ISO 8310:2012

Refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels - General requirements for automatic tank thermometers on board marine carriers and floating storage

ISO 8310:2012 specifies the essential requirements and verification procedures for automatic tank thermometers (ATTs) consisting of platinum resistance thermometers (PRT) and an indicating device used for custody transfer measurement of liquefied natural gas, liquefied petroleum and chemical gases on board ships. Temperature detectors other than PRT are considered acceptable for use in the custody transfer service of liquefied gases if they meet the performance requirements of ISO 8310:2012 and are approved by national regulations.

Hydrocarbures réfrigérés et combustibles gazeux liquéfiés à base non pétrolière — Exigences générales pour les thermomètres de réservoir automatiques à bord des transporteurs de cargaison en mer et des stocks flottants

General Information

• Status: Published
• Publication Date: 04-Nov-2012
• ICS: 75.180.30 - Volumetric equipment and measurements
• Technical Committee: ISO/TC 28/SC 5 - Measurement of refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels
• Drafting Committee: ISO/TC 28/SC 5 - Measurement of refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels
• Current Stage: 9093 - International Standard confirmed
• Start Date: 06-Jun-2023
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 8310:1991 - Refrigerated light hydrocarbon fluids - Measurement of temperature in tanks containing liquefied gases - Resistance thermometers and thermocouples
• Effective Date: 19-Mar-2011

Overview

ISO 8310:2012 - Refrigerated hydrocarbon and non‑petroleum based liquefied gaseous fuels - specifies general requirements for automatic tank thermometers (ATTs) used on board marine carriers and floating storage (FPSO/FSO). The standard covers ATTs that typically use platinum resistance thermometers (PRTs) and an indicating device for custody transfer measurement of liquefied natural gas (LNG), liquefied petroleum gas (LPG) and other refrigerated liquefied gases. It defines essential design, safety, calibration and verification procedures to ensure accurate temperature measurement (ITS‑90 referenced) for volumetric and mass calculations.

Key Topics and Requirements

• Scope and purpose: Requirements for ATTs used in custody transfer and integration into custody transfer measurement systems (CTMS).
• Temperature sensors: PRTs (three‑ or four‑wire) per IEC 60751 are preferred; manufacturers must calibrate each PRT and declare nominal resistance and constants. Routine production tests include insulation resistance, sheath integrity, dimensional and tolerance acceptance.
• Indicating devices: High‑impedance analogue inputs to minimize measurement error; consideration of electronic transmission and display.
• Installation & mounting: Minimum of three PRTs per tank (IGC Code requirement); placement and number depend on tank size/height. Provisions against pump vortexing, spray, sloshing and thermal contraction are required.
• Safety & environmental design: Gastight construction for gas‑dangerous zones, electrical area classification compliance, chemical compatibility with cargo, mechanical rigidity and low‑temperature tolerance.
• Calibration & verification: Factory calibration, post‑installation verification, and periodic accuracy checks are mandated; records of ATT calibration must be maintained.
• Performance aspects: Dynamic response, measurable temperature range, data processing and reporting, compensation for cargo temperature variation, sealing/security, redundancy and data communication.
• Type approval: Design and installation subject to approval by a national metrology institute (NMI) or classification society.

Applications - who uses it and why

• Shipowners and operators of LNG/LPG carriers, FPSOs and FSOs implementing reliable custody transfer measurement.
• Instrument manufacturers and suppliers designing and producing ATTs, PRTs and indicating devices.
• Classification societies, national metrology institutes and surveyors responsible for type approval, installation acceptance and verification.
• Terminal operators and trading parties relying on temperature accuracy for volumetric and energy/mass reconciliation during cargo transfers.

Related Standards

• IEC 60751 - Industrial platinum resistance thermometers and platinum temperature sensors (normative reference).
• IGC Code - requirements for ships carrying liquefied gases in bulk (installation and safety context).
• IACS Unified Requirements E10 - electrical considerations for equipment in hazardous zones.

ISO 8310:2012 is essential for ensuring accurate, safe and verifiable temperature measurement in refrigerated liquefied gas marine operations, supporting fair custody transfer and regulatory compliance.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 8310
Second edition
2012-11-01
Refrigerated hydrocarbon and non-
petroleum based liquefied gaseous
fuels — General requirements for
automatic tank thermometers on board
marine carriers and floating storage
Hydrocarbures réfrigérés et combustibles gazeux liquéfiés à base non
pétrolière — Exigences générales pour les thermomètres de réservoir
automatiques à bord des transporteurs de cargaison en mer et des
stocks flottants
Reference number
©
ISO 2012
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
address below or ISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Safety precautions . 2
4.1 General . 2
4.2 Equipment precautions . 3
5 Design requirements . 3
5.1 General . 3
5.2 Temperature sensors . 3
5.3 Indicating device . 4
5.4 Installation . 4
5.5 Provisions for routine maintenance and verification . 4
5.6 Provision against sudden malfunctions . 4
5.7 Dynamic response . 4
5.8 Measurable range . 4
5.9 Data processing and reporting . 4
5.10 Compensation for variation of cargo temperatures . 5
5.11 Sealing, security and unsealing . 5
5.12 Redundancy . 5
5.13 Data communication . 5
6 Calibration and accuracy verification . 5
6.1 General . 5
6.2 Calibration reference . 6
6.3 Calibration and accuracy verification at factory . 6
6.4 Calibration and accuracy verification after installation . 6
6.5 Periodic accuracy verification . 9
7 Accuracy requirement . 9
7.1 Overall error . 9
7.2 Resolution .10
8 ATT calibration records .10
Annex A (informative) Information on platinum resistance thermometers .11
Bibliography .12
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
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.
ISO 8310 was prepared by Technical Committee ISO/TC 28, Petroleum products and lubricants,
Subcommittee SC 5, Measurement of refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels.
This second edition cancels and replaces the first edition (ISO 8310:1991), which has been technically revised.
iv © ISO 2012 – All rights reserved

Introduction
Large quantities of liquefied natural gas (LNG), liquefied petroleum gas (LPG) and other liquefied
gases are usually transported by marine carriers dedicated for these applications and traded based on
static measurement on board by automatic tank measurement. Such an automatic tank measurement
may be a part of the custody transfer measurement system (CTMS) which involves determination of
liquid/vapour interface, i.e. liquid level, average temperatures of liquid and vapour, and vapour pressure.
The volumetric quantity of the liquid and gas is then computed with the tank capacity table based on
which the delivered quantity in terms of energy content or mass is calculated.
In most cases, shore tank measurement is not used due to the active and dynamic conditions of the
shore tank operations. In the absence of other means of acceptable measurement, custody transfer
measurement usually takes place on board the carrier or floating production storage offshore (FPSO)
and floating storage offshore (FSO). Liquid cargo density is very sensitive to temperature; therefore,
obtaining accurate temperature readings is extremely important. For example, a change of 0,2 °C for
liquid methane cargo results in a change in density of approximately 0,07 %.
This International Standard also discusses use of automatic tank thermometers on board marine vessels for
other volatile, non-petroleum liquids in fully refrigerated conditions. Many of these non-petroleum liquids,
such as di-methyl ether (DME) are measured in a similar manner to that used for fully refrigerated LPGs.
Values of temperature in this International Standard are in terms of the International Temperature
Scale of 1990, ITS-90. Temperatures in degrees Celsius are denoted by the symbol t.
INTERNATIONAL STANDARD ISO 8310:2012(E)
Refrigerated hydrocarbon and non-petroleum based
liquefied gaseous fuels — General requirements for
automatic tank thermometers on board marine carriers
and floating storage
1 Scope
This International Standard specifies the essential requirements and verification procedures for
automatic tank thermometers (ATTs) consisting of platinum resistance thermometers (PRT) and an
indicating device used for custody transfer measurement of liquefied natural gas, liquefied petroleum
and chemical gases on board ships. Temperature detectors other than PRT are considered acceptable for
use in the custody transfer service of liquefied gases if they meet the performance requirements of this
International Standard and are approved by national regulations.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
IEC 60751, Industrial platinum resistance thermometers and platinum temperature sensors
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
automatic tank gauge
ATG
automatic level gauge
ALG
instrument that automatically measures and displays liquid levels or ullages in one or more tanks, either
continuously, periodically or on demand
3.2
automatic tank gauging system
ATG system
system that includes ATGs at the cargo tanks and control/display unit that processes and displays
output signals from the ATG along with any other parameters required to determine the liquid level, i.e.
liquid/vapour interface
3.3
automatic tank thermometer
ATT
automatic tank temperature system
instrument that continuously measures temperature in cargo tanks
NOTE 1 An ATT typically includes temperature sensors, such as PRTs, field-mounted transmitters for electronic
signal transmission, and indicating device(s).
NOTE 2 ATTs on liquefied gas carriers are usually multiple-point ATTs which consist of three or more
temperature sensors, such as PRTs, to measure the temperatures at selected heights in the cargo tank.
3.4
custody transfer measurement system
CTMS
system that processes inputs from an ATG system, an ATT, pressure gauges, etc. and provides custody
transfer measurement information on board, generating documents with regard to custody transfer of
liquefied gases
NOTE An ATT can be incorporated as part of a CTMS.
3.5
gas dangerous space or zone
space or zone defined by the International Code for the Construction and Equipment of Ships Carrying
Liquefied Gases in Bulk (IGC Code)
3.6
indicating device
displaying device
set of components of a measuring instrument intended to indicate the measured value
3.7
inherent error
intrinsic error
error of a gauge when it is tested against a reference standard under controlled conditions as specified
by the manufacturer
3.8
nominal resistance
expected resistance R of a PRT at 0 °C, declared by the manufacturer and shown in the thermometer
marking, usually rounded to the nearest ohm
3.9
nominal temperature/resistance relationship
relationship between temperature and resistance of a nominal PRT
3.10
platinum resistance thermometer
PRT
resistance temperature detector
RTD
temperature-responsive device consisting of one or more sensing platinum resistors within a
protective sheath, internal connecting wires and external terminals to permit connection of electrical
measurement instruments
3.11
uncertainty
non-negative parameter characterizing the dispersion of the quantity values being attributed to a
measurand, based on the information used
4 Safety precautions
4.1 General
Nothing contained in this International Standard is intended to supersede any regulatory requirements
or recommended operating practices issued by organizations such as the International Maritime
Organization (IMO), International Chamber of Shipping (ICS), Oil Companies International Marine
Forum (OCIMF), International Association of Classification Societies (IACS) and individual operating
companies, nor is this International Standard intended to conflict with any safety or environmental
considerations, local regulations, or the specific provisions of any contract.
2 © ISO 2012 – All rights reserved

4.2 Equipment precautions
4.2.1 General
All electric components of an ATT for use in electrically classified areas shall meet the electrical area
classification. They shall conform to applicable sections of the national and/or international electrical
safety standards. All ATTs shall be maintained in a safe operating condition and manufacturers’
maintenance instructions should be complied with.
4.2.2 Mechanical rigidity
All ATTs shall be capable of withstanding the pressure, temperature, dynamic loads generated from
rolling/pitching, and sloshing from environmental conditions likely to be encountered in the service.
Where a PRT is installed near a submerged pump or the end of a loading/unloading line in a cargo
tank, appropriate measures shall be applied to prevent the ATT from being affected by the vortex or
vaporization, i.e. boiling, of cargo caused by cargo loading or cargo unloading operations. In addition, all
PRTs shall be mounted such that they are not affected by the spray of liquefied gas whenever the spray
nozzles are in operation.
4.2.3 Gastight design
All parts of ATTs exposed to a gas dangerous space or zone shall be of gastight construction.
4.2.4 Compatibility with cargo
All parts of the ATT in contact with liquefied gases or their vapour shall be chemically compatible with
the product, to avoid both product contamination and corrosion of the ATT.
4.2.5 Tolerance against low temperatures
ATTs shall be designed to measure the low temperatures encountered in refrigerated liquefied gas
service. They shall also be designed to withstand the low-temperature thermal contraction of their
components and of the tanks. Additionally, change in the height of PRT in the tanks by such thermal
contraction shall be compensated for in an appropriate manner.
4.2.6 Type approval
The design and installation of ATTs shall be subject to the approval of a national metrology institute (NMI)
[10]
or class society. For electrical considerations, refer to IACS Unified Requirements E10 . Type approval
is normally issued after an ATT has been subjected to a s
...