API MPMS 6 5-1991 Manual of Petroleum Measurement Standards Chapter 6-Metering Assemblies Section 5-Metering Systems for Loading and Unloading Marine Bulk Carri.pdf

1、Manual of PetroleumMeasurement StandardsChapter 6Metering AssembliesSection 5Metering Systems for Loading and Unloading Marine Bulk CarriersSECOND EDITION, MAY 1991REAFFIRMED, MAY 2012Manual of PetroleumMeasurement StandardsChapter 6Metering AssembliesSection 5Metering Systems for Loading andUnloadi

2、ng Marine Bulk CarriersMeasurement CoordinationSECOND EDITION, MAY 1991REAFFIRMED, MAY 2012SPECIAL NOTES 1. API PUBLICATIONS NECESSARILY ADDRESS PROBLEMS OF A GENERAL NATURE. WITH RESPECT TO PARTICULAR CIRCUMSTANCES, LOCAL, STATE, AND FEDERAL LAWS AND REGULATIONS SHOULD BE REVIEWED. 2. API IS NOT UN

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7、TION CAN BE ASCERTAINED FROM THE API PUBLICATIONS AND MATERIALS IS PUBLISHED ANNUALLY AND UPDATED QUARTERLY BY API, 1220 L STREET, N.W., WASHINGTON, D.C. 20005. ONE-TIME EXTENSION OF UP TO TWO YEARS WILL BE ADDED TO THIS AUTHORING DEPARTMENT (TELEPHONE 202 682-8000). A CATALOG OF API Copyright0 1991

8、 American Petroleum Institute FOREWORD This publication deals with the operation and special arrangements of meters, provers, manifolding, instruments, and accessory equipment used for measurement during loading and unloading of marine bulk carriers. API publications may be used by anyone desiring t

9、o do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for los

10、s or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict. Suggested revisions are invited and should be submitted to the director of the Measure- ment Coordination Department, American Petroleum Institute, 1220 L

11、Street, N.W., Washington, D.C. 20005. iii CONTENTS Page SECTION 5-METERING SYSTEMS FOR LOADING AND UNLOADING MARINE BULK CARRIERS 6.5.1 Introduction . 1 6.5.2 Scope and Field of Application . 1 6.5.3 Referenced Publications . 1 6.5.4 Meter Facility Design . 1 6.5.5 Equipment Selection . 1 6.5.5.1 Ty

12、pe of Meter 1 6.5.5.2 Meter Sizing 4 6.5.5.3 Meter Prover . 4 6.5.5.4 Strainers . 4 6.5.5.5 Air/Gas Eliminators 4 6.5.5.6 Flow Control and Back-Pressure 4 6.5.5.7 Valves 4 6.5.5.8 Instrumentation . 4 6.5.5.9 Sampler . 5 6.5.6 Transfer of Liquid Hydrocarbons to and from Marine Bulk Caniers 5 General

13、Operating Conditions 5 6.5.6.2 Loading . 5 6.5.6.3 Unloading 5 6.5.6.1 6.5.7 Preventive Maintenance . 5 6.5.7.1 Meters . 5 6.5.7.2 Meter Accessories . 5 .6.5. 7.3 Prover . 5 6.5.7.4 Valves . 5 6.5.7.5 ReadoutRrintout Equipment . 6 6.5.7.6 Meter Records 6 6.5.7.7 Personnel Qualifications 6 6.5.7.8 Lu

14、brication . 6 6.5.7.9 Strainer Screens and Filters 6 Figures 1-Schematic Arrangement of a Loading Marine Bulk Carrier 2-Schematic Arrangement of an Unloading Marine Bulk Carrier Meter Station With Three Meters and a Prover 2 Meter Station With Three Meters and a Prover 3 . V Chapter 6-Metering Assem

15、blies SECTION Bfi 11 10 11 thus, only low-capacity aidgas elimination equip- ment may be required. Carrier unloading presents a different situation because air is introduced each time load-arm con- nections are made to the carrier. Air may also be introduced during a vessels stripping operations. Ai

16、dgas eliminators at carrier unloading meter installations must be large enough so that the rate of flow can be reduced to allow gas-fluid separation. Adequate vent capacity and control valves must be provided to slow the flow temporarily as the liquid in the eliminator drops to a predetermined level

17、. The performance of airgas eliminators is adversely affected by increases in velocity and viscosity. The eliminator vessel should also be equipped with armored liquid level sight gauges so that the level can be determined before and after the unloading operation. 6.5.5.6 FLOW CONTROL AND BACK-PRESS

18、URE The need for controlling flow through each meter depends on several factors, including the size of the facility, flow demand, compartment stripping and topping, and proving. Flow should be controlled so that meters are protected against excessive speed, operated within the manufacturers recom- m

19、ended range, and proved at their normal flow rate. Adequate back-pressure must be maintained at all meters and meter provers on high-vapor pressure fluids. Flow control and back-pressure can be maintained by local or remote manual or automatic valves operated by controllers or control systems. 6.5.5

20、.7 VALVES High-integrity, double-block and bleed-type valves are required at all prover and meter isolation points to verify the valve seal and to prevent leaks. (See Figures 1 and 2.) 6.5.5.8 INSTRUMENTATION Instrumentation required at a measurement facility may vary from relatively simple meter to

21、talizers, with or without remote reading pressure gauges and thermometers, to quite complex elements used in fully automated facilities that often incorporate current computer technologies. In general, the higher level of automation and control is designed to comply with specific requirements for a

22、particular measurement SECTION &METERING SYSTEMS FOR LOADING facility. Refer to Chapter 5.4 for information on standardized meter accessory equipment common throughout the industry. 6.5.5.9 SAMPLER For crude oil measurement, automatic, flow-proportional line samplers are recommended as an integral p

23、art of the measurement system. The sampler takes a representative sample of the fluid metered for quantitative and qualitative analyses. The sampler should not be located between the meter and meter prover. (See Figures 1 and 2.) If the meter station is remote from the unloading arm, the sampler sho

24、uld be located at the unloading arm to ensure a representative sample for the marine bulk carrier. Mixing devices may be used if required. (Refer to Chapter 8, Section 2.) 6.5.6 Transfer of Liquid Hydrocarbons to and from Marine Bulk Carriers 6.5.6.1 GENERAL OPERATING CONDITIONS Smooth meter station

25、 operation depends on proper proce- dures and the need to exercise reasonable caution. Significant areas of concern to ensure smooth operations are listed below. a. Start-up procedures should be performed at low-flow levels and should be closely monitored. b. Air should not be introduced into the sy

26、stems. c. If air is inadvertently introduced into the system, it should be purged at a point upstream from the meter(s). d. Fiow should be maintained within the manufacturers? recommended ranges for the equipment selected. e. Stable flow and pressure conditions are necessary for meter accuracy. f. P

27、rovisions shall be made to correct for line-fill between the custody point and the meter location. g. Adequate back-pressure should be maintained in the meter installation. h. Provisions shall be made to account for hydrocarbon between the meters and the carrier or, in unloading, between the carrier

28、 and the meters. i. Sources of back-up measurement data that could be used in the event of equipment malfunction or failure of procedures should be considered. j. Double-block and bleed-valves should be checked at each full operation. k. The integnty of the totalizer and/or the meter gear-train shou

29、ld be verified by comparing the totalizer volume with the prover counter. For additional information pertaining to the selection, installation, operation, and maintenance of meters see Chap- ters 5.1,5.2, and 5.3. I i AND UNLOADING MARINE BULK CARRIERS 5 6.5.6.2 LOADING Uniform loading meter flow ra

30、te should be maintained by proper management of compartment filling. Periods of low flow should be minimized to the extent practical during compartment topping off because the meter factor may not be applicable in the low flow range. If meters are mounted in parallel, one or more meters can be close

31、d off during the topping-off operation so that the remaining meter or meters may operate at near-normal flow rates. 6.5.6.3 UNLOADING A uniform discharge flow rate should be maintained during unloading operations by proper management of com- partment stripping. Low-flow removal rates should be mini-

32、 mized to the extent practical during compartment stripping. If meters are mounted in parallel, one or more meters can be closed off during the stripping operation, because the meter factor may not be applicable in the low-flow range. 6.5.7 Preventive Maintenance 6.5.7.1 METERS Meter-proving records

33、 can be beneficial in a preventive maintenance program. Excessive meter factor drift on a given product indicates abnormal wear. Accurate information will permit maintenance to be scheduled at a convenient time. New meter factors must be determined when adjustments are made or maintenance is perform

34、ed on meters. Meter factor control charts or other meter performance records should be maintained to assist in monitoring meter performance. 6.5.7.2 METER ACCESSORIES Meter accessories, such as automatic temperature com- pensators or gravity selectors, temperature, or pressure devices associated wit

35、h measurement, should have periodic performance checks and should be recalibrated as required. 6.5.7.3 PROVER The meter-prover system should be periodically recalibrated as required and checked to ensure that ail as- sociated equipment is in good working order and that no deficiencies exist that mig

36、ht affect results. 6.5.7.4 VALVES Double-block and bleed-valves should be maintained and/or repaired if evidence of leakage is found. 6 CHAPTER &METERING ASSEMBLIES 6.5.7.5 READOUT/PRINTOUT EQUIPMENT Meter readout and printout equipment should be peri- odically inspected, checked, and calibrated to

37、ensure that all components are operating properly. 6.5.7.6 METER RECORDS Individual meter records should be maintained to verify that prescribed tests and maintenance have been performed periodically and to schedule preventive maintenance. 6.5.7.7 PERSONNEL QUALIFICATIONS All maintenance should be p

38、erformed with approved equipment and by authorized, qualified personnel who have been properly trained or otherwise qualified to perform the required tests, adjustments, or repairs. 6.5.7.8 LUBRICATION , All miscellaneous components requiring lubrication for proper operation, such as valves, should

39、be periodically lubri- cated, repacked, or otherwise repaired as appropriate for the specific item. 6.5.7.9 STRAINER SCREENS AND FILTERS Strainer screens or filters should be cleaned at prescribed intervals or when pressure differentials become excessive. Any strainer screens or filters showing sign

40、s of excessive wear, bulges, or apparent deterioration should be replaced with new elements of the proper size for the particular service. Disposable filters should be replaced when they reach their maximum recommended differential operating pressure. A means should be provided to indicate the pressure differential across the strainer. Order No. 852-301 25 American Petroleum Institute 1220 L Street, Northwest rlj Washington, D.C. 20005 I