Manual of Petroleum Measurement                 Standards                 Chapter 19-Evaporative Loss                     ...
STD.API/PETRO        MPMS 17-2-ENGL 1777   0732270 0 5 b 4 4 7 7 BTb   m                   Manual of Petroleum Measurement...
SPECIAL NOTES                         API publications necessarily address problems of a general nature. With respect to p...
S T D - A P I i P E T R O MPMS L 7 = 2 - E N G L 1797                0732290 05b1i48L Y54                                 ...
~                                            ~              STD.API/PETRO MPMS 1 9 - 2 - E N G L 1997                     ...
= 0732290                                                                                                                 ...
S T D * A P I / P E T R O MPMS L S * Z - E N G L 1997              = 0732290 05b948Li                   Lb3               ...
~                     -~    ~                                                  ~                STD*API/PETRO MPMS 1 7 - 2...
S T D - A P I I P E T R O MPMS L S = Z - E N G L 1997               0732290 05bllllBb T3b                                 ...
~~~                    STD-API/PETRO MPMS 17-2-ENGL 1777                                    0732290 05b1ig87 772       4  ...
SECTIONEVAPORATIVE Loss FROMFLONING-ROOF                                                                                  ...
6                                                         19-EvAPoRATIvE Loss MEASUREMENT                                 ...
S T D * A P I / P E T R O MPMS L 7 - 2 - E N G L 1997                   0732290 05bqLi90 Lib7                             ...
Table 2-Summary           of Procedure for Calculating Standing Storage Loss       ~~                                     ...
STD.API/PETRO M P M S 19.2-ENGL                                  1997       m        0?32270 05b4Li72 Z I T               ...
-           ~~                    STD.API/PETRO MPMS 1 9 - 2 - E N G L 1997                        0732290 05bVV93 L7b    ...
~                STD*API/PETRO MPMS 19.2-ENGL                                    1997                0732290 05b449Li 002 ...
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  1. 1. Manual of Petroleum Measurement Standards Chapter 19-Evaporative Loss Measurement Section 2-Evaporative Loss From Floating-Roof Tanks FIRST EDITION, APRIL 1997 (FORMERLY, API PUBLICATIONS 2517 AND 2519) American Petroleum InstituteCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  2. 2. STD.API/PETRO MPMS 17-2-ENGL 1777 0732270 0 5 b 4 4 7 7 BTb m Manual of Petroleum Measurement Standards Chapter 19-Evaporative Loss Measurement Section 2-Evaporative Loss From Floating-RoofTanks Measurement Coordination FIRST EDITION, APRIL 1997 (FORMERLY, API PUBLICATIONS 2517 AND 2519) American Petroleum InstituteCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  3. 3. 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 train and equip their employees, and others exposed, concerning health and safety risks and precautions, nor undertaking their obligations under local, state, or federal 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 M publication is to be construed as granting any right, by I 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 infiingement of letters patent. Generally,API standards are reviewed and revised, reaffirmed, 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 Authoring Department [telephone (202) 682-8000]. A catalog of API publications and materials is published annually and updated quarterly by API, 1220 L Street, N.W., Washington, D.C. 20005. This document was produced under API standardization procedures 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 director of the Authoring Department (shown on the title page of this document), 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 director. 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 applicable API standard. All rights reserved No part o this work m y be reproduced, stored in a retrieval system, or f transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission from the publisher: Contact the Publishec API Publishing Services, 1220 L Street, N. N,Washington.D.C. 20005. Copyright Q 1997 American Petroleum InstituteCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  4. 4. S T D - A P I i P E T R O MPMS L 7 = 2 - E N G L 1797 0732290 05b1i48L Y54 FOREWORD This new standard was formerly M I Publications 25 17 and 25 19. API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection wt this publication ih and hereby expressly disclaims 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 conflict. Suggested revisions are invited and should be submitted to the Measurement Coordinator, American Petroleum Institute, 1220L Street, N.W., Washington, D.C. 20005. ... 111COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  5. 5. ~ ~ STD.API/PETRO MPMS 1 9 - 2 - E N G L 1997 07I2270 05b11482 390 CONTENTS page SECTION 2-EVAPORATIVE LOSS FROM FLOATING-ROOFTANKS SCOPE ......................................................................................................................... 1 REFERENCED PUBLICATIONS .............................................................................. 2 DEFINITIONS............................................................................................................. 4 EQUATIONS FOR ESTIMATING LOSSES .............................................................. 7 STANDING STORAGE LOSS .................................................................................. 10 WITHDRAWAL LOSS FACTORS ........................................................................... 21 SAMPLE PROBLEMS .............................................................................................. 26 DESCRIPTION OF FLOATING-ROOFTANKS ..................................................... 35 DETAILS OF LOSS ANALYSIS............................................................................... 53 APPENDIX A-DEVELOPMENT OF RIM-SEAL LOSS FACTORS ......................... 61 APPENDIX B-DEVELOPMENT OF RIM-SEAL RELATIONSHIP BETWEEN AIRFLOW RATE AND WIND SPEED............................................... 65 APPENDIX C-DEVELOPMENT OF DIAMETER FUNCTION................................ 67 APPENDIX %DEVELOPMENT OF DECK-FITTING LOSS FACTORS ................69 APPENDIX E-DEVELOPMENT OF VAPOR PRESSURE FUNCTION ................... 71 APPENDIX F-DEVELOPMENT OF PRODUCT FACTORS ..................................... 73 APPENDIX G-DEVELOPMENT OF CLINGAGE FACTORS................................... 75 APPENDIX H-DEVELOPMENT OF FITTING WIND-SPEED CORRECTION FACTOR ............................................................................................... 77 APPENDIX I-DEVELOPMENT OF DECK-SEAM LOSS FACTORS ....................... 79 APPENDIX J-DOCUMENTATION RECORDS.......................................................... 81 Figures 1-True Vapor Pressure (P) of Refined Petroleum Stocks With a Reid Vapor Pressure of 1 to 20 Pounds per Square Inch ......................................................... 22 2-True Vapor Pressure (P) of Crude Oil Stocks With a Reid Vapor Pressure of 2 to 15 Pounds per Square Inch ............................................................................ 23 3-Vapor Pressure Function Coefficient (A) of Refined Petroleum Stocks With a Reid Vapor Pressure of 1 to 20 Pounds per Square Inch, Extrapolated to 0.1 Pounds per Square Inch ......................................................................................... 24 +Vapor Pressure Function Coefficient (B) of Refined Petroleum Stocks With a Reid Vapor Pressure of 1 to 20 Pounds per Square Inch, Extrapolated to 0.1 Pounds per Square Inch .................................................................................. 24 5-Vapor Pressure Function Coefficient (A) of Crude Oil Stocks With a Reid Vapor Pressure of 2 to 15 Pounds per Square Inch, Extrapolated to 0.1 Pounds per Square Inch ........................................................................................ 25 &Vapor Pressure Function Coefficient (B) of Crude Oil Stocks With a Reid Vapor Pressure of 2 to 15 Pounds per Square Inch, Extrapolated to 0.1 Pounds per Square Inch ........................................................................................ 25 VCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  6. 6. = 0732290 ~ ~~ STD-API/PETRO MPMS 19.2-ENGL 1997 O’ibYV83 227 page Figures (Continued) 7-External Floating-Roof Tank With Pontoon Floating Roof .................................. 37 8-External Floating-Roof Tank With Double-Deck Floating Roof .......................... 38 9-Internal Floating-Roof Tank With Noncontact Deck ............................................ 39 1-overed Floating-Roof Tank With External-Type Floating Roof ....................... 40 1I-Vapor-Mounted Primary Seals ............................................................................ 42 12-Liquid-Mounted Primary Seals ........................................................................... 43 13-Mechanical-Sh~e Primary Seals ......................................................................... ..... 43 14-Secondary S . .................................................................................................. 45 15-Access Hatch ....................................................................................................... 46 . 16-Fixed-Roof Support Column............................................................................. .. ” * 46 17-Gauge Float (Automatic Gauge) ......................................................................... 47 18-Gauge Hatch Sample Ports ................................................................................. 47 k i 19-Vacuum Breaker .................................................................................................. 48 20-Deck Drains......................................................................................................... 48 2 1-Deck Leg ............................................................................................................. 49 22-Rim Vent .............................................................................................................. 49 23-Vertical Ladder ............................ ....................................................................... 50 24-Unslotted (Unperforated) Guidepole .................................................................. 51 25Plotted (Perforated)Guidepole ........................................................................... 52 C-l-Calculated Losses as a Function of Diameter Exponent................................... 68 Tables 1-Nomenclature .......................................................................................................... 5 2-Summary of Procedure for Calculating Standing Storage Loss ............................. 8 3-Summary of Procedure for Calculating Withdrawal Loss .................................... 11 4-Rim-Seal Loss Factors Km,Kh and n; and Rim-Seal Loss Factors, K,., at Selected Average Ambient Wind Speeds .............................................................. . 13 5-Average Annual Ambient Wind Speed. for Selected U.S. Locations................ 14 &Deck-Fitting Loss Factors Kfa,K , and m;Typical Number of Deck-Fittings, N, and Deck-Fitting Loss Factors Kf, at Selected Average Ambient Wind Speeds ................................................................................................................... 16 7-Typical Number of Columns, Nfc.for Tanks with Column-Supported Fixed Roofs ........................................................................................................... 18 8-Typical Number of Vacuum Breakers, Nfvc, Deck Drains, Nfdd, for API and Standard 650, Appendix C Decks (EFRTs and CFRTs) ....................................... 18 9-Typical Number of Deck Legs, Nfd,for API Standard 659, Appendix C Decks (EFRTs and eFwrs)................................................................................... 19 1GDeck-Seam Length Factors, s‘, for Qpical Deck Constiüiions .......................... 19 d’ ion, P*, as a Function of Stock True Vapor Pressure, P ..... 20 12-ASTM Distill ope, S, for Selected Refined Petroleum Stocks................... 21 13-Properties (Mu. e W,,, A. B) of Selected Petroleum Liquids ................................ 26 14-Properties (M”. W,,, A, B) of Selected Petrochemicals ..................................... 27 . 15-Average Annual Ambient Temperature, T, for Selected U.S.Locations.............. 28 16-Average Annual Stock Storage Temperature, Ts, a Function of Tank as Paint Color ............................................................................................................ 30 17-Average Clingage Factors. C,For Steel Tanker .................................................... 30 viCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  7. 7. S T D * A P I / P E T R O MPMS L S * Z - E N G L 1997 = 0732290 05b948Li Lb3 Chapter 1+Evaporative Loss Measurement SECTION 2-EVAPORATIVE LOSS FROM FLOATING-ROOFTANKS 1 Scope a. To estimate losses from unstable or boiling stocks or from petroleum liquids or petrochemicals for which the vapor pres- This publication contains methods for estimating the total sure is not known or cannot readily be predicted. evaporative losses or the equivalent atmospheric hydrocarbon b. To estimate losses from tanks in which the materials used emissions from external floating-roof tanks ( E m s ) and in the rim seal, deck fittings, or deck seams have either deteri- freely vented internal floating-roof tanks (IFRTs), as well as orated or been significantly permeated by the stored stock. for tanks with external-type floating roofs that also have a c. To estimate losses from storage tanks that do not have a freely vented fixed roof. This type of tank is referred to as a floating roof of any kind. covered floating-roof tank (CFRT) this document. in d. To estimate losses from closed internal or covered float- The equations that appeared separately in API Publication ing-roof tanks (that is, tanks vented only through a pressure- 2517 [1] and API Publication 2519 [2] are combined in this vacuum relief vent, blanketed with an inert gas, vented to a document. The standing storage loss factors have been vapor processing unit, or otherwise restricted from being revised to reflect the results of the most recent testing. freely vented). This publication was developed by the API Environmental Technical Advisory Group. The equations and factors pre- The equations for estimating evaporative stock loss or the sented are based on recent laboratory, test-tank, and field-tank equivalent total atmospheric emissions from volatile stocks data and supercede previous publications. The equations are stored in floating-roof tanks are given in Section 4. The fac- intended to provide loss estimates for general equipment tors for the standing storage loss equation are discussed in types, since it is not within the scope of this publication to Section 5 and for the withdrawal loss equation in Section 6. address proprietary equipment designs. Sample problems illustrating the use of the equations are pro- Typical currently available types of floating roofs, rim seal vided in Section 7. systems, and deck fittings are described for information only. These loss-estimating procedures are applicable only to This publication is not intended to be used as a guide for EFRTs (as described in Appendix C of API Standard 650, equipment design, selection, or operation. Welded Steel Tanks for Ol Storage) [3], IFRTs of freely i The equations are intended to be used to estimate annual vented design (as described in Appendix H of API Standard losses from floating-roof tanks that contain multicomponent 650) [3], and CFRTs (as described in Appendix G of API hydrocarbon mixtures (such as petroleum liquid stocks like Standard 650) [3] of freely vented design (as described in crude oils and gasolines) or single-component hydrocarbon Appendix H of API Standard 650) [3]. Descriptions of the stocks (such as petrochemicals). The equations are applicable types of construction covered by this publication are given in to the various types of tank construction, floating roof con- Section 8. struction, rim seal systems, and deck fittings, as described in The bases and development of the loss-estimation proce- Section 8, as well as for various liquid stocks, stock vapor dures presented in Sections 4 through 7 are described in Sec- pressures, tank sizes, and wind speeds (EFRTs). The equa- tion 9. tions are applicable to properly maintained equipment under The estimation procedures were developed to provide esti- normal working conditions. mates of typical losses from floating-roof tanks that are prop The equations were developed for liquids that are not boil- erly maintained and in normal working condition. Losses ing, stocks with a true vapor pressure ranging from approxi- from poorly maintained tanks may be greater. Because the mately 0.1 to less than 14.7 pounds per square inch absolute loss equations are based on equipment conditions that repre- (but not greater than the atmospheric pressure at the tank sent a large population of tanks, a loss estimate for a group of location), average wind speeds ranging from 0 to 15 miles per floating-roof tanks will be more accurate than a loss esti- hour (EFRTs), and tank diameters greater than 20 feet. The mate for an individual tank. It is difficult to determine pre- estimation techniques become more approximate when used cise values of the loss-related parameters for any to estimate losses for time periods shorter than one year. The individual tank. estimation may be improved by using detailed field informa- Equipment should not be selected for use based solely on tion, including climatic data and operational data for the evaporative-loss considerations. Many other factors not appropriate time period. addressed in this publication, such as tank operation, mainte- The equations are not intended to be used in the following nance, and safety, are important in designing and selecting applications: tank equipment for a given application. 1COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  8. 8. ~ -~ ~ ~ STD*API/PETRO MPMS 1 7 - 2 - E N G L 1797 0732290 05b1i485 OTT 2 CHAPTER 1%-EVApoFullVE LOSS MEASUREMENT 2 Referenced Publications a Product at Various Vapor Pressures” (Report 2, Research [l] American Petroleum Institute, Evaporative Loss from Contract R-0134),Chicago Bridge & Iron Company, Plain- Extern1 Floating-Roof T h , Publication 2517, Third Edi- field, Iilinois, October 25, 1977. tion, Washington, D.C., February 1989. [I71 R.J. Laverman, “Floating Roof Seal Development, [2] American Petroleum Institute, Evaporation Loss fram Emission Test Measurements on Proposed CBI Wiper Type Intemai Floating-Roof Tanks, Publication 2519, Third Edi- Secondary Seal for SR-1 Seals” (Letter Report, Research tion, Washington, D.C., June 1983. Contract R-0134), Chicago Bridge & iron Company, Plain- [3] American Petroleum Institute, WeldedSteel Tanksfor Oil field, Illinois, February 23, 1977. Storage, Standard 650, Ninth Edition, Washington, D.C., July [ 181 W.N. Cherniwchan, “Hydrocarbon Emissions from a 1993. Leaky SR-1 Seal With a Mayflower Secondary Seal” (Report [4] U.S. Department of Commerce, National Oceanic and 1, Research Contract R-0177). Chicago Bridge & Iron Com- Atmospheric Administration, Comparative Climatic Data pany, Plainfield, Illinois, September 20, 1977. nirough 1990, National Climatic Data Center; Asheville, [19] “Hydrocarbon Emission Loss Measurements on a 20 North Carolina, 1990. Foot Diameter External Floating-Roof Tank Fitted With a [5] Laverman, R.J., Gallagher,T.A., and Cherniwchan, W.N., CBI SR-5 Liquid Filled Seal“ (Final Report, Research Con- “Emission Reduction Options for Floating Roof Tank Fit- tract R-0167), Chicago Bridge & Iron Company, Plainfield, tings,” Paper presented at Energy Week 1996, Held in Hous- Illinois,August 31, 1978. ton, Texas, January 29-February 2, 1996. [20] “SOHIO/CBI Floating-Roof Emission Test Program” [6] American Petroleum Institute, Evaporation Loss from (interim Report, Research Contract R-0101), Chicago Bridge Fixed-Roof T m h , Bulletin 2518, First Edition, Washington, & Iron Company, Plainfield, Illinois, October 7, 1976. D.C., June 1962. [211 “SOHIO/CBI Floating-Roof Emission Test Program” [7] The Chemical Rubber Co., Handbook of Chemistry and (Final Report, Research Contract R-OlOI), Chicago Bridge & Physics, 51st Edition, R.C. Weast, Editor, Cleveland, Ohio, Iron Company, Plainfield, Illinois, November 18, 1976. pp. DI46-D165,1970. [22] Radian Corporation, “Field Testing Program to Deter- [8] American Petroleum Institute, Technical Data Book- mine Hydrocarbon Emissions from Floating-Roof Tanks,” Petroleum RefUting, Publication 999, Ninth Revision, Wash- Repon prepared for the Floating-Roof Tank Subcommittee, ington, D.C., 1988. Committee on Evaporation Loss Measurement, American [9] Perry’s Chemical Engineers’ Handbook, Sixth Edition, Petroleum Institute, Washington, D.C., May 1979. R.H. Perry, D.W. Green, and J.O. Maloney, Editors, [23] “‘Measurementof Emissions f o a Tubeseal Equipped rm McGraw-Hill Book Co., Inc., New York, New York, 1984. Floating-Roof Tank,” Pittsburgh-DesMoines Steel Company, [ 101 American Petroleum Institute, Design, Construction, Pittsburgh, Pennsylvania, December 4, 1978 (including s u p Operation, Maintenance, and Inspection of Tenninal and plemental report issued January 16,1979). Tank Facilities. Standard 2610, First Edition, Washington, [241 Engineering Science, Inc., “Phase I, Test Rogram and D.C., July 1994. Procedures,” Report prepared for the Floating-Roof Tank [ 111 Ferry, R.L., “Development of Deck-Fitting Loss Factors Subcommittee, Committee on Evaporation Loss Measure- for Floating-Roof Tanks,” Report prepared by The TGB Part- ment, American Petroleum Institute, Washington, D.C., nership, prepared for API, Committee on Evaporation Loss November 1977. Measurement,Task Group 3, Washington, D.C., 1996. [25] Chicago Bridge & Iron Company, “Development of [ 121 Courtesy of Rob Ferry, The TGB Partnership, Hillsbor- Laboratory Procedures for Use in the Field Testing Program ough, N r h Carolina. ot to Determine Hydrocarbon Emissions from Floating-Roof [I31 “Western Oil and Gas Association Metallic Sealing Tanks,” Report prepared for the Floating-Roof Tank Subcom- Ring Emission Test Program” (Interim Report, Research mittee, Committee on Evaporation Loss Measurement, Contract R-0136), Chicago Bridge & Iron Company, Plain- Amencan Petroleum Institute, Washington, D.C., May 18, field, Illinois, January 19, 1977. 1978. [14] “Western Oil and Gas Association Metallic Sealing [26] Chicago Bridge & Iron Company, ‘‘Hydrocarbon Emis- Ring Emission Test Program” (Final Report, Research Con- sion Measurements of Crude Oil on the 20 Foot Diameter tract R-0136), Chicago Bridge & Iron Company, Plainfield, Floating-Roof Pilot Test Tank,” Repori prepared for the Fioat- Illinois, March 25, 1977. ing-Roof Tank Subcommittee, Committee on Evaporation [15] “Western Oil and Gas Association Metallic Sealing Loss Measurement, American Petroleum Institute, Washing- Ring Emission Test hgram” (supplemental Report, ton, D.C., August 15, 1978. Research Contract R-0136), Chicago Bridge & Iron Com- [27] “SOHIO/CBI Floating-Roof Emission Test Program’’ pany, Plainfield, Illinois, June 30, 1977. (Supplemental Report, Research Contract R-0101), Chicago [16] “Hydrocarbon Emission Loss Measurements on a 20 Bridge & I r p Company, Plainfield, Illinois, February 15, Foot Diameter Floating-RoofTank With a Qpe SR- 1 Seal for 1977.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  9. 9. S T D - A P I I P E T R O MPMS L S = Z - E N G L 1997 0732290 05bllllBb T3b SECTION 2-EVAPORATIVE LOSS FROMFLOATING-ROOF TANKS 3 [28] Docket OAQ PS 78-2 Petroleum Liquid Storage Vessels Characteristics of a Liquid Storage Tank,” Fluidyne Engineer- Part 4-B-7, Memo: “Gap Criteria for External Floating-Roof ing Corp., Fluidyne Report No. 1114, (CBI Research Con- Seals,” from L. Hayes of TRW EED to the NSS Docket, tract R-0150), June 1977. December 4, 1979. [39] Runchal, A.K., “Influence of Wind on Hydrocarbon [291 Chicago Bridge & Iron Co., “Testing Program to Mea- Emissions from Internal Floating Roof Tanks,’’ prepared by sure Hydrocarbon Emissions from a Controlled Internal Analytical and Computational Research, Inc., prepared for Floating-Roof Tank,” Final Report, prepared for API, CBI API, Washington, D.C., November 17, 1980. Contract No. 05000, Washington, D.C., March 1982. [40] J.F. Marchman, “Wind Effects on Floating Surfaces in [30] CBI Industries, Inc., “Testing Program to Measure Large Open-Top Storage Tanks,” Paper presented at the Third Hydrocarbon Evaporation Loss from External Floating-Roof Conference on Wind Effects on Buildings and Structures, Fittings” (CBI Contract 41851), Final report prepared for the Tokyo, 1971. Committee on Evaporation Loss Measurement, American [41] J.F. Marchman, “Surface Loading in Open-Top Tanks,” Petroleum Institute, Washington, D.C., September 13, 1985. Journal of the Structural Division, American Society of Civil 1311 R.L. Russell, “Analysis of Chicago Bridge & Iron Co. Engineers, November 1970, Volume 96, Number STl 1, pp. External Floating-Roof Tank Fitting Loss Data,” Report pre- 255 1-2556. pared for Task Group 25 17, Committee on Evaporation Loss [42] Engineering Science, Inc., “Hydrocarbon EmissionsI Measurement, American Petroleum Institute, Washington, from Floating-Roof Storage Tanks,” Report prepared for the D.C., October 17, 1985. Western Oil and Gas Association, Los Angeles, January 1977. [32] Owens, J.E., Laverman, R.J., Winters, P.J., Johnson, [43] Ferry, R.L., “Documentation of Rim Seal Loss Factors J.G., Gemelli, M.J., “Testing Program to Measure Evapora- for the Manual of Petroleum Measurement Standards, Chap tive Losses from Floating Roof Fittings,” Final Report, pre- ter 19-Evaporative Loss Measurement, Section 2-Evapora- pared by Chicago Bridge & Iron Technical Services Co., tive Loss from Floating-Roof Tanks,” Report prepared by The prepared for API, Committee on Evaporation Loss Mea- TGB Partnership, prepared for API,Committee on Evapora- surement, Task Group 3, Washington, D.C., October l , tion Loss Measurement, Task Group 3, Washington, D.C., 1993. April 5, 1995. [33] Owens, J.E., Laverman, R.J., Winters, “Testing Program [44] R.J. Laverman, “Emission Measurements on a Floating to Measure Evaporative Losses from Floating Roof Fittings,” Roof Pilot Test Tank,” 1979 Proceedings-Refining Depart- Supplemental Report Number 1, prepared by Chicago Bridge ment, Volume 58, American Petroleum Institute, Washington, & Iron Technical Services Co., prepared for API, Committee D.C., 1979, pp. 301-322. on Evaporation Loss Measurement, Task Group 3, Washing- [45] ‘Wind Speed Versus Air Flow Rate Calibration of 20 ton, D.C., December 3 1,1993. Foot Diameter Floating-Roof Test Tank” (Final Report, [34] Laverman, R.J. and Schoemer, W.S., “Testing Program Research Contract R-0177), Chicago Bridge & Iron Com- to Measure Evaporative Losses from Slotted Guidepole Fit- pany, Plainfield, Illinois, October 5, 1977. tings,” Final Report, prepared by Chicago Bridge & Iron [46] American Petroleum Institute, Evaporation Loss from Technical Services Co., prepared for API, Committee on Floating-Roof Tanks, Bulletin 25 17, First Edition, Washing- Evaporation Loss Measurement, Task Group 3, Washington, ton, D.C., 1962. D.C., November 10,1995. [47] American Petroleum Institute, Evaporation Loss from [35] Petersen, R.L. and Cochran, B.C., “Wind Tunnel Testing External Floaring-Roof Tanks, Publication 25 17, Second Edi- of External Floating Roof Storage Tanks,” (CPP Reports 92- tion, Washington, D.C., February 1980. 0869, 93-0934, and 93-1024), prepared by Cermak, Peterka [48] American Petroleum Institute, Documentation File fur Petersen, Inc., prepared for M I , Committee on Evaporation Revised API Publication 251 7, Washington, D.C., June 26, Loss Measurement, Task Group 3, Washington, D.C., 1993. 1981. [36] Ferry, R.L., “Documentation of the Fitting Wind-Speed [49] Runchal, A.K., “Hydrocarbon Vapor Emissions from Correction Factor,” Report prepared by The TGB Partnership, Floating-Roof Tanks and the Role of Aerodynamic Modifica- prepared for API,Committee on Evaporation Loss Measure- tions,” Air Pollution Control Association Journal, Volume 28, ment, Task Group 3, Washington, D.C., March 25, 1995. Number 5, May 1978, pp. 498-501. [37] Parker, A. and Neulicht, R., “Fitting Wind Speed Cor- [50] J.G. Zabaga, “API Floating-Roof Tank Test Program,” rection Factor for External Floating Roof Tanks,” Letter Paper presented at the 72nd Air Pollution Control Association report prepared by Midwest Research Institute, prepared for Meeting, Cincinnati, Ohio, June 26, 1979. U.S. EPA, September 25, 1995. [5 11 American Petroleum Institute, Documentation File for [38] Helm, N.C. and Giese, P.D., “Wind Tunnel Tests of a API Publication 2519, Publication 2519D, First Edition, 0.017-Scale Model to Determine Pressure, Flow, and Venting Washington, D.C., March 1993. COPYRIGHT American Petroleum Institute Licensed by Information Handling Services
  10. 10. ~~~ STD-API/PETRO MPMS 17-2-ENGL 1777 0732290 05b1ig87 772 4 CHAPTER ~~-EVAPORATNE MEASUREMENT LOSS 3 Definitions comprised of a deck, a rim seal, and miscellaneous deck fit- tings. Selected terms are defined in this section, and a complete list of nomenclature is given in Table 1. 3.7 floating-roof tank A vessel for storing bulk liquids, having a vertical cylindrical shell and also having a floating 3.1 covered floating-roof tank (CFRT): A floating- roof that rests on the stored liquid. A floating-roof tank may roof tank that has both a fixed roof at the top of the tank shell, additionally have a fixed roof attached to the top of the tank and an external-type of floating roof designed in accordance shell. Floating-roof tanks are described in more detail in 8.2, with Appendix C of the N I Standard 650 [3]. The CFRTs are thus distinguished from external floating-roof tanks (EFRTs), 3.8 internal floating-roof tank (IFRT): A floating-roof which do not have a fixed roof, and internal floating-roof tank that has a fixed roof at the top of the tank shell, and a tanks (IFRTs), which have a fixed roof but have the lighter lightweight floating roof designed in accordance with Appen- type of floating roof (designed in accordance with Appendix dix H of the API Standard 650 [3]. Internal floating-roof tanks H of API Standard 650) [3]. The CFRTs are described in are thus distinguished from external floating-roof tanks and more detail in 8.2.3. covered floating-roof tanks, both of which have the heavier type of floating roof (designed in accordance with Appendix 3.2 deck: That part of a floating roof that provides bouy- C of API Standard 650) [3]. Some deck fittings, such as deck ancy and structure and that covers the majority of the liquid legs, may more closely resemble the construction typical of surface in a floating-roof tank. The deck has an annular space API Standard 650, Appendix C-type decks [3]. Judgment around its perimeter to allow it to rise and descend (as the should be used in determining the appropriate loss factor for a tank is filled and emptied) without binding against the tank specific deck fitting. Internal floating-roof tanks are described shell. This annular space is closed by a flexible device called in more detail in 8.2.2. a rim seal. The deck also may have penetrations, closed by fit- tings, which accomodate some functional or operational fea- 3.9 loss factor: An expression used to describe the evap- ture of the tank. Typical deck constructions are described in orative loss rate characteristics of a given floating-roof 8.1.2. device. In order to obtain the total standing storage evapora- 3.3 deck fitting: A device that substantially closes or tive loss rate for a floating-roof tank, the sum of the evapora- tive loss factors for each of the individual devices is modified seals a penetration in the deck of a floating-roof tank. Such penetrations are typically for the purpose of accommodating by certain characteristics of both the climatic conditions and some functional or operational feature of the tank. Typical the stored liquid. The characteristics of the stored liquid are expressed as a vapor pressure function, the stock vapor deck fittings are described in 8.1.4. molecular weight, and a product factor. Loss factors for typi- 3.4 deck seam: The joint attaching adjacent sheets or cal floating-roof equipment are presented in 5.2. panels in the floating deck. Certain types of internal floating- roof decks are constructed of sheets or panels that are joined 3.10 product factor: A factor that describes the evapora- by mechanical means, such as by bolting or clamping. Such tive loss characteristics of a given liquid. The product factor, mechanically-joined deck seams have an associated deck- the stock vapor molecular weight, and the vapor pressure seam loss. Other types of internal floating-roof decks, and function are multiplied by the sum of the floating-roof loss virtually all external floating-roof decks, are constructed of factors to determine the total standing storage evaporative metal sheets that are joined by welding. Such deck seams do loss rate of a floating-roof tank. Product factors are presented not have an associated deck-seam loss. Deck seams are in 5.3.3. described in more detail in 8.1.5. 3.11 rim seal: A flexible device on a floating roof that 3.5 external floating-roof tank (EFRT): A floating- closes the annular space between the deck and the tank shell. roof tank that does not have a fixed roof at the top of the shell. When a floating roof has two such devices, one mounted The EFRTs are thus distinguished from internal floating-roof above the other, the lower is the primary seal and the upper is tanks (IFRTs) and covered floating-roof tanks (CFRTs), both the secondary seal. Qpical rim seal systems are described in of which do have fixed roofs to protect the floating roofs from 8.1.3. environmental loads. External floating roofs are typically 3.12 standing storage loss: Loss of stored liquid stock designed in accordance with Appendix C of API Standard by evaporation past the floating roof during normal service 650 [3]. The EFRTs are described in more detail in 8.2.1. conditions. This does not include evaporation of liquid that 3.6 floating roof: A device that floats on the surface of clings to the tank shell (and fixed-roof support columns, if the stored liquid in a floating-roof tank. A floating roof sub- any) and is exposed to evaporation when the tank is being stantially covers the liquid product surface, thereby reducing emptied (withdrawal loss). Nor does it include vapor loss that its potential for exposure to evaporation. Floating roofs are may occur when the liquid level is sufficiently low so as toCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  11. 11. SECTIONEVAPORATIVE Loss FROMFLONING-ROOF TANKS 5 Table 1-Nomenclature Reference information Symbol Description Units Equations Tables Figura Constant in the vapor pressure equation dimensionless 20.21.24 2 3.5 Area of the deck square feet 18 Constant in the vapor pressure. equation degrees Rankine 20,22,25 2 4.6 Clingage factor barrels per IO00 square feet 6 3 Tank diameter fat 6, IO. 17 3 Exponential function 20 2 Effective column diameter feet 6,27 3 Total deck-seam loss factor pound-moles per year 1.5, 17 2 Total deck-fitting loss factor pound-moles per year 1,4, 13 2 Total rim-seal loss factor pound-moles per year 1.3, IO 2 _. Fitting number, I, 2, . . k dimensionless 13.14 Total number of different types of deck fittings dimensionless 13, 14 Roduct factor dimensionless 1,3,4,5 Deck-seam loss per unit seam length factor pound-moles per fooi*year 17 Zero-wind-speed loss factor for a paiticular pound-moles per year 14 type of deck fitting Wind-dependent loss factor for a paiticular pound-moles per 14 type of deck fitting (miles per hourpyear Loss factor for a particular type of deck fitting pound-moles per year 13, 14 Rim-seal loss factor pound-moles per foot*year IO. 12 Zero-wind-speed rim-seal loss factor pound-moles per foot*year 11.12 Wind-dependentrim-seal loss factor pound-moles per II (miles per hourpfoot*year Fitting wind-speed correction factor dimensionless 14, 15 Length of a deck panel feet 10 Total deck-seam loss pounds per year 5 Total deck-fitting loss pounds per year 4 Natural logarithm function 2 I , 22,24,25 Rim-seal loss pounds per year 3 Standing storage loss pounds per year or I , 2,8,9 barrels per year Total length of deck seams feet 18 Total loss pounds per year or 8,9 barrels per year Withdrawal loss pounds per year or 3 barrels per year Wind-dependent loss exponent for a particular dimensionless 14 6 type of deck fittingCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  12. 12. 6 19-EvAPoRATIvE Loss MEASUREMENT CHAPTER Table 1-Nomenclature (Continued) Reference Information Symbol Description Units Equations Tables Figures Average molecular weight of stock vapor pounds per pound-mole 1.3.4, $26 2 Wind-dependent rim-seal loss exponent dimensionless II 4 Number of access hatches dimensionless 6 Number of fixed-roof support columns dimensionless 6 3.6.7 Number of deck drains dimensionless 6 8 Number of deck legs dimensionless 6.9 Number of gauge floats (automatic gauge) dimensionless 6 Number of deck fittings of a particular type dimensionless 13 6 Number of vertical ladders dimensionless 6 Number of rim vents dimensionless 6 Number of slotted (perforated)guidepoles dimensionless 6 Number of gauge hatchlsample ports dimensionless 6 Number of unslotted (unperforated) guidepoles dimensionless 6 Number of vacuum breakers dimensionless 6.8 Stock true vapor pressure at the average stock pounds per square inch absolute 19,20 2 1.2 storage temperature Average atmospheric pressure at the tank location pounds per square inch absolute 19 2 Vapor pressure function dimensionless 1,3,4,5,19 2 Annual net throughput (associated with barrels per year 6 3 lowering the liquid stock level in the tank) Stock Reid vapor pressure pounds per square inch 21,22,24,25 2 Stock ASTM-D86-Distillation of Petroleum degrees Fahrenheit per 21,22,23 2 products distillation slope at 10 volume volume percent percent evaporated Deck-seam length factor feet per square feet 17,18 10 Temperature at which 5 volume percent is evaporated degrees Fahrenheit 23 2 Temperature at which I5 volume percent is evaporated degrees Fahrenheit 23 2 Average annual ambient temperature degrees Fahrenheit 15.16 Average stock storage temperature degrees Fahrenheit 20 2 1.2 Average ambient wind speed at the tank site miles per hour 11.14 5 Width of deck sheet or panel feet IO Average liquid stock density at the average pounds per gallon 6 3 storage temperature Average liquid stock density a WF t pounds per gallon 7 3 Density of the condensed vapor pounds per gallon 2.26 2COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  13. 13. S T D * A P I / P E T R O MPMS L 7 - 2 - E N G L 1997 0732290 05bqLi90 Lib7 SECTION 2-EVAPORATIVE LOSS F O FLOATING-ROOF T N S R M AK 7 I allow the floating roof to rest on its support legs. The standing b. The type of rim seal system. I storage loss equation is presented in 4.2. c. The type and number of deck fittings. d. The type of floating-roof deck construction (pontoon or 3.13 vapor pressure function: A dimensionless factor double-deck, if API Standard 650, Appendix C type (EFRTs used in the loss estimation procedure, that is a function of the and CFRTs); welded or bolted, and length of bolted deck ratio of the vapor pressure of the stored liquid to average seams, if API Standard 650, Appendix H type (IFRTs) [3]). atmospheric pressure at the storage location. The vapor pres- e. The molecular weight of the stock vapor. sure function, the stock vapor molecular weight, and the product factor are multiplied by the sum of the equipment The standing storage loss, Ls, includes losses from the rim loss factors to determine the total standing storage evapora- seal and the deck fittings, and from the deck seams if they are tive loss rate of a floating-roof tank. The vapor pressure func- of bolted construction (IFRTs).The standing storage loss can tion is presented in 5.3.1. be estimated as follows: 3.14 withdrawal loss: Loss by evaporation of the liquid that clings to the tank shell (and fixed-roof support columns, if any) and is exposed to evaporation when the tank is being emptied (withdrawal loss). The withdrawal loss equation is L, = standing storage loss, in pounds per year. presented in 4.3. F, = total rim-seal loss factor, in pound-moles per year. Ff = t t l deck-fittingloss factor, in pound-moles per year. oa 4 Equations for Estimating Losses Fd = total deck-seam loss factor, in pound-moles per year. 4.1 GENERAL P* = vapor pressure function (dimensionless). M, = average molecular weight of stock vapor, in pounds This section presents the equations for estimating the total per pound-mole. annual evaporative stock loss or the equivalent atmospheric K, = product factor (dimensionless). hydrocarbon vapor emissions from volatile stocks stored in floating-roof tanks. The total loss, L,, the sum of the stand- is The standing storage loss is converted from pounds per ing storage loss, Ls, and the withdrawal loss, L,. In some ,, year to barrels per year as follows: cases, the withdrawal loss may be negligible (see section 6); in these cases, the total loss is approximatelyequal to the stand- ing storage loss. The loss mechanisms are discussed in 9.2. barrels For convenience, a description of each variable is given Ls ( = E) 42 W , (2) after its first usage in an equation in each section. In addition, a complete list of nomenclature is given in Table 1. Where: 4.2 STANDING STORAGE LOSS W, = density of the condensed vapor, in pounds per gallon. The following minimum information is needed to estimate the standing storage loss, L,: The constant, 42, in Equation 2 has units of gallons per barrel. a. The true vapor pressure of the stock (or the Reid vapor The procedures used to calculate the standing storage loss pressure and average storage temperature of the stock). are summarized in Table 2. b. The type of stock. Equation 1 was derived by adding together the three equa- c. The tank diameter. tions that represent the independentloss contributionsof the rim d. The type of floating roof (external type built in accordance seal, the deck fittings, and the deck seams. The following equa- with API Standard 650, Appendix C (EFRTs and CFRTs); or tions can be used to estimatethese independent contributions: internal type built in accordance with API Standard 650, Appendix H (IFRTs) [3]). L, = F, P*M, K, (3) e. The type of fixed roof construction (column-supported or Lf = Ff P * M , K, (4) self-supporting (IFRTs and CFRTs); or none (EFRTs)). f. The average ambient wind speed at the tank site, for tanks L, = F, P * M , K, (5) that do not have a fixed roof (EFRTs). Where: Improved estimates of the standing storage loss can be obtained through a knowledge of some or all of the following L, = total rim-seal loss, in pounds per year. additional information: Lf = total deck-fitting loss, in pounds per year. Ld = total deck-seam loss, in pounds per year. a. The type of tank shell construction (welded or riveted) (EFRTs). The other variables are as defined in Equation 1.COPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  14. 14. Table 2-Summary of Procedure for Calculating Standing Storage Loss ~~ Standing Storage Loss Equations: Ls (poundsfyear) = [(F,) + (Ff) + (Fd)] P*MVK c (Equation I ) Ls (barrelsfyear) = Ls (poundsfyear) I 4 2 W,, (Equation 2) Equipment-RelatedFactors Variable Definition Units of Measurement Source Fr =total rim-seal loss factor pound-moles per year For tanks without a fixed roof (EFRT): =KID (Equation 10) Equation IO, using values from Table 4; or Kr = rim-seal loss factor pound-moles per footrear read values for Krdirectly from Table 4 for = K , + KhV" (Equation I I ) selected wind speeds. K , = zero-wind-speed rim-seal loss factor pound-moles per footmyear Krb = winddependent rim-seal loss factor pound-moles per (miles per hour)".foot-year V = average ambient wind speed at the tank site miles per hour User specified or Table 5. n = winddependent rim-seal loss exponent (dimensionless) For tanks with a fixed roof (IFRTICFRT): The value of V in equation 11 is set equal to zero,therefore Kr in equation 11 is equal to K from Table 4. , D =tank diameter feet User specified. ~~ ~ F, = total deck-fitting loss factor pound-moles per year if specific information about the type and = [(N&) + (NnKn) + ...+ (N&&)] number of deck fittings is available: (Equation 13) Equations 13 and 14, using values from NE = number of fittings of a patticular type (dimensionless) Tables 6 9 ; or read values for KRdirectly K , = deck-fitting loss factor for a particular pound-moles per year from Table 6 for selected wind speeds. type of fitting If specific information is not available: = Kfai+ Kfbi ( K , V ) ~ (Equation 14) Typical values may be obtained from Tables 6-9 (EFRT/IFRT/CFRT) Kfpi = zero-wind-speed deck-fitting loss factor pounds-moles per year Kfbi = wind-dependent deck-fitting loss factor pound-moles per (miles per hour)" year K, = fitting wind-speed correction factor (dimensionless) K, = 0.7 (EFRT) mi = wind-dependent deck-fitting loss exponent (dimensionless) i =fitting number, 1,2, ..., k (dimensionless) For tanks with a fixed rwf (IFRT/CFRT): V = average wind speed at the tank site miles per hour The value of V in equation 14 is set equal to k = total number of different types of deck (dimensionless) zero,therefore K f iin equation 13 is equal to fittings Kfpifrom Table 6 Fd =total d e c k - m IOSS factor pound-moles per year Equation 17, where: (IFRT) = K$@ (Equation 17) Kd equals: Kd = deck seam loss per unit seam length pound-moles per foot-year 0 for a welded deck factor 0.34 for a bolted deck sd = deck-seam length factor feet per square feet s d equals: =L - IA , (Equation 18) If Lam known, Table 10 is not L I =total length of deck feet = area of deck square feet if Lxm is not known. Equation 18 =d l 4 D =tankdiameter feetCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  15. 15. STD.API/PETRO M P M S 19.2-ENGL 1997 m 0?32270 05b4Li72 Z I T m SECTION 2-EVAWRATIVE LOSS FROM FLOATING-ROOF TANKS 9 Table 2-Summary of Procedure for Calculating Standing Storage Loss (Continued) Standing Storage Loss Equations: Ls (poundslyear) = [ ( F J + (Ff) + (Fd)] P*MV Kc (Equation I ) Ls (barrelslyear) = Ls (poundslyear)I 4 2 W y (Equation 2) Stock-Related Factors Variable Definition Units of Measurement Source P’ = vapor pressure function (dimensionless) Table 1 I or Equation 19 =(P/fa)/ ( i+[i-(P/fa)]0.5)* (Equation 19) Pa = average atmosphericpressure at the pounds per square inch absolute Equal to 14.7 unless user specified. tank site P =true vapor pressure at the average pounds per square inch absolute Equation 20, or stock storage temperature for refined petroleum stocks: Figure I = exp [A - B/(Ts+459.6)] (Equation 20) for crude oils: Figure 2 exp = experimental functions Ts = average storage temperature of stock degrees Fahrenheit User specified or Tables 15 and 16. A = constant in the vapor pressure equation (dimensionless) For refined petroleum stocks: = 15.64- 1.85@.5-(0.8742-0.3280p.5)1n(RVPJ Equation 21 or Figure 3. for refined petroleum stocks (Equation 21) For crude oils: Equation 24 or Figure 5 . or, for crude oils: For selected other petroleum liquids: Table 13. = 12.82 - 0.9672 ln(RVP) (Equation 24) For selected petrochemicals: Table 14. B = constant in the vapor pressure equation degrees Rankine For refined petroleum stocks: = 8742-1042p.5-(1049-179.4p.’)ln(RVPJ Equation 22 or Figure 4. for refined petroleum stocks (Equation 22) For crude oils: Equation 25 or Figure 6. or, for crude oils: For selected other petroleum liquids: Table 13. =7261 - 1216 In(RVPJ (Equation 25 For selected petrochemicals: Table 14 RVP = Reid vapor pressure pounds per square inch User specified. S = slope of the ASTM-D86distillation curve, degrees Fahrenheit Table 12 or Equation 23. at 10 percent evaporated volume percent = (T„-T5)/1O (Equation 23) r 5 = temperature a which 5 percent volume is t degrees Fahrenheit evaporated T,5 =temperature at which 15 percent volume is degrees Fahrenheit evawrated M, = average molecular weight of stock vapor pounds per pound-mole User specified or: 64 for gasoline 50 for midcontinent crude oil Table 14 for selected petrochemicals Kc = product factor (dimensionless) 1.O for refined stocks 0.4 for crude oil 1 .O for single-component stocks W, = density of condensed vapor pounds per gallon User specified or: 0.08Mv for gasoline (Equation 26) Table 14 for selected petrochemicals Equal to liquid stock density for single- component stocksCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  16. 16. - ~~ STD.API/PETRO MPMS 1 9 - 2 - E N G L 1997 0732290 05bVV93 L7b 10 CHAPTER 14-EvmmnvE LOSS MEASUREMENT 4.3 WITHDRAWAL LOSS 4.4 TOTALLOSS The withdrawal loss, L, , can be estimated from the fol- The total loss, L,, pounds per year and barrels per year, in lowing information: can be estimated as follows: a. The annual net throughput (associated with lowering the pounds pounds liquid stock level in the tank). (8) b. The type of stock. c. The average liquid stock density. d. The t n diameter. ak barrels barrels (9) e. The condition of the tank shell [and fixed-roof support col- umns, if any ( F T and CFRTs)]. IRs Where: A slight improvement in the withdrawal loss estimate can be obtained for tanks with column-supported fixed roofs if L, = total loss. the type, condition,and number of columns are known for the Ls = standing storage loss. particular tank under consideration. L, = withdrawal loss. The withdrawal loss, & pertains to the evaporation of liq- uid stock that clings to the tank shell (and any fixed-roof sup- port columns) while the stock is withdrawn. The withdrawal 5 Standing Storage Loss Factors loss can be estimated as follows: 5.1 GENERAL Information is given in this section on how to determine specific values for the variables in the standing storage loss equations given in 4.2. Tables, figures, and the range of values Where: of the variables for which the standing storage loss equations are applicable are cited for reference. Where appropriate, a L, = withdrawal loss, in pounds per year. distinction is made between EFRT,IFRT, and CFRT values. Q = annual net throughput (associated with lowering the These distinctionsprimarily involve wind effects and the con- liquid stock level in the tank), in barrels per year. struction of the floating roof. C = clingage factor, in barrels per lo00 square feet. To obtain the most accurate estimate, the detailed quanti- W, = average liquid stock density at the average storage ties, sizes, and other information pertinent to the specific tank temperature,in pounds per gallon. or tanks under consideration should be used. The typical D = tank diameter, in feet. quantities and sizes included in the tables should be used only Nfc = number of fixed-roof support columns (dimension- when actual detailed information is not available. More less)(IFRTs and CFRTs). detailed discussions of the development, definition, and F, = effective column diameter, in feet (IFRTs and effects of these variables are given in Section 9 and the CFIMS). appendixes. The constant, 0.943,in Equation 6 has dimensions of Those standing storage loss factors that pertain to the (lo00 cubic feet) x [gallons per (barrel squared)]. design of the tank and floating roof are designated equip- The withdrawal loss is converted from pounds per year to ment-related factors and are considered separately from those barrels per year as follows: factors that pertain to the characteristics of the stored liquid stock. The equipment-related factors are F, Ff, and Fd from Equation 1 and are described in Section 5 for each type of barrels floating-roof tank. (7) The standing storage loss factors that pertain to the charac- teristics of the stored liquid stock are designated stock-related where: factors. The stock-related factors are P*,M, , and K, from Equation 1, and are described in 5.3. W, = average liquid stock density a W F ,in pounds per t While the equipment-related loss factors are expressed in gallon. units of pound-moles per year, they must be multiplied by the The constant, 42, in Equation 7 has units of gallons per dimensionless stock-related factors, PC and Kc, in oder to barrel. determine actual pound-moles per year of evaporative loss for The procedures used to calculate withdrawal loss are sum- a given liquid product. To convert the actual pound-moles per marized in Table 3. year to pounds per year, multiply by the molecular weight ofCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services
  17. 17. ~ STD*API/PETRO MPMS 19.2-ENGL 1997 0732290 05b449Li 002 W LOSS f ROM FLOATING-ROOFTANKS SECTION 2-EVAPORATIVE 11 the product in its vapor phase, hi, with molecular weight hav- ing units of pounds per pound-mole. Where: 5.2 EQUIPMENT-RELATED FACTORS F, = total rim-seal loss factor, in pound-moles per year. The equipment-related factors are the t o d rim-seal loss K, = rim-seal loss factor, in pound-moles per foot*year. factor, F, discussed in Section 5.2.1 ; the total deck-fitting loss D = tank diameter, in feet. factor, Ff,discussed in Section 5.2.2; and the total deck-seam The rim-seal loss factor, K , can be estimated as follows: loss factor, Fd, discussed in Section 5.2.3 (IF’RTs).These loss factors are dependent on the tank size, the type of floating roof deck, the type of rim seal and the type of fixed roof, if one is present (IFRTs and CFRTs). The tank size is described Where: by the diameter, D, in feet. The various types of floating roof K , = zero-wind-speed rim-seal loss factor, in pound-moles decks, rim seals, and deck fittings are described more fully in per footoyear. Section 8. Krb= wind-dependent rim-seal loss factor, in pound-moles per (miles per hour)”.foot-year. 5.2.1 Rim-Seal Loss Factor V = average ambient wind speed at the tank site, in miles The rim-seal loss factor, F, can be estimated as follows: per hour. Table %Summary of Procedure for Calculating Withdrawal Loss Standing Storage Loss Equations: (Equation 6) pounds barrels L- year ,) ( = L”(year ) (Equation 7) 42 W, Variable Definition Units of Measurement Source ~ Q =annual net throughput (associated with barrels per year User specified lowering the liquid stock level in the tank) C = clingage factor barrels per loo0 square feet Table 17 W, = average liquid stock density at the average pounds per gallon User specified,or stock storage temperature (for Equation 6) 6.1 for gasoline Table 14 for selected petrochemicals D =tankdiameter feet User specified Nf, = number of fixed-roof support columns (dimensionless) For tanks with a column-supported fixed roof (IFRTs): User specified or Table 7 For tanks with a self-supporting fixed roof (CFRTs) or without a fixed roof EFRTs): 0 F, =effective column diameter feet Equation 27, with user specified column perimeter. or - column perimeter 3.1416 (feet) (Equation 27) For 9-inch by 7-inch built-up columns: 1.1 For 8-inch diameter pipe columns: 0.7 If column type is not known 1.o W, = average liquid stock density pounds per gallon User specified, or at 60’F (for Equation 7) 6. I for gasoline Table 14 for selected petrochemicalsCOPYRIGHT American Petroleum InstituteLicensed by Information Handling Services

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