1、BSI Standards PublicationBS ISO 10976:2015Refrigerated light hydrocarbonfluids Measurement ofcargoes on board LNG carriersBS ISO 10976:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 10976:2015. It supersedes BS ISO 10976:2012 which is withdrawn.The UK par
2、ticipation in its preparation was entrusted to Technical Committee PTI/12, Petroleum Measurement and Sampling.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Use
3、rs are responsible for its correct application. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 89889 1 ICS 75.180.30 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority
4、of the Standards Policy and Strategy Committee on 31 December 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 10976:2015 ISO 2015Refrigerated light hydrocarbon fluids Measurement of cargoes on board LNG carriersHydrocarbures lgers rfrigrs Mesurage des cargaisons
5、 bord des navires mthaniersINTERNATIONAL STANDARDISO10976Second edition2015-12-15Reference numberISO 10976:2015(E)BS ISO 10976:2015ISO 10976:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part o
6、f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body
7、in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 10976:2015ISO 10976:2015(E)Foreword vIntroduction vi1 Scope . 12 Normative references 13 Terms, definitions and
8、 abbreviated terms 13.1 Terms and definitions . 13.2 Abbreviated terms . 54 General operating safety precautions and regulatory requirements . 64.1 General . 64.2 Electrical equipment classification . 74.3 Electromagnetic disturbance 74.4 Maintenance 74.5 Service conditions 74.6 Compatibility 74.7 P
9、ersonnel protection . 74.8 Procedures 75 Measurement systems and equipment . 85.1 General . 85.2 Measurement equipment performance . 85.3 Calibration and certification of measurement equipment 95.4 Verification of measurement equipment between dry dockings 95.5 Inspection of measurement equipment du
10、ring transfer operations 95.6 Static measurement systems and equipment 105.6.1 General. 105.6.2 Tank capacity tables .105.6.3 Trim and list measurement . 125.6.4 Tank gassing-up tables or means of determination .125.6.5 Tank cool-down tables or means of determination 135.6.6 Liquid level measurement
11、 equipment .135.6.7 Temperature measurement equipment 175.6.8 Pressure measurement equipment 185.6.9 Custody transfer measurement system.185.7 Dynamic measurement systems and equipment .196 Measurement procedures 196.1 General 196.2 Static measurement . 206.2.1 General. 206.2.2 Measuring liquid leve
12、l 216.2.3 Loading 216.2.4 Discharge . 216.2.5 Shipboard measurements . 216.2.6 Liquid level .226.2.7 Temperature . 236.2.8 Pressure 246.2.9 CTMS . 246.2.10 Sampling. 246.2.11 Vapour return 256.3 Gas-up and cool-down quantification 256.3.1 General. 256.3.2 Inerting 256.3.3 Gas up and cool down .256.4
13、 Dynamic measurement . 26 ISO 2015 All rights reserved iiiContents PageBS ISO 10976:2015ISO 10976:2015(E)7 Cargo calculations 267.1 General 267.2 LNG volume determination . 267.2.1 General. 267.2.2 Liquid levels below lower measurable limit .277.3 LNG density determination . 27Annex A (informative)
14、LNGC design and marine operations28Annex B (informative) Additional considerations for measurement on board an LNGC 36Annex C (informative) Examples of tank capacity tables for a spherical tank .40Annex D (informative) Calculation examples .46Annex E (informative) Sampling 55Annex F (informative) Ma
15、rine measurement witnessing checklists 59Bibliography .62iv ISO 2015 All rights reservedBS ISO 10976:2015ISO 10976:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International S
16、tandards 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, als
17、o take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. I
18、n particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the element
19、s of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (
20、see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence
21、 to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 28, Petroleum products and lubricants, Subcommittee SC 5, Measurement of refrigerated hydrocarbon and non-petroleum based l
22、iquefied gaseous fuels.This second edition cancels and replaces the first edition (ISO 10976:2012), of which it constitutes a minor revision. ISO 2015 All rights reserved vBS ISO 10976:2015ISO 10976:2015(E)IntroductionThis International Standard provides accepted methods for measuring quantities on
23、liquefied natural gas (LNG) carriers for those involved in the LNG trade on ships and onshore. It includes recommended methods for measuring, reporting and documenting quantities on board these vessels.This International Standard is intended to establish uniform practices for the measurement of the
24、quantity of cargo on board LNG carriers from which the energy is computed. It details the commonly used current methods of cargo measurement, but is not intended to preclude the use or development of any other technologies or methods or the revision of the methods presented. It is intended that the
25、reader review, in detail, the latest editions of the publications, standards and documents referenced in this International Standard in order to gain a better understanding of the methods described.This International Standard is not intended to supersede any safety or operating practices recommended
26、 by organizations, such as the International Maritime Organization (IMO), the International Chamber of Shipping (ICS), the Oil Companies lnternational Marine Forum (OCIMF), the International Group of LNG Importers (GIIGNL) and the Society of International Gas Tanker and Terminal Operators (SIGTTO),
27、or individual operating companies. This International Standard is not intended to supersede any other safety or environmental considerations, local regulations or the specific provisions of any contract.The International System of units (SI) is used throughout this International Standard as the prim
28、ary units of measure since this system is commonly used in the industry for these types of cargoes. However, as some LNG carrier tanks are calibrated in US customary units and some sales and purchase agreements (SPA) are made in US customary units, both SI and US customary equivalents are shown. Pro
29、per unit conversion is intended to be applied, documented and agreed upon among all parties involved in the LNG custody transfer.vi ISO 2015 All rights reservedBS ISO 10976:2015Refrigerated light hydrocarbon fluids Measurement of cargoes on board LNG carriers1 ScopeThis International Standard establ
30、ishes all of the steps needed to properly measure and account for the quantities of cargoes on liquefied natural gas (LNG) carriers. This includes, but is not limited to, the measurement of liquid volume, vapour volume, temperature and pressure, and accounting for the total quantity of the cargo on
31、board. This International Standard describes the use of common measurement systems used on board LNG carriers, the aim of which is to improve the general knowledge and processes in the measurement of LNG for all parties concerned. This International Standard provides general requirements for those i
32、nvolved in the LNG trade on ships and onshore.2 Normative referencesThe 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
33、 the referenced document (including any amendments) applies.ISO 8310, Refrigerated hydrocarbon and non-petroleum based liquefied gaseous fuels General requirements for automatic tank thermometers on board marine carriers and floating storageISO 8943, Refrigerated light hydrocarbon fluids Sampling of
34、 liquefied natural gas Continuous and intermittent methodsISO 18132-1, 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 storageIEC 6053
35、3, Electrical and electronic installations in ships Electromagnetic compatibilityEN 1160, Installations and equipment for liquefied natural gas General characteristics of liquefied natural gasIACS, Unified Requirements E103 Terms, definitions and abbreviated terms3.1 Terms and definitionsFor the pur
36、poses of this document, the following terms and definitions apply.3.1.1absolute pressuretotal of the gauge pressure plus the pressure of the surrounding atmosphere3.1.2aeratingintroduction of fresh air with an acceptable dew point into the tank to purge inert gases and to increase the oxygen content
37、 to approximately 21 % of volume so as to ensure a breathable atmosphereINTERNATIONAL STANDARD ISO 10976:2015(E) ISO 2015 All rights reserved 1BS ISO 10976:2015ISO 10976:2015(E)3.1.3approved equipmentequipment of a design approved by a recognized authority, such as a governmental agency, classificat
38、ion society or other accredited agency which certifies the particular equipment as safe for use in a specified hazardous atmosphere3.1.4automatic tank gaugeATGinstrument that automatically measures and displays liquid levels or ullages in one or more tanks, either continuously, periodically or on de
39、mand3.1.5automatic tank thermometerATTinstrument that automatically measures and displays the temperature of the contents in a tank, continuously, periodically or on demand3.1.6boil offprocess of evaporation of a liquid resulting from heat ingress or a drop in pressure3.1.7boil-off gasvapour produce
40、d by boil off3.1.8cool downprocess of reducing the temperature of equipment, such as piping, transfer arms and tanks associated with custody transfer cargo movements, to required operating temperatures3.1.9constant pressure/floating piston sample containerCP/FP sample containersample container, usua
41、lly used for intermittent sampling, capable of maintaining constant pressure during the sampling of gas from the process line into the gas cylinderSOURCE: ISO 8943:2007, 3.4, modified3.1.10continuous samplingsampling from gasified LNG with constant flow rateSOURCE: ISO 8943:2007, 3.53.1.11dryingproc
42、ess of reducing the moisture in the ship tank by displacement or dilution with an inert gas or by the use of a drying system3.1.12filling limitfilling ratioquantity to which a tank may be safely filled, taking into account the possible expansion (and change in density) of the liquidNote 1 to entry:
43、Filling limit (i.e. volume) and filling ratio are expressed as a percentage of the total capacity of a tank.2 ISO 2015 All rights reservedBS ISO 10976:2015ISO 10976:2015(E)3.1.13gas codesregulations on the construction of ships carrying liquefied gases developed by the International Maritime Organiz
44、ationNote 1 to entry: These include the IMO International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code) (generally applies to ships built after 17 July 1986), the IMO Code for Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (GC Code
45、) (generally applies to ships built on or after 31 December 1976 but prior to 17 July 1986) and the IMO Code for Existing Ships Carrying Liquefied Gases in Bulk (generally applies to ships delivered before 31 December 1976), as applicable to each vessel.3.1.14gas sample containersample container, us
46、ually used for continuous sampling and used for the retention of the gas sample and for its transfer to an analysing instrumentSOURCE: ISO 8943:2007, 3.63.1.15gassing upprocess of replacing an inert atmosphere in a cargo tank with the vapour from shore or from another cargo tank to a suitable level
47、to allow cooling down and subsequent loading to achieve a specified environment with at least a defined methane (CH4), carbon dioxide (CO2) and oxygen (O2) content3.1.16heelamount of cargo retained in a cargo tank prior to loading or after discharge3.1.17inertingintroduction of inert gas into a tank
48、 with the object of attaining the inert condition3.1.18intermittent samplingsampling from gasified LNG with predetermined intervals or with predetermined flow amount intervalsSOURCE: ISO 8943:2007, 3.93.1.19letter of protestletter issued by any participant in a custody transfer citing any condition
49、with which issue is taken and which serves as a written record that a particular action or finding was observed/questioned at the time of occurrence3.1.20LNG carriercargo ship specifically constructed and used for the carriage of LNG in bulk3.1.21LNG sample vaporizerapparatus to completely gasify the LNG sample collected from the LNG transfer lineSOURCE: ISO 8943:2007, 3.11 ISO 2015 All rights reserved 3BS ISO 10976:2015ISO 10976:2015(E)3.1.22multiple-spot ATTmultiple-point ATTATT consisting of multiple spot temperature
