1、BRITISH STANDARDBS ISO 18132-2:2008Refrigerated light hydrocarbon fluids General requirements for automatic level gauges Part 2: Gauges in refrigerated-type shore tanksICS 75.180.30g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g3
2、6g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS ISO 18132-2:2008This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 May 2008 BSI 2008ISBN 978 0 580 57513 6National forewordThis British Standard is the UK imp
3、lementation of ISO 18132-2:2008. Together with ISO 18132-1:2006, it supersedes BS 7701:1993 (which implemented ISO 10574) and BS ISO 13689:2001 which are withdrawn. The UK participation in its preparation was entrusted to Technical Committee PTI/12, Petroleum measurement and sampling.A list of organ
4、izations 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. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligatio
5、ns.Amendments/corrigenda issued since publicationDate CommentsReference numberISO 18132-2:2008(E)INTERNATIONAL STANDARD ISO18132-2First edition2008-03-15Refrigerated light hydrocarbon fluids General requirements for automatic level gauges Part 2: Gauges in refrigerated-type shore tanks BS ISO 18132-
6、2:2008ii iiiForeword 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 f
7、or 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
8、 all matters of electrotechnical standardization. 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 a
9、re 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. 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
10、responsible for identifying any or all such patent rights. ISO 18132-5 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 part of ISO 18132 together with IS
11、O 18132-1 cancels and replaces ISO 8309:1991, ISO 10574:1993 and ISO 13689:2001, which have been technically revised. ISO 18132 consists of the following parts, under the general title Refrigerated light hydrocarbon fluids General requirements for automatic level gauges: Part 1: Gauges onboard ships
12、 carrying liquefied gases Part 2: Gauges in refrigerated-type shore tanks BS ISO 18132-2:2008iv Introduction Large quantities of light hydrocarbon liquids consisting of compounds having primarily one to four carbon atoms are stored and transported in bulk as refrigerated liquids at near-atmospheric
13、pressure. These liquids can be divided into two main groups: liquefied natural gas (LNG) and liquefied petroleum gas (LPG). In general, the quantity of these light hydrocarbons transferred is determined and recorded on the basis of volume and/or mass, with the energy content calculated in calorific
14、units. If the static-measurement method is used, the liquid level in the tank is one of the variables which most significantly influences the determination. In addition to the level measurement, the following parameters are needed to determine the quantity and energy content of the light hydrocarbon
15、s in a bulk storage tank: a) tank calibration table; b) composition of and/or physical data for the liquefied gases and vapour; c) vapour pressure, vapour and liquid temperature; d) volume of liquid in the pipelines; e) status of the flush valves for connecting lines. The various error factors that
16、influence the quantification based on measurements of liquid level are considered in Annex A. It is necessary to gauge shore tanks for one or more of the following reasons: a) tank farm operations and process control; b) tank inventory control; c) where parties involved require custody transfer on s
17、hore tanks. ISO 18132-2 removes technical dependency and ensures that the market is open to all newcomers in this industrial sector. BS ISO 18132-2:20081Refrigerated light hydrocarbon fluids General requirements for automatic level gauges Part 2: Gauges in refrigerated-type shore tanks 1 Scope This
18、part of ISO 18132 establishes the general requirements for the specification, installation and calibration/verification testing of automatic level gauges (ALG) used for refrigerated light hydrocarbon fluids, i.e., LNG and LPG, stored in bulk storage tanks on shore at pressures close to atmosphere. T
19、his part of ISO 18132 is not applicable to pressurized shore tanks. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced doc
20、ument (including any amendments) applies. OIML R 85, Automatic level gauges for measuring the level of liquid in fixed storage tanks 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 automatic level gauge ALG level gauge that automatically meas
21、ures the liquid level in a tank, either by innage or outage (ullage) NOTE An ALG is also commonly referred to as an automatic tank gauge (ATG). 3.2 datum level tank lowest level that corresponds to zero level and zero volume in tank table 3.3 hazardous area area in which an explosive gas atmosphere
22、is present, or can be expected to be present, in quantities such as to require special precautions for the construction, installation and use of apparatus IEC 60079-10 BS ISO 18132-2:20082 3.4 upper reference point point clearly defined on the gauge hatch directly above the datum level to indicate t
23、he position (and upper datum) from which ullaging should be carried out NOTE It is often the top of the mounting flange of an ullage ALG. 3.5 reference height distance between the upper reference point and the datum level 3.6 liquid level distance between the liquid surface in a tank and the datum l
24、evel NOTE This is also known as innage. 3.7 ullage distance between the liquid surface in a tank and the upper reference point 3.8 lower reference point lowest measurable level located above the datum level that can be measured by an ALG 3.9 overall error total error including the intrinsic error of
25、 an ALG and error due to the effect of installation and operating condition 3.10 intrinsic error error of an ALG when tested under controlled condition as specified by the manufacturer 4 Safety precautions 4.1 General International Standards, government codes and regulations on safety and material c
26、ompatibility precautions applicable to light hydrocarbon fluids shall be followed when selecting and installing ALGs. In addition, specific recommendations from ALG manufacturers should be followed. 4.2 Equipment precautions 4.2.1 All ALGs shall be designed and installed in accordance with applicabl
27、e national standards and/or International Standards. See OIML R 85. 4.2.2 All ALGs shall be certified for use in the hazardous-area classification that corresponds to their installation. 4.2.3 All ALGs should be maintained in safe operating condition. Manufacturers maintenance and operating instruct
28、ions specific to the ALG should be complied with. 5 Conformity to national standards and regulations In addition to conformity with this International Standard, all ALGs shall also conform to OIML R 85. BS ISO 18132-2:200836 Specification of level gauges 6.1 Compatibility with process conditions in
29、the tank All ALGs shall be designed to withstand cryogenic and corrosive conditions, turbulence in the fluid and vibration in the fluid and operating environment. 6.2 Provisions for routine maintenance All ALGs shall allow routine maintenance to be performed without compromising the integrity of the
30、 tank. All ALGs shall have provisions to allow field calibration or verification without taking the tank out of service. This shall include means of verifying the level gauge accuracy at high and low levels. 6.3 Self-diagnostics or other measures All ALGs shall provide self-diagnostics or other mean
31、s to minimize the time required for trouble shooting, searching for the cause(s) and eliminating the abnormal condition(s). 6.4 Countermeasures against sudden malfunctions For ease of maintenance and of repair in case of a malfunction, ALGs should preferably be installed such that they can be isolat
32、ed from the tanks, e.g. through an isolation valve. 6.5 Compatibility for electro-magnetic and other environmental conditions All ALGs shall be designed for electromagnetic compatibility, complying with user requirements and other proper standards, which means that the gauge shall neither interfere
33、with nor be affected by interference from other equipment. Refer to OIML D11. In addition, ALGs shall be provided with electrostatic and lightning protection embedded in or external to the equipment. 6.6 Confirmation of functioning All ALGs shall be designed to enable confirmation of functioning, ev
34、en under service. For this purpose, at least one verification point that does not conflict with normal measurement within the intended measuring range shall be arranged in the tank. 6.7 Minimizing the unmeasured zone AII ALGs shall be designed so as to minimize its unmeasured zone in the operating r
35、ange. 6.8 Instantaneous response All ALGs shall provide essentially instantaneous dynamic response in tracking tank-level variations arising during the operation of receiving or delivering of liquid. 6.9 Security against tampering All ALGs shall be provided with security measures to prevent unauthor
36、ized adjustment or tampering. This security may consist of (a) software password(s). 6.10 Minimum resolution It is recommended that the minimum resolution of the reading be 1 mm or better. BS ISO 18132-2:20084 6.11 Power source voltage variation capability All ALGs shall be designed with the capabil
37、ity to operate under power-source voltage variations in accordance with environmental requirements. 6.12 Compensation for thermal effects ALGs partially or completely installed in tanks shall be equipped with a measurement function or by other equivalent means to compensate for measuring errors caus
38、ed by thermal contraction/expansion of the materials from which the level gauges are constructed. 6.13 Reference factors All ALGs shall be calibrated by the manufacturer to measure the liquid level accurately at a predetermined reference factor, such as reference temperature, reference density or re
39、ference dielectric constant, etc. 6.14 Compensation for changes in physical properties and process condition of liquid and vapor ALG shall compensate for the possible influence of the physical properties and process condition of the liquid and vapour in the tank on the accuracy of the level measured
40、 by the ALG. 7 Installation of ALG 7.1 Redundancy It is recommended that two or more ALGs be installed on each tank. These ALGs should operate independently, such that failure of one ALG shall not affect the other. One of the ALGs shall be designated as the primary ALG. The same ALG shall be used fo
41、r the opening and closing gauge during a transfer. 7.2 Manufacturers instructions on installation All ALGs shall be installed in accordance with the manufacturers instructions and the instructions mandated by the regulatory authorities. 7.3 Location of installation It is recommended that each ALG be
42、 installed in a position that minimizes the measurement inaccuracies due to effects of boiling and turbulence, which can occur during the receiving and delivery of liquid. Such installations shall have provisions that protect the ALGs and the tanks from physical damage. 8 Accuracy tests 8.1 General
43、All ALGs installed on shore tanks shall be subject to tests to ensure their proper functioning and accuracy before shipment from the manufacturer (first step, initial verification prior to installation) and after installation on shore tanks (second step, initial verification) but before commencement
44、 of use. However, if any test item cannot be repeated after installation onto the shore tanks, this test item can be skipped. In such cases, results of the first step, initial verification prior to installation, can also be used for the second step, initial verification. In addition to the above, th
45、e ALGs should be subjected to subsequent verification. BS ISO 18132-2:200858.2 Mutual consensus on test items Test methods and procedures vary according to the type of ALG and/or national regulations. ALG manufacturers shall obtain, in advance of implementation of the tests, the consensus of the par
46、ties concerned regarding test methods, test items, etc.; whether to apply sampling or full tests; timing of implementation and other details, such as the inspection organization; and whether the tank owners, tank constructers, or other parties shall witness the tests. 9 First step Initial verificati
47、on prior to installation Accuracy tests are conducted by comparing an indication of simulated level against that of a reference standard device. The reference standard shall be traceable to the national standard and should be a device external to the ALG sensor. However, in some cases, the reference
48、 standard is incorporated as part of the ALG. In either case, the reference standard shall bear a valid certification traceable to national standards. The difference between the reference and the ALG measurement over the entire operating range shall not exceed 3 mm. 10 Second step initial verificati
49、on after installation 10.1 Initial setting The initial settings shall be configured when installing the ALG on the shore tank. The ALG settings shall be adjusted to indicate the accurate liquid level measured from the datum level. The zero point of some ullage types of ALGs is at the top reference point, e.g., at the mounting flange or process connection. In either case, configuring an ALG mounted on a tank prior to service can include compensation for the influence of the factors described in Clause 6. 10.2 Verification of an ALG with the tank out of service After c
