_RP_550-1-2-1980_scan.pdf

API RECOMMENDED PRACTICE 550FOURTH EDITION,FEBRUARY 1980Manual on Installation of RefineryInstruments and Control SystemsPart I-Process Instrumentation and ControlSection2一Level622.323AmeACc ND.:3034.Manual on Installation of RefineryInstruments and Control SystemsPart I-Process Instrumentation and ControiSection 2-LevelRefining DepartmentAPI RECOMMENDED PRACTICE 550FOURTH EDITION,FEBRUARY 1980OFFICIAL PUBLICATIONREG US PATENT OFFICEAPI recommended practices are published as an aid to standardization of methodsand procedures.These recommended practices are not intended to inhibit the use ofpractices other than those of API nor to inhibit the purchase or production or productsmade to specifications other than API.Nothing contained in any API recommended practice is to be construed as granting anyright,by implication or otherwise,for the manufacture,sale,or use in connection withany method,apparatus,or product covered by letters patent nor as insuring anyoneagainst liability for infringement of letters patent.API recommended practices may be used by anyone desiring to do so.Every effort hasbeen made by the Institute to assure the accuracy and reliability of the data contained inthem;however,the Institute makes no representation,warranty,or guarantee in con-nection with the publication of API recommended practices.The Institute hereby ex-pressly disclaims any liability or responsibility for loss or damage resulting from theiruse;for the violation of any federal,state,or municipal regulation with which an APIrecommended practice may conflict;or for the infringement of any patent resulting fromthe use of an API recommended practiceCopyright 1980 American Petroleum InstituteFOREWORDThis recommended practice is based on the accumulated knowledge and experience ofengineers in the petroleum industry.Its purpose is to aid in the installation of the moregenerally used measuring,control,and analytical instruments;transmission systems;andrelated accessories to achieve safe,continuous,accurate,and efficient operation withminimum maintenance.Although the information contained has been prepared primarilyfor use in petroleum refineries,much of it is applicable without change in chemicalplants,gasoline plants,and similar installationsSuccessful instrumentation depends upon a workable arrangement which incorporatesthe simplest systems and devices that will satisfy specific requirements.Sufficientschedules,drawings,sketches,and other data should be provided to enable the construc-tor to install the equipment in the desired manner.Various industry codes and standards aswell as laws and rules of regulating bodies should be followed where applicable.For maximum plant personnel safety,transmission systems are used to eliminate thepiping of hydrocarbons,acids,and other hazardous or noxious materials to instruments incontrol rooms.Proper installation is essential to use fully the capabilities that are builtinto the instrument or transmission system.When installing an instrument,the various components must be accessible for efficientmaintenance,and certain of these elements must be readable for good operation.Orifices.control valves,transmitters,thermocouples,level gages,and local controllers as well asanalyzer sample points generally should be readily accessible from grade,permanentplatforms,or fixed ladders.In this manual,special consideration is given to the location,accessibility,and readability of the elements.Users of this manual are reminded that in the rapidly advancing field of instrumentationno publication of this type can be complete nor can any written document be substitutedfor qualified engineering analysis.Certain systems are not covered in this section because of their highly specializednature and limited use.When any of these systems gains wide-spread usage and installa-tion reaches a fair degree of standardization,this section will be revised to incorporatesuch additional information.Acknowledgment is made to all the engineers and operating and maintenance person-nel who,through years of study,observation,invention,and sometimes trial and error,have contributed to the technology of instrumentation.Suggested revisions are invited and should be submitted to the director,RefiningDepartment,American Petroleum Institute,2101 L Street,N W.,Washington,D.C20037.