Refrigerated light hydrocarbon fluids — General requirements for automatic level gauges — Part 2: Gauges in refrigerated-type shore tanks

ISO 18132:2008 establishes the general requirements for the specification, installation and calibration/verification testing of automatic level gauges (ALG) used for refrigerated light hydrocarbon fluids, i.e., LNG and LPG, stored in bulk storage tanks on shore at pressures close to atmosphere. ISO 18132:2008 is not applicable to pressurized shore tanks.

Hydrocarbures légers réfrigérés — Exigences générales pour jauges de niveau automatiques — Partie 2: Jauges pour réservoirs côtiers de type réfrigéré

General Information

Status
Published
Publication Date
03-Mar-2008
Current Stage
9020 - International Standard under periodical review
Start Date
15-Jan-2011
Completion Date
15-Apr-2022
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INTERNATIONAL ISO
STANDARD 18132-2
First edition
2008-03-15
Refrigerated light hydrocarbon fluids —
General requirements for automatic level
gauges —
Part 2:
Gauges in refrigerated-type shore tanks
Hydrocarbures légers réfrigérés — Exigences générales pour jauges de
niveau automatiques —
Partie 2: Jauges pour réservoirs côtiers de type réfrigéré
Reference number
ISO 18132-2:2008(E)
ISO 2008
---------------------- Page: 1 ----------------------
ISO 18132-2:2008(E)
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© ISO 2008

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ii © ISO 2008 – All rights reserved
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ISO 18132-2:2008(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.

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 18132-5 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 part of ISO 18132 together with ISO 18132-1 cancels and replaces ISO 8309:1991, ISO 10574:1993 and

ISO 13689:2001, which have been technically revised.

ISO 18132 consists of the following parts, under the general title Refrigerated light hydrocarbon fluids —

General requirements for automatic level gauges:
⎯ Part 1: Gauges onboard ships carrying liquefied gases
⎯ Part 2: Gauges in refrigerated-type shore tanks
© ISO 2008 – All rights reserved iii
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ISO 18132-2:2008(E)
Introduction

Large quantities of light hydrocarbon liquids consisting of compounds having primarily one to four carbon

atoms are stored and transported in bulk as refrigerated liquids at near-atmospheric pressure. These liquids

can be divided into two main groups: liquefied natural gas (LNG) and liquefied petroleum gas (LPG).

In general, the quantity of these light hydrocarbons transferred is determined and recorded on the basis of

volume and/or mass, with the energy content calculated in calorific units. If the static-measurement method is

used, the liquid level in the tank is one of the variables which most significantly influences the determination.

In addition to the level measurement, the following parameters are needed to determine the quantity and

energy content of the light hydrocarbons in a bulk storage tank:
a) tank calibration table;
b) composition of and/or physical data for the liquefied gases and vapour;
c) vapour pressure, vapour and liquid temperature;
d) volume of liquid in the pipelines;
e) status of the flush valves for connecting lines.

The various error factors that influence the quantification based on measurements of liquid level are

considered in Annex A.
It is necessary to gauge shore tanks for one or more of the following reasons:
a) tank farm operations and process control;
b) tank inventory control;
c) where parties involved require custody transfer on shore tanks.

ISO 18132-2 removes technical dependency and ensures that the market is open to all newcomers in this

industrial sector.
iv © ISO 2008 – All rights reserved
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INTERNATIONAL STANDARD ISO 18132-2:2008(E)
Refrigerated light hydrocarbon fluids — General requirements
for automatic level gauges —
Part 2:
Gauges in refrigerated-type shore tanks
1 Scope

This part of ISO 18132 establishes the general requirements for the specification, installation and

calibration/verification testing of automatic level gauges (ALG) used for refrigerated light hydrocarbon fluids,

i.e., LNG and LPG, stored in bulk storage tanks on shore at pressures close to atmosphere.

This part of ISO 18132 is not applicable to pressurized shore tanks.
2 Normative references

The following referenced documents are indispensable for the application 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.

OIML R 85, Automatic level gauges for measuring the level of liquid in fixed storage tanks

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
automatic level gauge
ALG

level gauge that automatically measures the liquid level in a tank, either by innage or outage (ullage)

NOTE An ALG is also commonly referred to as an automatic tank gauge (ATG).
3.2
datum level
tank lowest level that corresponds to zero level and zero volume in tank table
3.3
hazardous area

area in which an explosive gas atmosphere is present, or can be expected to be present, in quantities such as

to require special precautions for the construction, installation and use of apparatus

[IEC 60079-10]
© ISO 2008 – All rights reserved 1
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ISO 18132-2:2008(E)
3.4
upper reference point

point clearly defined on the gauge hatch directly above the datum level to indicate the position (and upper

datum) from which ullaging should be carried out
NOTE It is often the top of the mounting flange of an ullage ALG.
3.5
reference height
distance between the upper reference point and the datum level
3.6
liquid level
distance between the liquid surface in a tank and the datum level
NOTE This is also known as innage.
3.7
ullage
distance between the liquid surface in a tank and the upper reference point
3.8
lower reference point

lowest measurable level located above the datum level that can be measured by an ALG

3.9
overall error

total error including the intrinsic error of an ALG and error due to the effect of installation and operating

condition
3.10
intrinsic error

error of an ALG when tested under controlled condition as specified by the manufacturer

4 Safety precautions
4.1 General

International Standards, government codes and regulations on safety and material compatibility precautions

applicable to light hydrocarbon fluids shall be followed when selecting and installing ALGs. In addition, specific

recommendations from ALG manufacturers should be followed.
4.2 Equipment precautions

4.2.1 All ALGs shall be designed and installed in accordance with applicable national standards and/or

International Standards. See OIML R 85.

4.2.2 All ALGs shall be certified for use in the hazardous-area classification that corresponds to their

installation.

4.2.3 All ALGs should be maintained in safe operating condition. Manufacturers’ maintenance and

operating instructions specific to the ALG should be complied with.
5 Conformity to national standards and regulations

In addition to conformity with this International Standard, all ALGs shall also conform to OIML R 85.

2 © ISO 2008 – All rights reserved
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ISO 18132-2:2008(E)
6 Specification of level gauges
6.1 Compatibility with process conditions in the tank

All ALGs shall be designed to withstand cryogenic and corrosive conditions, turbulence in the fluid and

vibration in the fluid and operating environment.
6.2 Provisions for routine maintenance

All ALGs shall allow routine maintenance to be performed without compromising the integrity of the tank. All

ALGs shall have provisions to allow field calibration or verification without taking the tank out of service. This

shall include means of verifying the level gauge accuracy at high and low levels.

6.3 Self-diagnostics or other measures

All ALGs shall provide self-diagnostics or other means to minimize the time required for trouble shooting,

searching for the cause(s) and eliminating the abnormal condition(s).
6.4 Countermeasures against sudden malfunctions

For ease of maintenance and of repair in case of a malfunction, ALGs should preferably be installed such that

they can be isolated from the tanks, e.g. through an isolation valve.
6.5 Compatibility for electro-magnetic and other environmental conditions

All ALGs shall be designed for electromagnetic compatibility, complying with user requirements and other

proper standards, whic
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