1、Reconditioning of Metallic Gate,Globe,and Check ValvesAPI RECOMMENDED PRACTICE 621FOURTH EDITION,OCTOBER 2018Special 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
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15、aterials 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 20005,standardsapi.org.iiiContentsPage1Scope.12Normative References .13Terms and Definitions.24Owner Acces
16、s and Responsibilities.35Inspection,Identification,and Disassembly of Valves.35.1General.35.2Identification Number.45.3Traveler Documents.45.4Disassembly and Cleaning of Valves.46Repair of Valve Parts.56.1General.56.2Inspection of Valve Parts.66.3Handwheel Nut.66.4Handwheel.66.5Yoke.76.6Stem Nut and Stem Nut Housing.76.7Stem Nut Retainer.76.8Packing Gland Flange.76.9Packing Gland.76.10 Backseat Bushing.86.11 Body and Bonnet.86.12 Body Guides .136.13 Body Seat Ring(s).136.14 Wedge Guides.146.15 O
