1、Risk-based Approach for Managing Hydrocarbon Vapor Exposure during Tank Gauging, Sampling, and Maintenance of Onshore Production FacilitiesAPI RECOMMENDED PRACTICE 77FIRST EDITION, JUNE 2018Special NotesAPI publications necessarily address problems of a general nature. With respect to particular cir
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16、t every five years. A one-timeextension of up to two years may be added to this review cycle. Status of the publication can be ascertained from theAPI Standards Department, telephone (202) 682-8000. A catalog of API publications and materials is publishedannually by API, 1220 L Street, NW, Washingto
17、n, DC 20005.Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW,Washington, DC 20005, standardsapi.org.iiiContentsPage1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、. . . . . . . . . . . . . . . . . . . . . . . 12 Terms and Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Hazard Identification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.2 Fluid Characteristics. . . . . . . . . . . . . .
20、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.3 Process Design, Operational, and Maintenance Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Exposure and Risk Assessment . . . . . . . . . . . .
21、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.2 Purpose of Exposure and
22、Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44.3 Risk Assessment and Life Cycle Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44.4 Risk Assessment Approaches. .
23、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65.1 Gen
24、eral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65.2 Open-hatch Sampling or Gauging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25、. . . . . . . . . . 65.3 Pressure Relief Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85.4 Hatch Proximity to Worker Breathing Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26、 . . . . . . . . . . . . . . 86 Operational and Maintenance Practices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Personnel Training and Communication of Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
27、. . . . . . 108 Operator and Contractor Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28、 . . . . . . . . . . . . . . . . . . 108.2 Operators Responsibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108.3 Contractor Responsibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29、. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Annex A (informative) Design and Operational Considerations Checklists. . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Annex B (informative) Risk Assessment Methodologies and Tools . . . . . . . . . . . . . . . . . . . . . . . . . .
30、. . . . . . . . 15Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Figures1 Exposure Control Effectiveness Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31、 . . . . . . . . . . . . . . . . . . . . . . 72 Example of Tank Fitted with Site Glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Example Catwalk Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32、. . . . . . . . . . . . . . . . . . . . . . . . . 9B.1 Oil Production Flow Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15B.2 Fault Tree ExampleAcute Exposure to Hydrocarbons during Manual Tank Gauging. . . . . . .
33、 . . . . . . . 16B.3 Facility System Interactions That Can Result in Acute Exposures to Hazardous Levels of Hydrocarbons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17B.4 Bow Tie Example. . . . . . . . . . . . . . . . . . . . . . . . . .
34、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19TablesA.1 Facilities/Process Design Considerations Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12A.2 Operational Practices Checklist . . . . . . . . . . .
35、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13A.3 Examples of Risk Conditions for Facility Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14ivIntroductionA combination of risk management consideratio
36、ns, practices, and communication can ensure safe operations for tankgauging, sampling, and maintenance of onshore production facilities. This combination of risk management strategiesincorporating facility design, operational procedures, and activity-based risk assessment integrated across a life cy
37、cleis recommended for safe tank operations.v1Risk-based Approach for Managing Hydrocarbon Vapor Exposure during Tank Gauging, Sampling, and Maintenance of Onshore Production Facilities1 Scope The scope of this standard covers recommended risk assessment and risk management practices to reduce thepot
38、ential for acute worker hydrocarbon exposures and related atmospheric risks (i.e. potential oxygen deficiency).Specifically, this recommended practice is limited to onshore production tanks (including flowback tanks) duringgauging and sampling, open-top tank sampling, and select tank maintenance act
39、ivities involving removal or openingof tank appurtenances. While the tools and practices recommended in this document can be useful in otheroperations, this recommended practice does not specifically apply to downstream, refining, or offshore tankapplications. This standard specifically excludes ris
40、k assessment and management practices related toa) chronic hydrocarbon exposures,b) non-hydrocarbon substances such as hydrogen sulfide, andc) opening other process equipment, confined space entry, tank cleaning, or decommissioning activities.2 Terms and Definitions For the purposes of this document
41、, the following terms and definitions apply.2.1communication protocolsA system of rules which allow for two or more entities of a communications system to transmit information.2.2flashing losses The release of entrained gas from a liquid as the pressure on the liquid drops.2.3gas-to-oil ratioThe rat
42、io of the gas produced in standard cubic feet to one barrel of oil produced during any stated period.2.4hazardA situation, inherent chemical or physical property with the potential to do harm.EXAMPLE Flammability, oxygen deficiency, toxicity, corrosivity, stored electrical, chemical or mechanical en
43、ergy.2.5hydrocarbonHCClass of organic chemical compounds composed only of the elements carbon (C) and hydrogen (H). NOTE The carbon atoms join together to form the framework of the compound, and the hydrogen atoms attach to them in manydifferent configurations.2 API RECOMMENDED PRACTICE 77 2.6riskA
44、measure of potential injury, environmental damage, or economic loss in terms of both the incident likelihood and theseverity of the loss or injury.2.7risk assessmentThe identification and analysis, either qualitative or quantitative, of the likelihood and outcome of specific hazardexposure events or
45、 scenarios with judgements of probability and consequences.2.8stop work authorityA program designed to provide employees and contract workers with the responsibility and obligation to stop workwhen a perceived unsafe condition or behavior can result in an unwanted event.2.9thief hatchA closable aper
46、ture in a tank or vessel which are used to take samples of the tanks contents, determining the level ofthe tank and protect the tank from over pressure and excessive vacuum.2.10volatile organic compoundsVOCsA chemical class of hydrocarbons that participates in atmospheric photochemical reactions, wh
47、ich have an initialboiling point less than or equal to 250 C (482 F) measured at standard atmospheric pressure of 101.3 kPa (14.7psi).EXAMPLE Methane, ethane, acetone, acrolein, benzene, carbon disulfide, carbon tetrachloride, chlorobenzene, chloroethane,dichlorobenzenes, dichloropropenes, ethylbenz
48、ene, formaldehyde, gasoline, hexachlorobutadiene, n-hexane, styrene,tetrachloroethylene (PERC), toluene, trichloroethylene (TCE), vinyl chloride, and xylenes, to name a few.3 Hazard Identification3.1 GeneralHazard identification begins with understanding the source of the natural gas and the process
49、es that can potentiallycontribute to concentrations of tank vapors. Successful and safe tank management begins with an understanding ofthe production fluid characteristics, and the influence of process design, operations, and maintenance considerationsthat can impact risk. 3.2 Fluid CharacteristicsUnderstanding the physical properties of produced VOCs, including hydrocarbons, is essential in identifying potentialhazards. Tank contents, including volatile hydrocarbons and other agents such as hydrogen sulfide or benzene,should be considered, and are addressed in API 49, API 55, a
