# BS ISO 13740-1998 (1999)

BRITISH STANDARD BS ISO 13740:1998 Crude petroleum and petroleum products — Transfer accountability — Assessment of vessel experience factor on loading (VEFL) and vessel experience factor on discharging (VEFD) of ocean-going tanker vessels ICS 75.180.30BSISO13740:1998 This British Standard, having been prepared under the directionof the Sector Committeefor Materials and Chemicals, was published underthe authority of the Standards Committee and comesinto effect on 15January1999 © BSI 05-1999 ISBN 0 580 32000 6 National foreword This British Standard reproduces verbatim ISO13740:1998 and implements it as the UK national standard. The UK participation in its preparation was entrusted by Technical Committee PTI/12, Petroleum measuring and sampling, to Subcommittee PTI/12/3, Bulk cargo transfer, which has the responsibility to: — aid enquirers to understand the text; — present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; — monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theISO title page, pages ii to iv, pages 1 to 4, an inside back cover and abackcover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSISO13740:1998 © BSI 05-1999 i Contents Page National foreword Inside front cover Foreword iii Text of ISO13740 1 ii blankBSISO13740:1998 ii © BSI 05-1999 Contents Page Foreword iii Introduction 1 1 Scope 1 2 Normative reference 1 3 Method1 1 4 Method2 2 5 Expression of results 3 6 Assessment report 3 Annex A (informative) Example of the calculation procedure using method 1 4 Annex B (informative) Example of the calculation procedure using method 2 Inside back cover Table 1 — Critical values at the 95% probability level 3 Table A.1 — Data for examples of calculations by Methods 1 and 2 4BSISO13740:1998 © BSI 05-1999 iii 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. 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. International Standard ISO 13740 was prepared by Technical Committee ISO/TC 28, Petroleum products and lubricants, Subcommittee SC 6, Bulk cargo transfer, accountability, inspection and reconciliation. Annex A and Annex B of this International Standard are for information only. Descriptors: Crude oil, petroleum products, petroleum products transport, tanker ships, loading, tests, determination, quantity, rules of calculation, volume measurement.iv blankBSISO13740:1998 © BSI 05-1999 1 Introduction For a particular vessel, an approximately constant ratio can be established between the quantity of oil measured on board the vessel and the corresponding measurement at a shore terminal. Vessel experience factors are used as a means for monitoring Bills of Lading and/or outturn quantities. 1 Scope This International Standard specifies two methods for establishing the average ratio between the quantity of oil measured on board an ocean-going tanker vessel and the corresponding quantity measured at a terminal. Method 1 is commonly used in the field. Method 2 is more statistically rigorous and is the referee method to be used in cases of dispute. Either method can be used on loading the vessel [vessel experience factor on loading (VEFL)] or on discharging the vessel [vessel experience factor on discharging (VEFD)]. This International Standard applies to shore terminals that determine volumes received or delivered using static tank measurements or dynamic meter measurements carried out according to good accepted industry practice. It also applies to floating storage or off-shore facilities that load ocean-going vessels using dynamic meter measurements carried out according to good accepted industry practice. This International Standard is not applicable to the assessment of the vessel experience factors of barges. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 8697:—, Crude petroleum and petroleum products — Transfer accountability — Assessment of on board quantity (OBQ) and quantity remaining on board (ROB) 1) . 3 Method 1 3.1 Procedure for collection of data 3.1.1 General All the data shall be collected in, or converted to, the same unit of quantity. Conversions from observed data shall be made using the same petroleum measurement tables. Data shall not be collected for a) the first voyage after the vessel has been constructed; b) voyages for which the terminal measurements are not available; c) voyages prior to structural modifications which affect the cargo capacity of the vessel. Data collected for VEFL shall not be used for the calculation of VEFD. Data collected for VEFD shall not be used for the calculation of VEFL. 3.1.2 Data for the calculation of VEFL Obtain from ship’s records, for the maximum number of voyages which conform to3.1.1, the total quantity measured on board the vessel after loading and the corresponding on board quantity (OBQ), measured in accordance with ISO8697. For these voyages, obtain from available records the total quantity measured as being delivered by the shore terminal. As some sets of data may be rejected in the calculation procedure, it is advisable to obtain data from more than5voyages to ensure that a valid result is obtained. NOTEFor practical reasons, data from no more than the20 most recent voyages should be collected. 3.1.3 Data for the calculation of VEFD Obtain from ship’s records, for the maximum number of voyages which conform to 3.1.1, the total quantity measured on board the vessel prior to discharge and the corresponding quantity remaining on board (ROB), measured in accordance with ISO 8697. For these voyages, obtain from available records the total quantity measured as received by the shore terminal. As some sets of data may be rejected in the calculation procedure, it is advisable to obtain data from more than5 voyages to ensure that a valid result is obtained. NOTEFor practical reasons, data from no more than the20 most recent voyages should be collected. 1) To be published.BSISO13740:1998 2 © BSI 05-1999 3.2 Calculations NOTEAn example of the use of this calculation procedure is given in Annex A. 3.2.1 The VEFL and/or the VEFD shall be calculated in accordance with 3.2.2 to 3.2.9 using the data collected in 3.1.2 and/or 3.1.3. 3.2.2 For each set of data, calculate the total quantity of cargo measured on board the vessel (t v ) using the equation t v= Quantity of cargo measured on board the vessel minus OBQ or ROB. 3.2.3 For each voyage, calculate the ratio, r, of the quantities t vand t sto five places of decimals using the equation where t sis the quantity of cargo measured at the terminal. 3.2.4 Sum all the vessel cargo quantities (t v ) to obtain T v . 3.2.5 Sum all the terminal quantities (t s ) to obtain T s . 3.2.6 Calculate the average ratio, R, of the total quantities to five places of decimals, using the equation. 3.2.7 Compare the individual ratios from 3.2.3 with the ratio of the total. Reject the data from any voyages in which the individual ratios differ from the total by more than ± 0,3%. 3.2.8 For the data from a minimum of5 remaining voyages, separately sum the ship quantities and the shore quantities. Calculate the ratio of these total quantities to five places of decimals, round to four places and record it. 3.2.9 If data from less than5 voyages remain, the VEFL/VEFD shall not be calculated. 4 Method 2 4.1 Principle A statistical rejection procedure is applied to the collected data to eliminate any outliers. The remaining data is used to calculate the VEFL/VEFD. 4.2 Procedure for collection of data 4.2.1 General All data shall be collected in, or converted to, the same unit of quantity. Conversions from observed data shall be made using the same petroleum measurement tables. Data shall only be collected if terminal measurements are also available. 4.2.2 Data for the calculation of VEFL Obtain from ship’s records, for the maximum number of voyages which conform to 3.1.1, the total quantity measured on board the vessel after loading and the corresponding on board quantity (OBQ) measured in accordance with ISO8697. For these voyages, obtain from available records the total quantity measured as delivered by the shore terminal. As some sets of data may be rejected in the calculation procedure, it is advisable to obtain data from more than8 voyages to ensure that a valid result is obtained. NOTEFor practical reasons, data from no more than the20 most recent voyages should be collected. 4.2.3 Data for the calculation of VEFD Obtain from ship’s records, for the maximum number of voyages which conform to 3.1.1, the total quantity measured on board the vessel prior to discharge and the corresponding quantity remaining on board (ROB), measured in accordance with ISO8697. For these voyages, obtain from available records the total quantity measured as received by the shore terminal. As some sets of data may be rejected in the calculation procedure, it is advisable to obtain data from more than8 voyages to ensure that a valid result is obtained. NOTEFor practical reasons, data from no more than the20 most recent voyages should be collected. 4.3 Calculations NOTEAn example of the use of this calculation procedure is given in Annex B. 4.3.1 The VEFL and/or the VEFD shall be calculated in accordance with 4.3.2 to 4.3.9 using the data collected in 4.2.2 and/or 4.2.3. 4.3.2 For each set of data, calculate the total quantity of cargo measured on board the vessel (t v ) using the equation t v= Quantity of cargo measured on board the vessel minus OBQ or ROB 4.3.3 For each voyage, calculate the ratio, r, of the quantities t vand t sto five places of decimals using the equation where t sis the quantity of cargo measured at the terminal. r t v t s ---- = R T v T s ------ = r t v t s ---- =BSISO13740:1998 © BSI 05-1999 3 List the ratios in ascending order and label them r 1to r n . 4.3.4 If the number of ratios listed is from8 to10, calculate R L(low) and R H(high) using the equations where n is the number of voyages for which data is being considered. 4.3.5 If the number of ratios listed is from11 to13, calculate R Land R Husing the equations 4.3.6 If the number of ratios listed is from14 to25, calculate R Land R Husing the equations 4.3.7 Compare R Land R Hwith the critical value given in Table 1. Reject from the list (see 4.3.3) any ratios for which the R Land R Hvalues are greater than the critical value given in Table 1. If any ratios are rejected, relabel the remaining ratios in ascending order as r 1to r n . 4.3.8 Repeat 4.3.5 to 4.3.7 until no more ratios are rejected. If the number of ratios falls to8,9 or10, calculate R Land R Husing the equations in 4.3.4: Record the number of ratios, N, left in the list. If the number of ratios falls below8, discontinue Method2 since the quality of the data cannot support this statistical list. Table 1 — Critical values at the 95% probability level 4.3.9 Calculate the statistical mean, r, to five places of decimals using the sum of the ratios divided by the number of ratios used: Round the mean, r, to four places of decimals and record it. 5 Expression of results Report the VEFL and/or the VEFD of the vessel calculated in 3.2.8 or 4.3.9 to four decimal places. 6 Assessment report The assessment report shall contain at least the following information: a) a reference to this International Standard; b) all data used to establish the vessel experience factor; c) all details necessary to identify the vessel assessed; d) the method used for the assessment (i.e.Method 1 or Method 2); e) the result of the assessment in accordance with clause 5; f) the date of the assessment. n Critical value n Critical value 3 4 5 6 7 8 9 10 11 12 13 0,941 0,765 0,642 0,560 0,507 0,554 0,512 0,477 0,576 0,546 0,521 14 15 16 17 18 19 20 21 22 23 24 25 0,546 0,525 0,507 0,490 0,475 0,462 0,450 0,440 0,430 0,421 0,413 0,406BSISO13740:1998 4 © BSI 05-1999 Annex A (informative) Example of the calculation procedure using method 1 For the purposes of this example, the data according to 3.1, expressed in cubic metres, is given in Table A.1. Table A.1 — Data for examples of calculations by Methods 1 and 2 Calculate the quantity of cargo measured on board the vessel minus the OBQ or ROB (t v ). Calculate the voyage ratios, r, by dividing t v by t s . Sum the values (t v ) and record the result: T v= 250744 m 3 Sum the values (t s ) and record the result: T s= 250366 m 3 Calculate the ratio, R, of the total quantities by dividing T vby T s : R = 1,00151 Calculate 0,3% of R = 0,00300 Delete ratios (r) lying outside the range 1,001 51±0,003, i.e. 1,00451 to 0,99851. Thus ratios (r) for voyages2 and8 are deleted. Recalculate the ratio, R, to four decimal places, for the remaining8 voyages: R = 1,000 9 and report it as the vessel experience factor (loading or discharging