ISO 18132-1-2011 Refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels - General requirements for automatic tank gauges - Part 1 Automatic ta.pdf

1、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 Hydrocarbures rfrigrs et combustibles gazeux liqufis base non ptrolire Exigen

2、ces gnrales pour jauges de rservoir automatiques Partie 1: Jauges de rservoir automatiques pour gaz naturel liqufi bord des transporteurs de cargaison en mer et des stocks flottants ISO 2011 Reference number ISO 18132-1:2011(E) Second edition 2011-08-01 ISO 18132-1 INTERNATIONAL STANDARDISO 18132-1:

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 writing from either ISO at the ad

4、dress 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 18132-1:2011(E)Contents Page Forewo

5、rd 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 . 2 3.1 Compliance with safety regulations, standards, and classification rules . 2 3.2 Equipment precautions . 3 4 Design requirements 3 4

6、.1 General . 3 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 composition 4 4.8 Sealing, s

7、ecurity and unsealing 5 4.9 Redundancy 5 4.10 Data communication . 5 5 Installation . 5 5.1 General . 5 5.2 Location of installation 5 5.3 Protection of tank surface . 6 5.4 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

8、.4 Readout 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

9、 common use 8 Annex B (normative) Calibration and verification of radar-type ATG .10 Annex C (normative) Calibration and verification of capacitance-type ATG 13 Annex D (normative) Calibration and verification of float-type ATG 16 Annex E (informative) Accuracy limitations of LNG level measurement .

10、20 Annex F (informative) Uncertainty associated with accuracy test of float-type ATG .21 Bibliography .22 ISO 2011 All rights reserved iiiISO 18132-1:2011(E)iv ISO 2011 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standar

11、ds 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 organi

12、zations, 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

13、 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 %

14、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, Petro

15、leum 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

16、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 refrigerate

17、d-type shore tanks Part 3: Automatic tank gauges for liquefied petroleum and chemical gases on board marine carriers and floating storageISO 18132-1:2011(E) ISO 2011 All rights reserved v Introduction Large quantities of liquefied natural gas (LNG) are transported by LNG carriers and traded by stati

18、c 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 q

19、uantity 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 determ

20、ination 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.INTERNATIONAL STANDA

21、RD ISO 18132-1:2011(E) 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 1 Scope This part of ISO 18132 establishes general prin

22、ciples 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

23、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 accurac

24、y limitations are given in the annexes. 2 Terms, definitions and abbreviated terms For the purposes of this document, the following terms, definitions and abbreviated terms apply. 2.1 Terms and definitions 2.1.1 automatic tank gauge ATG instrument that continuously measures liquid height (dip or ull

25、age) 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. NOTE 2 Automatic tank gauges are also known as automatic level gauges (ALGs). 2.1.2 automatic tank gauging system ATG system system th

26、at 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 NOTE The ATG system can also compute the volume of LNG in tanks, using the values

27、of cargo tank temperature and pressure, draft, and tank capacity table. 2.1.3 capacitance-type ATG ATG that uses electrodes, i.e. coaxial aluminium tubes, vertically assembled in the cargo tanks to detect the dielectric constant of LNG, thereby determining the liquid level NOTE See Annex C for furth

28、er descriptions. ISO 2011 All rights reserved 12.1.4 custody transfer measurement system CTMS system that processes inputs from an ATG system, thermometers, pressure gauges, etc., and provides custody transfer measurement information on board, generating documents with regard to custody transfer of

29、LNG NOTE The ATG system can be incorporated as part of a CTMS. 2.1.5 float-type ATG ATG that uses a float to detect 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. S

30、ee Annex D for more descriptions. 2.1.6 intrinsic error inherent error error of an ATG when it is tested against a reference standard under controlled conditions as specified by the manufacturer 2.1.7 radar-type ATG microwave-type ATG ATG that utilizes an antenna to transmit electromagnetic continuo

31、us 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 measurement system EMC electromagnetic compatibility FPSO floati

32、ng production, storage and offloading FSO floating storage and offloading IACS international association of classification societies LNG liquefied natural gas LPG liquefied petroleum gas 3 General safety precautions 3.1 Compliance with safety regulations, standards, and classification rules This par

33、t 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 recommended by applicable regulatory agencies and organizations. It is the responsibility of the user of this part of ISO 18132 to establi

34、sh appropriate health and safety practices and determine the applicability of regulatory limitations prior to use. ISO 18132-1:2011(E)2 ISO 2011 All rights reserved3.2 Equipment precautions 3.2.1 General All electric components of an ATG for use in electrically classified areas shall meet the electr

35、ical 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 manufacturers maintenance instructions should be complied with. 3.2.2 Mechanical rigidi

36、ty 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 loading/unloading line in a cargo tank, appropriate measures shall be applied to pr

37、event 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 penetration for the ATG is of gastight construction in order to minimize the escape of va

38、pour 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 the LNG or its vapour shall be chemically compatible with the product, to avoid both

39、 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 and of the tanks. Additionally, level measurement errors caused by such thermal contraction shall be compensated f

40、or 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 a specific series of tests. NOTE Type approval is normally performed by a national measurement organization or c

41、lass 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 not listed in this part of ISO 18132, are considered acceptable for use in LNG custody transfer service if they

42、 are judged to be compatible with those ATGs in this part of ISO 18132 by the parties to the sales contract of LNG, and approval by national regulations. 4 Design requirements 4.1 General The following design requirements apply to all types of ATGs on LNG carriers, FPSOs and FSOs. These requirements

43、, which may be in addition to the technical specifications by the ATG manufacturer, should be met where they are applicable. ISO 18132-1:2011(E) ISO 2011 All rights reserved 3ATGs, except that of float-type, are normally connected to a computer system designed for processing their output signal, and

44、 displaying the level, as well as temperature and other parameters, thus forming a part of an ATG system. Complete design requirements 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 vap

45、our from cargo tanks, and allow routine maintenance to be performed without compromising the integrity of the tank. This includes means 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 v

46、erification of proper functioning of the ATGs at the time of each custody transfer. 4.3 Provision against sudden malfunctions ATGs shall be designed to minimize the frequency and severity of any malfunction and shall be provided with self-diagnostic features. Electronics essential for the proper fun

47、ctioning of the system should ideally be accessible from the deck and be serviceable with tanks in operation. 4.4 Dynamic response ATGs shall have sufficient dynamic response to track the liquid level during maximum tank filling or emptying rates. Float-type ATGs are usually installed in a pipe to p

48、rotect them from surge of LNG in a cargo tank. To ensure equalization of the tank level and that in the pipe, the bottom and top of the pipe shall be open and equipped with sufficient perforations throughout the length. 4.5 Minimum measurable level Because LNG carriers often retain a tank heel after

49、 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 consult tank capacity tables for liquid volumes. Internal filtering algorithms shall be provided in ATG systems to reduce the impact of interferences and also applied to readouts to en