ISO 4266-5:2024

International
Standard
ISO 4266-5
Second edition
Petroleum and liquid petroleum
2024-09
products — Measurement of level
and temperature in storage tanks by
automatic methods —
Part 5:
Measurement of temperature in
marine vessels
Pétrole et produits pétroliers liquides — Mesurage du niveau et
de la température dans les réservoirs de stockage par méthodes
automatiques —
Partie 5: Mesurage de la température dans les citernes de navire
Reference number
© ISO 2024
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Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative reference . 1
3 Terms and definitions . 1
4 Precautions . 2
4.1 Safety precautions .2
4.2 Equipment precautions .2
4.3 General precautions .2
5 Accuracy . 3
5.1 General .3
5.2 Intrinsic error of ATTs .3
5.3 Calibration prior to installation .3
5.3.1 General .3
5.3.2 ATT calibrated as a system .4
5.3.3 ATT calibrated by components .4
5.3.4 Multiple-point ATTs .4
5.3.5 Uncertainty of the reference .4
5.4 Error caused by installation and operating conditions .4
5.5 Overall accuracy . .4
5.5.1 General .4
5.5.2 Use of ATT for fiscal/custody transfer purposes .5
6 Selection of ATTs . 5
6.1 General .5
6.2 ATTs for fiscal/custody transfer purpose .5
7 Description of ATT equipment — Electrical temperature elements . 6
7.1 General .6
8 Installation of marine ATTs . 6
8.1 General .6
8.2 Location of temperature-sensing element(s) .6
8.3 Location of manual (temperature) gauge hatch .6
8.4 Temperature measurement of inerted tanks .6
9 Calibration and on-board verification of marine ATTs . 7
9.1 General .7
9.2 Calibration of single-point temperature element ATTs for fiscal/custody transfer
purposes .7
9.2.1 Calibration prior to installation .7
9.2.2 Initial verification at shipyard or during sea trials .7
9.3 Calibration of multiple-point ATTs for fiscal/custody transfer purposes .8
9.3.1 Calibration prior to installation .8
9.3.2 Initial on-board verification at shipyard or during sea trials .8
9.4 Subsequent verification of ATTs .9
9.4.1 General .9
9.4.2 Frequency of subsequent verification .9
9.4.3 Record keeping .9
10 Data communication and receiving . 10
Annex A (informative) Accuracy limitations of tank-temperature measurements on board
marine vessels .11
Bibliography .12

iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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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 www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels
and lubricants from natural or synthetic sources, Subcommittee SC 2, Measurement of petroleum and related
products.
This second edition cancels and replaces the first edition (ISO 4266-5:2002), which has been technically
revised.
The main changes are as follows:
— slightly modified the scope;
— updated normative references;
— expanded safety precautions;
— clarified the expectations for calibrated equipment throughout the document;
— added references to the bibliography.
A list of all parts in the ISO 4266 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
International Standard ISO 4266-5:2024(en)
Petroleum and liquid petroleum products — Measurement
of level and temperature in storage tanks by automatic
methods —
Part 5:
Measurement of temperature in marine vessels
1 Scope
This document provides requirements and guidance on the selection, accuracy, installation, commissioning,
calibration and verification of automatic tank thermometers (ATTs) in fiscal/custody transfer applications.
The ATT is used for measuring the temperature of petroleum and liquid petroleum products having a Reid
vapour pressure less than 100 kPa, stored in cargo tanks on board marine vessels (i.e. tankers and barges).
This document is not applicable to the measurement of temperature in refrigerated storage tanks, or
pressurized cargo tanks on board marine vessels, which is covered in ISO 8310.
2 Normative reference
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 amendment
...