API MPMS 7.5-2014 Manual of Petroleum Measurement Standards Chapter 7.5 Temperature Determination - Automatic Tank Temperature Measurement Onboard Marine Vessels Carrying Refigerat.pdf

1、Manual of PetroleumMeasurement StandardsChapter 7.5Temperature DeterminationAutomatic Tank Temperature Measurement Onboard Marine Vessels Carrying Refrigerated Hydrocarbonand Chemical Gas Fluids ANSI/API MPMS CHAPTER 7.5FIRST EDITION, SEPTEMBER 2014ISO 8310:2012 (Identical), Refrigerated hydrocarbon

2、 and non-petroleum based liquefied gaseous fuelsGeneral requirements for automatic tank thermometers on board marine carriers and floating storageSpecial NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, local,state, and federal laws an

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5、hts.Classified areas may vary depending on the location, conditions, equipment, and substances involved in any givensituation. Users of this standard should consult with the appropriate authorities having jurisdiction.Users of this standard should not rely exclusively on the information contained in

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16、This standard shall become effective on the date printed on the cover but may be used voluntarily from the date ofdistribution.Standards referenced herein may be replaced by other international or national standards that can be shown to meetor exceed the requirements of the referenced standard.This

17、American National Standard is under the jurisdiction of the API Subcommittee on Measurement Accountability.This standard is considered identical to the English version of ISO 8310. ISO 8310 was prepared by TechnicalCommittee ISO/TC 28, Subcommittee 5, Measurement of refrigerated hydrocarbon and non-

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22、rg.iiiv Contents Page API Foreword iii Introduction . vii 1 Scope . 1 2 Normative references . 1 3 Terms and definitions . 1 4 Safety precautions 2 4.1 General . 2 4.2 Equipment precautions 3 4.2.1 General . 3 4.2.2 Mechanical rigidity 3 4.2.3 Gastight design . 3 4.2.4 Compatibility with cargo 3 4.2

23、.5 Tolerance against low temperatures . 3 4.2.6 Type approval 3 5 Design requirements 3 5.1 General . 3 5.2 Temperature sensors 4 5.3 Indicating device . 4 5.4 Installation . 4 5.5 Provisions for routine maintenance and verification 4 5.6 Provision against sudden malfunctions . 4 5.7 Dynamic respons

24、e 4 5.8 Measurable range 5 5.9 Data processing and reporting 5 5.10 Compensation for variation of cargo temperatures . 5 5.11 Sealing, security and unsealing 5 5.12 Redundancy . 5 5.13 Data communication . 5 6 Calibration and accuracy verification . 6 6.1 General . 6 6.2 Calibration reference 6 6.3

25、Calibration and accuracy verification at factory 6 6.3.1 Calibration at factory 6 6.3.2 Accuracy of PRTs . 6 6.3.3 Factory acceptance test (FAT) . 7 6.4 Calibration and accuracy verification after installation . 7 6.4.1 Calibration and inspection after installation 7 6.4.2 Site acceptance test (SAT)

26、 . 7 6.4.3 Accuracy of indicating device . 7 6.5 Periodic accuracy verification . 9 6.5.1 General . 9 6.5.2 Method of periodic verification 9 6.5.3 Frequency of subsequent calibration and recertification . 9 6.5.4 Customary verification . 9 7 Accuracy requirement 9 7.1 Overall error . 9 vi 7.2 Resol

27、ution . 10 8 ATT calibration records 10 Annex A (informative) Information on platinum resistance thermometers 11 A.1 General . 11 A.2 Characteristics of platinum resistance thermometers 11 A.3 Nominal temperature/resistance relationship 11 Bibliography 12 vii Introduction Large quantities of liquefi

28、ed natural gas (LNG), liquefied petroleum gas (LPG) and other liquefied gases are usually transported by marine carriers dedicated for these applications and traded based on static measurement on board by automatic tank measurement. Such an automatic tank measurement may be a part of the custody tra

29、nsfer measurement system (CTMS) which involves determination of liquid/vapor interface, i.e. liquid level, average temperatures of liquid and vapor, and vapor pressure. The volumetric quantity of the liquid and gas is then computed with the tank capacity table based on which the delivered quantity i

30、n terms of energy content or mass is calculated. In most cases, shore tank measurement is not used due to the active and dynamic conditions of the shore tank operations. In the absence of other means of acceptable measurement, custody transfer measurement usually takes place on board the carrier or

31、floating production storage offshore (FPSO) and floating storage offshore (FSO). Liquid cargo density is very sensitive to temperature; therefore, obtaining accurate temperature readings is extremely important. For example, a change of 0.2 C ( 0.36 F) for liquid methane cargo results in a change in

32、density of approximately 0.07 %. This International Standard also discusses use of automatic tank thermometers on board marine vessels for other volatile, non-petroleum liquids in fully refrigerated conditions. Many of these non-petroleum liquids, such as di-methyl ether (DME) are measured in a simi

33、lar manner to that used for fully refrigerated LPGs. Values of temperature in this International Standard are in terms of the International Temperature Scale of 1990, ITS-90. Temperatures in degrees Celsius are denoted by the symbol t. API MPMS Chapter 7.5/ISO 8310:20121 Automatic Tank Temperature M

34、easurement onboard Marine Vessels Carrying Refrigerated Hydrocarbon and Chemical Gas Fluids 1 Scope This International Standard specifies the essential requirements and verification procedures for automatic tank thermometers (ATTs) consisting of platinum resistance thermometers (PRT) and an indicati

35、ng device used for custody transfer measurement of liquefied natural gas, liquefied petroleum and chemical gases on board ships. Temperature detectors other than PRT are considered acceptable for use in the custody transfer service of liquefied gases if they meet the performance requirements of this

36、 International Standard and are approved by national regulations. 2 Normative references The 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,

37、the latest edition of the referenced document (including any amendments) applies. IEC 60751, Industrial platinum resistance thermometers and platinum temperature sensors ASTM E1137, Standard Specification for Industrial Platinum Resistance Thermometers 3 Terms and definitions For the purposes of thi

38、s document, the following terms and definitions apply. 3.1 automatic tank gauge ATG automatic level gauge ALG instrument that automatically measures and displays liquid levels or ullages in one or more tanks, either continuously, periodically or on demand 3.2 automatic tank gauging system ATG system

39、 system that 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/vapor interface 3.3 automatic tank thermometer ATT automatic tank temperature system inst

40、rument that continuously measures temperature in cargo tanks NOTE 1 An ATT typically includes temperature sensors, such as PRTs, field-mounted transmitters for electronic signal transmission, and indicating device(s). NOTE 2 ATTs on liquefied gas carriers are usually multiple-point ATTs which consis

41、t of three or more temperature sensors, such as PRTs, to measure the temperatures at selected heights in the cargo tank. 2 API MPMS CHAPTER 7.5/ISO 8310:2012 3.4 custody transfer measurement system CTMS system that processes inputs from an ATG system, an ATT, pressure gauges, etc. and provides custo

42、dy transfer measurement information on board, generating documents with regard to custody transfer of liquefied gases NOTE An ATT can be incorporated as part of a CTMS. 3.5 gas dangerous space or zone space or zone defined by the International Code for the Construction and Equipment of Ships Carryin

43、g Liquefied Gases in Bulk (IGC Code) 3.6 indicating device displaying device set of components of a measuring instrument intended to indicate the measured value 3.7 inherent error intrinsic error error of a gauge when it is tested against a reference standard under controlled conditions as specified

44、 by the manufacturer 3.8 nominal resistance expected resistance R0of a PRT at 0 C (32 F), declared by the manufacturer and shown in the thermometer marking, usually rounded to the nearest ohm 3.9 nominal temperature/resistance relationship relationship between temperature and resistance of a nominal

45、 PRT 3.10 platinum resistance thermometer PRT resistance temperature detector RTD temperature-responsive device consisting of one or more sensing platinum resistors within a protective sheath, internal connecting wires and external terminals to permit connection of electrical measurement instruments

46、 3.11 uncertainty non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used 4 Safety precautions 4.1 General Nothing contained in this International Standard is intended to supersede any regulatory requirements or recom

47、mended operating practices issued by organizations such as the International Maritime Organization (IMO), International Chamber of Shipping (ICS), Oil Companies International Marine Forum (OCIMF), International Association of Classification Societies (IACS) and individual operating companies, nor is

48、 this TEMPERATURE DETERMINATIONAUTOMATIC TANK TEMPERATURE MEASUREMENT ONBOARD MARINE VESSELS CARRYING REFRIGERATED HYDROCARBON AND CHEMICAL GAS FLUIDS 3 International Standard intended to conflict with any safety or environmental considerations, local regulations, or the specific provisions of any c

49、ontract. 4.2 Equipment precautions 4.2.1 General All electric components of an ATT for use in electrically classified areas shall meet the electrical area classification. They shall conform to applicable sections of the national and/or international electrical safety standards. All ATTs shall be maintained in a safe operating condition and manufacturers maintenance instructions should be complied with. 4.2.2 Mechanical rigidity All ATTs shall be capable of withstanding the pressure, temperature, dynamic loads generated from rolling/pitching, and sloshing from environmental conditi