1、Manual of PetroleumMeasurement StandardsChapter 6Metering AssembliesSection 1Lease Automatic Custody Transfer (LACT) SystemsSECOND EDITION, MAY 1991REAFFIRMED, MAY 2012Manual of PetroleumMeasurement StandardsChapter 6Metering AssembliesSection 1Lease Automatic Custody Transfer(LACT) SystemsMeasureme
2、nt CoordinationSECOND EDITION, MAY 1991REAFFIRMED, MAY 2012SPECIAL NOTES1. API PUBLICATIONS NECESSARILY ADDRESS PROBLEMS OF A GENERALNATURE. WITH RESPECT TO PARTICULAR CIRCUMSTANCES, LOCAL, STATE,AND FEDERAL LAWS AND REGULATIONS SHOULD BE REVIEWED.2. API IS NOT UNDERTAKING TO MEET THE DUTIES OF EMPL
3、OYERS,MANUFACTURERS, OR SUPPLIERS TO WARN AND PROPERLY TRAIN ANDEQUIP THEIR EMPLOYEES, AND OTHERS EXPOSED, CONCERNING HEALTHAND SAFETY RISKS AND PRECAUTIONS NOR UNDERTAKING THEIR OBLIGA TIONS UNDER LOCAL, STATE, OR FEDERAL LAWS.3. INFORMATION CONCERNING SAFETY AND HEALTH RISKS AND PROPERPRECAUTIONS
4、WITH RESPECT TO PARTICULAR MATERIALS AND CONDI TIONS SHOULD BE OBTAINED FROM THE EMPLOYER, THE MANUFACTUREROR SUPPLIER OF THAT MATERIAL, OR THE MATERIAL SAFETY DATA SHEET.4. NOTHING CONTAINED IN ANY API PUBLICATION IS TO BE CONSTRUED ASGRANTING ANY RIGHT, BY IMPLICATION OR OTHERWISE, FOR THEMANUFACT
5、URE, SALE, OR USE OF ANY METHOD, APPARATUS, OR PRODUCTCOVERED BY LETTERS PATENT. NEITHER SHOULD ANYTHING CONTAINEDIN THE PUBLICATION BE CONSTRUED AS INSURING ANYONE AGAINSTLIABILITY FOR INFRINGEMENT OF LETTERS PATENT.5. GENERALLY, API STANDARDS ARE REVIEWED AND REVISED, REAF FIRMED, OR WITHDRAWN AT
6、LEAST EVERY FIVE. YEARS. SOMETIMES AONE-TIME EXTENSION OF UP TO TWO YEARS WILL BE ADDED TO THISREVIEW CYCLE. THIS PUBLICATION WILL NO LONGER BE IN EFFECT AS ANOPERATIVE API STANDARD FIVE YEARS AFTER ITS PUBLICATION DATE OR,WHERE AN EXTENSION HAS BEEN GRANTED, UPON REPUBLICATION. THESTATUS OF THE PUB
7、LICATION CAN BE ASCERTAINED FROM THE APIAUTHORING DEPARTMENT (TELEPHONE 202 682-8000). A CATALOG OF APIPUBLICATIONS AND MATERIALS IS PUBLISHED ANNUALLY AND UPDATEDQUARTERLY BY API, 1220 L STREET, N.W., WASHINGTON, D.C. 20005.Copyright 1991 American Petroleum InstituteFOREWORDThis publication covers
8、the design, installation,calibrationand operation of leaseautomatic custody transfer (LACT) systems.API publications may be used by anyone desiring to do so. Every effort has been madeby the Institute to assure the accuracy and reliability ofthe data contained in them; however,the Institute makes no
9、 representation, warranty, or guarantee in connection with thispublication and hereby expressly disclaims any liability or responsibility for loss or damageresulting from its use or for the violation ofany federal, state, or municipal regulation withwhich this publication may conflict.Suggested revi
10、sions are invited and should be submitted to the director ofthe Measure ment Coordination Department, American Petroleum Institute, 1220 L Street, N.W.,Washington, D.C. 20005.iii11111111111111111111111111111111111CONTENTSPageSECTION I-LEASE AUTOMATIC CUSTODY TRANSFER(LACT) SYSTEMS6.1.1 Introduction
11、16.1.1.1 Compliance 16.1.1.2 Future Developments , 16.1.2 Scope_“ 16.1.3 Field of Application “ , 16.1.4 Referenced Publications 16.1.5 Requirements for All LACT Systems 16.1.5.1 Sampling _ : : 26.1.5.2 Maintaining Allowables 26.1.5.3 Monitoring Quality 36.1.6 Displacement and Turbine Meter LACT Sys
12、tems .36.1.6.1 Installation .36.1.6.2 Specific Requirements .36.1.6.3 Facilities and Procedures for Proving Displacementand Turbine Meters .36.1.6.4 Displacement and Turbine Meter System Operation 56.1.6.5 Nonmerchantable Oil Interruption 5FigureI-Typical Displacement or Turbine MeterLACT Unit Schem
13、atic Diagram .4vChapter 6-Metering AssembliesSECTION 1-LEASE AUTOMATIC CUSTODY TRANSFER (LACT) SYSTEMS6.1.1 IntroductionThis publication has been prepared as a guide for thedesign, installation, calibration, and operation ofa lease auto matic custody transfer (LACT) system.A LACT system is an arrang
14、ement ofequipment designedfor the unattended custody transfer of liquid hydrocarbonsfrom producing leases to the transporting carrier. The systemmust determine net volume and quality, provide for fail-safeand tamperproof operation, and meet requirements of ac curacy and dependability as agreed to by
15、 mutually concernedparties, such as the producer, the transporter, the royaltyowner, and federal, state, and municipal regulatorybodies.6.1.1.1 COMPLIANCECompliance with the provisions ofthis standard may resultin an approach to accuracy or may establish safeguards thatare not necessary under all co
16、nditions. When not required,those portions ofthis standard not considered applicable maybe disregarded with the mutual agreement ofall parties con cerned. The compulsory verb form shall,“ while not neces sarily binding for all conditions, has been used when adeviation from the standard is likely to
17、adversely affect thesatisfactory operation of a system that is designed for op timum operation under typical producing conditions.6.1.1.2 FUTURE DEVELOPMENTSAlthough this standard presents the concurrence of theindustry on system requirements for lease automatic custodytransfer, it is not intended i
18、n any way to restrict futuredevelopments. Equipment now exists in the design or field proving stages that may further improve the art of leaseautomatic custody transfer. The industry encourages suchdevelopments, and when concerned parties mutually agreeto use such systems or components, every effort
19、 should bemade to expedite their use and standardization.6.1.2 ScopeThis publication describes the metering function of aLACT unit and is intended to complement API SpecificationII N,Specificationfor Lease Automatic Custody Transfer(LACT) Equipment. LACT equipment includes a meter(either displacemen
20、t or turbine), a proving system (eitherfixed or portable), devices for determining temperatureand pressure and for sampling the liquid, and a meansofdetermining nonmerchantable oil. Many ofthe aspectsof the metering function of a LACT unit are considered atlength in other parts of this manual and ar
21、e referencedin 6.1.4.6.1.3 Field of ApplicationThe field of application of this publication is the unat tended and automatic measurement by meter ofhydrocarbonliquids produced in the field and transferred to a pipeline ineither a scheduled or a nonscheduled operation.Note: The information contained
22、in Chapter 6.7 should also be con sidered when measuring viscous fluids by meter.6.1.4 Referenced PublicationsMany ofthe aspects ofthe metering function are discussedat length in other parts of this manual. Please refer to thefollowing chapters for more information.APIManual ofPetroleum Measurement
23、StandardsChapter 4-“Proving Systems“Chapter 5.1, “General Considerations forMeasurement by Meters“Chapter 5.2, “Measurement of LiquidHydrocarbons by Displacement Meters“Chapter 5.3, “Measurement of LiquidHydrocarbons by Turbine Meters“Chapter 6.7, “Metering Viscous Hydrocar bons“Chapter 7-“Temperatu
24、re Determination“Chapter 8-“Sampling“Chapter 8.2, “Automatic Sampling ofPetroleum and Petroleum Products“Chapter 9-“Density Determination“Chapter 1O-“Sediment and Water“Chapter 12.2, “Calculation of LiquidPetroleum Quantities Measured by Turbineor Displacement Meters“Spec lIN Specification for Lease
25、 Automatic CustodyTransfer (LACT) Equipment6.1.5 ReqUirements for All LACTSystemsThe requirements for all LACT systems are as follows:a. When hydrocarbon liquids are measured and trans ferred, the fluid should be stable to permit subsequentstorage during transportation without abnormal evapora tion
26、losses.2 CHAPTER 6-METERING ASSEMBLIESb. During custody transfer, provisions shall be made fordetermining net standard volume. (See Chapter 12.2.)c. Temperature measurements, recordings, or correctionsapplicable to volumetric measurement shall be made in ac cordance with Chapter 7.d. Temperature and
27、 pressure measurements (either recordedor indicated) shall be taken, and corrections applicable tovolumetric measurements shall be made in accordance withChapter 12.2. The method ofperforming temperature com pensation is a matter of negotiation but should beaccomplished by use of volume-weighted tem
28、perature averaging devices or temperature compensators for op timum accuracy.e. A representative sample oftransferred oil for determiningdensity (API gravity), sediment and water content, and anyother physical properties required shall be obtained. (SeeChapter 8, Chapter 9, and Chapter 10.)f. The me
29、rchantability ofhydrocarbon liquids should beestablished when they are transferred; that is, when theliquids are within a specified density (API gravity) range,do not contain more than a specified sediment and waterpercentage, are at an acceptable temperature, and are ofan acceptable Reid vapor pres
30、sure. A means shall beprovided to stop the flow of oil to the carriers system andto the sampling system if the oil becomes unmerchant able.g. A means should be provided to control flow rates, periodsof flow, and net quantities of oil delivered into the carrierssystem.h. A means shall be provided to
31、stop the flow of oil into thecarriers system at or before completion of delivery of theleases assigned allowable capacity.i. The control and recording system shall include fail-safecomponents to prevent mismeasurement orhazardous operat ing conditions in the event of a power or system functionalfail
32、ure of any of the systems components required for theLACT.j. All components of the system that require periodiccalibration and/or inspection should be accessible forinspection by all parties involved in the custody transfertransaction. Adjustment, repair, or replacement will beperformed by those res
33、ponsible for the operation of thesystem. The design of the system shall provide a meansfor readily detecting leakage throughout the system, forexample, double-block and bleed-type valves, sightdrains, or pressure instruments.k. The piping system shall not have connections orbypassesthat would permit
34、 liquids to be transferred without measure ment and shall be designed or equipped so that a reverse flowof liquid through the measuring device cannot occur.1. A means shall be provided to lock or seal components thataffect control or indicate measurement ofquantity or quality.Unless this requirement
35、 has been specifically waived, suchcomponents shall be unlocked or unsealed only after priornotice to and consent ofthe parties concerned.m. System malfunctions shall be anticipated, anddeliveries that could occur during such periods shall beestimated. This requirement may be met by independentgross
36、 fluid delivery-recording systems, that is, by usinga dual-head meter and temperature recorder, by using ameter in series, or by recording temperature or pressureor other instruments that indicate periods of flow. Ininstallations where such apparatus is not used, prioragreement should be established
37、 for calculating or es timating procedures that will be followed in instances ofmeasurement system malfunction.n. Sediment and water content and density (API gravity)measurements shall be made from composite samples ob tained by automatic samplers ofacceptable design. Samplersshall be installed in a
38、ccordance with Chapter 8.2.6.1.5.1 SAMPLINGIn most cases, accounting for a crude oil run is determinedon the basis of net standaFd volume, which includes correc tions for meter factor, temperature, pressure, and sedimentand water content. Therefore, the composite sample accumu lated in a run period
39、and any portion used for the determina tion ofdensity (API gravity) and sediment and water contentmust represent all crude oil delivered during that run period.When density (API gravity) and sediment and water contentare based on a sample from the composite sample ofthe run,the procedures used must
40、ensure that this secondary sampleis representative ofthe composite sample. (See Chapter 8 foradditional details.) The sampling should be proportioned tothe flow rate through the meter.6.1.5.2 MAINTAINING ALLOWABLESWhen regulatory agencies apply production allowables,runs from the LACT system shall c
41、onform to but shall notexceed these allowances. Automatic means shall be used toaccomplish this requirement. The system must be fail-safe,tamperproof, and sealed so that neither the producer nor thecarrier can change the arrangement without the consentand/or knowledge ofthe other party.System device
42、s must be capable ofbeing pre-set and verifiedfor a predetermined volume that will approach but not exceedthe lease allowable. When the predetermined volume hasbeen reached, the arrangement used mllst prevent anyfurther movement ofoil from the lease until it is manuallyreset. The arrangement must be
43、 adjustable so that chan ges in production allowables are accommodated.Registers and counters should be readily visible so thatoil deliveries can be checked at any time.SECTION 1-LEASE AUTOMATIC CUSTODY TRANSFER (LACT) SYSTEMS 36.1.5.3 MONITORING QUALITYMeans shall be provided to prevent water-conta
44、minatedoil or slugs of water from entering a carriers system. Theparties shall agree on the maximum permissible sedimentand water content of the crude oil. One such satisfactoryautomatic device which detects water is an instrument thatmeasures capacitance (dielectric constant of the liquidstream). T
45、his device should be installed in a vertical riserin the piping before the meter and should be used to actuatecontrols so that water-contaminated oil is not delivered tothe pipeline. A time-delay element may be incorporatedinto the monitor system.6.1.6 Displacement and Turbine MeterLACT SystemsPract
46、ical methods for obtaining accurate measurements oflease oil runs, using either a displacement or a turbine meter,with equipment arranged to meet the requirements defined inthis chapter are outlined in 6.1.6.1 through 6.1.6.5. (SeeChapters 5.1, 5.2, and 5.3 for details on meter selection.)6.1.6.1 IN
47、STALLATIONLACT systems that use meters shall be designed in accord ance with applicable industry codes or standards. Each itemessential to quantity and quality control shall be located sothat it will consistently perform its function.Figure 1is a schematic flow diagram showing the principalcomponent
48、s ofa meter-equippedLACTunit. All items shownmay be used in an installation, but if certain components arenot required for the integrity ofquantity and quality control,they may be omitted.6.1.6.2 SPECIFIC REQUIREMENTSThe design and function ofa LACT system are matters ofnegotiation. These negotiatio
49、ns determine which of the re quirements are applicable. However, when the quantity orquality measurement or control depends on compliance withthe requirement, the specific conditions detailed in 6.1.1.1shall apply.LACT systems that use meters shall maintain fluid pres sure throughout the measurement system in excess of theproduct bubble-point pressure by an amount sufficient toprevent the formation ofvapor. Ifvapor is introduced into themeasurement system, the measurement will be inaccurate.When vapor removers are specified, they shall be sized forreleasing vapor to the atmosphere o
