1、Refrigerated hydrocarbon and non- petroleum based liquefied gaseous fuels General requirements for automatic tank gauges Part 3: Automatic tank gauges for liquefied petroleum and chemical gases on board marine carriers and floating storage Hydrocarbures rfrigrs et combustibles gazeux liqufis base no
2、n ptrolire Exigences gnrales pour jauges de rservoir automatiques Partie 3: Jauges de rservoir automatiques pour ptrole liqufi et gaz chimiques bord des transporteurs de cargaison en mer et des stocks flottants ISO 2011 Reference number ISO 18132-3:2011(E) First edition 2011-08-01 ISO 18132-3 INTERN
3、ATIONAL STANDARDISO 18132-3:2011(E)COPYRIGHT PROTECTED DOCUMENT ISO 2011 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 writi
4、ng from either ISO at the address below or ISOs 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 copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2011 All rights reservedISO 18132-3
5、:2011(E)Contents Page Foreword iv Introduction v 1 Scope 1 2 Terms, definitions and abbreviated terms 1 2.1 Terms and definitions . 1 2.2 Abbreviated terms . 2 3 General safety precautions . 3 3.1 Compliance with safety regulations, standards, and classification rules . 3 3.2 Equipment precautions .
6、 3 4 Design requirements 4 4.1 General . 4 4.2 Provisions for routine maintenance and verification 4 4.3 Provision against sudden malfunctions . 4 4.4 Dynamic response 4 4.5 Minimum measurable level . 4 4.6 Data filtering and averaging . 4 4.7 Compensation for variation of cargo temperatures and/or
7、composition 5 4.8 Sealing, security and unsealing 5 4.9 Redundancy 5 4.10 Data communication . 5 5 Installation . 6 5.1 General . 6 5.2 Location of installation 6 5.3 Interference of ATGs in a cargo tank . 6 6 Accuracy 6 6.1 General . 6 6.2 Calibration reference 6 6.3 Accuracy requirement 6 6.4 Read
8、out resolution . 7 7 Recertification of ATGs 7 7.1 General . 7 7.2 Method of periodic certification 7 7.3 Maximum permissible error 7 7.4 Frequency of subsequent calibration and recertification 7 8 ATG calibration records . 7 Annex A (normative) Calibration and verification of various ATGs in common
9、 use 8 Annex B (normative) Calibration and verification of radar-type ATG .10 Annex C (normative) Calibration and verification of magnetic-type ATG .13 Annex D (normative) Calibration and verification of float-type ATG 16 Annex E (normative) Calibration and verification of hydrostatic-type ATG .19 A
10、nnex F (informative) Accuracy limitations of level measurement of LPG and chemical gases .23 Annex G (informative) Uncertainty associated with accuracy test of float-type ATG 24 Bibliography .25 ISO 2011 All rights reserved iiiISO 18132-3:2011(E)iv ISO 2011 All rights reserved Foreword ISO (the Inte
11、rnational 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
12、 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 s
13、tandardization. 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
14、 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
15、 all such patent rights. ISO 18132-3 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 first edition of ISO 18132-3, together with ISO 18132-1:2011, cancel
16、s 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
17、 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 storageISO 18132-3:2011(E) ISO 2011 All rights reserved v Introduction Large quant
18、ities of liquefied petroleum and chemical gases are transported by marine carriers and traded by static measurement of the cargo on board by automatic tank measurement. The automatic tank measurement by a custody transfer measurement system (CTMS) involves determination of liquid/vapour interface, i
19、.e. liquid level, temperatures of liquid and vapour, and vapour pressure. The volumetric quantity of the liquid and gas is given by the tank capacity table, on the basis of which the delivered quantity in terms of mass is calculated. To ensure accurate quantitative determination of liquefied petrole
20、um and chemical gases, custody transfer measurement usually takes place on board the gas 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 cargo on board.INTERNATIONAL STA
21、NDARD ISO 18132-3:2011(E) Refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels General requirements for automatic tank gauges Part 3: Automatic tank gauges for liquefied petroleum and chemical gases on board marine carriers and floating storage 1 Scope This part of ISO 18132 esta
22、blishes general principles for the accuracy, installation, calibration and verification of automatic tank gauges (ATGs) used for custody transfer measurement of liquefied petroleum and chemical gases on board a gas carrier or floating storage. The part of ISO 18132 also describes the technical requi
23、rements for data collection, transmission and reception. Specific technical requirements for various automatic tank gauges and accuracy limitations are given in the annexes. 2 Terms, definitions and abbreviated terms For the purposes of this document, the following terms, definitions and abbreviated
24、 terms apply. 2.1 Terms and definitions 2.1.1 automatic tank gauge ATG instrument that continuously measures liquid height (dip or ullage) in storage tanks NOTE 1 An automatic tank gauge usually includes a level sensor, a gauge head and associated mounting hardware, and in some cases local display.
25、NOTE 2 Automatic tank gauges are also known as automatic level gauges (ALGs). 2.1.2 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 deter
26、mine the liquid level, i.e. liquid/vapour interface NOTE The ATG system can also compute the volume of LNG in tanks, using the values of cargo tank temperature and pressure, draft, and tank capacity table. 2.1.3 custody transfer measurement system CTMS system that processes inputs from an ATG system
27、, thermometers, pressure gauges, etc., and provides custody transfer measurement information on board, generating documents with regard to custody transfer of LNG NOTE The ATG system can be incorporated as part of a CTMS. ISO 2011 All rights reserved 12.1.4 float-type ATG ATG that uses a float to de
28、tect the liquid level NOTE The float is guided by a tape or wire that is connected to a drum or a ratchet in the gauge head, where the level measured is displayed locally and/or remotely. See Annex D for more descriptions. 2.1.5 hydrostatic-type ATG hydrostatic tank gauge HTG ATG that determines liq
29、uid level based on the differential of pressures measured by the pressure sensors vertically installed in a cargo tank with temperature sensors NOTE See Annex E for further descriptions. 2.1.6 intrinsic error inherent error error of an ATG when it is tested against a reference standard under control
30、led conditions as specified by the manufacturer 2.1.7 magnetic-type ATG ATG that measures the liquid level by magnetic reed switches with a float sensor including magnets, or by magneto-strictive principle NOTE See Annex C for further descriptions. 2.1.8 radar-type ATG microwave-type ATG ATG that ut
31、ilizes an antenna to transmit electromagnetic continuous waves toward the liquid in a tank, and to receive electromagnetic waves which are reflected at the surface of the liquid NOTE See Annex B for further descriptions. 2.2 Abbreviated terms ATG automatic tank gauge CTMS custody transfer measuremen
32、t system EMC electromagnetic compatibility FPSO floating production, storage and offloading FSO floating storage and offloading HTG hydrostatic-type ATG IACS international association of classification societies LNG liquefied natural gas LPG liquefied petroleum gas ISO 18132-3:2011(E)2 ISO 2011 All
33、rights reserved3 General safety precautions 3.1 Compliance with safety regulations, standards, and classification rules This part of ISO 18132 may involve hazardous materials, operations, and equipment. This part of ISO 18132 does not purport to supersede any safety or operating practices recommende
34、d by applicable regulatory agencies and organizations. It is the responsibility of the user of this part of ISO 18132 to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use. 3.2 Equipment precautions 3.2.1 General All electric comp
35、onents of an ATG for use in electrically classified areas shall meet the electrical area classification (see IEC 60079-0). They shall conform to applicable sections of the national and/or international electrical safety standards. All ATGs shall be maintained in safe operating condition and manufact
36、urers maintenance instructions should be complied with. 3.2.2 Mechanical rigidity All ATGs shall be capable of withstanding the pressure, temperature, operating, and environmental conditions likely to be encountered in the service. Where an ATG is installed near a submerged pump or the end of a load
37、ing/unloading line in a cargo tank, appropriate measures shall be applied to prevent the ATG from being affected by the vortex or vaporization (i.e. boiling) of cargo caused by the cargo loading or cargo unloading operations. 3.2.3 Gastight design ATGs shall be designed such that the tank penetratio
38、n for the ATG is of gastight construction in order to minimize the escape of vapour from the cargo tank. The gauge head or transmitter located on the deck shall be so constructed as to minimize leakage of vapour from the tank. 3.2.4 Compatibility with cargo All parts of the ATG in contact with lique
39、fied petroleum and chemical gases or their vapour shall be chemically compatible with the product, to avoid both product contamination and corrosion of the ATG. 3.2.5 Tolerance against low temperatures ATGs shall be designed to withstand the low-temperature thermal contraction of their components an
40、d of the tanks. Additionally, level measurement errors caused by such thermal contraction shall be compensated for in an appropriate manner. 3.2.6 Type approval The design and installation of ATGs shall be subject to type approval. Type approval is normally issued after an ATG has been subjected to
41、a specific series of tests. NOTE Type approval is normally performed by a national measurement organization or class society for environmental considerations (see IACS Unified Requirements E 10). 3.2.7 Use of an ATG in custody transfer service ATGs, including those which use measurement technologies
42、 not listed in this part of ISO 18132, are considered acceptable for use in the custody transfer service of liquefied petroleum and chemical gases if they are judged to be compatible with those ATGs in this part of ISO 18132 by the parties to the sales contract of liquefied gases, and approval by na
43、tional regulations. ISO 18132-3:2011(E) ISO 2011 All rights reserved 34 Design requirements 4.1 General The following design requirements apply to all types of ATGs on LPG carriers, FPSOs and FSOs. These requirements, which may be in addition to the technical specifications by the ATG manufacturer,
44、should be met where they are applicable. ATGs, except that of float-type, are normally connected to a computer system designed for processing their output signal, and displaying the level, as well as temperature and other parameters, thus forming a part of an ATG system. Complete design requirements
45、 for the ATG system are not specified in this part of ISO 18132. 4.2 Provisions for routine maintenance and verification All ATGs shall be capable of withstanding vapour from cargo tanks, and allow routine maintenance to be performed without compromising the integrity of the tank. This includes mean
46、s of verification whereby the ATG accuracy can be checked at high and low tank levels with the tank in service. ATG shall be equipped with a provision which enables verification of proper functioning of the ATGs at the time of each custody transfer. 4.3 Provision against sudden malfunctions ATGs sha
47、ll be designed to minimize the frequency and severity of any malfunction and shall be provided with self-diagnostic features. Electronics essential for the proper functioning of the system should ideally be accessible from the deck and be serviceable with tanks in operation. 4.4 Dynamic response ATG
48、s shall have sufficient dynamic response to track the liquid level during maximum tank filling or emptying rates. Float-type ATGs are often installed in a pipe to protect them from surge of liquefied gas in a cargo tank. To ensure equalization of the tank level and that in the pipe, the bottom and t
49、op of the pipe shall be open and equipped with sufficient perforations throughout the length. 4.5 Minimum measurable level Because liquefied gas carriers often retain a tank heel after a discharge, the ATG shall be able to measure levels as near to the bottom of the tank as possible. 4.6 Data filtering and averaging The ATG system shall be designed to automatically scan, average/filter and display the level in each cargo tank. A common practice is to use five consecutive readings to compute an averaged liquid level used to
