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  • 1. ManuaI of PetroIeum Measurement Standards Chapter 4-Proving Systems Section 2-Pipe Provers (Provers Accumulating at Least 10,000 Pulses) SECOND EDITION, MARCH 2001 American Petroleum Institute Helping You Get The Job Done Right?COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 2. COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 3. Manual of Petroleum Measurement Standards Chapter 4-Proving Systems Section 2-Pipe Provers (Provers Accumulating at Least 10,000 Pulses) Measurement Coordination SECOND EDITION, MARCH 2001 American Petroleum Institute Helping You Get The Job Done Right?COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 4. SPECIAL NOTES API publications necessarily address problems of a general nature. With respect to partic- ular circumstances, local, state, and federal laws and regulations should be reviewed. API is not undertaking to meet the duties of employers, manufacturers, or suppliers to warn and properly t a n and equip their employees, and others exposed, concerning health ri and safety risks and precautions, nor undertaking their obligations under local, state, or fed- eral laws. Information concerning safety and health risks and proper precautions with respect to par- ticular materials and conditions should be obtained from the employer, the manufacturer or supplier of that material, or the material safety data sheet. Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the manufacture, sale, or use of any method, apparatus, or prod- uct covered by letters patent. Neither should anything contained in the publication be con- strued as insuring anyone against liability for infringement of letters patent. Generally,API standards are reviewed and revised, r e a f h e d , or withdrawn at least every five years. Sometimes a one-time extension of up to two years will be added to this review cycle. This publication will no longer be in effect five years after its publication date as an operative API standard or, where an extension has been granted, upon republication. Status of the publication can be ascertained from the API Upstream Segment [telephone(202) 682- 80001. A catalog of API publications and materials is published annually and updated quar- terly by API, 1220 L Street, N.W., Washington, D.C. 20005. This document was produced under API standardizationprocedures that ensure appropri- ate notification and participation in the developmental process and is designated as an API standard. Questions concerning the interpretation of the content of this standard or com- ments and questions concerning the procedures under which this standard was developed should be directed in writing to the standardization manager,American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005. Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the gen- eral manager. API standards are published to facilitate the broad availability of proven, sound engineer- ing and operating practices. These standards are not intended to obviate the need for apply- ing sound engineering judgment regarding when and where these standards should be utilized. The formulation and publication of API standards is not intended in any way to inhibit anyone from using any other practices. Any manufacturer marking equipment or materials in conformance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard. API does not represent, warrant, or guarantee that such prod- ucts do in fact conform to the applicableAPI standard. All rights resewed. No part o this work may be reproduced, stored in a retrieval system, or f transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, withoutprior written permission fiom the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, N.W, Washington,D.C. 20005. Copyright O 2001 American Petroleum InstituteCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 5. FOREWORD Chapter 4 of the Manual o Petroleum Measurement Standards was prepared as a guide for the f design, installation, calibration, and operation of meter proving systems commonly used by the majority of petroleum operators. The devices and practices covered in this chapter may not be appli- cable to all liquid hydrocarbonsunder a l operating conditions. other types of proving devices that are l not covered in this chapter may be appropriate for use if agreed upon by the parties involved. The information contained in this edition of Chapter 4 supersedes the information contained in the previous edition (First Edition, May 1978), which is no longer in print. It also supersedesthe informa- tion on proving systems contained in API Standard 1101, Measurement o Petroleum Liquid Hydro- f carbons by Positive Displacement Meter (First Edition, 1960); API Standard 2531, Mechanical Displacement Meter Provers; API Standard 2533, Metering Escous Hydrocarbons; and API Standard 2534, Measurement o Liquid Hydrocarbons by Turbine-MeterSystems, which are no longer in print. f This publication is primarily intended for use in the United States and is related to the standards, specifications, and procedures of the National Institute of Standards and Technology (NIST). When the information provided herein is used in other countries, the specifications and procedures of the appropriate national standards organizations may apply. Where appropriate, other test codes and pro- cedures for checking pressure and electricalequipment may be used. For the purposes of business transactions, limits on error or measurement tolerance are usually set by law, regulation, or mutual agreement between contracting parties. This publication is not intended to set tolerances for such purposes; it is intended only to describe methods by which acceptable approaches to any desired accuracy can be achieved. Chapter 4 now contains the following sections: Section 1, “Introduction” Section 2, “Pipe Provers” Section 3, “SmallVolume Provers” Section4, “Tank Provers” Section 5, “Master-MeterProvers” Section 6, “Pulse Interpolation” Section7, “Field-StandardTest Measures” Section 8, “Operation of Proving Systems” Section 9, “Calibrationof Provers” API publications may be used by anyone desiring to do so. Every effort has been made by the Insti- tute 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 dis- claims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conñict. Suggested revisions are invited and should be submitted to the standardization manager, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005. ... 111COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 6. COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 7. CONTENTS Page 1 INTRODUCTION...................................................... 1 1.1 Scope ........................................................... 1 1.2 Pipe Prover Systems ............................................... 1 1.3 DefinitionofTerms ................................................ 1 1.4 Referenced Publications ............................................ 2 2 G E N E W PERFORMANCE CONSIDERATIONS.......................... 2 2.1 Repeatability and Accuracy .......................................... 2 2.2 Base Prover Volume ................................................ 2 2.3 Valve Seating ..................................................... 2 2.4 Flow Stability..................................................... 2 2.5 Freedom From Shock .............................................. 2 2.6 Temperature Stability............................................... 2 2.7 Pressure Drop Across the Prover ...................................... 2 2.8 MeterPulseTrain .................................................. 3 3 GENERAL EQUIPMENT CONSIDERATIONS ............................. 3 3.1 Materials and Fabrication ........................................... 3 3.2 Internal and External Coatings ....................................... 3 3.3 Temperature Measurement .......................................... 3 3.4 Pressure Measurement .............................................. 3 3.5 Displacing Devices ................................................ 3 3.6 Valves ........................................................... 4 3.7 Connections ...................................................... 4 3.8 Detectors ........................................................ 5 3.9 Peripheral Equipment .............................................. 5 3.10 Unidirectional Pipe Provers .......................................... 6 3.1 1 Bidirectional Pipe Provers ........................................... 6 4 DESIGN OF PIPE PROVERS ............................................ 6 4.1 Initial Considerations ............................................... 6 4.2 Design Accuracy Requirements ..................................... 10 4.3 Dimensions of a Pipe Prover ........................................ 11 5 INSTALLATION ..................................................... 15 5.1 General Considerations ............................................ 15 5.2 ProverLocation .................................................. 15 APPENDIX A ANALYSIS OF SPHEREPOSITION REPEATABILlTY .......... 17 APPENDIX B EXAMPLES OF PROVER SIZING ............................ 21 APPENDIX C A PROCEDURE FOR ESTIMATINGMEASUREMENT SYSTEM UNCERTAINTY................................... 25 APPENDIX D TYPICAL PIPE PROVER DESIGN DATA SHEET............... 31 VCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 8. Page Figures 1 Typical Unidirectional Return-Type Prover System ....................... 7 2 Typical Bidirectional U-Type Sphere Prover System........................ 8 3 Typical Bidirectional Straight-Type Piston Prover System ................... 9 4 Interpulse Deviations................................................ 11 A-1 Diagram Showing the Relationship Between Sphere Position Repeatability and Mechanical Detector Actuation Repeatability......................... 17 Graphs A- 1 Sphere Versus Detector Relationship at Various Insertion Depths for a 12in. Prover with a 0.75in. Diameter Detector Ball ............................ 19 A-2 Prover Length Versus Detector Repeatability at Various Insertion Depths for a 12in. Unidirectional Prover with a 0.75in. Diameter Detector Ball ....... 19 Tables C-1 Range to Standard Deviation Conversion Factors ......................... 27 C-2 Student t Distribution Factors for Individual Measurements ................. 28 C-3 Estimated Measurement Uncertainty of the System at the 95% Confidence Level for Data that Agree within a Range of 0.05% ....................... 29 viCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 9. Chapter 4-P roving Systems 1 Introduction pipe by the liquid stream being metered. The corresponding metered volume is simultaneouslydetermined. This document addresses pipe provers with sufficient vol- ume to accumulate a minimum of 10,OOO whole-unaltered 1.2.2 A meter that is being proved on a continuous-flow meter pulses between detector switches for each pass of the basis must be connected at the time of proof to an electronic displacer. Historically this type of prover has been referred to pulse counter that can be instantly started and stopped by the as a ‘‘conventionfl pipe prover. Pipe provers may be straight signaling detectors. The counter is started and stopped when or folded in the form of a loop. Both mobile and stationary the displacing device actuates the two detectors at the ends of provers may be constructed in accordance with the principles the calibrated section. described in this chapter. Pipe provers are also used for pipe- 1.2.3 The two types of continuous-flow pipe provers are lines in which a calibrated portion of the pipeline (straight,U- shaped, or folded) serves as the reference volume. Some unidirectional and bidirectional. The unidirectional prover provers are arranged so that liquid can be displaced in either allows the displacerto travel in only one directionthrough the direction. proving section and has an arrangement for returning the dis- placer to its starting position. The bidirectional prover allows When using a pipe prover the flow of liquid is not inter- the displacer to travel first in one direction and then in the rupted during proving. This uninterrupted flow permits the other and incorporates a means of reversing the flow through meter to be proved under specific operating conditions and at the pipe prover. a uniform rate of flow without having to start and stop. The reference volume (the volume needed between detec- 1.2.4 Both unidirectional and bidirectional provers must be tors) required of a pipe prover depends on such factors as the constructed so that the full flow of the stream through a meter discrimination of the proving register, the repeatability of the being proved will pass through the prover. Pipe provers may detectors, and the repeatability required of the proving system be manually or automatically operated. as a whole. At least 10,000 meter pulses without pulse inter- polation are required for meter factors derived to a resolution 1.3 DEFINITION OF TERMS of 0.0001. The relationship between the flow range of the meter and the reference volume must also be taken into Terms used in this chapter are deñned below. account. 1.3.1 interpulse deviations: Random variations In those applications where the pipe prover volume andor between consecutive meter pulses when the meter is operated the meter pulse generation rate does not permit the minimum at a constant flow rate. accumulation of 10,000discrete pulses, refer to Chapter 4.3. 1.3.2 meter proof: Multiple passes or round trips of the 1.1 SCOPE displacer in a prover for purposes of determining a meter factor. This chapter outlines the essential elements of unidirec- tional and bidirectional conventional pipe provers and pro- 1.3.3 meter prover: An open or closed vessel of known vides design, and installation details for the types of pipe volume utilized as a volumetric reference standard for the cal- provers that are currently in use. The pipe provers discussed ibration of meters in liquid petroleum service. Such provers in this chapter are designed for proving measurement devices are designed, fabricated, and operated within the recommen- under dynamic operating conditions with single-phase liquid dations of Chapter 4. hydrocarbons.These provers consist of a pipe section through which a displacer travels and activates detection devices 1.3.4 prover pass: One movement of the displacer before stopping at the end of the run as the stream is diverted between the detectors in a prover. or bypassed. 1.3.5 prover round trip: The forward and reverse passes in a bidirectional prover 1.2 PIPE PROVER SYSTEMS 1.3.6 prover run: Equivalent to a prover pass in a unidi- 1.2.1 All types of pipe prover systems operate on the com- rectional prover or a round trip in a bidirectional prover. mon principle of the repeatable displacement of a known vol- ume of liquid from a calibrated section of pipe between two 1.3.7 pulse rate modulation: A consistent variation in signaling detectors. Displacement is achieved by means of a meter pulse spacing when the meter is operated at a constant slightly oversized sphere or piston that is driven along the flow rate. 1COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 10. 2 CHAPTER 4-PROVING SYSTEMS 1.4 REFERENCED PUBLICATIONS 2.2.3 For the initial base volume determination of a new, modified, or refurbished prover, more than three calibration API Manual of Petroleum Measurement Standards runs may be used to establishhigher confidencein the calibra- Chapter 1 “Vocabulary” tion. When conditions exist that are likely to affect the volume of the prover, (e.g. corrosion, coating loss, deposit buildup) Chapter 4 “Proving Systems,” the prover should be repaired if necessary and recalibrated. Chapter 5, “Metering Systems” 2.2.4 Historical calibration data should be retained and Chapter 6 “MeteringAssemblies” evaluated to judge the suitability of prover calibration proce- dures and intervals. Chapter 7 “TemperatureDetermination” Chapter 11 “Physical Properties Data” 2.3 VALVE SEATING Chapter 13 “Statistical Concepts and Procedures in 2.3.1 All valves used in pipe prover systems that can pro- Measurement” vide or contribute to a bypass of liquid around the prover or meter or to leakage between the prover and meter shall be of DOT’ the block-and-bleedtype or an equivalent with a provision for 49 Code o Federal Regulations, Parts 171-177 (Subchap- f seal verification. ter C, “Hazardous Materials Regulations”) and 3%397 2.3.2 The sphere interchange in a unidirectional prover or (Subchapter B, “Federal Motor Carrier Safety Regula- the flow-divertervalve or valves in a bidirectional prover shall tions”) be fully seated and sealed before the displacer actuates the first detector. These and any other valves whose leakage can 2 General Performance Considerations affect the accuracy of proving shall be provided with some means of demonstrating before, during, or after the proving 2.1 REPEATABILITY AND ACCURACY run that they are leak free. Repeatability is usually adopted as the primary criterion 2.4 FLOW STABILITY for a prover’s acceptability. Good repeatability does not nec- essarily indicate good accuracy because of the possibility of The flow rate must be stable while the displacer is moving unknown systematic errors. The ultimate requirement for a through the calibrated section of the prover. Some factors prover is that it prove meters accurately. However, accuracy affecting flow rate stability include: adequate pre-run length, cannot be established directly because it depends on the types of pumps in system, operating parameters, etc. repeatability of the meter, the accuracy of the instrumenta- tion, and the uncertainty of the prover’s base volume. The 2.5 FREEDOM FROM SHOCK repeatability of any provedmeter combination can be deter- When the prover is operating within design flow range, the mined by carrying out a series of repeated measurements displacer shall decelerate and come to rest safely at the end of under carefully controlled conditions and analyzing the its travel without shock. results statistically. 2.6 TEMPERATURE STABILITY 2.2 BASE PROVERVOLUME Temperature stability is necessary to achieve acceptable 2.2.1 The base volume of a unidirectional prover is the cal- proving results. This is normally accomplished by circulating ibrated volume between detectors corrected to standard tem- liquid through the prover section until temperature stabiliza- perature and pressure conditions. The base volume of a tion is reached. When provers are installed aboveground,the bidirectional prover is expressed as the sum of the calibrated application of thermal insulationwill contribute to better tem- volumes between detectors in two consecutive one-way perature stabilization. passes in opposite directions, each corrected to standard tem- perature and pressure conditions. 2.7 PRESSURE DROP ACROSS THE PROVER 2.2.2 The base prover volume is determined with three or In determining the size of the piping and openings to be more consecutive calibration runs that lie within a range of used in the manifolding and the prover, the pressure loss 0.02 percent (see Chapter 4.9). through the pipe prover system should be compatible with the acceptable pressure loss in the metering installation. Exces- ‘U.S. Department of Transportation. The Code of Federal Regula- sive pressure drop may prevent the meter from being proved tions is available from the U.S. Government Printing Office, at its normal flow rate@) andor minimum backpressure Washington, DC 20402. required for the meter.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 11. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 3 2.8 METER PULSE TRAIN 3.4 PRESSURE MEASUREMENT The pulse output from the meter can exhibit variations Pressure-measurementdevices of suitable range and accu- even though the flow rate through the meter is constant. These racy are used at appropriate locations to indicate the pressure variations may be caused by mechanical and electricalimper- in the meter and the pressure in the prover. Caution must be fections of the meter, and in signal processing techniques. exercised to ensure that the pressure sensors are located Variations in the meter pulse output may result in unaccept- where they will not be isolated from the liquid path. able proving performance. 3.5 DISPLACING DEVICES 3 General Equipment Considerations Prover displacers are devices, which travel through the 3.1 MATERIALS AND FABRICATION prover calibrated section, operating the detector switches, and sweeping out the calibrated liquid volume. There are two The materials selected for a prover shall conform to appli- types of displacers in common use, inflatable elastomer cable codes, pressure and temperature ratings, corrosion spheres and metallic pistons. resistance, and area classifications. Pipe, fittings, and bends should be selected for roundness and smoothness to ensure 3.5.1 Sphere Displacers consistent sealing of the displacer during a prover pass. Because of the tight tolerances on seals, a piston prover may 3.5.1.1 Materials used in the construction of elastomer require the internal surface to be honed. spheres vary widely according to the applications for which they are to be used. Most commonly used are three basic 3.2 INTERNAL AND EXTERNAL COATINGS materials, neoprene, nitrile and urethane. In order to obtain the best performance from any of these materials the operator 3.2.1 Internally coating the prover section with a coating should consider the chemical composition of the liquid that material that will provide a hard, smooth, long-lasting ñnish will be passing through the prover. Operating temperatures will reduce corrosion and prolong the life of the displacer and and pressures also affect the performance of these com- the prover. Experience has shown that internal coatings are pounds in prover spheres. No one material or compound is particularly useful when the prover is used with liquids that ideal for all applications, therefore, proper material selection have poor lubricating properties, such as gasoline or liquefied is extremely important. petroleum gas; however, in certain cases, satisfactory results and displacer longevity may be achieved when uncoated pipe 3.5.1.2 Aromatic compounds, certain chemicals and oxy- is used. The materials selected for the internal coating appli- genates (h4TBE, etc.) can attack all the above mentioned cation should be compatible with the liquid types expected. materials causing various degrees of softening, swelling and The coatings should be applied according to the manufac- distortion of the shape of the sphere. Other materials such as turer’s recommendations. Extreme caution should be exer- Viton, Teflon, Buna, etc., have also been used in sphere con- cised in the surface preparation so that the coating is applied struction for applications that involve proving operations on over a clean white blasted metal with a minimum anchor pat- specialized chemicals. Consultation with the manufacturer is tern as specifiedby the manufacturer. recommended to determine the best material to be used in prover operations on a specific product. 3.2.2 Externally coating the prover section and associated piping will reduce corrosion and will prolong the life of the 3.5.1.3 The most common type of displacer is the inflat- prover, particularly for installations where the prover is bur- able elastomer sphere. It is usually made of neoprene, nitrile, ied. Additionally,external insulation of the prover section and or polyurethane. It has a hollow center with one or more associated piping may be necessary to control sudden valves used to inñate the sphere. The sphere is filled with gly- changes in temperature between the meter and prover. col, or a 50/50-glycol and water mixture to prevent freezing. Care must be exercised to ensure that no air remains inside 3.3 TEMPERATURE MEASUREMENT the sphere, and the sphere has a negative buoyancy. Once the sphere has been filled, it is further inñated in order to increase Temperature-measurement sensors shall be of suitable its size over and above the inside diameter of the pipe. This range and accuracy and should reflect the temperature within over inñation is usually in the range of 2 to 3 percent for nor- the meter and the temperature within the calibrated section of mal proving operations, depending upon the pipe diameter the prover. A means shall be provided to measure temperature and condition of the pipe. For water draw calibrations of the at the inlet and outlet of the prover (see Chapter 7 for detail prover it may necessary to increase the inñation of the sphere requirements). Caution must be exercised to ensure that the (see Chapter 4.9 forfurther information). This arrangement temperature sensors are located where they will not be iso- allows the sphere to form a tight leakproof seal against the lated from the liquid path. inside walls and to sweep the walls clean of any materialCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 12. 4 CHAPTER 4-PROVING SYSTEMS (wax, etc.) that may accumulate. During proving runs the service and are designed to weigh as little as possible. Provers sphere will usually rotate and wear equally around its surface. with piston type displacers require magnetic-type proximity detector switches. 3.5.1.4 Excessive over inflation of the sphere may result in sticking of the sphere, damage to the sphere, excessive wear, 3.5.2.2 Aluminum or nonmagnetic stainless steel, or com- increased pressure drops, and damage to the prover. The binations of both are used in the fabrication of the piston effect is more pronounced in small diameter provers. body, which must also contain a magnetic sensor-exciting ring to actuate the proximity detector switches. 3.5.1.5 Under inñation can result in bypass around the sphere (leak) causing inaccuracies in the proving volume. 3.5.2.3 The piston sealing rings or cups are made from This can be caused by the sphere contact length (the part either Teflon, Viton, polyurethane, nitrile, Buna or neoprene, touching the pipe wall) being less than the length of any depending upon the liquid or gas product and the operating opening in the pipe wall. It is possible that the prover can pro- temperatures and pressures to which the seals are exposed in duce repeatable results by consistent bypass around the the prover. Piston type displacers must have a wear ring at sphere that will be in error. both ends of the piston to prevent the metal body of the piston from contacting and damaging the honed andor coated sur- 3.5.1.6 Measurement of the sphere can be accomplished face of the prover measuring chamber. either by means of a set of calipers, a sizing ring, or a flexible 3.5.2.4 Pistons fitted with scraper cups made from various steel tape, by which the circumference is measured and the elastomer compounds do not require extenders to maintain diameter calculated. Regardless of the method used, the mea- the seal between the cup edges and the bore of the prover. If surement should be taken across several diameters. The Teflon cups are used then the piston must be equipped with smallest diameter measured is to be considered the real diam- some type of expander device or material since Teflon is not eter of the sphere so that whatever inflation is chosen, the an elastomer and has no shape retention memory such as rub- sphere will have a minimum diameter of that amount. Each ber compounds. measurement of a large sphere should be in a vertical plane. The purpose of sizing the sphere is to effect a seal across the 3.6 VALVES displacer during its travel through the calibrated section of pipe. Any leakage across this sphere would result in an error Al valves in the proving system between the meter and the l in measurement. prover outlet shall be double block and bleed, skilleted, or have provisions for verifying the valve integrity.This includes 3.5.1.7 The sphere size shall be verified periodically, and valves to adjoining meter runs, vents, and drains. Thermo- the sphere resized if necessary. Since wear is a function of relief and pressure equalizing valves should not be installed lubricity, crude oil or lubricating oils give exceptionally long between the meter and the prover. life, as opposed to prolonged service in a non-lubricating product such as LPG which gives no lubrication and 3.7 CONNECTIONS enhances wear. Normally many hundreds of runs can be 3.7.1 Connections shall be provided on the prover or con- made without resizing the sphere. necting piping to allow for calibration,venting, and draining. 3.5.1.8 Elastomer sphere displacers have a wide range of 3.7.2 Drains and vents for the prover, prover piping, and operating velocities, which is dependent upon operating con- block and bleed valves should be connected to drain systems ditions and fluids. or other means should be provided to facilitate the handling of 3.5.1.9 In order to perform maintenance and inspection of vented and drained fluids in a safe and environmentally suit- the sphere, provisions should be provided to easily and safely able manner. Drains should be placed at locations to facilitate remove the sphere from the prover. These may include a removal of water used for hydrostatic testing and calibrations. quick opening closure to provide access to the launching Figures 3, 4, and 5 show connections for water draw andor chamber(s), a sphere removal tool to pick up the sphere, a master meter calibrations. Drains are not shown on the figures, hoist to lift the sphere, and access platforms around the but they should be placed at numerous low points on the pip- launching chambers. ing. Vents should be installed at all high points on the piping. 3.7.3 The calibrated section of the prover between the 3.5.2 Piston Displacers detectors should be designed to exclude any appurtenances such as vents or drains. 3.5.2.1 Piston type displacers are used in bidirectional provers that are specificallydesigned for their use. The design 3.7.4 For drains and vents between the meter and cali- of a piston displacer varies according to different manufactur- brated sections, a means should be provided to allow inspec- ers and the requirements of the user. However, they are usu- tions for leakage or block and bleed valves should be ally made of materials compatible with the liquid or gas fluid provided on these connections.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 13. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 5 3.7.5 Flanges or other provisions should be provided for imity-type magnetically actuated detectors, are described access to the inside surfaces of the calibrated and prerun below: sections. Internal access is an important consideration when internal coating of the prover is required. Care shall be exer- 3.8.2 Mechanically Actuated Detector Switches cised to ensure and maintain proper alignment and concen- tricity of pipe joints. Al pipe, flanges, and fittings shall have l The mechanical type of detector switch is used primarily the same internal diameter in the calibrated and pre-run sec- with elastomer sphere displacers. It is operated when the dis- tions. Flanges in the calibrated volume shall be match bored placer contacts a stainless steel rod or ball, which protrudes and uniquely doweled or otherwise designed to maintain the into the prover pipe at the beginning and end of the prover match-bored position of the flanges. The calibrated section calibrated section. When the displacer contacts this stainless shall be designed to seal on a flange-face metal-to-metal steel rod or ball, a rod containing a magnet will lift and cause makeup, with the sealing being obtained from an O-ring an external reed switch to operate. Detector switches are nor- type seal. Al internal welds and metal surfaces shall be l mally hydraulically balanced and serviceable under pressure. ground smooth to preclude damage to and leakage around Contact detectors on bidirectional provers should be installed the displacer. under close tolerance so that the sensing characteristicsin one direction are similar to those in the reverse direction. The 3.8 DETECTORS electronic sensing elements in contact detectors should be designed so that the detector is not significantly affected by 3.8.1 General Considerations rotation of the mechanical plunger or by mechanical shock of the displacer. Openings through the pipe wall for detectors 3.8.1. I A detector switch is an externally mounted device must be smaller than the longitudinal seaiing area of the on a prover, which has the ability to detect and repeat, within sphere and on pistons, multiple seals must be provided. close tolerances, the displacer entrance into and its exit from the prover calibrated section. The amount of fluid that is dis- 3.8.3 ProximityType Magnetically Actuated placed between two detector switches is the calibrated vol- Detector Switches ume of the prover. Detector switches are normally required at each end of the prover measuring section. Provers normally Proximity-type magnetically actuated switches are used have two detector switches, which are connected to an elec- only with piston type displacers. This type of switch is tronic meter-proving counter, this counter in turn being con- mounted externally from the prover measuring section, with nected to a pulse generator on a meter. The detector switches no parts inserted through the wall of the prover. It is actuated define the calibrated measuring section of the prover. Addi- by either a magnetic material, such as a carbon steel or stain- tional switches may be used if more than one calibrated vol- less steel exciter ring or magnets on the piston displacer pass- ume is required on the same prover, or they can also be used ing beneath the detector proximity switch. These switches to signal the entrance of a displacer into the sphere resting have the ability to detect within close tolerances, the entrance chamber. and exit of the displacer into and out of the prover measuring section. These non-contact types of switches do not have to 3.8.1.2 Displacer detectors must accurately and consis- make physical contact with the displacer. However, non-con- tently indicate the position of the displacer within a close tol- tact sensors have a limited sensing distance that may also be erance. The accuracy with which the detector can determine displacer velocity dependent. To ensure consistent detection the position of the displacer is one of the governing factors in of the displacer, the distance between the detector and the dis- determining the length of the prover’s calibrated section. The placer’s detection elements should be no more than half the detection devices must be rugged and reliable because maximum sensing distance of the detector. It is important to replacement usually requires recalibration of the prover and ensure that these distances can be maintained. To accomplish temporary loss of meter proving capability. this the non-contact detectors should be installed on the side 3.8.1.3 When the worn or damaged parts of a detector are of the prover and the piston’s seals should have sufficient replaced, care must be taken to ensure that neither the detec- stiffness to consistently support the weight of the piston. The tor’s actuating depth nor its electrical switch components are sensing characteristics of the non-contact detector should be altered to the extent that the prover volume is changed. This is symmetrical and consistent between detectors so that detec- especially true for unidirectional provers because changes in tors can be interchangeable. detector actuation are not compensated for round trip sphere travel as they are in bidirectional provers. Recalibration of 3.9 PERIPHERAL EQUIPMENT unidirectional provers is in order as soon as practical. 3.9.1 A meter pulse generator shall be provided for trans- 3.8.1.4 The two types of detector switches presently in use mission of flow data and must provide electrical pulses with for pipe provers, mechanically actuated detectors and prox- satisfactory characteristics for the type of proving counterCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 14. 6 CHAPTER 4-PROVING SYSTEMS used. The device should generate a sufficient number of ing tee should have a slight inclinationdownwards toward the pulses per unit volume to provide the required discrimination prover section, or another means should be provided to (see Chapter 5.4). ensure that the sphere moves into the prover during periods of low flow, which might occur during calibration by the water- 3.9.2 An electronic pulse counter or flow computer is usu- draw method. ally used in meter proving because of the ease and accuracy with which it can count high-frequency pulses and its ability 3.10.5 Debris Removal to transmit this count to remote locations. The pulse-counting devices are equipped with an electronic start/stop switching Some means for removal of debris and other contaminants circuit that is actuated by the pipe prover’s detectors. should be considered in the design of new provers. 3.10 UNIDIRECTIONAL PIPE PROVERS 3.11 BIDIRECTIONALPIPE PROVERS 3.10.1 General 3.11. I General Typical unidirectional prover piping is arranged so that the Typical bidirectional provers (see Figures 2 and 3) have a displacer is returned to a start position using a sphere han- length of pipe through which the displacer travels back and dling interchange (see Figure 1). The interchange is the forth, actuating a detector at each end of the calibrated sec- means by which the displacer is transferred from the down- tion. Suitable supplementarypipework and a reversing valve stream to the upstream end of the loop without being or valve assembly that is either manually or automatically removed from the prover. The separator tee is the means by operated make possible the reversal of the flow through the which the displacer’s velocity is reduced to zero to allow it to prover. The main body of the prover is often a straight piece enter into the interchange. The launching tee provides the of pipe, but it may be contoured or folded to fit in a limited means for allowingthe displacer to enter the flowing stream. space or to make it more readily mobile. A sphere is used as the displacer in the folded or contoured type; a piston or 3.10.2 Sphere Interchange sphere may be used in the straight-pipe type. The sphere interchange provides a means for transferring the sphere from the downstreamend of the proving section to 3.11.2 Outlets and Inlets the upstream end. Sphere interchange may be accomplished The outlets and inlets on the pipe prover end chambers of with several differentcombinations of valves or other devices bidirectional provers are designed to pass liquids while to minimize bypass flow or flow reversal through the inter- restraining the displacer. The chambers should be at least two change during the sphere transfer process. A leaktight valve pipe sizes larger than the nominal size of the sphere or loop. seal is essential before the sphere reaches the first detector Sizing is best determined by experience.The openings shall switch of the proving section. be deburred. Inlets and outlets to the 4-way diverter valve shall have an area sufficient to avoid excessive pressure loss, 3.10.3 SeparatorTees and shall have a means to prevent entry of the displacer. The Separator tees should be at least two pipe sizes larger than transition from the chamber to the pre-run needs to be a con- the nominal size of the sphere or loop. Sizing is best deter- centric reducer for a vertical chamber orientation and an mined by experience. The design of the separator tee shall eccentric reducer for all other orientations. ensure dependable separation of the sphere from the stream for all rates within the flow range of the prover. For practical 3.11.3 Flow Reversal purposes, the mean liquid velocity through the tee should not A single multiport valve is commonly used for reversing exceed 5 ft (1.5 m) per second; a considerably lower liquid the direction of the displacer. Other means of flow reversal velocity is often desirable. The tee must sometimes be sized may also be used. All valves must be leak free and allow con- several sizes larger. Smooth-flow transition fittings on both tinuous flow through the meter during proving. A method of ends of the tee are important. A means of directing the sphere checking for seal leakage during a proving pass shall be pro- into the interchange shall be provided at the downstream end. vided for all valves. The valve size and actuator shall be Care should be taken in designing this device to prevent dam- selected to limit hydraulic shock. age to a sphere. 4 Design of Pipe Provers 3.10.4 LaunchingTees 4.1 INITIAL CONSIDERATIONS Launching tees should be at least two pipe sizes larger than the nominal size of the sphere or loop. They shall have Before a pipe prover is designed or selected, it is necessary smooth transition fittings leading into the prover. The launch- to establish the type of prover required for the application andCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 15. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT Figure I-Typical Unidirectional Return-Type Prover SystemCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 16. 8 CHAPTER 4-PROVING SYSTEMS Figure 2-Typical Bidirectional U-Type Sphere Prover SystemCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 17. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 9 Figure 3-Typical Bidirectional Straight-Type Piston Prover SystemCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 18. 10 CHAPTER 4-PROVING SYSTEMS the manner in which it will be connected with the meter pip- dard deviation is based on a value known as Student’s t. For ing. Based on the application, intended use, and space limita- the purpose of this document, all statistical data presented in tions, the following should be established. A typical data this section will use: sheet is shown is Appendix D. a. A 95% confidence level. If the prover is stationary,determine: b. Degree of freedom (n-1 for n measurements). 1. Whether it will be dedicated (on line) or used as part of c. Student’s t distribution. a central system. 2. Whether it will be kept in service continuously or iso- 4.2.1.4 Appendix C provides tables to convert range to lated from the metered stream when it is not being used to standard deviation (Table C-i) and Student’s t distribution prove a meter. values for 95% probability (Table C-2). For further informa- 3. What portions, if any, are desired below ground. tion concerning statisticalanalysis, see API Chapter 13. 4. What foundation andor support requirements are needed. 4.2.2 Displacer Detectors If the prover is mobile, what leveling devices are required? The minimum distance between detector switches depends The ranges of temperature and pressure that will be on the detector’s ability to consistently locate the position of encountered. the displacer. The performance of the detectors and the dis- d. The maximum and minimum flow rates expected. placer affects both prover calibrationand meter proving oper- e. The flow rate stability. ations. The total uncertainty of the detector and displacer at f. The maximum pressure drop allowable across the prover. the 95% confidence level shall be limited to f 0.01% of the g. The physical properties of the fluids to be handled. length of the calibrated section. The prover or detector’s man- ufacturer or the prover’s designer is responsible for demon- h. The degree of automation to be incorporated in the prov- strating through testing and technical analysis that the ing operation. displacer’s detection system meets the stated performance i. Available utilities. requirement. For additional information on displacer position j. Volume requirements (minimum 10,000 unaltered meter calculations see Appendix A. pulses) 4.2.3 Pulse Count Resolution and Uncertainty 4.2 DESIGN ACCURACY REQUIREMENTS During a single prover pass, a meter pulse counter can 4.2.1 General Considerations potentially add a pulse at the start of the pass and can poten- 4.2.1. I The ultimate requirement for a prover is that it tially lose a pulse at the end of the pass. The indicated pulse prove meters accurately; however, accuracy cannot be estab- count of a perfectly uniform pulse train has a potential uncer- lished directly because it depends on the repeatability of the tainty o f f 1 pulse during a single prover pass. The potential meters, the accuracy of the instrumentation, and the uncer- uncertainty in pulse count of a perfectly uniform pulse train is tainty of the prover’s base volume. The accuracy of any determined as follows: provedmeter combination can be determined by carrying out a series of measurements under carefully controlled condi- f 1 pulse tions and analyzing the results statistically.Appendix C pro- u(N,) = ~ x 100% Nm vides one method of estimating this accuracy. 4.2.1.2 The nature of physical measurements makes it impossible to measure a physical variable without error. potential uncertainty of the recorded pulse Absolute accuracy is only achievable when it is possible to count the objects or events; even then, when large numbers count during a prover pass, I% pulse, are involved,it may be necessary to approximate. of the three number of whole meter pulses collected during basic types of error (spurious errors, systematic errors, and a prover pass. random errors), only random error can be estimated through statisticalmethods. The uncertainty in the average pulse count of a series of prover passes can be estimated as follows: 4.2.1.3 For applications of statistics to custody measure- ment, the 95% confidence level is traditionally used for ana- lyzing and reporting uncertainties in measured values. The limit of random uncertainty calculated from estimated stan-COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 19. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 11 where meter is constant. Both types of variations also affect the meter pulse count during a proving run and the uncertainty in a(N,)’ = uncertainty in the average pulse count for a the meter pulse count. series of prover passes, I % pluses, 4.2.5 Base ProverVolume Variation np = number of prover passes. The procedural uncertainty (at the 95% confidence level) 4.2.4 Metering PulseTrainVariation in the average of three calibration runs that agree within a range of 0.02% is I 0.029% (see Chapter 4.9). This means 4.2.4.1 The output from the primary flow element of dis- that there is a 95% probability that the true prover volume lies placement and turbine meters can exhibit variations even inside the range described by 0.029% of the calculated base when flow rate through the meter is constant. These variations volume. Conversely, there is only a 5% probability that the are caused by imperfections andor wear in bearings, blades, true prover base volume lies outside the range described by I sensory plugs and other moving parts. Gears, universaljoints, 0.029% of the calculatedbase volume. clutches and other mechanical devices that compensate, cali- brate and transmit the output of the primary flow element can 4.3 DIMENSIONS OF A PIPE PROVER cause variations in the indicated flow rate signal that are greater than those caused by the primary flow element. 4.3.1 General Considerations 4.3.1.1 In order to achieve the desired accuracy of the 4.2.4.2 Two types of pulse train variations are interpulse proving system, the following items shall be considered by deviations which refers to random variation between consec- the designer in determining the dimensions of a prover: utive pulses and pulse rate modulation which refers to a pat- tern of variation in pulse rate or K-factor (see Figure 4). Both a. The repeatability of the detectors. types of variations occur even when the flow rate through the b. The number of pulses per unit volume @e.,K-factor). Uniform pulse train nn Non-uniform pulse train with interpulse deviations Non-uniform pulse train with pulse rate modulations Figure 41 nterpuIse Deviations -COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 20. 12 4- CHAPTER -PROVINGSYSTEMS Note: The actual pulses per unit volume can vary considerably from accommodate a minimum number of test measures used dur- the nominal number supplied by the meter manufacturer due to ing a waterdraw calibration. The least number of test mea- influences such as flow rate, rangeability, hydrocarbon being mea- sures used will reduce the overall uncertainty of the sured, and wear over time. Similar meters (same size and manufac- turer) can and will be different. calibrationprocedure. c. The maximum and minimum flow rates of the metering Example: systems. If the original design requirements call for 92 gallons d. The type of meter(s) to be proved, potential variations in between detector switches, the minimum test measures the meter’s pulse train and the potential of the meter being required would be: nonlinear. 1 - 50 gallon test measure e. Whether prover is bidirectional or unidirectional. 1 - 25 gallon test measure f. The type of displacer and the velocity limitations of the 1 - 10 gallon test measure displacer. 1 -5 gallon test measure g. The prerun and post-run requirements. 2-1 gallon test measure h. Wall thickness and internal diameter of piping and fitting components to meet operating requirements. This would require six scale and temperature readings, six i. The physical space and weight limitations. calculations,and would take a considerable amount of time to j. The cycle time and velocity limitationsof the flow reversal fill and drain the six test measures. valve or interchange. If the prover volume would be adjusted up to 100 gallons between the switches, the calibration would require only one 4.3.1.2 The dimensions selected for provers are a compro- 100 gallon test measure. This will reduce the calibrationtime mise between displacer velocity limits and uncertainty limits and uncertainty. on detection of the displacerspositions and uncertainty in the other things to consider that may increase the volume meter pulse count. Decreasing the diameter of the prover pipe required include: increases the length between detectorsfor a given volume and a. The variance of the actual K-factor from the manufac- reduces the uncertainty on positions of the displacers. turer’s typical published K-factor for turbine meters may Decreasing the pipe diameter also increases displacer veloc- result in less than 10,000 pulses. ity, which may become a limiting factor. Increasing the diam- b. For small displacement meters, generally under 4 in., eter of the prover pipe has the opposite effect; the velocity of which use mechanical gearing in their pulse generation t a n ri, the displacer is reduced, but the resulting decrease in length the volume may need to be increased to the next whole unit of increases uncertainty in positions of the displacer and thus volume per revolution of the meter to avoid the cyclical may become a limiting factor. Examples of prover sizing can effects of the clutch calibrator. For example, 5 gallon incre- be found in Appendix B. ments on 5 to 1 gallon geared meters. 4.3.2 Volume 4.3.3 DisplacerVelocities 4.3.2.1 To meet the requirement of at least 10,000 pulses, Some practical limit to the maximum velocity of a dis- the minimum volume of the calibrated prover pass (between placer must be established to prevent damage to the displacer detector switches) is: and the detectors. Nevertheless,the developing state of the art advises against setting a fr limit to displacer velocity as a ìm 10,000 pulses criterion for design. Demonstrated results are better to use as V,2 (3) k a criterion. The results are manifested in the repeatability and reproducibility of meter factors using the prover in question. where Other considerations include consistency of the prover diam- Vp = Volume of prover pass, barrels, eter and prover surfaces along with the friction between the prover and displacer’s sealing surfaces. k = K-factor for meter, pulses per barrel. For example, if k = 1000 pulses per barrel, Vp is: 4.3.3.1 Maximum DisplacerVelocities 4.3.3.1. I For sphere displacers,most operators and design- ers agree that 10 fth is a typical design specificationfor unidi- rectional provers, whereas velocities up to 5 fth are typical in bidirectional provers. Higher velocities may be possible if the 4.3.2.2 After designing a meter prover for a specific appli- design incorporates a means of limiting mechanical and cation, the volume of the prover should be adjusted up to hydraulic shock as the displacer completes its pass.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 21. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 13 4.3.3.1.2 For piston displacers,a maximum velocity of 3 fvs This standard is not intended to limit the velocity of dis- is recommended although a greatervelocity can be tolerated by placers. Provided that acceptable performancecan be assured, special design of the prover. no arbitrary limit is imposed on velocity. 4.3.3.2 Minimum DisplacerVelocities 4.3.4 Prover Diameter 4.3.3.2.1 Minimum displacer velocity must also be The prover diameter depends on the minimum and maxi- considered, especially for proving meters in a liquid that has mum flow rates and the minimum and maximum displacer little or no lubricating ability, such as gasoline that contains velocities. The prover diameter to meet a prescribed velocity high proportions of aromatics or liquefied petroleum gas. The limit is determined using Equation 5 and is repeated as follows: displacer should move at a uniform velocity between detectors. At low velocities when the lubricating ability is poor, the sealing friction is high, andor the prover surface is rough, the displacermay chatter. 4.3.3.2.2 Typical minimum velocities for lubricating flu- where ids are 0.5 to 1.0 fVs for spheres, 0.25 to 0.5 fVs for piston Dp = inside diameter of prover, in., elastomer cup seals and 0.1 fVs or less for piston spring loaded plastic cup seals. For non-lubricating fluids such as Q = flowrate,bbl/hr, LPGs and NGLs higher minimum velocities will be nec- v d = displacer velocity, feet per second. essary for sphere type displacers. 4.3.3.3 DisplacerVelocity Calculations For example, if the maximum flow rate for a meter is 2300 bbl/hr and a bidirectionalprover will be used, Dp is: The velocity of the displaceris dependent upon the internal diameter of the prover pipe and the maximum and flow rates of the meters to be proved. The velocity of the displacer can be calculated as follows: Flow Rate If the minimum flow rate for the same meter is 473 bbl/hr, Velocity = the v d from equation 4 is: Area of the pipe From this example the prover diameter of 11.47 in. would 4 x 42 gal/bbl x 231h3/gal x Q satis3 both the maximum and minimum velocity recommen- Vd = dationsfor a bidirectional prover. 7c x 12 in./ft x 3600 s/hr x D i The final design diameter should be based upon a nominal pipe size that meets the design operating pressure require- (4) ments of the system. 4.3.5 Minimum Calibrated Section Length where 4.3.5.1 Two calculations are required to determine the Q = flow rate, barrels per hour, length of the calibrated section of the prover. The length shall Dp = inside diameter of the prover, in., be dependent upon the greaterof (1) the length of the calibrated section based on the minimum required volume, or (2) the v d = displacer velocity, fVs. length required to meet the accuracy of the detectors.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 22. 14 CHAPTER 4-PROVING SYSTEMS 4.3.5.2 The calculation for the calibrated section length where based upon the minimum required volume is: LminD,, = minimum calibrated section length of a prover run based upon the prover detectors, AX = displacer position repeatability resulting from Min. volume of the prover Min. calibrated sect. length = detector uncertainty during a prover pass Area of the prover (inches). The AX of a sphere displacer must be determined using AppendixA. For piston dis- placers consult the manufacturer. 4 x 42 gal/bbl x 231h3/gal x V p Lmin, = ND,, = number of times a detector is actuated for a cal- 7c x 12 in./ft x Di ibration run (unidirectional = 2 for a single pass, bidirectional = 4 for two passes), Pa = desired prover accuracy. 1029.41 x V , Lmin, = Di 4.3.5.5 For example, if AX = I 0.030 in. (0.060 in. total) and the desired accuracy is 0.02%,h i n & , for a bidirectional prover becomes at least: where Lmin,, = minimumcalibrai d s ction length based upon Lmin,,, = *O6 in* = 50.0ft/nin(=25.0 fdpass) volume (ft), 0.0002 x 12 in./ft Vp = Volume of calibrated section (bbl), 4.3.5.6 For a bidirectional prover a prover run consists of two passes. Since 78.24 ft (from Lmin,,)is greater than 25.0 ft Dp = prover inside diameter (in.). (from LminD,,), the calibrated section of the prover must be at least 78.24 ft long. 4.3.5.3 For example, if the volume of the calibrated section is 10 barrels, as calculated in Equation 3, and the prover inside 4.3.6 Prerun diameter is 11.47 in. as calculated in Equation 5, h i n , is: 4.3.6.1 Prover prerun is the length of pipe required for the displacer to travel from its holding or resting location to the first detector. The minimum prerun length must allow suffi- Lmin, = lo = 78.24 ft cient time at maximum velocity for the interchange or flow 11.47 reversing (e.g., four-way) valve to cycle, seal, and the flow to stabilize. 4.3.5.4 The minimum calibrated length between detector 4.3.6.2 The valve and interchange manufacturer should be switches depends on the accuracy with which the detector consulted to establish minimum travel and seal times, and switch can repeatedly determine the position of the displacer maximum dowable velocity. Consideration should be given and the desired discrimination of the prover system during to instdation of a valve or interchange seal detector so that calibration. The total uncertainty in positions of the displacer the proving controls can determine that a seal has been estab- during a prover run is limited to I 0.01%(I 0.0001 or 0.0002 lished before the displacerreaches the first detector in the cal- range) of the length of the prover run (see 4.3.2). Minimum ibrated section. length of the prover run based on the accuracy of the detec- 4.3.6.3 Methods used to shorten this prerun, such as faster tors is determined as follows: operation of the valve or delay of the displacer launching, Minimum calibrated section length equals the displacer require that caution be exercised in the design so that hydrau- position repeatability times the square root of the number of lic shock or additional undesired pressure drop is not intro- times the detector is actuated divided by the desired prover duced. If more than one flow-directing valve is used, they accuracy. should be sequencedto prevent shock. Note: Generally accepted statistical methods use the square root of 4.3.6.4 The prerun length is calculated as follows: the number of events to arrive at the 95%confidence level. Min. Prerun Length = ( E) x (v2zty) F: x AxJNDet Lmin,,, = (7) PaCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 23. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 15 where: 5.1.5 All units shall be equipped with vent and drain con- nections. Vent valves should be installed on the topmost por- Lpr = minimum prerun length (ft), tion of the pipe and should be located where all air is vented Tpr = cycle time (s), from dead spaces that are not swept by the displacer. Provi- sions should be made for the disposal of liquids or vapors that V,, = the maximum velocity of displacer (Ms), are drained or vented from the prover. This may be accom- SF = stabilization factor determined by the manufac- plished by pumping liquids or vapors back into the system or turer or designer. by diverting them to a collectingpoint. 4.3.6.5 Cycle Time: 5.1.6 Temperaturesensors in accordance with 3.3 and pres- sure gauges in accordancewith 3.4 should be installedin suit- For a bidirectional prover, total cycle time is defined as able locations at each end of the prover to determine the the time required to reverse the flow including unseating temperatures and pressures of the prover’s calibrated section the valve(s), changing valve positions, and reseating the (Note: temperature sensors and pressure gauges should also valve(s). The movement of the sphere starts at the mid be installed in suitable locations near the meter). Blind flange travel point of the valves, therefor only one half of the or valve connections should be provided on either side of a total cycle time is used in the calculation. leak-free block valve in the piping system to serve as a con- For a unidirectional prover, total cycle time is defined nection for proving portable meters or as a means for calibrat- as the total time required for the interchange mecha- ing the prover by the master-meter method. Connections at nism to operate (this includes the upstroke, hold, and the inlet and outlet should be provided for calibration by the downstroke). The movement of the sphere starts at the waterdraw method. Examples of suitable connections are start of the downstroke portion of the cycle. shown in Figures 3 through 5. For example, given a 4-way valve cycle time of 8 seconds, 5.1.7 Pressure relief valves with discharge piping and leak- a displacer maximum velocity of 5 Ms, and a stabilization detection facilities are usually installed to control thermal factor of 1.25, Lpr is calculated as: expansion of the liquid in the prover while it is isolated from the mainstream. Where practical, pressure relief valves should 8 not be installed in piping between the meters and the prover. L,, = - x 5 x 1.25 = 25 ft 2 Power and remote controls should be suitably protected with lockout switches, circuits, or both, between remote and adja- 5 Installation cent panel locations to prevent accidental remote operation while a unit is being controlled locally. Suitable safety devices 5.1 GENERAL CONSIDERATIONS and locks or seals should be installed to prevent inadvertent 5.1. I All components of the prover installation, including operation of, or unauthorizedtampering with equipment. electrical, piping, valves, and manifolds, shall be in accor- 5.1.8 Provers and metering equipment should be protected dance with applicable codes. Once the prover is on stream, it by straining or filtering equipment. becomes a part of the pressure piping system. 5.1.9 All wiring and controls shall conform to applicable 5.1.2 The proving section and related components shall codes. Components shall conform to the class and group have suitable hangers and supports prescribed by applicable appropriate to the location and operation. All electrical con- codes and sound engineering principles. When proving sys- trols and components should be placed in a location conve- tems are designed and installed, precautions should be taken nient for operation and maintenance. Manufacturers’ to cope with expansion, contraction, vibration, pressure instructions should be strictly followed during the installation surges, and other conditions that may affect piping and and grounding of electronic counters, controls, power units, related equipment. and signal cables. 5.1.3 Adequate access to all equipment and parts of the 5.2 PROVER LOCATION prover system for maintenancepurposes, meter proving activ- ities and prover calibration requirements shall be provided. Pipe provers may be either mobile (portable) or stationary. This may include walkways, space for field standard installa- tion and truck access. 5.2.1 Mobile Prover 5.1.4 Consideration should be given to the installation of 5.2.1. I A mobile prover is normally mounted on a road suitable valving to isolate the prover unit from line pressure vehicle or trailer so that it can be taken to various sites for when it is not on stream (for example, during maintenance or on-site proving of meters in their installed positions while removal of the displacer). they are in normal operation. Mobile provers are occasion-COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 24. 16 CHAPTER 4-PROVING SYSTEMS ally housed in containers or mounted on self-contained burst pressures of the hoses are adequate for the procedure skids so that they may be transported by road, rail, or sea. and the material of construction is compatible with the liquid Mobile provers are always provided with a means of safely to be used in proving. and conveniently connecting them to the metering system. Mobile provers are designed to operate in the meter’s envi- 5.2.2 Stationary Prover ronment. Provisions must be made to electrically ground the prover. A stationary prover is connected by a system of pipes and valves to a meter or battery of meters. Its sole function is to 5.2.1.2 Portable meter provers mounted on a truck or prove the meters one at a time at intervals, as required. trailer fall within the purview of the DOT Code o Federal f Regulations for the transportation of hazardous materials. The 5.2.3 Central Prover code is applicable when portable meter provers are moved on public roads and contain flammable or combustible liquids or A central prover is permanently installed at a location are empty but not gas free. The most recent edition of 49 CFR where pumping facilities and a supply of liquid are available. Parts 171-177 (Subchapter C, “Hazardous Materials Regula- It is used to prove meters that are periodically brought to the tions”) and 390-397 (Subchapter B, “Federal Motor Carrier prover and temporarily connected. The following precautions Safety Regulations”) should be consulted. (See specifically should be followed: Sections 172.500, 172.503, 172.504, 172.506, 172.507, 173, Meters are to be proved on liquids similar to those 177.817, 177.823, 391.11(a)(7), 391.41.49, and 393.86.) The under normal operating conditions DOT provides an exemption from 173.119, 173.304, and The meter should be operated at a flow rate typical to 173.315 for portable meter provers. operating flow rates 5.2.1.3 When flexible hoses are used to connect a portable Meters should not be mishandled in a way that could prover to a metering system, caution must be taken to ensure destroy their reliability when they are reinstalled in the that the hoses are in good physical condition, the working and line.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 25. APPENDIX A-ANALYSIS OF SPHERE POSITION REPEATABILITY A.l General where: The equation discussed in this appendix is used to deter- R = radiusofthesphere, mine the change in linear position of a sphere displacer rela- tive to the actuation of a prover detector. Because of this D = diameter of sphere or inside diameter of the relationship,the accuracy of a prover can be determined from pipe prover, the actuation tolerance of the sphere detector. The equation r = radius of the actuator detector probe, may also be used to determine the minimum length of a prover if the detector tolerance and required repeatability of d = diameter of actuator detector probe, the proving system are know. Zl = maximum detector actuation depth, A.2 Mathematical Explanation of Sphere Z2 = minimum detector actuation depth, Position Repeatability: Zl- Z2 = range of detector actuation repeatability, The relationship between sphere position repeatability and detector actuation tolerance, is described below and as illus- X I = center of the sphere from actuator axis for max- trated in Figure A- 1. imum insertion depth for switch activation, t Actuator Movement I I I * I I Figure A-I-Diagram Showing the Relationship Between Sphere Position Repeatability and Mechanical Detector Actuation Repeatability 17COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 26. 18 CHAPTER 4-PROVING SYSTEMS X2 = center of the sphere from actuator axis for mini- Conversely, if the desired prover accuracy is known, the mum insertion depth for switch activation, minimum prover length for a given detector accuracy can be determined by: AX = sphere position repeatability or range of sphere positions. LminDet= A X K t (A-3) Subscript 1 and 2 are the switch activation limits of the Pa maximum and minimum insertion depth of the actuator, where respectively. Distance X1 and X2 are the distances of the center of the sphere from the center of the actuator, for LminD,, = minimum calibrated section length based upon the maximum and minimum insertion depth limits of the prover detectors. actuation. Due to the mathematical relationship between the sphere Using Pythagorus theorem for triangle O1A1B1. and the detector, the following points should be noted when designing a prover or troubleshooting prover problems. x1 = ,IO~A;-A~B; a. Sphere position repeatability (i.e., its uncertainty) is sev- eral magnitudes greater than the detector actuation = J ( R + r)- (R-Z1 + r) repeatability. With most provers this can range between 3-6 times greater. (See Graphs A- 1 and A-2.) = J ( R + r)- ( R + r) + 2 x ( R + r ) X I , -z; b. To minimize proving error caused by detector uncertainty, the detector actuation depth should be as long as practicable. = ,/(D+d)xZ,-ZS (See Graphs A-1 and A-2.) Using the same logic for triangle 02A2B1,, A.3 Examples For example, if using the Equation A-1, assuming the fol- Xz = ,/(D+d)XZ,-Z; lowing values: D = 13.250 in. (the internal diameter of 14 in., 0.375 wall Therefore, the sphere travel uncertainty of switch actua- pipe), tion is, d = 1.0 in. (the diameter of the detector probe end), Zl = 0.1875 in. (the actuation insertion depth of the detec- AX = Xi - Xz tor), (A-1) Z2 = 0.1625 in. = Zl - 0.0250 in. (the detector repeatability AX = ,./(O+ d)(Zl) ZS - ,,/(D+ d)(Z,)- Z; - of 0.0250 in.), AX = ,/( 13.250 + 1.0)(0.1875)- 0.1875- Once the linear accuracy of the displacer with respect to the detector is known, the accuracy of a prover can be deter- ,( 13.250 + 1.0)(0.1625)- 0.1625, / mined from the equation: AX = 0.111 in. - Displ. posit. repeatability (detector Based on Equation A-1,AX = O. 1 11 in. This means that in Prover ACC.- this example the sphere position repeatability as signaled Length of the calibrated sect. of the prover (AX) is 4.44 times as great as the detector repeatability (0.0250 in.). Using this example, if the desired overall system repeat- ability using a unidirectional prover is (0.02%),the minimum prover length can be determined as follows: where 0.02%, Pa = prover accuracy, 0.111 in., NDet = number of times a detector is actuated during a 2 (since a unidirectional prover is used in the calibrationrun (unidirectional = 2 for a single example), pass, bidirectional = 4 for two passes), O. .J2 = 65.40 ft L = length of the calibrated section of the prover. 0.0002 x 12 in./ftCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 27. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 19 1.4 4 1 h v) 1.2 Insertion Depth r g 1.0 + O125 : i- rn O25 0.8 > A 0375 E 0.6 e! 05 r Q 0.4 v) 0.2 O O 0.05 0.1 0.15 0.2 0.25 Detector Movement (inches) Graph A-I-Sphere Versus Detector Relationshipat Various Insertion Depths for a 12 in. Prover with a 0.75in. Diameter Detector Ball Insertion DeDth i h v - + 0.125 3 5 rn rn 0.25 3 m 1 m A 0.375 3 L a 0.5 3 O 0.01 0.02 0.03 0.04 0.05 0.06 Detector Repeatability (inches) Graph A-2-Prover Length Versus Detector Repeatability at Various Insertion Depths for a 12in. Unidirectional Prover with a 0.75in. Diameter Detector BallCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 28. COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 29. APPENDIX B-EXAMPLES OF PROVER SIZING B.l General 2) Min: The following are two examples of typical prover sizing determinations.The choice of meter and prover combinations 0.286 x 800 BPH are for illustrative purpose only. Vd = 122 B.2 Bidirectional Prover Example -- - 228.8 144 Given: Batching operation of diesel, gasolines and jet fuel = 1.59 ft/s with a bank of 4” turbine meters (1,000 pulseshbl), 1,800 BPH normal flow rate through each meter (maximumflow rate expected 2,100 BPH-minimum Note: There are a couple of options when considering flow flow rate expected 800 BPH), 12” piping, gasoline rates in design calculations. One is to consider the normal, service, bidirectional sphere prover. maximum and minimum flow rates that are expectedfor the metering system and operations (used in this example). Step 1: Determine minimum volume between detector Another is to consider the meter manufacturer’s specifica- switches to achieve at least 10,000 pulses per proving tions for maximum and minimum, or extended maximum flow rates. Additionally the fluid properties being metered pass. should be considered. a. Using Equation 3 from Section 4.3.2.1 Step 3: Determine the prover pipe diameter 10,000 pulses V,2 k a. Using the maximum expected flow rate (Equation 5, - 10,000 pulses Section 4.3.4) - 1,000 pulses per barrel = 1Obbl Step 2: Determine displacer velocity D, = i, 0.286Q a. Using Equation 4 from Section 4.3.3.3 4.17 - 0.286 x 1,800 BPH - =A l m 9 122 = 12.001 in. + Use 12 in. nominal -- - 514.8 144 b. Using the minimum expected flow rate (Equation 5, = 3.575 ft/s Section 4.3.4) This velocity falls within the “typical accepted” range o 1-581s for bidirectional sphere provers. f b. Test against max and min expected flow rates: i) Max: Vd = 0.286 x 2,100 BPH = J 0.286 x 800 BPH 1.59 ft/s 122 -- - 600.6 144 =A l m 9 = 4.17 ft/s = 11.996 in. + Use 12 in. nominal 21COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 30. 22 CHAPTER 4-PROVING SYSTEMS Step 4: Determine the minimum calibrated section length This is a good place to step back and take a look at the results, compare the calculated results to the known a. Using Equation 6 from Section 4.3.5.2 quantities(e.g., nominal pipe sizes; standard test mea- sures) and space limitations. 1029.41 Vp Lmin, = Step 7: Adjust for space limitations, calibrated volumes to D2 match standard test measure volumes, nominal pipe - 1029.41 x 10 - sizes, etc. and rework the formulae to determine the 12’ final sizing. - 10,294.1 -- 144 B.3 Uni-Directional Prover Example: = 71.49 ft =+ 72 ft Given: 4,200 BPH normal flow rate (maximum flow rate expected 4,600 BPH-minimum flow rate expected b. Using Equation 7 from Section 4.3.5.4. If detector 600 BPH), 16” piping, crude oil service, unidirec- repeatability is f 0.030 and desired accuracy is tional sphere prover, 10”PD meters with pulse rate of 0.02%,then: 8,400 pulsesharrel. Step 1: Determine minimum volume between detector switches to achieve at least 10,000 pulses per proving pass. - 0.06h a. Use equation (3) from Section4.3.2.1 - 0.0002 x 12 in./ft 10,000 pulses - - 0.12 V p2 - k 0.0024 - 10,000 pulses - = 50 ft for a run (= 25 ft for a pass) 8,400 pulses per barrel = 1.19 barrels Since Lmin,, > Lmindet the minimum length o the cal- f ibrated section must be at least 72ft long. Step 2: Determine displacer velocity Step 5: Determine the prerun length Using Equation 4 from Section 4.3.3.3 The cycling characteristics of the 4-way valve or 0.286 x Q other switching equipment must be known. Assume a Vd = cycle time of 8 seconds for this example. Remember, DB the flow of the sphere starts at the mid-travel point - 0.286 x 4,200 BPH - (only l/2 the travel time is used in the calculation). 16’ a. Using Equation 8 from Section 4.3.6.4 -- - 1201.2 259 Tpr Vdmax SF = 4.69 fth 8 sec -x 4.17 ft/S x 1.25 2 This velocity falls within the “typical accepted” range o 0.5 - loftsfor uni-directionalprovers. f 20.85 =+ 21 ft Test against max and min expected flow rates: manufacturer’s safety factor gor the purpose o this example it is assumed SF = 1.25) 1. Max: f Step 6: Review the calculatedresults. 0.286 x 4600 BPH Vd = 16’ a. Provervolume: = 10bbl b. Prover diameter: = 12 in. -- - 1315.6 c. Calibratedsection: = 72ft 256 d. Prerun: = 21ft = 5.14 fthCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 31. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 23 2. Min: b. Using Equation 7 from Section 4.3.5.4. If detector repeatability is f 0.030 and desired accuracy is 0.286 x 600 BPH Vd = 0.02%,then: 16 -- - 171.6 256 Lmin,,, = A x K t = 0.67 ft/s Pa - - 0.06& Note: There are a couple of options when considering flow 0.0002 x 12 in./ft rates in design calculations. One is to consider the normal, maximum and minimum flow rates that are expectedfor the - -0.085 - metering system and operations (used in this example). 0.0024 Another is to consider the meter manufacturers specifica- tions for maximum and minimum, or extended maximum = 35.36 ft for a pass + use 36 ft flow rates. Additionally the fluid properties being metered should be considered. Since Lmind,,, => hin,, the minimum length o the f calibrated section must be at least 36feet long. Step 3: Determine the prover diameter Step 5: Determine the prerun length a. Using the maximum expected flow rate (Equation 5, Section 4.3.4) You must know the cycling characteristics of your sphere interchange mechanism. Assume a cycle time of 4 seconds for this example. a. Using Equation 8 from Section 4.3.6.4 J 0.286 x 4600 BPH 5.14 ftls Lpr = Tpr VdmaxxSF = 4 seconds x 5.14 ft/s x 1.25 = 25.7 + 26 fth Alm5 Where: SF = manufacturers safety factor gor the 15.998 in. + Use 16 in. nominal purpose o this example it is assumed SF = 1.25) f b. Using the minimum expected flow rate (Equation 5, Step 6: Review the calculatedresults. Section 4.3.4 a. Prover volume: = 1.19 bbl b. Prover diameter: = 16 in. c. Calibratedsection: = 36ft d. Prerun: = 26ft This is a good place to step back and take a look at the primary results, compare the calculated results to the known quantities (e.g., nominal pipe sizes; standard test measures) and space limitations. = *j256.12 = 16.004 in. + Use 16 in. nominal Step 7: Adjust for space limitations, calibrated volumes to match standard test measure volumes, nominal pipe Step 4: Determine the minimum calibrated section length sizes, etc. and rework the formulae to determine the final sizing. a. Using Equation 6 from Section 4.3.5.2 1029.41 V, Lmin, = 0 - 1029.41 x 1.19 - 16 - 1225.00 -- 256 = 4.79 ft + 5 ftCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 32. COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 33. APPENDIX C-A PROCEDURE FOR ESTIMATING MEASUREMENT SYSTEM UNCERTAINTY C.l General Considerations For example, the uncertainty at the 95% confidence level of the average of 5 runs that agree within a range of 0.05% Field proving procedures are covered in Chapter 4.8. Nor- can be calculated as follows: mally, meter-proving procedures consist of a minimum num- ber of consecutiveproving runs that agree within a prescribed From Table C-1: D(5) = 2.326 and range limit. When meters are proved, it is expected that the From Table C-2: t(%, 4) = 2.776. proving set will consistently meet the range limits. If the range limits are not met, several additional sets of meter prov- ing runs are made. If none of the additional sets of proving runs meet the range limits, the meter proving activity is nor- mally rescheduled resulting in lost time. Therefore, it is desir- able that a meter and proving system meet the prescribed Example of a field test and estimation of System Uncertainty: proving procedures at least 95%of the time. Data set of 20 runs has the following K-factor values for a C.2 Evaluation Test Procedure meter: When experience is limited on the variation of a type of 52.324 52.315 52.299 52.304 52.312 meter pulse train andor the suitability of specific meter prov- 52.318 52.311 52.319 52.303 52.313 ing procedure to yield an appropriate meter factor, a field test may be performed to estimate the measurement system 52.315 52.319 52.306 52.316 52.323 uncertainty. A test consisting of 15 to 25 prover passes or 52.322 52.310 52.322 52.325 52.314 round trips can be gathered to statistically evaluate the system uncertainty of the existing meter proving procedure. The data The high and low values of the data set are in bold and set should at least have 15 runs and include as many prover underlined. The average value of the data set is 52.3145 and passes as the operator of the metering facility would be will- the range of high and low of 20 data set is; ing to perform to prove the meter, but the maximum number of runs should be limited to a maximum of 25 runs. The procedural uncertainty of any proving procedures can be estimated as follows: For the data set of the example, the estimated uncertainty of the system is calculated as follows: Number of data for the test is 20. where From Table C-1: D(20) = 3.735 and a(MF) = estimated uncertainty of the average in the From Table C-2: t(%, 19) = 2.093 meter proving set, a(MF)= 2*093 0.0062% w(MF) = (normalized high value - normalized low value) of n runs in the meter proving set; i.e. 3.735 x fio (high-low) divided by the average of the data set, For the above example, if the first 15 data are considered; t(%, n - 1) = student ‘Y factor for converting standard devia- 52.324 52.315 52.299 52.304 52.312 tion to uncertainty at a prescribed confidence 52.318 52.311 52.319 52.303 52.313 level agreed to by the custody transfer parties 52.315 52.319 52.306 52.316 52.323 (see Table C-2), n - 1 = degree of freedom, The average of the set is 52.3131 and the range of high and low is; D(n) = range to standard deviation conversionfactor (see Table C-i), n = number of proving runs in the data set. 25COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 34. 26 CHAPTER 4-PROVING SYSTEMS The system uncertainty would be calculated as follows: b. Increase the number of proving runs (passes or round trips) and increase the range limits approximately to control Number of data for the test is 15. the uncertainty of the average of the moving set of proving From Table C-1: D(15) = 3.472 and runs. From Table C-2: t(%,14)= 2.145 The requirements for acceptance of a proving procedure qualification test data should be more rigorous than nor- m d y required for other locations with similar fluids, cus- tody transfer quantities and meter proving intervals. Several methods can be employed to increase the confidence that Using the above calculation method, the Measurement the proving procedures that meet the qualification require- Uncertainty of the System can be estimated for any number ments will consistently provide a suitable meter factor. of samples for a specific range of high and low values of These procedures include, but are not limited to the follow- actual data. Table C-3 shows the Estimated Measurement ing concepts: Uncertainty of the System at the 95% of the confidence level a. Reduce the range limit for a prescribed number of proving for different number of runs when the range of high and low for the data agree within a range 0.05%.When the actual test runs; results yield a value of W(MF) other than 0.05%, the mea- b. Increase the minimum number of proving runs to meet a surement uncertainty of the system (for 95% confidence prescribed range limit; level) can be estimated by following the above examples, c. Use a higher statistical confidence level to evaluate the which will be different from the corresponding value given in qualification test data than normdy used to evaluate mea- Table C-3. surement procedural uncertainties;or If the proving procedure qualification test data does not d. Use the same statistical confidence level to evaluate the consistently meet the requirement for a specified number of qualification test data as normdy used to evaluate procedural proving to agree within a given range limit, the normal prac- uncertainties, but reduce the uncertainty limit for the qualifi- tice is to try one or both of the following variations from the cation test data to a lower level than normdy required for normal meter proving operations. routine sets of meter proving runs. a. Average several provers passes or round trips for each e. Determine the average range or uncertainty from records proving run and compare the averages of these groups for with a specific meter proving procedure and require the quali- acceptance of the proving data. fication test data at least meet the average.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 35. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 27 Table C-I-Range to Standard Deviation Conversion Factors Number of Data Sets Range to Standard Deviation or Measurements Conversion Factor 1.128 1.693 2.059 2.326 6 2.534 7 2.704 8 2.847 9 2.970 10 3.078 11 3.173 12 3.258 13 3.336 14 3.407 15 3.472 16 3.532 17 3.588 18 3.640 19 3.689 20 3.735 21 3.778 22 3.819 23 3.858 24 3.895 25 3.931COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 36. 28 CHAPTER 4-PROVING SYSTEMS Table C-2-Student t Distribution Factors for Individual Measurements Number of Sets or Number of Degrees Distribution Factor vs. 95% Measurements of Freedom Confidence Level n n-1 t(%, n-i) 12.706 4.303 3.182 2.776 6 2.571 7 2.447 8 2.365 9 2.306 10 2.262 11 10 2.228 12 11 2.201 13 12 2.179 14 13 2.160 15 14 2.145 16 15 2.131 17 16 2.120 18 17 2.110 19 18 2.101 20 19 2.093 21 20 2.086 22 21 2.080 23 22 2.074 24 23 2.069 25 24 2.064 Infinity Infinity 1.960COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 37. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 29 Table C-3-Estimated Measurement Uncertainty of the System at the 95% Confidence Level for Data that Agree within a Range of 0.05% 0.05 x t ( % , n ) Number of Sets or Distribution Factor for 95% Range of Standard Deviation a(A4F) = Measurements Confidence Level Conversion Factor D ( n )x h n t(%, n-i) D(n) 4MF) 5 2.776 2.326 Io.0267% 6 2.571 2.534 Io.0207% 7 2.447 2.704 Io.0171% 8 2.365 2.847 Io.0147% 9 2.306 2.970 Io.0129% 10 2.262 3.078 Io.01 16% 11 2.228 3.173 Io.0106% 12 2.201 3.258 Io.0098% 13 2.179 3.336 Io.0091% 14 2.160 3.407 Io.0085% 15 2.145 3.472 Io.0080% 16 2.131 3.532 Io.0075% 17 2.120 3.588 Io.0072% 18 2.110 3.640 Io.0068% 19 2.101 3.689 Io.0065% 20 2.093 3.735 Io.0063% 21 2.086 3.778 Io.0060% 22 2.080 3.819 Io.0058% 23 2.074 3.858 Io.0056% 24 2.069 3.895 Io.0054% 25 2.064 3.931 Io.0053%COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 38. COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 39. APPENDIX D-TYPICAL PIPE PROVER DESIGN DATA SHEET 1.0 GENERAL 1.1 Service: O Crude, O RefinedProducts, O LPGlNGL, O Chemicals 1.2 m e : O Bidirectional, O Uni-directional, O U-tube, O StraightTube 1.3 Displacer: O Sphere, O Cup Piston, O Precision Seal Piston 2.0 DESIGN DATA 2.1 Flow Rate: (BPH), Minimum ,Normal ,Maximum 2.2 Pressure: (PSIG), Normal ,Maximum 2.3 Temperature: (OF),Nomal ,Maximum 2.4 Fluid Relative Density ,~lSCOSity 0 CST 0 CP 0 SSU 2.5 Design Considerations: (corrosive properties,etc.) 2.6 Meter Qpe: O Turbine, O Positive Displacement, O Other 2.6.1 Manufacturer: ,Model: ,Size: 2.6.2 Meter “ K Factor (PPB): 3.0 VALVES 3.1 4-Way Valve (or Interchange Valve) 3.1.1 Manufacturer: ,Model: 3.1.2 Size: in., ANSI Rating: 9 Connection: 3.1.3 Material: @ody): ,(Elastomers): 3.1.4 Valve Operator 3.1.4.1 Manufacturer: ,Model: 9 3.1.4.2 Cycle time: sec, Type: O Elect. O Hydraulic O Manual 3.1.4.3 Electric Data: Voltage: ,Phase ,HP 3.1.4.4 Hydraulic System Press: ,Fiuid: 3.2 Drainvalves 3.2.1 Manufacturer: ,Model: 3.2.2 Size: in., ANSI Rating: 9 Connection: 3.2.3 Material: @ody) ,(Elastomer) 3.3 Vent Valves 3.3.1 Manufacturer: ,Model: 3.3.2 Size: in., ANSI Rating: 9 Connection: 3.3.3 Material: @ody) ,(Elastomer) 31COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 40. 32 CHAPTER 4-PROVING SYSTEMS 4.0 DESIGN DETAILS 4.1 Piping 4.1.1 Prover Nominal Diameter: in. 4.1.2 Pipe OD (in.): ,ID (in.): ,WT (in.): 4.1.3 Material: O carbon steel, O stainless steel 4.1.4 Full length honing: O Yes O No, Final surface roughness: 4.2 Flanges 4.2.1 ANSI Ratings: ,TYPE: 4.2.2 O Matched Bored & Doweled 4.3 Displacer 4.3.1 SpherefistonVelocity 4.3.1.1 Minimum fVs, Normal fvs, Maximum 4.3.2 Spherefiston Cup Material: O Polyurethane, O Buna N, O Teflon, O Viton, OUHMWPE, OOther 4.3.3 Piston Material: O Aluminum, O Stainless Steel, O Other 4.3.4 Piston WiperlWearRing Material: O PEEK, O Teflon, O UHMWPE, O Other 4.4 Detector Switch 4.4.1 Type: O Mechanical, O Electro-magnetic 4.4.2 No. required: O 2, O Other (quantity) 4.4.3 Manufacturer: ,Model: 4.5 Internal Coating 4.5.1 O Baked Epoxy-phenolic;Manufacturer ,Type 9 Thickness mils 4.5.2 O Air Dried Epoxy; Manufacturer 9 Type 9 Thickness mils 4.5.3 O None 4.6 External Coating 4.6.1 Piping, skid and supports 4.6.1.1 O Primer (Ist coat), MFG 4.6.1.2 O Mid-coat (2ndcoat), MFG 4.6.1.3 O Top-coat (3rdcoat), MFG 4.6.1.4 O None 4.6.2 Grating: 4.6.3 Stud Bolts and Nuts: 4.7 Insulation 4.7.1 Type: O RigidFiberglass, O None, O Other 4.7.2 MinimumThickness: inches 4.7.3 JackeVCovering: O Aluminum, O Stainless Steel 4.8 Closures 4.8.1 Type: ,Quantity: O Two O One, ANSI Rating: 4.8.2 Manufacturer: ,Model: Note: Quick-openingclosures should have a permissive warning device.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 41. SECTION 2-PIPE PROVERS (PROVERS ACCUMULATING LEAST10,000 PULSES) AT 33 5.0 PROVER BARREL DIMENSIONS 5.1 Volume Basis between detector switcheskensors 5.1.1 O Sphere Qpe: 10,000pulses minimum 5.1.2 O Piston Qpe: 10,000pulses minimum 5.2 Dimensions 5.2.1 Calibrated Section (length): ft, in. 5.2.2 Pre-run Section (length): fi, in. 5.2.3 Post-run Section (length): ft, in. 5.2.4 Launch Chamber Section (length): ft, in.S 5.2.5 Calibrated Section (ID): in. 5.2.6 Launch Chamber (ID): in. 6.0 ACCESSORY EQUIPMENT 6.1 Pressure 6.1.1 Ii-ansmitter(Electronic): O Smart Digid, O Smart Analog, O Analog MFG: ,Model: 9 Range: pig, Quantity: 6.1.2 Gauge: MFG: ,Model: 9 Range: pig, Quantity: 6.2 Temperature 6.2.1 Ii-ansmitter (Electronic): O Smart Digital, O Smart Analog, O Analog MFG: ,Model: 9 Range: pig, Quantity: 6.2.2 Thermometer: MFG ,Model 9 Range: "E Quantity: 6.2.3 Thermowell:Type: O Flanged, O Threaded, O Van Stone, O Other Material: O 316SS, O Other Bore Size: ,OD: ,Length: Quantity: , 6.3 Relief Valve 6.3.1 MFG: ,Model: ,Size: 9 Set Pressure: psig, Quantity: 6.4 Sphere Sizing Ring: 6.4.1 Diameter: , %Oversize: 6.5 Sphere Removal Equipment required: O Yes O NoCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 42. 34 CHAPTER 4-PROVING SYSTEMS 7.0 IEST(S) AND INSPECTIONS 7.1 Welding Qualifications tests: Test: O Yes O No, Notification O Yes O No 7.2 Radiographic testing: Test: O Yes O No; O 100% O other %, Notification O Yes O No 7.3 Hydrostatic test: Test: O Yes O No, Notification O Yes O No 7.4 Water Draw Calibration: Test: O Yes O No, Notification O Yes O No 7.5 FunctiondOperational test: Test: O Yes O No, Notification O Yes O No 7.6 Surface Preparation (for coating): Test: O Yes O No, Notification O Yes O No 7.7 Coating Application: Test: O Yes O No, Notification O Yes O No 7.8 Block and Bleed valve test: Test: O Yes O No, Notification O Yes O No 7.9 Piston P l test: Test: O Yes O No, Notification O Yes O No ul 7.10 System Uncertainty Analysis per API 4.2, Appendix C: O Yes O No 7.10.1 Limits of uncertainty: 8.0 APPLICABLE CODES AND REGULATIONS (DESIGN, FABRICATION/CONSTRUCTIONAND TESTING) 8.1 ANSIPiping: O B31.3, O B31.4 8.2 API Classification: O Rp 500A, O Rp 500B, O Rp 500C 8.3 Pressure Vessels: O ASME Section VIE, Stamp: O Yes O No 8.4 OSHA 8.5 National Electric Code 8.6 DOT 195 8.7 API MPMS Chap. 4.2 Conventional Pipe Provers 9.0 ATTACHMENTS 9.1 Drawings; 9.2 Specifications:COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 43. Available through Global Engineering Documents Phone Orders: 1-800-854-7179 (Toll-free in the U.S. and Canada) 303-397-7956 (Local and International) Fax Orders: 303-397-2740 Online Orders: www.élobal.ihs.com Date: Q API Member (&&if%) Invoice To (U (hckhereifsaneas”%pTÓ~ ïìtle ïìtle T d b T d b Fax FMil. Quantity Product Number Title SO* Unit Price Total HO4012 MPMS Ch 4.1, Introduction $44.00 H30083 MPMS Ch 4.3, Small Volume Provers $50.00 HO4042 MPMS Ch 4.4, Tank Provers $55.00 HO4052 MPMS Ch 4.5, Master-Meter Provers $44.00 HO4062 MPMS Ch 4.6, Pulse Interpolation $44.00 I I HO4072 I MPMS Ch 4.7, Field-Standard Test Measures I I $55.00 I I HO4081 MPMS Ch 4.8, Operation of Proving Systems $72.00 m Payment Enclosed m P.O. No. ( E x h G w ) Subtotal I I m Charge My Global Account No. Applicable Sales Tax (szbelow) Rush Shipping Charge (szbelow) U m VISA m MasterCard m American Express m Discover Shipping and Handling (szbelow) CkdtChdM: Total (in US Dllars) rlnre(AItrnmW: *To be placed on Standlng Order for future edltlons of thls Exptlmw publlcatlon, place a check mark In the SO column and slgn here: SipLne ~ Prldng and avallablllty subJect to change wlthout notlce. - Mail Orders Payment by check or money order in US. dollars is required except for established accounts. State and local taxes, plus 5% for shipping and handling, must be added. Send mail orders to: API Publications, Global Engineering Documents, 15 InvernessWay East, M/S C303B, Englewood, CO 80112-5776, USA. - Purchase Orders Purchase orders are accepted from established accounts. Invoice will include actual freight cost, an $8.00 handling fee, plus state and local taxes. - Telephone Orders If ordering by telephone, an $8.00 handling fee and actual freight costs will be added to the order. - Sales Tax All US. purchases must include applicable state and local sales tax. Customers claiming tax-exempt status must provide Global with a copy of their exemption certificate. - Shipping (US. Orders) Orders shipped within the US. are sent via traceable means. Most orders are shipped the same day. Subscription updates are sent by First-class Mail. Other options, including nextday service, air service, fax transmission, and electronic delivery are available at additional cost. - Shipping (International Orders) Standard international shipping is by air express courier service. Subscription updates are sent by World Mail. Normal delivery is 3-4 days from shipping date. - Rush Shipping Fee In addition to the carrier charges, the following charges will be added: Next Day Delivery orders placed prior to 2:OO p.m. MST - $10.00 / Next Day Delivery orders placed after 2:OO p.m. MST- $20.00 (if time is available for order processing) - Returns All returns must be preapproved by calling Global’s Customer Service Department at 1-800-624-3974 for information and assistance. There may be a 15% restockingfee. Special order items, electronic documents, and agedated materials are non-returnable.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 44. fi rn-%2-4791 Fix m a - m American Petroleum Institute Helping You Get The Job Done Rights" 10.1.99COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 45. 03/01COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  • 46. Additional copies are available through Global Engineering Documents at (800) 854-7179 or (303) 397-7956 Information about API Publications, Programs and Services is available on the World Wide Web at: http://www.api.org American 1220 L Street, Northwest Petroleum Washington, D.C. 20005-4070 Institute 202-682-8000 Product No. HO4022COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services

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