1、Venting Atmospheric andLow-pressure Storage TanksAPI STANDARD 2000SEVENTH EDITION, MARCH 2014Special NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed.Neither API nor any
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3、 results of such use, of any information or process disclosed in this publication. Neither API nor any of APIs employees, subcontractors, consultants, or other assignees represent that use of this publication would not infringe upon privately owned rights.Users of this standard should not rely exclu
4、sively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein. Where applicable, authorities having jurisdiction should be consulted.API publications may be used by anyone desiring to do
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6、 damage resulting from its use or for the violation of any authorities having jurisdiction with which this publication may conflict.API publications are published to facilitate the broad availability of proven, sound engineering and operating practices. These publications are not intended to obviate
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15、d from the API Standards Department, telephone (202) 682-8000. A catalog of API publications and materials is published annually by API, 1220 L Street, NW, Washington, DC 20005.Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC
16、 20005, standardsapi.org.iiiContentsPage1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Terms, Definitions, and Abbreviated Terms . . . . . . . . . . . . . . . . . . . . . .
17、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Nonrefrigerated Aboveground Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.2 Causes of Overpressure or Vacuum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43.3 Determination of Venting Requirements. . . . . . . . . . . .
19、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.4 Means of Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.5 Considerations for Tanks with Potentially F
20、lammable Atmospheres. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.6 Relief-device Specification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223.7 Installation of Venting Devices and Open Vents . . . .
21、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 Refrigerated Aboveground and Belowground Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244.2 Causes of Overpressure or Vacuum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254.3 Relief-device Specification. . . . . . . . . . . .
23、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284.4 Installation of Venting Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 Testing of Venting Devices. . .
24、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295.
25、2 Flow-test Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295.3 Method for Determining Capacities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26、 . . . . . . 335.4 Production Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346 Manufacturers Documentation and Marking of Venting Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
27、 . . 356.1 Documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356.2 Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28、. . . . . . . . . . . . . . . . . . . . . . . 35Annex A (informative) Alternative Calculation of Normal Venting Requirements . . . . . . . . . . . . . . . . . . . . . . . . 37Annex B (informative) Basis of Emergency Venting for Table 7 and Table 8. . . . . . . . . . . . . . . . . . . . . . . . . . .
29、 . 46Annex C (informative) Types and Operating Characteristics of Venting Devices . . . . . . . . . . . . . . . . . . . . . . . . 51Annex D (informative) Basis of Sizing Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Annex E (informati
30、ve) Basis for Normal Out-breathing and Normal Inbreathing. . . . . . . . . . . . . . . . . . . . . . . . . 73Annex F (informative) Guidance for inert-gas Blanketing of Tanks for Flashback Protection. . . . . . . . . . . . . . 75Annex G (informative) Explanation of Differences in Thermal Inbreathing
31、Using the General Method and Annex A Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32、. . . . . . . . . . . . . . . . . . . . . . . . . . . . 83Figures1 Test Apparatus for Flow Testing of Venting Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302 Typical Ratio Limits for Capacity Testing of Venting Devices Using the Coefficient of Discharg
33、e Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33B.1 Curve for Determining Requirements for Emergency Venting During Fire Exposure (SI Units) . . . . . . . 49B.2 Curve for Determining Requirements
34、 for Emergency Venting During Fire Exposure (USC Units). . . . . 50C.1 Open Vent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51C.2 Side-by-side Pressure/Vacuum Vent. . . . . . . . . . . . .
35、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54C.3 Large, Weight-loaded Emergency Vent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54vContentsPageC.4 Direct-acting Vents . . . . . . . . . . . . .
36、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55C.5 Pilot-operated Pressure Vent (Single Diaphragm). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56C.6 Pilot-operated Pressure/Vacuum (Doub
37、le Diaphragm). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57D.1 Isentropic Expansion Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70F.1 Trip Pressure Diagram for Nitrogen Blanketin
38、g. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77G.1 Surface to Volume Ratio for Conical Roof Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79G.2 Rate of Change of Tank Vapor Space Temperature Used in t
39、he Two Sizing Methods . . . . . . . . . . . . . . . 80G.3 Maximum Inbreathing for Various Tanks Sizes; Solid Black LinesThermodynamic Model;Solid CrossesAnnex A Method; Red Line V = 5V0.7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81G.4 Rate of Change of Tank Va
40、por Space Temperature vs Rain Density. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Tables1 Y-factor for Various Latitudes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 C-factors . . . . . . . . . . . . .
41、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Heat Input, Q (Expressed in SI Units) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 Heat Input,
42、Q (Expressed in USC Units) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Venting Capacity (Expressed in SI Units) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 Venting Capaci
43、ty (Expressed in USC Units). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 Emergency Venting Required for Fire Exposure vs Wetted Surface Area (Expressed in SI Units). . . . . 168 Emergency Venting Required for Fire Exposure vs Wetted Surface A
44、rea (Expressed in USC Units) . . 179 Environmental Factors for Nonrefrigerated Aboveground Tanks (Expressed in SI and USC Units) . . . 1810 Maximum Allowable Leak Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34A.1 Normal
45、Venting Requirements (Expressed in SI Units) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40A.2 Normal Venting Requirements (Expressed in USC Units) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40A.3 Normal Venting Requirements for Th
46、ermal Effects (Expressed in SI Units) . . . . . . . . . . . . . . . . . . . . . . . 41A.4 Normal Venting Requirements for Thermal Effects (Expressed in USC Units) . . . . . . . . . . . . . . . . . . . . . 42D.1 Guidance on Converting Calculated Flows to Normal/Standard Conditions. . . . . . . . . .
47、. . . . . . . . . . . . . 67G.1 Surface to Volume Ratio of Small, Medium, and Large Flat Roof Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . 79G.2 Assumptions Used in the Annex A Method and General Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80viIntroductionThis
48、 standard has been developed from the accumulated knowledge and experience of qualified engineers of the oil, petroleum, petrochemical, chemical, and general bulk liquid storage industry.Engineering studies of a particular tank can indicate that the appropriate venting capacity for the tank is not t
49、he venting capacity estimated in accordance with this standard. The many variables associated with tank-venting requirements make it impractical to set forth definite, simple rules that are applicable to all locations and conditions.In this standard, where practical, U.S. customary (USC) units are included in parentheses or in separate tables, for information.vii1 Venting Atmospheric and Low-pressure Storage Tanks 1 Scope This standard covers the normal and emergency vapor venting requirements for aboveground liquid petroleum or petroleum products storage tanks and aboveground an
