1、Manual of PetroleumMeasurement StandardsChapter 3Tank GaugingSection 4Standard Practice for Level Measurement of Liquid Hydrocarbons on Marine Vessels by Automatic Tank GaugingFIRST EDITION, APRIL 1995 REAFFIRMED, MAY 2016Manual of PetroleumMeasurement StandardsChapter 3Tank GaugingSection 4Standard
2、 Practice for Level Measurement of Liquid Hydrocarbons on Marine Vessels by Automatic Tank GaugingMeasurement CoordinationFIRST EDITION, APRIL 1995 REAFFIRMED, MAY 2016SPECIAL NOTES1. API PUBLICATIONS NECESSARILY ADDRESS PROBLEMS OF A GENERALNATURE. WITH RESPECT TO PARTICULAR CIRCUMSTANCES, LOCAL, S
3、TATE,AND FEDERAL LAWS AND REGULATIONS SHOULD BE REVIEWED.2. API IS NOT UNDERTAKING TO MEET THE DUTIES OF EMPLOYERS, MANU-FACTURERS, OR SUPPLIERS TO WARN AND PROPERLY TRAIN AND EQUIPTHEIR EMPLOYEES, AND OTHERS EXPOSED, CONCERNING HEALTH ANDSAFETY RISKS AND PRECAUTIONS, NOR UNDERTAKING THEIR OBLIGATIO
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8、0 L STREET, N.W., WASHINGTON, D.C. 20005.Copyright 1995 American Petroleum InstituteFOREWORDThis publication covers standard practice for level measurement of liquid hydrocarbonson marine vessels by automatic tank gauging, and supersedes all applicable sections of APIStandard 2545, Method of Gaging
9、Petroleum and Petroleum Products (October 1965).API publications may be used by anyone desiring to do so. Every effort has been madeby the Institute to assure the accuracy and reliability of the data contained in them; however,the Institute makes no representation, warranty, or guarantee in connecti
10、on with this pub-lication and hereby expressly disclaims any liability or responsibility for loss or damage re-sulting from its use or for the violation of any federal, state, or municipal regulation withwhich this publication may conflict.Suggested revisions are invited and should be submitted to t
11、he Measurement Coordina-tor, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005.iviiiCONTENTSPage1 SCOPE . 12 REFERENCES 12.1 Standards . 12.2 Other References 13 GENERAL . 13.1 Safety Precautions 13.2 General Precautions 24 INSTALLATION OF MARINE ATGs 34.1 Location of the ATG
12、 . 34.2 Location of Manual Calibration Check Point 34.3 Gauging of Inerted Tanks . 35 CALIBRATION, ADJUSTMENT, AND VERIFICATIONOF MARINE ATGs . 35.1 Factory Calibration . 35.2 Initial Shipyard Adjustment . 35.3 Check for Smooth Operation of Float Gauges . 35.4 Verification by Innage or Outage Gaugin
13、g 45.5 Initial Verification 45.6 Subsequent Verification 45.7 Schedule for Regular ATG Verification . 45.8 ATG Verification Records 46 READOUT 46.1 General . 46.2 Transmitter Installation 57 REQUIREMENTS FOR DATA TRANSMISSION AND RECEIVING 57.1 General . 57.2 Data Transmission 57.3 Receiving Unit 57
14、.4 Transient and Lightning Protection 5APPENDIX AACCURACY LIMITATIONS OF MARINE LEVEL AND VOLUME MEASUREMENTS 7APPENDIX BDESCRIPTION OF VARIOUS ATGs IN COMMON USE . 91 ScopeThis standard provides guidance on the selection, installa-tion, calibration, and verification of automatic tank gauges(ATGs) f
15、or measuring the level of liquid hydrocarbons hav-ing a Reid vapor pressure less than 15 pounds per squareinch absolute (103 kPa), transported aboard marine vessels(tankers and barges).Marine ATGs are not normally used in custody transfersbecause of the limitations described in Appendix A. How-ever,
16、 level measurement by marine ATGs may be used incustody transfer when no other alternative measurement isavailable. The use of marine vessel-based ATGs for custodytransfer normally requires mutual contractual agreement be-tween the buyer and the seller and may be subject to govern-ment regulations.
17、This standard also provides guidance on the requirementsfor data collection, transmission, and receiving. The Ap-pendix B briefly describes the operation of the most com-monly used marine ATG equipment.This standard is not applicable to the following subjects:a. Conversion of tank level to liquid vo
18、lume.b. Measurement of free water or sediment lying under theliquid hydrocarbon.c. Measurement of temperature, density, or sediment andwater (S&W). These measurements are discussed in Chap-ters 7, 9, and 10 of the API Manual of Petroleum Measure-ment Standards (MPMS).d. Sampling for determination of
19、 the properties of the liquidhydrocarbon. This is discussed in API Chapter 8.e. Detection of tank leaks.Safety and material compatibility precautions shall be takenwhen using marine ATG equipment. The manufacturers rec-ommendations on the use and installation of the ATG equip-ment should be followed
20、. Users shall comply with allapplicable national and international codes and regulations.2 References2.1 STANDARDSUnless otherwise specified, the most recent editions or re-visions of the following standards shall, to the extent speci-fied herein, form a part of this standard.APIManual of Petroleum
21、Measurement StandardsChapter 1, “Vocabulary”Chapter 2, “Tank Calibration”Chapter 2.8B, “Recommended Practice for the establish-ment of the Location of the Reference Gauge Point and theGauge Height of Tanks on Marine Tank Vessels” (in press)Chapter 3, “Tank Gauging”Chapter 3.1A, “Standard Practice fo
22、r Manual Gauging ofPetroleum and Petroleum Products in Stationary Tanks”Chapter 7, “Temperature Determination”Chapter 8, “Sampling”Chapter 9, “Density Determination”Chapter 10, “Sediment and Water”Chapter 17, “Marine Measurement”Chapter 17.2, “Measurement of Cargoes on BoardTank Vessels”2.2 OTHER RE
23、FERENCESDOT133 Code of Federal Regulations Part 153.46 Code of Federal Regulations Part 39.20Guide for Electrical Installations on Merchant Vesselsand Mobile Offshore Drilling UnitsIMO2International Code for the Construction and Equipmentof Ships Carrying Dangerous Chemicals in Bulk(IBC Code)Chapter
24、 13.1, GaugingOCIMF3International Safety Guide for Oil Tankers and Terminals3 GeneralThis section is applicable to all types of marine ATGs.Safety precautions are listed separately from general precau-tions that affect accuracy or performance.3.1 SAFETY PRECAUTIONSThe following safety codes and regu
25、lations shall be fol-lowed:a. International Maritime Organization (IMO)Interna-tional Code for the Construction and Equipment of ShipsCarrying Dangerous Chemicals in Bulk (IBC Code) andIMO Chapter 13.1, Gauging.1Chapter 3Tank GaugingSECTION 4STANDARD PRACTICE FOR LEVEL MEASUREMENT OF LIQUIDHYDROCARB
26、ONS ON MARINE VESSELS BY AUTOMATIC TANK GAUGING1The Code of Federal Regulations is available from the U.S. GovernmentPrinting Office, Washington, D.C. 20402.2International Maritime Organization, London, England.3Oil Companies International Marine Forum, Portland House, Stag Place,London SW1E SBH, En
27、gland.3.2.1 Speed of ResponseMarine ATGs should have sufficient dynamic response totrack the liquid level during maximum tank filling or empty-ing rates.3.2.2 Protection from Mechanical DamageMarine ATGs should be designed to withstand damagecaused by waves in the tanks due to ship movement. Theysho
28、uld also be able to withstand damage from high velocityjets of water or oil used to wash the tanks. Note 1: This protection may require mounting the ATGs in slotted still pipes.Note 2: Alternately, this protection may require that the ATG float or dis-placer be raised to a store position when it is
29、not being used. Note that suchATGs cannot be used during tank washing.3.2.3 Manual GaugingWhen an ATG is checked or calibrated by manual gaug-ing, the manual gauging should be performed in accordancewith API Chapter 3.1A.3.2.4 Minimum Measurable LevelThe ATG should be able to measure levels as near
30、to thebottom of the tank as possible. This may require the provisionof a sump in the tank bottom in vessels with double bottoms.Note: The minimum measurable level of certain types of ATGs may limittheir ability to measure small volumes remaining on board (ROB) and/oron-board quantities (OBQ).3.2.5 T
31、rim and ListFor best accuracy, the vessel should be on an even keeland upright. In situations where both trim and list exist, ev-ery effort should be made to eliminate at least one condition,preferably list.Trim and list corrections are not required on vessel tanksof cuboid shape, provided that the
32、ATG is located at the ge-ometric center of the deck area for the tank. Where the ATGis not so located, correction will be required. On vessel tanksthat have curvature(s), such as the aft and forward wingtanks, trim and list corrections are recommended. Correc-tions for trim, list, and wedge is permi
33、ssible by table or cal-culation, using the procedure set forth in API Chapter 17.3.2.6 Product TemperaturesProduct temperature should be measured at the same timeas the tank level is measured. The temperature should be rep-resentative of the tank contents and should be measured inaccordance with API
34、 Chapter 7.3.2.7 CompatibilityAll parts of the ATG in contact with the product should becompatible with the product, to avoid both product contam-b. International Safety Guide for Oil Tankers and Terminals(ISGOTT).c. U.S. Coast Guard (USCG) regulationTitle 33 of theCode of Federal Regulations, Part
35、153.d. U.S. Coast Guard regulationTitle 46 of the Code ofFederal Regulations, Part 39.20.e. U.S. Coast Guard Marine Safety Center NVIC 2-89 BasicGuidance for Electrical Installations on Merchant Vessels.Other applicable safety codes and regulations shall becomplied with.3.1.1 Tank EntryWhenever a ta
36、nk that has contained hydrocarbon liquids,vapors, or toxic material is entered, regulations on entry toconfined spaces shall be followed.3.1.2 Electrical SafetyMarine ATGs shall be specified and installed in accor-dance with the appropriate national Underwriters Labo-ratory (UL), Factory Mutual (FM)
37、, Federal Com-munications Commission (FCC), and so forth and/or in-ternational International Maritime Organization (IMO),International Electrotechnical Commission (IEC),Committee for Electrotechnical Standardization (CEN-ELEC), International Organization for Standardization(ISO), and so forth marine
38、 electrical safety standards.3.1.3 MaintenanceAll marine ATG equipment shall be maintained in safe op-erating condition. The manufacturers maintenance instruc-tions should be complied with.3.1.4 EnvironmentAll marine ATGs shall be capable of withstanding thepressure, temperature, and other environme
39、ntal conditionslikely to be encountered in marine service. When an ATG isinstalled in a corrosive service, any parts exposed to the liq-uid or vapors shall be of durable, corrosion-resistant con-struction.3.1.5 SealingAll ATGs shall be sealed to withstand the vapor pressureof liquid in the tank. ATG
40、s mounted on vessels with an inertgas system (IGS) shall be designed to withstand the operat-ing pressure of the IGS.3.2 GENERAL PRECAUTIONSThe following general precautions affect the accuracy andperformance of all types of marine ATGs. They shall be ob-served where they are applicable.2CHAPTER 3TA
41、NK GAUGINGination and ATG corrosion. The ATG should be designed tomeet its intended operating conditions.3.2.8 Entrained Air and VaporsSufficient time should be allowed before gauging a tank topermit the liquid to free itself of entrained air or gas vapors.3.2.9 Vessel MotionDuring lightering or off
42、shore operation or when the vesselis at an exposed berth, vessel motion causes waves on thesurface of the product. At least three readings should betaken in minimum time and the readings should be averaged.If the vessel is in heavy motion due to large swells or waves,at least five readings should be
43、 taken in minimum time. Re-fer to API Chapter 3.1A.Note: Some ATGs provide internal filtering algorithms as part of the readoutto average the level readings over a time interval. The filtering time can befixed or made adaptive to the encountered motion.3.2.10 Use of Marine ATGs in Custody TransferMa
44、rine ATGs are not normally used in custody transfersbecause of the limitations described in Appendix A. How-ever, level measurement by marine ATGs may be used incustody transfer when no other alternative measurement isavailable. The use of marine vessel-based ATGs for custodytransfer normally requir
45、es a mutual contractual agreementbetween the buyer and the seller and may be subject to gov-ernment regulations. 4 Installation of Marine ATGsMarine ATGs should be installed in accordance with theATG manufacturers instructions.4.1 LOCATION OF THE ATGThe ATG should be located to minimize the effect o
46、f sur-face turbulence and waves in the tanks. The location shouldbe designed to avoid damage during tank washing. Mechan-ical, float-operated ATGs that cannot withstand waves ortank washing should be provided with the ability to store thefloat when the ATG is not in use.For vessel tanks of cuboid sh
47、ape, the ATG should be lo-cated at the geometric center of the tank, which usually elim-inates the need for trim and list corrections. On vessel tanksthat have curvature side(s), such as the aft and forward wingtanks, the ATG should be located nearer to the inboard bulk-head to avoid interference wi
48、th the curvature of the vesselstank bottom. For further information on reference gaugepoint location, see API Chapter 2.8B (in press).Presently, the combination of vessel design and ATG tech-nology limits the use of ATGs to the measurement of partiallyor fully loaded vessels. Therefore, a second mea
49、surement lo-cation is required to accommodate the measurement of smallvolumes (ROB/OBQ). This second location can be for a man-ual gauge or a portable gauging device. This second gaugepoint location must be located at the end of the tank, in thenormal direction of trim and should be far enough away fromthe bulkhead to avoid interference when gauging.Note: On vessels that are fitted with ATGs and a second means of measure-ment, the gauge point for the second measurement location should have thesame reference height (otherwise correction will be required) as well as belo
