1、BRITISH STANDARD BS 7849-1: 1996 ISO 11223-1: 1995 Petroleum and liquid petroleum products Direct static measurements Contents of vertical storage tanks Part 1: Mass measurement by hydrostatic tank gaugingBS7849-1:1996 This British Standard, having been prepared under the directionof the Sector Boar
2、d for Materials and Chemicals, was published under the authority ofthe Standards Board and comesinto effect on 15 April 1996 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference PTI/12 Draft for comment 92/55171 DC ISBN 0 580 25442 9 Committees responsibl
3、e for this British Standard The preparation of this British Standard was entrusted to Technical Committee PTI/12, Petroleum measurement and sampling, upon which the following bodies were represented: Department of Trade and Industry (National Engineering Laboratory) Department of Trade and Industry
4、(Oil and Gas Office) Institute of Petroleum Salvage Association The following body was also represented in the drafting of the standard, through subcommittees and panels: GAMBICA (BEAMA Ltd.) Amendments issued since publication Amd. No. Date CommentsBS7849-1:1996 BSI 10-1999 i Contents Page Committe
5、es responsible Inside front cover National foreword ii Introduction 1 1 Scope 1 2 Normative references 1 3 Definitions 1 4 System description 3 5 Installation 5 6 Maintenance 8 7 Safety 10 Annex A (normative) Calculation overview 11 Annex B (normative) Second-order influences 15 Annex C (informative
6、) Terminology 15 Annex D (informative) Bibliography 16 Figure 1 HTG system Functional diagram 3 Figure A.1 Measurement parameters and variables Fixed-roof tank 11 Figure A.2 Measurement parameters and variables Floating-roof tank 12 Table 1 Stored parameters for HTG data processing 5 Table A.1 Examp
7、le of inventory accuracies 15 List of references Inside back coverBS7849-1:1996 ii BSI 10-1999 National foreword This British Standard has been prepared by Technical Committee PTI/12. It is identical with ISO 11223-1:1995, Petroleum and liquid petroleum products Direct static measurements Contents o
8、f vertical storage tanks Part 1: Mass measurement by hydrostatic tank gauging, published by the International Organization for Standardization (ISO). ISO 11223-1 was prepared by Technical Committee ISO/TC 28, Petroleum products and lubricants, Subcommittee SC 3, Static petroleum measurement, in whic
9、h the UK participated. The Technical Committee has reviewed the provisions of IEC 79-0:1983 (with Amendment No. 1:1987) to which normative reference is made in the text, and has decided that it is acceptable for use in conjunction with this standard. CAUTION. Attention is drawn to the Health and Saf
10、ety at Work etc. Act 1974, and the need for ensuring that the guidance given in this British Standard is used with suitable precautions. The guidance given in this British Standard is intended to be used by appropriately qualified and experienced persons or other suitable trained and/or supervised p
11、ersonnel. Normal safety precautions should be observed in the use of the guidance. Cross-references International Standard Corresponding British Standard ISO 91-1:1992 BS 6441:1993 Schedule for petroleum measurement tables (Identical) ISO 3838:1983 BS 4699:1985 Methods for determination of density o
12、r relative density of petroleum and petroleum products (pyknometer methods) (Identical) ISO 3993:1984 BS EN ISO 3993:1996 Liquefied petroleum gas and light hydrocarbons Determination of density or relative density Pressure hydrometer method (Identical) ISO 4267-2:1988 BS 7286 Method for calculation
13、of quantities of petroleum and liquid petroleum products Part 2:1990 Dynamic measurement (Identical) ISO 7078:1985 BS 6953:1988 Glossary of terms for procedures for setting out, measurement and surveying in building construction (including guidance notes) (Identical) ISO 7507-1:1993 BS 7723 Methods
14、for calibration of vertical cylindrical tanks for petroleum and liquid petroleum products Part 1:1994 Strapping method (Identical) ISO 8311:1989 BS 7627:1993 Method for calibration by physical measurement of membrane tanks and prismatic tanks in ships for carriage of refrigerated light-hydrocarbon f
15、luids (Identical)BS7849-1:1996 BSI 10-1999 iii 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 obligat
16、ions. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages1to16, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the in
17、side front cover.iv blankBS7849-1:1996 BSI 10-1999 1 Introduction Hydrostatic tank gauging (HTG) is a method for the determination of total static mass of liquid petroleum and petroleum products in vertical cylindrical storage tanks. HTG uses high-precision stable pressure sensors mounted at specifi
18、c locations on the tank shell. Total static mass is derived from the measured pressures and the tank capacity table. Other variables, such as level, observed and standard volumes and observed and reference densities, can be calculated from the product type and temperature using the established indus
19、try standards for inventory calculations. The term “mass” is used in this part of ISO 11228 to indicate mass in vacuum (true mass). In the petroleum industry it is not uncommon to use apparent mass (in air) for commercial transactions. 1 Scope This part of ISO 11223 gives guidance on the installatio
20、n, commissioning, maintenance, validation and calibration of hydrostatic tank gauging (HTG) systems for the direct measurement of static mass in petroleum storage tanks. This part of ISO 11223 is applicable to hydrostatic tank gauging systems which use pressure sensors with one port open to the atmo
21、sphere. It is applicable to the use of hydrostatic tank gauging on vertical, cylindrical, atmospheric storage tanks with either fixed or floating roofs. This part of ISO 11223 is not applicable to the use of hydrostatic tank gauging on pressurized tanks. 2 Normative references The following standard
22、s contain provisions which, through reference in this text, constitute provisions of this part of ISO 11223. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 11223 are encouraged to investigate t
23、he possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 91-1:1992, Petroleum measurement tables Part 1: Tables based on reference temperatures of15 C and 60 degrees F. ISO 91-2:199
24、1, Petroleum measurement tables Part 2: Tables based on a reference temperature of20 C. ISO 3838:1983, Crude petroleum and liquid or solid petroleum products Determination of density or relative density Capillary-stoppered pyknometer and graduated bicapillary pyknometer methods. ISO 3993:1984, Lique
25、fied petroleum gas and light hydrocarbons Determination of density or relative density Pressure hydrometer method. ISO 4266:1994, Petroleum and liquid petroleum products Measurement of temperature and level in storage tanks Automatic methods. ISO 4267-2:1988, Petroleum and liquid petroleum products
26、Calculation of oil quantities Part 2: Dynamic measurement. ISO 7078:1985, Building construction Procedures for setting out, measurement and surveying Vocabulary and guidance notes. ISO 7507-1:1993, Petroleum and liquid petroleum products Calibration of vertical cylindrical tanksPart 1: Strapping met
27、hod. IEC 79-0:1983, Electrical apparatus for explosive gas atmospheres Part 0: General requirements. API 1)Standard 2545, Standard practice for gaging petroleum and petroleum products, 1965; reapproved 1990 (ANSI/ASTM D 1085). 3 Definitions For the purposes of this part of ISO 11223, the following d
28、efinitions apply. 3.1 ambient air density density of ambient air at the tank side on which the pressure sensors are mounted 3.2 ambient air temperature representative temperature of the ambient air at the tank side on which the HTG pressure sensors are mounted 3.3 critical zone height 1) Upper limit
29、 of the critical zone. 2) Level at which one or more of the floating roof or floating blanket legs first touch the tank bottom. 3.4 critical zone level range through which the floating roof or floating blanket is partially supported by its legs 1) American Petroleum Institute.BS7849-1:1996 2 BSI 10-
30、1999 3.5 dipped volume observed volume of product, sediment and water, calculated from the dip level and the tank capacity table 3.6 floating-roof mass value of the floating-roof mass, inclusive of any mass load on the roof, manually entered in the data processor 3.7 free water level level of any wa
31、ter and sediment that exist as layers separate from the product and lie beneath the product 3.8 gauge pressure sensor sensor that uses the ambient air pressure as pressure reference 3.9 head mass total measured mass between the HTG bottom sensor and the top of the tank 3.10 head space space inside t
32、he tank, above the bottom HTG sensor, in which product and in-tank vapour are present 3.11 heel space space inside the tank, below the bottom HTG sensor 3.12 HTG reference point stable reference point from which the HTG sensor positions are measured 3.13 hydrostatic tank gauging (HTG) method of dire
33、ct measurement of liquid mass in a storage tank based on measuring static pressures caused by the liquid head above the pressure sensor 3.14 in-tank vapour density density of the gas or vapour (mixture) in the ullage space at the observed conditions (product temperature and pressure) 3.15 pin height
34、 lower limit of the critical zone; the level at which the floating roof or floating blanket rests fully on its legs 3.16 pressure sensor effective centre point on the sensor from which the hydrostatic pressure head is measured 3.17 product heel mass mass of product below the bottom HTG sensor 3.18 p
35、roduct heel volume observed volume of product below the bottom HTG sensor, calculated by subtracting the water volume from the total heel volume 3.19 product mass sum of the head mass and the product heel mass, reduced by the floating-roof mass (if applicable) and the vapour mass 3.20 product temper
36、ature temperature of the tank liquid in the region where the HTG measurements are performed 3.21 reference density density at the reference temperature 3.22 reference temperature temperature to which reference density and standard volumes are referred 3.23 tank average cross-sectional area average c
37、ross-sectional area between the elevation of the bottom HTG sensor and the dip level, over which the hydrostatic pressures are integrated in order to obtain the head mass 3.24 tank lip tank bottom plate on the outside of the tank shell 3.25 total heel volume observed volume below the bottom HTG sens
38、or, calculated from the bottom sensor elevation and the tank capacity table, corrected for observed temperature 3.26 ullage pressure absolute pressure of the air (air or vapour) inside the tank, above the productBS7849-1:1996 BSI 10-1999 3 3.27 ullage volume observed volume of vapour/air mixture in
39、the ullage space, calculated as the difference between the total tank volume and the dipped volume 3.28 vapour relative density ratio of molecular mass of vapour (mixture) to that of air (mixture) 3.29 water volume observed volume of free sediment and water, calculated from the free water level and
40、the tank capacity tables 4 System description 4.1 General A hydrostatic tank gauging (HTG) system is a tank-inventory static mass-measuring system. It uses pressure and temperature inputs, the parameters of the tank and of the stored liquid to compute the mass of the tank contents and other variable
41、s as described in Table 1 and Annex A. SeeFigure 1. Determination of the other variables shown in brackets in Figure 1 are not included in the scope of this part of ISO 11223. Figure 1 HTG system Functional diagramBS7849-1:1996 4 BSI 10-1999 4.2 Sensors 4.2.1 Pressure sensors The hydrostatic tank ga
42、uging (HTG) system consists of up to three pressure sensors mounted on the tank shell. Additionally, temperature sensors can be included to measure the temperature of the tank contents (T) and of the ambient air (T a ). An ambient air pressure sensor (p a ) may be installed for measurements requirin
43、g high accuracy. Sensor P1 is installed at or near the tank bottom. Sensor P2 is the middle pressure sensor and is required for the calculation of density and levels. If the product density is known, the HTG system can operate without sensor P2 (in the absence of P2, the density data should be manua
44、lly entered in the data processor). Sensor P2, if installed, should be at a fixed vertical distance above sensor P1. Sensor P3 is the tank ullage space pressure sensor, normally installed on the tank roof. If the tank is freely vented, the HTG system can operate without P3. P3 is not required on flo
45、ating-roof tanks. 4.2.2 Temperature sensors The product temperature is needed for: a) calculation of volumetric expansion of the tank shell; b) calculation of reference density from observed density (used in HTG systems which calculate level and density as well as mass). If the reference density is
46、known and sensor P2 is not used, a temperature sensor may still be required for calculation of observed density. The ambient air temperature is needed for: c) calculation of ambient air density; d) calculation of volumetric expansion of the tank shell; e) corrections for thermal expansion of the sen
47、sor P1 and tie bars to sensors P1 and P2. 4.2.3 System configuration The sensor configurations vary depending on the application and data required. Some of the more common variations are as follows. 4.2.3.1 Known liquid density Sensor P2 is normally used for the tank liquid density measurement. It i
48、s not required if the average liquid density is known. 4.2.3.2 Known ullage pressure Sensor P3 is not required for those tanks which are vented to atmosphere (ullage gauge pressure = 0). This includes all floating-roof tanks and all fixed-roof tanks which are freely vented or which have gauging hatc
49、hes that are not sealed. NOTE 1Tank ullage pressure on atmospheric fixed-roof tanks may differ slightly from atmospheric pressure during transfers to and from the tank. Since inventory measurements are not taken during a transfer, errors due to this effect are not significant. If the ullage pressure is known, pressure P3 can be entered into the data processor as a constant and sensor P3 omitted on nonvented tanks. 4.2.3.3 Known tank liquid temperature Tank liquid and ambient temperatures are used to correct for
