ISO 18132-1:2011 冷蔵炭化水素および非石油ベースの液化ガス燃料—自動タンクゲージの一般要件—パート1：海上輸送船およびフローティングストレージに搭載された液化天然ガス用の自動タンクゲージ | ページ 2

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, 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 18132-1 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 of ISO 18132-1, together with ISO 18132-3:2011, cancels and replaces ISO 18132-1:2006, which has been technically revised.

ISO 18132 consists of the following parts, under the general title Refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels — General requirements for automatic tank gauges:

• Part 1: Automatic tank gauges for liquefied natural gas on board marine carriers and floating storage
• Part 2: Gauges in refrigerated-type shore tanks
• Part 3: Automatic tank gauges for liquefied petroleum and chemical gases on board marine carriers and floating storage

Introduction

Large quantities of liquefied natural gas (LNG) are transported by LNG carriers and traded by static measurement of the cargo on board by automatic tank measurement. The LNG automatic tank measurement by a custody transfer measurement system (CTMS) involves determination of liquid/vapour interface, i.e. liquid level, average temperatures of liquid and vapour, and vapour pressure. The volumetric quantity of the LNG transferred is calculated with the tank capacity table. The transferred energy content is determined on the basis of this volume, along with the density and heating value of LNG derived from chemical composition of the representative samples.

To ensure accurate quantitative determination of LNG, custody transfer measurement usually takes place on board the LNG carrier and floating storage, not at the shore tanks. Liquid level expressed in innage or ullage is one of the important measurement parameters needed to accurately determine the LNG cargo on board.

1 Scope

This part of ISO 18132 establishes general principles for the accuracy, installation, calibration and verification of automatic tank gauges (ATGs) used for custody transfer measurement of liquefied natural gas (LNG) on board an LNG carrier or floating storage.

The LNG described in this part of ISO 18132 is either fully refrigerated (i.e. at the cryogenic condition), or partially refrigerated, and therefore the fluid is at or near atmospheric pressure.

This part of ISO 18132 also specifies the technical requirements for data collection, transmission and reception. Specific technical requirements for various automatic tank gauges and accuracy limitations are given in the annexes.

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