3
Density, kg/m @ 20 °C 331,7 to 683,6
Temperature °C −46,0 to 93,0
Temperature °F −50,8 to 199,4
Saturation conditions (bubble point or saturation vapour
Pressure
pressure) (see Note 2 to 4.1)
This document also specifies standard reference conditions of pressure and temperature for
measurements carried out on crude petroleum and its products, including liquefied petroleum gases
(see Annex B).
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ISO 91:2017(E)
This document excludes specifying standard reference conditions for natural gas which are given in
[15].
ISO 13443
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
1)
API Manual of Petroleum Measurement Standards (MPMS) Chapter 11.1–2004 /Adjunct to ASTM
2)
D1250-04 /Adjunct to IP 200/04, Temperature and Pressure Volume Correction Factors for Generalized
Crude Oils, Refined Products, and Lubricating Oils/Addendum 1-2007
API MPMS Chapter 11.2.2-1986, Compressibility Factors for Hydrocarbons: 0.350–0.637 Relative Density
(60 °F/60 °F) and –50 °F to 140 °F Metering Temperature/Errata June 1996
API MPMS Chapter 11.2.2M-1986, Compressibility Factors for Hydrocarbons: 350–637 Kilograms per Cubic
Metre Density (15 °C) and –46 °C to 60 °C Metering Temperature
API MPMS Chapter 11.2.4-2007/GPA Technical Publication TP-27-2007, Temperature Correction for the
Volume of NGL and LPG, Tables 23E, 24E, 53E, 54E, 59E, and 60E
3)
API MPMS Chapter 11.5 Part 1-2009/Adjunct to ASTM D1250-08/Adjunct to IP 200/08, Density/Weight/
Volume Intraconversion — Part 1: Conversions of API gravity at 60° F
3)
API MPMS Chapter 11.5 Part 2-2009/Adjunct to ASTM D1250-08/Adjunct to IP 200/08, Density/Weight/
Volume Intraconversion — Part 2: Conversions for Relative Density (60/60° F)
3)
API MPMS Chapter 11.5 Part 3-2009/Adjunct to ASTM D1250-08/Adjunct to IP 200/08, Density/Weight/
Volume Intraconversion — Part 3: Conversions for Absolute Density at 15° C
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
4 Sources and usage guidelines for volume correction factors
4.1 Source of volume correction factors
For the purpose of custody transfer in accordance with this document, reference shall be made to API
MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04, including Addendum 1-2007.
API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04, including Addendum 1-2007,
recognizes three distinct commodity groups: crude oil, refined products, and lubricating oils. A special
1) Available from API. Order Product Number H11013.
2) Available from ASTM International. Order Product Number ADJD1250-E-PDF.
3) API MPMS Chapter 11.5 Parts 1-3 replaced Volumes XI and XII of API MPMS Chapter 11.1-1980/ASTM
D1250-80/IP 200/80 (see Annex C).
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ISO 91:2017(E)
application category is also included which provides volume correction based on the input of an
experimentally derived coefficient of thermal expansion.
NOTE 1 Additional API volume correction factor standards have subsequently been published or are under
development for particular applications. See Annex D.
API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04 provides general procedures
for the conversion of input data to generate the corrected values at the user specified base temperature
and pressure using the effect of temperature on the liquid (CTL), the compressibility coefficient (F ), the
p
correction for the effect of pressure on the liquid (CPL), or the correction for temperature and pressure
of a liquid (CTPL), in a form that is consistent with the computation procedures used to generate
VCF values. Two sets of procedures are given for computing the volume correction factor: one set for
data expressed in U.S. customary units (temperature in degrees Fahrenheit, pressure in pounds per
square inch gauge), the other for the metric system of units (temperature in degrees Celsius, pressure
in kilopascals). In contrast to API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80, the metric
procedures require the procedure for U.S. customary units be used first to compute density at 60 °F.
This value is then further corrected to give the metric output.
For density/weight/volume intraconversion, reference shall be made to API MPMS Chapter 11.5
Part 1 to Part 3/Adjunct to ASTM D1250-08 and IP 200/08. These standards provide conversion of
measurements from one system of units to another for both in vacuo and in air values.
For NGL and LPG, reference shall be made to API MPMS Chapter 11.2.4-2007/GPA Technical Publication
TP-27-2007. The implementation procedures describe how to calculate the CTL given an appropriate
density factor at basis temperature and an observed temperature, and 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 of
API MPMS Chapter 11.2.4-2007/GPA TP-27-2007 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 Table 54E and Table 53E at a base temperature of 15 °C, which
themselves make use of the procedures in Table 23E and Table 24E; these in turn are followed by the
procedures for Table 60E and Table 59E at a base temperature of 20 °C, which also make use of the
procedures described in Table 23E and Table 24E.
To correct NGL and LPG volumes metered under pressure to the corresponding volumes under
equilibrium pressure for the process temperature at the meter, reference shall be made to API MPMS
Chapter 11.2.2-1986 (including Errata June 1996) or API MPMS Chapter 11.2.2M-1986 or if outside of the
density range of these standards, API MPMS Chapter 11.2.1-1984 or API MPMS Chapter 11.2.1M-1984.
These methods require a knowledge of the equilibrium bubble point pressure (vapour pressure)
at the measured conditions. However, the vapour pressure of the process liquid is generally not
measured. The vapour pressure can also be calculated from compositional information, but the
composition is not always measured for natural gas liquids (NGLs). Therefore, a correlation for the
vapour pressure of NGLs based upon normally measured properties is required, and API MPMS
[19]
Chapter 11.2.5-2007/GPA Technical Publication TP-15 can be used for this purpose. The procedure
given in API MPMS Chapter 11.2.5/GPA TP-15 provides a simplified means of estimating equilibrium
vapour pressures of various NGLs from a knowledge of the fluid’s relative density (60 °F/60 °F)
and process temperature. The intended application of this procedure is to provide the values of P
e
(equilibrium vapour pressure) required to determine the pressure effect contributions to volume
correction factors as specified.
See Annex C for titles of petroleum measurement tables given in the 1980 editions of the API, ASTM,
and IP volume correction factor standards, as well as a list of the documents that have superseded
these documents.
4.2 Usage guidelines
Due to the nature of the changes in this document, it is recognized that guidance concerning an
implementation period might be needed in order to avoid disruptions within the industry and ensure
proper application. As a result, it is recommended that this document be utilized on all new applications
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ISO 91:2017(E)
no later than two years after the publication date. An application for this purpose is defined as the point
where the calculation is applied.
Once the revised standard is implemented in a particular application, the previous standard will no
longer be used in that application.
It is important to note that calculation results for crude oil, refined products or lubricating oils (but
not NGL or LPG) based on ISO 91-1 and ISO 91-2 do not differ significantly from this document. This
document also reflects changes that have been made to the calculation procedures leading to increased
precision. The ranges of the volume correction factor tables referenced in this document have also been
expanded (see Annex A).
If an existing application for crude oil, refined products or lubricating oils (but not NGL or LPG)
complies with ISO 91-1 or ISO 91-2, then it shall be considered in compliance with this document. Once
this document is implemented in a particular application, neither ISO 91-1 nor ISO 91-2 shall be used in
that application.
However, the use of International Standards is voluntary and the decision on when to utilize a standard
is an issue that is subject to the negotiations between the parties involved in the transaction.
NOTE Some ISO density standards might not have comparable discrimination levels to those specified in
this document.
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ISO 91:2017(E)
Annex A
(informative)
Changes to previous standards
Between the initial issuance of the 1980 volume correction factors (for crude oils, refined oils and
lubricating oils as given in API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80) and the mid-
1990s, a number of needs arose within the petroleum industry and a number of enhancements occurred
in computer technology. These needs and enhancements prompted several changes to be made and
incorporated into API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04/Adjunct to IP 200/04.
— Previous editions of the printed petroleum measurement tables assumed that density measurements
were made with a glass hydrometer. The odd-numbered printed 1980 petroleum measurement
tables (see Table C.1) all included a hydrometer correction on the observed density. In API MPMS
Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04, no glass hydrometer corrections are
applied. It is assumed that any densities measured with a glass hydrometer will be corrected before
applying the calculations.
— The API MPMS Chapter 11.1-1980 was based on data obtained using the International Practical
Temperature Scale 1968 (IPTS-68). This has been superseded by the International Temperature
Scale 1990 (ITS-90). API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04 takes
this into account by correcting the input temperature values to an IPTS-68 basis before any other
calculations are performed. Standard densities are also adjusted to take into account the small
shifts in the associated standard temperatures.
— The accepted value of the standard density of water at 60 °F has changed slightly from the value
used in the API MPMS Chapter 11.1-1980. This new water density only affects the inter-conversion
of density values with relative density and API gravity. The impact would be seen in Tables 5, 6, 23,
and 24 (see Table C.1) of API MPMS Chapter 11.1/Adjunct to ASTM D1250/Adjunct to IP 200.
— In 1988, the IP produced implementation procedures for 20 °C (Table 59 A, B and D, and Table 60
A, B and D, of API MPMS Chapter 11.1/ASTM D1250/IP 200; see Table C.1) by extending the
procedures used for the 15 °C Tables. This was in response to the needs of countries that use 20 °C
as their standard temperature. Although API never published these tables, they were adopted
[6]
internationally as the reference document for ISO 91-2 . ISO 91-2 complemented ISO 91-1, the
International Standard for temperatures of 60 °F and 15 °C that was based on Volume X of API
MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 (see Table C.1). The 2004 edition of API MPMS
Chapter 11.1/Adjunct to ASTM D1250/Adjunct to IP 200 incorporates the 20 °C volume correction
factors.
— Tables for lubricating oils were developed and approved as a part of the API MPMS Chapter 11.1-1980
but were never fully documented. Only the FORTRAN code was published by the API in Appendix A
and B of the printed 5D and 6D Tables of API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 (see
Table C.1). Implementation procedures for the lubricating oil tables first appeared in Reference [20]
and later in their 20 °C tables. The implementation procedures are now incorporated in API MPMS
Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04.
— For business reasons, the volume correction factors have been extended to lower temperatures and
higher densities, i.e. lower API gravities.
— Real-time density measurement using density meters has become more prevalent in the industry
for input into VCF calculations. These density measurements are often made at pressures greater
than atmospheric. This pressure effect has to be taken into account simultaneously with any
temperature effect when determining the density at standard conditions. Hence, pressure and
temperature corrections have been combined into one procedure.
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ISO 91:2017(E)
— Rounding and truncation of initial and intermediate values have been eliminated. Rounding only
applies to the final VCF values.
— API MPMS Chapter 11.1-1980 used a format that resulted in values for the correction for the effect
of temperature on liquid (CTL) rounded four or five decimal digits, depending upon whether the
CTL value was greater than or less than one. T
...
SLOVENSKI STANDARD
SIST ISO 91:2018
01-junij-2018
1DGRPHãþD
SIST ISO 5024:2001
SIST ISO 91-1:2001
SIST ISO 91-2:2001
1DIWQLLQVRURGQLSURL]YRGL9ROXPHQVNLNRUHNFLMVNLIDNWRUMLWHPSHUDWXUHLQWODND
PHULOQHWDEHOH]DQDIWQHSURL]YRGH LQVWDQGDUGQLUHIHUHQþQLSRJRML
Petroleum and related products - Temperature and pressure volume correction factors
(petroleum measurement tables) and standard reference conditions
Pétrole et produits connexes - Facteurs de correction de volume par rapport à la
température et à la pression (tables de mesure du pétrole) et conditions de référence
standard
Ta slovenski standard je istoveten z: ISO 91:2017
ICS:
75.180.30 Oprema za merjenje Volumetric equipment and
prostornine in merjenje measurements
SIST ISO 91:2018 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST ISO 91:2018
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SIST ISO 91:2018
INTERNATIONAL ISO
STANDARD 91
First edition
2017-05
Petroleum and related products —
Temperature and pressure volume
correction factors (petroleum
measurement tables) and standard
reference conditions
Pétrole et produits connexes — Facteurs de correction de volume
par rapport à la température et à la pression (tables de mesure du
pétrole) et conditions de référence standard
Reference number
ISO 91:2017(E)
©
ISO 2017
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SIST ISO 91:2018
ISO 91:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
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SIST ISO 91:2018
ISO 91:2017(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Sources and usage guidelines for volume correction factors . 2
4.1 Source of volume correction factors . 2
4.2 Usage guidelines . 3
Annex A (informative) Changes to previous standards . 5
Annex B (normative) Standard reference conditions . 7
Annex C (informative) Titles of petroleum measurement tables given in the API-ASTM-IP-
GPA standards for volume correction factors. 8
Annex D (informative) Other volume corrections factors standards .14
Bibliography .15
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SIST ISO 91:2018
ISO 91:2017(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical committee ISO/TC 28, Petroleum products and lubricants,
Subcommittee SC 2, Measurement of petroleum and related products.
This first edition cancels and replaces ISO 91-1:1992, ISO 91-2:1991, ISO 9770:1989, and ISO 5024:1999,
which have been technically revised.
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SIST ISO 91:2018
ISO 91:2017(E)
Introduction
Custody transfer of crude petroleum and its products are generally transacted in volumetric quantities.
Since crude oils and petroleum products have relatively high coefficients of thermal expansion and
compressibility, volumes are corrected to standard conditions of temperature and pressure in order
to provide a meaningful and consistent basis for measurement. The definition of standard reference
conditions is therefore of fundamental importance in measurement, calculation and accounting of
petroleum quantities.
Volume correction factors are used to account for the thermal expansion of liquid hydrocarbons
and convert observed volumes to volumes at standard temperature and pressure. Tables of volume
correction factors were originally developed by collecting empirical data relating to the volumetric
change of hydrocarbons over a range of temperatures and pressures. Cooperative international work
on volume correction factors dates from 1932. The temperature volume correction factor tables
[1]
(petroleum measurement tables) referenced in ISO Recommendation (R) 91:1959 were developed
during the late 1940s and published jointly by the American Society of Testing Materials (ASTM) in
[9]
1952 and the Institute of Petroleum (IP) (metric edition) in 1953 . These tables corrected to standard
temperatures of 15 °C and 60 °F only, and were based on data for crude petroleum and petroleum
fractions published in 1916 by the (United States) National Bureau of Standards (NBS) and some later
data on natural gasoline reported in 1942. These 1952 tables were referenced in API/Standard 2540-
[10]
1966 (also designated ASTM D1250-56). A few amendments to ISO/R 91 resulted in the publication
[2] [3]
of a second edition in 1970 . ISO/R 91:1970/Amd 1:1975 was published in 1975 for tables based on a
reference temperature of 20 °C.
In the early 1970s, it was demonstrated that the previously published tables were not satisfactorily
applicable to many crude oils of current economic importance. A revised standard was published
in 1980 by the American Petroleum Institute as the API Manual of Petroleum Measurement
Standards (MPMS) Chapter 11.1 (also designated API/Standard 2540, ASTM D1250-80 and IP 200/80)
following the development of a new database by API in cooperation with the US NBS. This study
included the examination of 463 samples of crude oil and refined products. The crude oil samples
represented 67 % of world production in 1974. The 1980 standard also constituted a major conceptual
departure from previous versions in the recognition of the use of computers in the petroleum industry.
The actual standard represented by API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 was
neither the hardcopy printed tables nor the set of equations used to represent the density data, but
was an explicit implementation procedure used to develop computer subroutines. The standardization
of an implementation procedure implied the standardization of the set of mathematical expressions,
including calculational sequence and round-off procedures, used within the computer code. Adherence
to the procedures given in API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 was an attempt to
ensure that all computers and computer codes meeting the stated specifications and restrictions would
be able to produce identical results. Hence, the published implementation procedures were the primary
standard, the distributed subroutines the secondary standard, and the published tables produced for
convenience.
[4]
API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 was referenced in ISO 91-1:1982 .
[5]
Corrections to the 1980 standard were listed in ISO 91-1:1992 .
Computer implementation procedures developed by the IP for corrections to 20 °C were published
in 1988. These implementation procedures were prepared as standard procedures to enable users
to produce their own computer programmes either for the generation of 20 °C tables or for use in
[8]
calculations without the generation of tables. IP Petroleum Measurement Paper No. 3 was referenced
[6]
in ISO 91-2:1991 , superseding Addendum 1:1975 to ISO/R 91.
Compressibility factors for hydrocarbons in the 0° to 100° API gravity range were developed in 1945
[12]
and published in 1960 as API/Standard 1101 , Appendix B, Table II. This table was superseded by
[13] [14]
API MPMS Chapters 11.2.1 and 11.2.1M published in 1984. API MPMS Chapter 11.2.1M-1984 was
[13]
adopted by ISO/TC 28 and published as ISO 9770:1989 .
Compressibility factors for hydrocarbons in the 0,500 to 0,611 relative density range and 20 °F to 128 °F
[15]
were published in 1984 as API MPMS Chapter 11.2.2 . A second edition of API MPMS Chapter 11.2.2
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was published in 1986 with an expanded relative density range of 0,350 to 0,637. A metric version of this
3 3
standard (350 kg/m to 637 kg/m range) was also published in 1986 as API MPMS Chapter 11.2.2M.
Unlike the 1980 temperature correction factor tables (API MPMS Chapter 11.1-1980), the compressibility
table values given in API MPMS Chapters 11.2.1 and 11.2.2 were the standard, not the implementation
procedure for the underlying equations.
In 2004, a revision to API MPMS Chapter 11.1 (also designated as an adjunct to ASTM D1250-04 and
IP 200/04) was published and established procedures for generalized crude oils, liquid refined products,
lubricating oils and individual and special applications, by which volume measurements taken at any
temperature and pressure (within the range of the standard) can be corrected to an equivalent volume
at 15 °C, 60 °F or 20 °C (or other reference temperature) and standard pressure, by use of a correction
factor for temperature and pressure of the liquid (CTPL). API MPMS Chapter 11.1-2004/Adjunct to
ASTM D1250-04/Adjunct to IP 200/04 superseded API MPMS Chapters 11.1-1980, 11.2.1-1984 and
11.2.1M-1984.
In 2007, Addendum 1 to API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04/Adjunct to IP 200/04
was published in order to include some minor updates to the standard.
Previously, most natural gas liquid (NGL) and liquefied petroleum gas (LPG) temperature correction
factors were obtained from a variety of sources.
[9] [4]
— ASTM-IP Petroleum Measurement Tables, 1952 , as referenced in ISO/R 91:1970 . This publication
is limited to a 60 °F relative density range of 0,500 and higher.
[16]
— GPA Standard 2142, published in 1957 .
[17]
— GPA Technical Publication TP-16, published in 1988 . It is limited to the following products: HD 5
propane with relative densities of 0,501, 0,505, and 0,510; iso-butane at a relative density of 0,565;
normal butane at a relative density of 0,585, and natural gasoline (12 psia to 14 psia Reid vapour
pressure) at a relative density of 0,664.
— API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 Volume XII, Table 33 “Specific
Gravity Reduction to 60 °F For Liquefied Petroleum Gases and Natural Gasoline”, as referenced in
[5]
ISO 91-1:1992 .
— API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 Volume XII, Table 34 “Reduction of Volume
to 60 °F Against Specific Gravity 60/60 °F For Liquefied Petroleum Gases and Natural Gasoline”, as
[5]
referenced in ISO 91-1:1992 .
[18]
— API/ASTM/GPA Technical Publication TP-25, published in 1988 .
In 2007, these documents were superseded by API MPMS Chapter 11.2.4/GPA Technical Publication TP-27.
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SIST ISO 91:2018
INTERNATIONAL STANDARD ISO 91:2017(E)
Petroleum and related products — Temperature
and pressure volume correction factors (petroleum
measurement tables) and standard reference conditions
1 Scope
This document refers to temperature volume correction factors, which allow users to convert volumes,
measured at ambient conditions, to those at reference conditions for transactional purposes. This
document also refers to compressibility factors required to correct hydrocarbon volumes measured
under pressure to the corresponding volumes at the equilibrium pressure for the measured
temperature.
Table 1 shows the defining limits and their associated units of correction factors referenced in this
document for crude oil, refined products and lubricating oils. These values are shown in bold italics.
Also shown in the table are the limits converted to their equivalent units (and, in the case of the densities,
other base temperatures). Table 2 shows defining limits of correction factors for light hydrocarbons
(natural gas liquids and liquefied petroleum gases).
Table 1 — Defining limits of correction factors for crude oil, refined products and lubricating oils
Crude oil Refined products Lubricating oils
3
Density, kg/m @ 60 °F 610,6 to 1 163,5 800,9 to 1 163,5
Relative density @ 60 °F 0,611 2 to 1,164 64 0,801 68 to 1,164 6
API gravity @ 60 °F 100 to –10 45 to –10
3
Density, kg/m @ 15 °C 611,16 to 1 163,79 611,16 to 1 163,86 801,25 to 1 163,85
3
Density, kg/m @ 20 °C 606,12 to 1 161,15 606,12 to 1 160,62 798,11 to 1 160,71
Temperature, °C –50,00 to 150
Temperature, °F –58,0 to 302
Pressure, psig 0 to 1 500
4
Pressure, kPa (gauge) 0 to 1,034 × 10
Pressure, bar (gauge) 0 to 103,4
60 °F thermal expansion
−6 −6
factor (α60), per °F 230,3 × 10 to 930,0 × 10
−6 −6
α60, Per °C 414,0 × 10 to 1 674,0 × 10
Table 2 — Defining limits of correction factors for light hydrocarbons (natural gas liquids and
liquefied petroleum gases)
3
Density, kg/m @ 60 °F 350,0 to 688,0
3
Density, kg/m @ 15 °C 351,7 to 687,8
3
Density, kg/m @ 20 °C 331,7 to 683,6
Temperature °C −46,0 to 93,0
Temperature °F −50,8 to 199,4
Saturation conditions (bubble point or saturation vapour
Pressure
pressure) (see Note 2 to 4.1)
This document also specifies standard reference conditions of pressure and temperature for
measurements carried out on crude petroleum and its products, including liquefied petroleum gases
(see Annex B).
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This document excludes specifying standard reference conditions for natural gas which are given in
[15].
ISO 13443
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
1)
API Manual of Petroleum Measurement Standards (MPMS) Chapter 11.1–2004 /Adjunct to ASTM
2)
D1250-04 /Adjunct to IP 200/04, Temperature and Pressure Volume Correction Factors for Generalized
Crude Oils, Refined Products, and Lubricating Oils/Addendum 1-2007
API MPMS Chapter 11.2.2-1986, Compressibility Factors for Hydrocarbons: 0.350–0.637 Relative Density
(60 °F/60 °F) and –50 °F to 140 °F Metering Temperature/Errata June 1996
API MPMS Chapter 11.2.2M-1986, Compressibility Factors for Hydrocarbons: 350–637 Kilograms per Cubic
Metre Density (15 °C) and –46 °C to 60 °C Metering Temperature
API MPMS Chapter 11.2.4-2007/GPA Technical Publication TP-27-2007, Temperature Correction for the
Volume of NGL and LPG, Tables 23E, 24E, 53E, 54E, 59E, and 60E
3)
API MPMS Chapter 11.5 Part 1-2009/Adjunct to ASTM D1250-08/Adjunct to IP 200/08, Density/Weight/
Volume Intraconversion — Part 1: Conversions of API gravity at 60° F
3)
API MPMS Chapter 11.5 Part 2-2009/Adjunct to ASTM D1250-08/Adjunct to IP 200/08, Density/Weight/
Volume Intraconversion — Part 2: Conversions for Relative Density (60/60° F)
3)
API MPMS Chapter 11.5 Part 3-2009/Adjunct to ASTM D1250-08/Adjunct to IP 200/08, Density/Weight/
Volume Intraconversion — Part 3: Conversions for Absolute Density at 15° C
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
4 Sources and usage guidelines for volume correction factors
4.1 Source of volume correction factors
For the purpose of custody transfer in accordance with this document, reference shall be made to API
MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04, including Addendum 1-2007.
API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04, including Addendum 1-2007,
recognizes three distinct commodity groups: crude oil, refined products, and lubricating oils. A special
1) Available from API. Order Product Number H11013.
2) Available from ASTM International. Order Product Number ADJD1250-E-PDF.
3) API MPMS Chapter 11.5 Parts 1-3 replaced Volumes XI and XII of API MPMS Chapter 11.1-1980/ASTM
D1250-80/IP 200/80 (see Annex C).
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application category is also included which provides volume correction based on the input of an
experimentally derived coefficient of thermal expansion.
NOTE 1 Additional API volume correction factor standards have subsequently been published or are under
development for particular applications. See Annex D.
API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04 provides general procedures
for the conversion of input data to generate the corrected values at the user specified base temperature
and pressure using the effect of temperature on the liquid (CTL), the compressibility coefficient (F ), the
p
correction for the effect of pressure on the liquid (CPL), or the correction for temperature and pressure
of a liquid (CTPL), in a form that is consistent with the computation procedures used to generate
VCF values. Two sets of procedures are given for computing the volume correction factor: one set for
data expressed in U.S. customary units (temperature in degrees Fahrenheit, pressure in pounds per
square inch gauge), the other for the metric system of units (temperature in degrees Celsius, pressure
in kilopascals). In contrast to API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80, the metric
procedures require the procedure for U.S. customary units be used first to compute density at 60 °F.
This value is then further corrected to give the metric output.
For density/weight/volume intraconversion, reference shall be made to API MPMS Chapter 11.5
Part 1 to Part 3/Adjunct to ASTM D1250-08 and IP 200/08. These standards provide conversion of
measurements from one system of units to another for both in vacuo and in air values.
For NGL and LPG, reference shall be made to API MPMS Chapter 11.2.4-2007/GPA Technical Publication
TP-27-2007. The implementation procedures describe how to calculate the CTL given an appropriate
density factor at basis temperature and an observed temperature, and 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 of
API MPMS Chapter 11.2.4-2007/GPA TP-27-2007 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 Table 54E and Table 53E at a base temperature of 15 °C, which
themselves make use of the procedures in Table 23E and Table 24E; these in turn are followed by the
procedures for Table 60E and Table 59E at a base temperature of 20 °C, which also make use of the
procedures described in Table 23E and Table 24E.
To correct NGL and LPG volumes metered under pressure to the corresponding volumes under
equilibrium pressure for the process temperature at the meter, reference shall be made to API MPMS
Chapter 11.2.2-1986 (including Errata June 1996) or API MPMS Chapter 11.2.2M-1986 or if outside of the
density range of these standards, API MPMS Chapter 11.2.1-1984 or API MPMS Chapter 11.2.1M-1984.
These methods require a knowledge of the equilibrium bubble point pressure (vapour pressure)
at the measured conditions. However, the vapour pressure of the process liquid is generally not
measured. The vapour pressure can also be calculated from compositional information, but the
composition is not always measured for natural gas liquids (NGLs). Therefore, a correlation for the
vapour pressure of NGLs based upon normally measured properties is required, and API MPMS
[19]
Chapter 11.2.5-2007/GPA Technical Publication TP-15 can be used for this purpose. The procedure
given in API MPMS Chapter 11.2.5/GPA TP-15 provides a simplified means of estimating equilibrium
vapour pressures of various NGLs from a knowledge of the fluid’s relative density (60 °F/60 °F)
and process temperature. The intended application of this procedure is to provide the values of P
e
(equilibrium vapour pressure) required to determine the pressure effect contributions to volume
correction factors as specified.
See Annex C for titles of petroleum measurement tables given in the 1980 editions of the API, ASTM,
and IP volume correction factor standards, as well as a list of the documents that have superseded
these documents.
4.2 Usage guidelines
Due to the nature of the changes in this document, it is recognized that guidance concerning an
implementation period might be needed in order to avoid disruptions within the industry and ensure
proper application. As a result, it is recommended that this document be utilized on all new applications
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no later than two years after the publication date. An application for this purpose is defined as the point
where the calculation is applied.
Once the revised standard is implemented in a particular application, the previous standard will no
longer be used in that application.
It is important to note that calculation results for crude oil, refined products or lubricating oils (but
not NGL or LPG) based on ISO 91-1 and ISO 91-2 do not differ significantly from this document. This
document also reflects changes that have been made to the calculation procedures leading to increased
precision. The ranges of the volume correction factor tables referenced in this document have also been
expanded (see Annex A).
If an existing application for crude oil, refined products or lubricating oils (but not NGL or LPG)
complies with ISO 91-1 or ISO 91-2, then it shall be considered in compliance with this document. Once
this document is implemented in a particular application, neither ISO 91-1 nor ISO 91-2 shall be used in
that application.
However, the use of International Standards is voluntary and the decision on when to utilize a standard
is an issue that is subject to the negotiations between the parties involved in the transaction.
NOTE Some ISO density standards might not have comparable discrimination levels to those specified in
this document.
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SIST ISO 91:2018
ISO 91:2017(E)
Annex A
(informative)
Changes to previous standards
Between the initial issuance of the 1980 volume correction factors (for crude oils, refined oils and
lubricating oils as given in API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80) and the mid-
1990s, a number of needs arose within the petroleum industry and a number of enhancements occurred
in computer technology. These needs and enhancements prompted several changes to be made and
incorporated into API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04/Adjunct to IP 200/04.
— Previous editions of the printed petroleum measurement tables assumed that density measurements
were made with a glass hydrometer. The odd-numbered printed 1980 petroleum measurement
tables (see Table C.1) all included a hydrometer correction on the observed density. In API MPMS
Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04, no glass hydrometer corrections are
applied. It is assumed that any densities measured with a glass hydrometer will be corrected before
applying the calculations.
— The API MPMS Chapter 11.1-1980 was based on data obtained using the International Practical
Temperature Scale 1968 (IPTS-68). This has been superseded by the International Temperature
Scale 1990 (ITS-90). API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04 and IP 200/04 takes
this into account by correcting the input temperature values to an IPTS-68 basis before any other
calculations are performed. Standard densities are also adjusted to take into account the small
shifts in the associated standard temperatures.
— The accepted value of the standard density of water at 60 °F has changed slightly from the value
used in the API MPMS Chapter 11.1-1980. This new water density only affects the inter-conversion
of density values with relative density and API gravity. The impact would be seen in Tables 5, 6, 23,
and 24 (see Table C.1) of API MPMS Chapter 11.1/Adjunct to ASTM D1250/Adjunct to IP 200.
— In 1988, the IP produced implementation procedures for 20 °C (Table 59 A, B and D, and Table 60
A, B and D, of API MPMS Chapter 11.1/ASTM D1250/IP 200; see Table C.1) by extending the
procedures used for the 15 °C Tables. This was in response to the needs of countries that use 20 °C
as their standard temperature. Although API never published these tables, they were adopted
[6]
internationally as the reference document for ISO 91-2 . ISO 91-2 complemented ISO 91-1, the
International Standard for temperatures of 60 °F and 15 °C that was based on Volume X of API
MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 (see Table C.1). The 2004 edition of API MPMS
Chapter 11.1/Adjunct to ASTM D1250/Adjunct to IP 200 incorporates the 20 °C volume correction
factors.
— Tables for lubricating oils were developed and approved as a part of the API MPMS Chapter 11.1-1980
but were never fully documented. Only the FORTRAN code was published by the API in Appendix A
and B of the printed 5D and 6D Tables of API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 (see
Table C.1). Implementation procedures for the lubricating oil tables first appeared in Reference [20]
and la
...
NORME ISO
INTERNATIONALE 91
Première édition
2017-05
Pétrole et produits connexes —
Facteurs de correction de volume
par rapport à la température et à
la pression (tables de mesure du
pétrole) et conditions de référence
standard
Petroleum and related products — Temperature and pressure volume
correction factors (petroleum measurement tables) and standard
reference conditions
Numéro de référence
ISO 91:2017(F)
©
ISO 2017
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ISO 91:2017(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2017, Publié en Suisse
Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni utilisée
sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie, l’affichage sur
l’internet ou sur un Intranet, sans autorisation écrite préalable. Les demandes d’autorisation peuvent être adressées à l’ISO à
l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – Tous droits réservés
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ISO 91:2017(F)
Sommaire Page
Avant-propos .iv
Introduction .v
1 Domaine d’application . 1
2 Références normatives . 2
3 Termes et définitions . 2
4 Origines des facteurs de correction de volume et lignes directrices d’utilisation .3
4.1 Origines des facteurs de correction de volume . 3
4.2 Lignes directrices d’utilisation . 4
Annexe A (informative) Modifications apportées aux normes précédentes .5
Annexe B (normative) Conditions de référence standard . 7
Annexe C (informative) Titres des tables de mesure du pétrole données dans les normes
API-ASTM-IP-GPA pour les facteurs de correction de volume . 8
Annexe D (informative) Autres normes sur les facteurs de correction du volume .15
Bibliographie .16
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ISO 91:2017(F)
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes
nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est
en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.
L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents
critères d’approbation requis pour les différents types de documents ISO. Le présent document a été
rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www
.iso .org/ directives).
L’attention est appelée sur le fait que certains des éléments du présent document peuvent faire l’objet de
droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de
brevets reçues par l’ISO (voir www .iso .org/ brevets).
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion
de l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles
techniques au commerce (OTC), voir le lien suivant: w w w . i s o .org/ iso/ fr/ avant -propos .html
Le présent document a été élaboré par le comité technique ISO/TC 28, Produits pétroliers et produits
connexes d’origine synthétique ou biologique, sous-comité SC 2, Mesurage du pétrole et des produits
connexes.
Cette première édition annule et remplace l’ISO 91-1:1992, l’ISO 91-2:1991, l’ISO 9770:1989 et
l’ISO 5024:1999, qui ont fait l’objet d’une révision technique.
iv © ISO 2017 – Tous droits réservés
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ISO 91:2017(F)
Introduction
Les transactions du commerce international du pétrole brut et de ses sous-produits sont en général
fixées par rapport aux volumes. Étant donné que les pétroles bruts et produits pétroliers présentent
des coefficients de dilatation thermique et de compressibilité relativement élevés, les volumes sont
corrigés par rapport aux conditions standard de température et de pression afin de disposer d’une
base de mesure significative et cohérente. La définition des conditions de référence standard est par
conséquent de la plus haute importance pour le mesurage, le calcul et la facturation des volumes de
produits pétroliers.
Des facteurs de correction de volume sont utilisés pour tenir compte de la dilatation thermique des
hydrocarbures liquides et convertir les volumes observés en volumes aux conditions standard de
température et de pression. Des tables de facteurs de correction de volume ont été initialement
développées par recueil de données empiriques sur les variations volumiques d’hydrocarbures sur
une plage donnée de températures et de pressions. Le travail international coopératif sur les facteurs
de correction de volume date de 1932. Les tables de facteurs de correction de volume basées sur les
[1]
températures (tables de mesure du pétrole) référencées dans la Recommandation ISO (R) 91:1959
ont été élaborées à la fin des années 1940 et ont été publiées conjointement par l’American Society of
[9]
Testing Materials (ASTM) en 1952 et l’Institute of Petroleum (IP) (édition avec unités SI) en 1953 . Ces
tables ont établi les corrections pour une conversion aux températures standard de 15 °C et de 60 °F
uniquement, et sont basées sur des données concernant le pétrole brut et des sous-produits pétroliers
publiées en 1916 par le bureau américain de normalisation, le National Bureau of Standards (NBS), et
sur des données plus récentes sur l’essence de gaz naturel parues en 1942. Ces tables de 1952 sont
[10]
référencées dans la norme API/Standard 2540-1966 (appelée également ASTM D1250-56). Quelques
modifications ont été apportées à l’ISO/R 91, qui, de ce fait, a fait l’objet d’une deuxième édition publiée
[2] [3]
en 1970 . L»ISO/R 91:1970/Am 1:1975 est paru en 1975 pour inclure des tables basées sur une
température de référence de 20 °C.
Au début des années 1970, il a été démontré que les tables précédemment publiées n’étaient pas
applicables de manière satisfaisante à nombre de pétroles bruts qui représentaient déjà des enjeux
économiques importants. Une norme révisée a été publiée en 1980 par l’American Petroleum Institute
sous le titre de API Manual of Petroleum Measurement Standards (MPMS) Chapter 11.1 (également
appelée norme API/Standard 2540, ASTM D1250-80 et IP 200/80) suite à l’élaboration d’une nouvelle
base de données par l’API en coopération avec l’US NBS (bureau américain de normalisation).
Cette étude est basée sur l’analyse de 463 échantillons de pétrole brut et de produits raffinés. Ces
échantillons de pétrole brut représentaient 67 % de la production mondiale en 1974. La norme de 1980
a également constitué un point de départ conceptuel majeur par rapport aux versions précédentes
dans la reconnaissance de l’utilisation des ordinateurs dans l’industrie pétrolière. Cette édition de la
norme portant la référence API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 ne correspondait
ni aux tables au format papier, ni à l’ensemble des équations utilisées pour représenter les données de
masse volumique, mais était une procédure explicite de mise en œuvre utilisée pour développer des
sous-programmes informatiques. La normalisation d’une procédure de mise en œuvre impliquait la
normalisation de l’ensemble d’expressions mathématiques, notamment de la séquence de calcul et des
procédures d’arrondissement, utilisées dans le code informatique. L’adoption des procédures données
dans l’API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 visait à garantir que tous les ordinateurs
et codes informatiques respectant les spécifications et restrictions mentionnées aboutiraient aux
mêmes résultats. Par conséquent, les procédures de mise en œuvre publiées ont constitué la norme
principale, les sous-programmes répartis, la norme secondaire et les tables publiées dans un souci de
commodité.
[4]
L’API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 a été référencé dans l’ISO 91-1:1982 . Les
[5]
corrections apportées à la norme de 1980 ont été répertoriées dans l’ISO 91-1:1992 .
Les procédures de mise en œuvre informatique développées par l’IP pour des conversions à 20 °C
ont été publiées en 1988. Ces procédures de mise en œuvre ont été préparées comme des procédures
standard pour permettre aux utilisateurs de construire leurs propres programmes informatiques
destinés soit à générer des tables basées sur une température de 20 °C, soit à être utilisés dans des
© ISO 2017 – Tous droits réservés v
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ISO 91:2017(F)
[8]
calculs sans générer de tables. Le document IP Petroleum Measurement Paper No. 3 a été référencé
[6]
dans l’ISO 91-2:1991 , supplantant l’Addendum 1:1975 à l’ISO/R 91.
Les facteurs de compressibilité des hydrocarbures dans la plage de densité API entre 0° et 100° ont été
[12]
développés en 1945 et publiés en 1960 en tant que norme API/Standard 1101 , Appendix B, Table II.
[13] [14]
Cette table a été remplacée par l’API MPMS Chapters 11.2.1 et 11.2.1M publié en 1984. L’API MPMS
[13]
Chapter 11.2.1M-1984 a été adopté par l’ISO/TC 28 et publié sous la référence ISO 9770:1989 .
Les facteurs de compressibilité des hydrocarbures dans la plage de densité relative entre 0,500 et 0,611,
[15]
et dans la plage de 20 °F à 128 °F ont été publiés en 1984 en tant que API MPMS Chapter 11.2.2 .
Une deuxième édition de l’API MPMS Chapter 11.2.2 est parue en 1986 avec une plage de densité
3
relative étendue allant de 0,350 à 0,637. Une version de cette norme en unités SI (plage de 350 kg/m
3
à 637 kg/m ) a également été publiée en 1986 en tant que API MPMS Chapter 11.2.2M.
Contrairement aux tables de facteurs de correction basées sur les températures de 1980 (API MPMS
Chapter 11.1-1980), les valeurs des tables de compressibilité données dans l’API MPMS Chapters 11.2.1
et 11.2.2 constituent la norme, et non la procédure de mise en œuvre pour les équations sous-jacentes.
En 2004, une révision de l’API MPMS Chapter 11.1 (également appelée adjunct to ASTM D1250-04 et
Adjunct to IP 200/04) a été publiée et a établi des procédures pour les pétroles bruts, les produits
raffinés liquides, les huiles lubrifiantes et des applications particulières et spéciales, grâce auxquelles les
mesures de volume relevées à n’importe quelles température et pression (dans les limites de la plage de la
norme) peuvent être corrigées de manière à être converties en volume équivalent à 15 °C, 60 °F ou 20 °C
(ou à une autre température de référence) et à pression standard, à l’aide d’un facteur de correction
pour la température et la pression du liquide (correction CTPL). L’API MPMS Chapter 11.1-2004/Adjunct
to ASTM D1250-04/Adjunct to IP 200/04 a remplacé l’API MPMS Chapters 11.1-1980, 11.2.1-1984
et 11.2.1M-1984.
En 2007, l’Addendum 1 to API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04/Adjunct to
IP 200/04 a été publié afin d’inclure plusieurs modifications mineures apportées à la norme.
Précédemment, la plupart des facteurs de correction de température des liquides de gaz naturel (GNL)
et des gaz de pétrole liquéfiés (GPL) ont été obtenus à partir de sources diverses:
[9]
— le document ASTM-IP Petroleum Measurement Tables (Tables de mesure du pétrole), 1952 , comme
[4]
référencé dans l’ISO/R 91:1970 . Cette publication est limitée à la plage des densités relatives à
60 °F supérieures ou égales à 0,500;
[16]
— la norme GPA Standard 2142, publiée en 1957 ;
[17]
— la publication technique GPA Technical Publication TP-16, publiée en 1988 . Cette dernière est
limitée aux produits suivants: propane HD-5 de densité relative égale à 0,501, 0,505, et 0,510; iso-
butane de densité relative égale à 0,565; butane normal de densité relative égale à 0,585, et essence
de gaz naturel (pression de vapeur Reid comprise entre 12 psia et 14 psia) de densité relative égale
à 0,664;
— le document API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 Volume XII, Table 33 «Specific
Gravity Reduction to 60 °F For Liquefied Petroleum Gases and Natural Gasoline» (conversion à 60 °F
de la densité relative pour les gaz de pétrole liquéfiés et les essences de gaz naturel), comme référencé
[5]
dans l’ISO 91-1:1992 ;
— le document API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80 Volume XII, Table 34
«Reduction of Volume to 60 °F Against Specific Gravity 60/60 °F For Liquefied Petroleum Gases and
Natural Gasoline» (conversion à 60 °F des volumes en fonction de la densité relative 60/60 °F pour les
[5]
gaz de pétrole liquéfiés et les essences de gaz naturel), comme référencé dans l’ISO 91-1:1992 ;
[18]
— le document API/ASTM/GPA Technical Publication TP-25, publié en 1988 .
En 2007, ces documents ont été remplacés par l’API MPMS Chapter 11.2.4/GPA Technical Publication TP-27.
vi © ISO 2017 – Tous droits réservés
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NORME INTERNATIONALE ISO 91:2017(F)
Pétrole et produits connexes — Facteurs de correction
de volume par rapport à la température et à la pression
(tables de mesure du pétrole) et conditions de référence
standard
1 Domaine d’application
Le présent document fait référence aux facteurs de correction de volume par rapport à la température,
qui permettent à l’utilisateur de convertir des volumes, mesurés à des conditions ambiantes, en volumes
qui auraient été relevés aux conditions de référence à des fins commerciales. Le présent document fait
également référence aux facteurs de compressibilité requis pour corriger des volumes d’hydrocarbures
mesurés sous une certaine pression afin de les convertir en volumes correspondants à la pression
d’équilibre pour la température mesurée.
Le Tableau 1 présente les limites de définition et leurs unités associées pour les facteurs de correction
référencés dans le présent document pour le pétrole brut, les produits raffinés et les huiles lubrifiantes.
Ces valeurs sont indiquées en italique et en gras. Le tableau présente également les conversions des
limites exprimées selon d’autres unités équivalentes (et, dans le cas des masses volumiques, selon
d’autres températures de base). Le Tableau 2 présente les limites de définition des facteurs de correction
pour les hydrocarbures légers (liquides de gaz naturel et gaz de pétrole liquéfiés).
Tableau 1 — Limites de définition des facteurs de correction pour le pétrole brut, les produits
raffinés et les huiles lubrifiantes
Pétrole brut Produits raffinés Huiles lubrifiantes
3
Masse volumique, kg/m à 60 °F 610,6 à 1 163,5 800,9 à 1 163,5
Densité relative à 60 °F 0,611 2 à 1,164 64 0,801 68 à 1,164 6
Densité API à 60 °F 100 à –10 45 à –10
3
Masse volumique, kg/m à 15 °C 611,16 à 1 163,79 611,16 à 1 163,86 801,25 à 1 163,85
3
Masse volumique, kg/m à 20 °C 606,12 à 1 161,15 606,12 à 1 160,62 798,11 à 1 160,71
Température, °C –50,00 à 150
Température, °F –58,0 à 302
Pression, psig 0 à 1 500
4
Pression, kPa (manométrique) 0 à 1,034 × 10
Pression, bar (manométrique) 0 à 103,4
Facteur de dilatation thermique
−6 −6
230,3 × 10 à 930,0 × 10
à 60 °F (α60), par °F
−6 −6
α60, par °C 414,0 × 10 à 1 674,0 × 10
© ISO 2017 – Tous droits réservés 1
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ISO 91:2017(F)
Tableau 2 — Limites de définition des facteurs de correction pour les hydrocarbures légers
(liquides de gaz naturel et gaz de pétrole liquéfiés)
3
Masse volumique, kg/m à 60 °F 350,0 à 688,0
3
Masse volumique, kg/m à 15 °C 351,7 à 687,8
3
Masse volumique, kg/m à 20 °C 331,7 à 683,6
Température °C −46,0 à 93,0
Température °F −50,8 à 199,4
Pression Conditions de saturation (point d’ébullition ou pression de
vapeur de saturation) – voir Note 2 à 4.1
Le présent document spécifie également des conditions de référence standard de température et de
pression pour les mesurages effectués sur le pétrole brut et ses sous-produits, notamment les gaz de
pétrole liquéfiés (voir Annexe B).
Le présent document exclut la spécification des conditions de référence standard pour le gaz naturel,
[15]
lesquelles sont données dans l’ISO 13443 .
2 Références normatives
Les documents suivants, en totalité ou en partie, sont référencés normativement dans ce documents
et sont indispensables pour son application. Pour les références datées, seule l’édition citée s’applique.
Pour les références non datées, la dernière édition du document de référence s’applique (y compris les
éventuels amendements).
1)
API Manual of Petroleum Measurement Standards (MPMS) Chapter 11.1–2004 /Adjunct to ASTM
2)
D1250-04 /Adjunct to IP 200/04, Temperature and Pressure Volume Correction Factors for Generalized
Crude Oils, Refined Products, and Lubricating Oils/Addendum 1-2007
API MPMS Chapter 11.2.2-1986, Compressibility Factors for Hydrocarbons: 0.350–0.637 Relative Density
(60 °F/60 °F) and –50 °F to 140 °F Metering Temperature/Errata June 1996
API MPMS Chapter 11.2.2M-1986, Compressibility Factors for Hydrocarbons: 350–637 Kilograms per Cubic
Metre Density (15 °C) and –46 °C to 60 °C Metering Temperature
API MPMS Chapter 11.2.4-2007/GPA Technical Publication TP-27-2007, Temperature Correction for the
Volume of NGL and LPG, Tables 23E, 24E, 53E, 54E, 59E, and 60E
3)
API MPMS Chapter 11.5 Part 1-2009/Adjunct to ASTM D1250-08/Adjunct to IP 200/08, Density/Weight/
Volume Intraconversion — Part 1: Conversions of API gravity at 60 °F
3)
API MPMS Chapter 11.5 Part 2-2009/Adjunct to ASTM D1250-08/Adjunct to IP 200/08, Density/Weight/
Volume Intraconversion — Part 2: Conversions for Relative Density (60/60 °F)
3)
API MPMS Chapter 11.5 Part 3-2009/Adjunct to ASTM D1250-08/Adjunct to IP 200/08, Density/Weight/
Volume Intraconversion — Part 3: Conversions for Absolute Density at 15 °C
3 Termes et définitions
Aucun terme ni aucune définition ne sont donnés dans ce document.
1) Disponible sur CD-ROM chez l’API. Référence produit H11013
2) Disponible sur CD-ROM chez ASTM International Headquarters. Référence produit ADJD1250CD
3) API MPMS Chapter 11.5 Parts 1-3 remplace les Volumes XI et XII de l’API MPMS Chapter 11.1-1980/ASTM
D1250-80/IP 200/80 (voir Annexe B).
2 © ISO 2017 – Tous droits réservés
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ISO 91:2017(F)
L’ISO et la IEC tiennent à jour des bases de données terminologiques pour la normalisation aux adresses
suivantes:
— Electropedia IEC: consultable sur http:// www .electropedia .org/
— Plateforme ISO de navigation en ligne: consultable sur http:// www .iso .org/ obp
4 Origines des facteurs de correction de volume et lignes directrices d’utilisation
4.1 Origines des facteurs de correction de volume
Pour le commerce international en accord avec le présent document, il doit être fait référence à l’API MPMS
Chapter 11.1-2004/Adjunct to ASTM D1250-04/Adjunct to IP 200/04, incluant l’Addendum 1-2007.
L’API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04/Adjunct to IP 200/04, incluant
l’Addendum 1-2007, fait la distinction entre les trois groupes de produits suivants: pétrole brut,
produits raffinés, et huiles lubrifiantes. Une catégorie d’application spéciale est également incluse,
laquelle indique une correction de volume basée sur l’entrée d’un coefficient de dilatation thermique
obtenu expérimentalement.
NOTE 1 Des normes complémentaires sur le facteur de correction de volume API ont été publiées
ultérieurement ou sont en cours d’élaboration pour des applications particulières. Voir Annexe D.
L’API MPMS Chapter 11.1-2004/Adjunct to ASTM D1250-04/Adjunct to IP 200/04 délivre des procédures
générales de conversion des données d’entrée pour générer les valeurs corrigées à la température et à
la pression de base spécifiées par l’utilisateur, utilisant la correction de l’effet de la température sur le
liquide (correction CTL), le coefficient de compressibilité (F ), la correction de l’effet de la pression sur
p
le liquide (correction CPL), ou la correction pour la température et la pression d’un liquide (correction
CTPL), selon une forme qui est cohérente avec les procédures de calcul utilisées pour générer des
valeurs de facteur de correction de volume (facteur VCF). Deux ensembles de procédures sont donnés
pour le calcul du facteur de correction de volume: un ensemble pour les données exprimées en unités
de mesure américaines (température en degrés Fahrenheit, pression manométrique en livres par pouce
carré (psig)), l’autre ensemble pour le système d’unités SI (température en degrés Celsius, pression en
kilopascal). Contrairement à l’API MPMS Chapter 11.1-1980/ASTM D1250-80/IP 200/80, les procédures
avec unités SI nécessite d’utiliser la procédure pour les unités de mesure américaines pour calculer la
masse volumique à 60 °F. Cette valeur est ensuite corrigée pour donner un résultat en unités SI.
Pour l’intraconversion de masse volumique/masse/volume, il doit être fait référence à l’API MPMS
Chapter 11.5 Part 1 à Part 3/Adjunct to ASTM D1250-08/Adjunct to IP 200/08. Ces normes spécifient la
conversion des mesures d’un système d’unités à l’autre pour des valeurs obtenues sous vide et dans l’air.
Pour les GNL et les GPL, il doit être fait référence à l’API MPMS Chapter 11.2.4-2007/GPA Technical
Publication TP-27-2007. Les procédures de mise en œuvre décrivent la manière de calculer la correction
CTL à partir d’un facteur de masse volumique adéquat à une température de base et à une température
observée, et de calculer le facteur de masse volumique adéquat à une température de base à partir
d’une densité relative à une température observée. Les procédures de mise en œuvre sont présentées
par paires pour chaque température de base. Les procédures des Tables 23E et 24E de l’API MPMS
Chapter 11.2.4-2007/GPA TP-27-2007 à une température de base de 60 °F sont données en premier.
La procédure de la Table 23E utilise la procédure décrite dans la Table 24E, c’est pourquoi la Table
24E est présentée en premier. Ces procédures sont suivies des procédures des Tables 54E et 53E à
une température de base de 15 °C, lesquelles utilisent les procédures des Tables 23E et 24E et sont à
leur tour suivies des procédures des Tables 60E et 59E à une température de base de 20 °C, lesquelles
utilisent les procédures décrites dans les Tables 23E et 24E.
Pour corriger les volumes de GNL et de GPL mesurés sous une certaine pression de manière à les
convertir en volumes correspondants sous pression d’équilibre pour la température de la procédure
telle que mesurée, il doit être fait référence à l’API MPMS Chapter 11.2.2-1986 (incluant les Errata de
juin 1996) ou à l’API MPMS Chapter 11.2.2M-1986 ou si la masse volumique se trouve hors de l’intervalle
de ces normes, API MPMS Chapter 11.2.1-1984 ou API MPMS Chapter 11.2.1M-1984.
© ISO 2017 – Tous droits réservés 3
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ISO 91:2017(F)
Ces méthodes nécessitent de connaître la pression du point d’ébullition à l’équilibre (pression de vapeur)
aux conditions mesurées. Cependant, la pression de vapeur du liquide de procédé n’est en général pas
mesurée. La pression de vapeur peut également être calculée d’après des informations de composition,
mais la composition n’est pas toujours mesurée pour les liquides de gaz naturel (GNL). Par conséquent,
une corrélation pour la pression de vapeur des GNL fondée sur des propriétés qui sont normalement
[19]
mesurées est requise, et l’API MPMS Chapter 11.2.5-2007/GPA Technical Publication TP-15 peut être
utilisé à cette fin. La procédure donnée dans l’API MPMS Chapter 11.2.5/GPA TP-15 donne un moyen
simplifié pour estimer les pressions de vapeur à l’équilibre de divers GNL à partir de valeurs connues
de densité relative (60 °F/60 °F) et de température de procédé du fluide. L’application prévue de cette
procédure est de donner les valeurs de P (pression de vapeur à l’équilibre) requises pour déterminer
e
les contributions de l’effet de pression sur les facteurs de correction de volume comme spécifié.
Se reporter à l’Annexe C pour connaître les titres des tables de mesure du pétrole données dans les
éditions de 1980 des normes API, ASTM et IP sur le facteur de correction de volume, et la liste des
documents ayant remplacé ces documents.
4.2 Lignes directrices d’utilisation
En raison de la nature des modifications incluses dans le présent document, il est admis que des
préconisations concernant une période de mise en œuvre pourraient être nécessaires pour éviter des
perturbations dans l’industrie et garantir une application correcte. En conséquence, il est recommandé
d’appliquer le présent document à toutes les nouvelles applications de moins de deux ans à compter de
la date de publication. Une application dans ce contexte est définie comme le point au niveau duquel le
calcul est appliqué.
Une fois la norme révisée mise en œuvre dans une application particulière, la norme précédente ne sera
plus utilisée pour cette application.
Il est important de noter que les résultats des calculs pour le pétrole brut, les produits raffinés ou les
huiles lubrifiantes (mais pas pour les GNL ou les GPL) basés sur l’ISO 91-1 et l’ISO 91-2 ne s’écartent pas
de manière significative du présent document. Le présent document reflète également les modifications
qui ont été apportées aux procédures de calcul conduisant à une meilleure précision. Les plages des
tables de facteur de correction de volume référencées dans le présent document ont été étendues (voir
Annexe A).
Si une application existante pour le pétrole brut, les produits raffinés ou les huiles lubrifiantes (mais pas
pour les GNL ou les GPL) est conforme à l’ISO 91-1 ou à l’ISO 91-2, elle doit alors être considérée comme
conforme au présent document. Une fois ce document mis en œuvre dans une application particulière,
ni l’ISO 91-1 ni l’ISO 91-2 ne doivent être utilisées dans cette application.
Néanmoins, l’utilisation de Normes internationales est facultative et la décision sur quand utiliser une
norme est une question qui est soumise à négociations entre les parties impliquées dans la transaction.
NOTE Certaines normes ISO de détermination de la masse volumique pourraient ne pas avoir de niveaux de
discrimination comparables à ceux spécifiés dans le présent document.
4 © ISO 2017 – Tous droits réservés
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ISO 91:2017(F)
Annexe A
(informative)
Modifications apportées aux normes précédentes
Entre la première publication des facteurs de correction de volume de 1980 (pour les
pétroles bruts, les pétroles raffinés et les huiles lubrifiantes tels que donnés dans l’API MPMS
Chapter 11.1-1980/ASTM D1250-80/IP 200/80) et le milieu des années 1990, un certain nombre de
besoins sont apparus dans l’industrie pétrolière et un certain nombre d’améliorations ont été mises
en place dans la technologie informatique. Ces besoins et améliorations ont conduit à apporter et
intégrer plusieurs modifications à l’API MPMS Chapter 1
...
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