Teko ea bopaki ke karolo ea bohlokoa ea ho boloka botšepehi ba polokeho ea litsamaiso tsa rona tsa lisebelisoa tsa polokeho (SIS) le litsamaiso tse amanang le polokeho (mohlala, lialamo tsa bohlokoa, litsamaiso tsa mollo le khase, litsamaiso tsa ho notlela tse nang le lisebelisoa, jj.). Teko ea bopaki ke teko ea nako le nako ho lemoha ho hloleha ho kotsi, ho leka ts'ebetso e amanang le polokeho (mohlala, ho seta bocha, ho palama li-passport, lialamo, ho hlahloba, ho tima ka letsoho, jj.), le ho netefatsa hore sistimi e fihlela litekanyetso tsa k'hamphani le tsa kantle. Liphetho tsa liteko tsa bopaki le tsona ke tekanyo ea katleho ea lenaneo la botšepehi ba mechini la SIS le botšepehi ba tšimo ba sistimi.
Mekhoa ea liteko tsa bopaki e akaretsa mehato ea liteko ho tloha ho fumaneng mangolo a tumello, ho etsa litsebiso le ho tlosa sistimi tšebeletsong bakeng sa tlhahlobo ho isa ho netefatseng liteko tse felletseng, ho ngola tlhahlobo ea bopaki le liphetho tsa eona, ho khutlisetsa sistimi tšebetsong, le ho lekola liphetho tsa liteko tsa hajoale le liphetho tsa liteko tsa bopaki tse fetileng.
ANSI/ISA/IEC 61511-1, Molawana wa 16, o akaretsa diteko tsa bopaki ba SIS. Tlaleho ya botekgeniki ya ISA TR84.00.03 – “Botshepehi ba Mechanical of Safety Instrumented Systems (SIS),” e akaretsa diteko tsa bopaki mme hajwale e ntse e ntjhafatswa mme mofuta o motjha o lebelletswe ho tswa haufinyane. Tlaleho ya botekgeniki ya ISA TR96.05.02 – “Teko ya Bopaki ba Di-valve tse Iketsang” e ntse e ntjhafatswa hajwale.
Tlaleho ea HSE ea UK CRR 428/2002 – “Melao-motheo ea liteko tsa bopaki ba litsamaiso tse nang le lisebelisoa tsa polokeho indastering ea lik'hemik'hale” e fana ka tlhahisoleseling mabapi le liteko tsa bopaki le seo lik'hamphani li se etsang UK.
Mokhoa oa teko ea bopaki o ipapisitse le tlhahlobo ea mekhoa e tsebahalang ea ho hloleha ho kotsi bakeng sa karolo ka 'ngoe tseleng ea leeto la lisebelisoa tsa polokeho (SIF), ts'ebetso ea SIF joalo ka sistimi, le mokhoa (le haeba) oa ho leka mokhoa oa ho hloleha ho kotsi. Nts'etsopele ea ts'ebetso e lokela ho qala mohatong oa moralo oa SIF ka moralo oa sistimi, khetho ea likarolo, le ho fumana hore na tlhahlobo ea bopaki e lokela ho etsoa neng le joang. Lisebelisoa tsa SIS li na le maemo a fapaneng a bothata ba tlhahlobo ea bopaki bo lokelang ho nahanoa moralong, ts'ebetsong le tlhokomelong ea SIF. Mohlala, li-orifice metres le li-transmitter tsa khatello li bonolo ho li leka ho feta li-flowmeter tsa boima ba Coriolis, li-mag metres kapa li-sensor tsa boemo ba radar tse tsamaeang moeeng. Ts'ebeliso le moralo oa li-valve le tsona li ka ama botlalo ba teko ea bopaki ba li-valve ho netefatsa hore ho hloleha ho kotsi le ho qalang ka lebaka la ho senyeha, ho hokela kapa ho hloleha ho itšetlehileng ka nako ha ho lebise ho hloleheng ho hoholo nakong ea tlhahlobo e khethiloeng.
Leha mekhoa ea liteko tsa bopaki e atisa ho ntlafatsoa nakong ea mohato oa boenjiniere ba SIF, e lokela ho hlahlojoa hape ke Bolaoli ba Theknoloji ba SIS ba sebaka seo, Ts'ebetso le litsebi tsa lisebelisoa tse tla etsa liteko. Tlhahlobo ea polokeho ea mosebetsi (JSA) le eona e lokela ho etsoa. Ho bohlokoa ho fumana tumello ea fektheri mabapi le hore na ke liteko life tse tla etsoa le hore na li tla etsoa neng, le monyetla oa tsona oa 'mele le polokeho. Mohlala, ha ho na thuso ho hlalosa tlhahlobo ea karoloana ea stroke ha sehlopha sa Ts'ebetso se sa lumellane ho e etsa. Ho boetse ho khothaletsoa hore mekhoa ea liteko tsa bopaki e hlahlojoe ke setsebi se ikemetseng sa taba (SME). Teko e tloaelehileng e hlokahalang bakeng sa teko ea bopaki bo felletseng ba ts'ebetso e bontšitsoe ho Setšoantšo sa 1.
Litlhoko tsa teko ea bopaki bo felletseng ba ts'ebetso Setšoantšo sa 1: Tlhaloso e felletseng ea teko ea bopaki bo felletseng ba ts'ebetso bakeng sa ts'ebetso e nang le lisebelisoa tsa polokeho (SIF) le sistimi ea eona ea lisebelisoa tsa polokeho (SIS) e lokela ho hlalosa kapa ho supa mehato ka tatellano ho tloha litokisetsong tsa liteko le mekhoa ea liteko ho ea ho litsebiso le litokomane.
Setšoantšo sa 1: Tlhaloso e felletseng ea teko ea bopaki ba mosebetsi bakeng sa mosebetsi o nang le lisebelisoa tsa polokeho (SIF) le sistimi ea eona ea lisebelisoa tsa polokeho (SIS) e lokela ho hlalosa kapa ho supa mehato ka tatellano ho tloha litokisetsong tsa liteko le mekhoa ea liteko ho ea ho litsebiso le litokomane.
Teko ea bopaki ke ketso e reriloeng ea tlhokomelo e lokelang ho etsoa ke basebetsi ba nang le boiphihlelo ba koetlisitsoeng tlhahlobong ea SIS, mokhoa oa bopaki, le li-loop tsa SIS tseo ba tla li leka. Ho lokela hore ho be le tlhahlobo ea ts'ebetso pele ho etsoa teko ea pele ea bopaki, le maikutlo ho Bolaoli ba Theknoloji ea SIS ea sebaka seo kamora moo bakeng sa lintlafatso kapa litokiso.
Ho na le mekhoa e 'meli ea mantlha ea ho hloleha (e bolokehileng kapa e kotsi), e arotsoeng ka mekhoa e mene—e kotsi e sa lemohuoeng, e kotsi e lemohuoeng (ka ho hlahloba), e sireletsehileng e sa lemohuoeng le e sireletsehileng e lemohuoeng. Mantsoe a kotsi le a kotsi a sa lemohuoeng a sebelisoa ka ho fapanyetsana sehloohong sena.
Tekong ea bopaki ba SIF, re thahasella haholo mekhoa e kotsi ea ho hloleha e sa lemohuoeng, empa haeba ho na le litlhahlobo tsa basebelisi tse lemohang ho hloleha ho kotsi, litlhahlobo tsena li lokela ho hlahlojoa ka bopaki. Hlokomela hore ho fapana le litlhahlobo tsa basebelisi, litlhahlobo tsa kahare ho sesebelisoa hangata li ke ke tsa netefatsoa e le tse sebetsang ke mosebelisi, 'me sena se ka susumetsa filosofi ea tlhahlobo ea bopaki. Ha mokitlane oa tlhahlobo o nkuoa lipalo tsa SIL, lialamo tsa tlhahlobo (mohlala, lialamo tse kantle ho sebaka) li lokela ho lekoa e le karolo ea teko ea bopaki.
Mekhoa ea ho hloleha e ka aroloa hape ka e lekiloeng nakong ea teko ea bopaki, e sa lekoang bakeng sa eona, le ho hloleha ho qalang kapa ho hloleha ho itšetlehileng ka nako. Mekhoa e meng e kotsi ea ho hloleha e kanna ea se ke ea lekoa ka kotloloho ka mabaka a fapaneng (mohlala, bothata, boenjiniere kapa qeto ea ts'ebetso, ho hloka tsebo, ho se tsebe, ho se etse liphoso tsa tsamaiso, monyetla o tlase oa ho etsahala, jj.). Haeba ho na le mekhoa e tsebahalang ea ho hloleha e ke keng ea lekoa bakeng sa eona, puseletso e lokela ho etsoa moralong oa sesebelisoa, ts'ebetso ea teko, ho nkeloa sebaka ha sesebelisoa nako le nako kapa ho tsosolosoa, le/kapa tlhahlobo ea ho nahana e lokela ho etsoa ho fokotsa phello botšepehing ba SIF ba ho se leke.
Ho hloleha ha mosebelisi ke boemo bo nyenyefatsang hoo ho hloleha ho tebileng, ho kotsi ho ka lebelloang ka nepo haeba mehato ea tokiso e sa nkuoe ka nako. Hangata li bonoa ka ho bapisa ts'ebetso le liteko tsa morao-rao kapa tsa pele tsa bopaki (mohlala, lipontšo tsa valve kapa linako tsa karabelo ea valve) kapa ka tlhahlobo (mohlala, koung ea ts'ebetso e hoketsoeng). Ho hloleha ha mosebelisi hangata ho itšetlehile ka nako—ha sesebelisoa kapa kopano e ntse e sebetsa nako e telele, e ntse e senyeha le ho feta; maemo a nolofalletsang ho hloleha ho sa reroang a ba le monyetla o moholo, ho hokela koung ea ts'ebetso kapa ho bokellana ha sensor ha nako e ntse e ea, bophelo ba ts'ebeliso bo felile, jj. Ka hona, ha nako ea teko ea bopaki e le telele, ho hloleha ha mosebelisi kapa ho itšetleha ka nako ho ka etsahala haholoanyane. Tšireletso efe kapa efe khahlanong le ho hloleha ha mosebelisi le eona e tlameha ho lekoa ka bopaki (ho hloekisa koung, ho latela mocheso, jj.).
Mekhoa e tlameha ho ngoloa ho ea tekong ea bopaki bakeng sa ho hloleha ho kotsi (ho sa lemohuoeng). Mekhoa ea mokhoa oa ho hloleha le tlhahlobo ea phello (FMEA) kapa mokhoa oa ho hloleha, tlhahlobo ea phello le tlhahlobo (FMEDA) e ka thusa ho khetholla ho hloleha ho kotsi ho sa lemohuoeng, le moo ho lokelang ho ntlafatsoa tšireletso ea liteko tsa bopaki.
Mekhoa e mengata ea liteko tsa bopaki ke boiphihlelo bo ngotsoeng bo thehiloeng holima le litempele tse tsoang lits'ebetsong tse seng li ntse li le teng. Mekhoa e mecha le li-SIF tse rarahaneng haholoanyane li hloka mokhoa o ntlafalitsoeng haholoanyane o sebelisang FMEA/FMEDA ho sekaseka liphoso tse kotsi, ho fumana hore na mokhoa oa teko o tla leka kapa o ke ke oa leka liphoso tseo joang, le ho akaretsa liteko. Setšoantšo sa block ea tlhahlobo ea mokhoa oa ho hloleha oa boemo bo holimo bakeng sa sensor se bontšitsoe ho Setšoantšo sa 2. Hangata FMEA e hloka ho etsoa hanngoe feela bakeng sa mofuta o itseng oa sesebelisoa le ho sebelisoa hape bakeng sa lisebelisoa tse tšoanang ka ho nahana ka ts'ebeletso ea tsona ea ts'ebetso, ho kenya le bokhoni ba tlhahlobo ea sebaka.
Tlhahlobo ea ho hloleha ha boemo ba macro Setšoantšo sa 2: Setšoantšo sena sa block ea tlhahlobo ea mokhoa oa ho hloleha ha boemo ba macro bakeng sa sensor le transmitter ea khatello (PT) se bontša mesebetsi e meholo eo hangata e tla aroloa ka har'a litlhahlobo tse ngata tsa ho hloleha ha macro ho hlalosa ka botlalo ho hloleha ho ka bang teng ho tla rarolloa litekong tsa ts'ebetso.
Setšoantšo sa 2: Setšoantšo sena sa block ea tlhahlobo ea mokhoa oa ho hloleha ha maemo a macro bakeng sa sensor le transmitter ea khatello (PT) se bontša mesebetsi e meholo eo hangata e tla aroloa ka har'a litlhahlobo tse ngata tsa ho hloleha ha micro ho hlalosa ka botlalo ho hloleha ho ka bang teng ho tla rarolloa litekong tsa ts'ebetso.
Peresente ea liphoso tse tsejoang, tse kotsi, tse sa lemohuoang tse lekiloeng ka bopaki e bitsoa tšireletso ea teko ea bopaki (PTC). PTC e sebelisoa hangata lipalo tsa SIL ho "buseletsa" ho hloleha ho leka SIF ka botlalo. Batho ba na le tumelo e fosahetseng ea hore hobane ba nahanne ka khaello ea tšireletso ea teko lipalo tsa bona tsa SIL, ba entse SIF e tšepahalang. 'Nete ke hore, haeba tšireletso ea hau ea teko e le 75%, 'me haeba u kenyelelitse palo eo palong ea hau ea SIL le linthong tseo u seng u ntse u li leka khafetsa, 25% ea liphoso tse kotsi e ntse e ka etsahala ka lipalo-palo. Ka 'nete ha ke batle ho ba ho 25%.
Litlaleho tsa tumello ea FMEDA le libukana tsa polokeho bakeng sa lisebelisoa hangata li fana ka mokhoa o fokolang oa tlhahlobo ea bopaki le tšireletso ea tlhahlobo ea bopaki. Tsena li fana ka tataiso feela, eseng mehato eohle ea liteko e hlokahalang bakeng sa ts'ebetso e felletseng ea tlhahlobo ea bopaki. Mefuta e meng ea tlhahlobo ea ho hloleha, joalo ka tlhahlobo ea sefate sa liphoso le tlhokomelo e shebaneng le ts'epo, le eona e sebelisoa ho sekaseka ho hloleha ho kotsi.
Liteko tsa bopaki li ka aroloa ka liteko tse sebetsang ka botlalo (ho tloha qalong ho isa qetellong) kapa tlhahlobo ea ts'ebetso e sa fellang (Setšoantšo sa 3). Teko ea ts'ebetso e sa fellang hangata e etsoa ha likarolo tsa SIF li na le linako tse fapaneng tsa liteko lipalo tsa SIL tse sa tsamaellaneng le ho koaloa kapa ho fetoloa ho reriloeng. Ho bohlokoa hore mekhoa ea teko ea bopaki ba ts'ebetso e sa fellang e kopane hoo hammoho e lekang ts'ebetso eohle ea polokeho ea SIF. Ka liteko tse sebetsang tse sa fellang, ho ntse ho khothaletsoa hore SIF e be le teko ea pele ea bopaki ba ho tloha qetellong ho isa qetellong, le tse latelang nakong ea ho fetoloa.
Liteko tsa bopaki bo sa fellang li lokela ho kopanya Setšoantšo sa 3: Liteko tse kopantsoeng tsa bopaki bo sa fellang (tlase) li lokela ho akaretsa mesebetsi eohle ea teko e felletseng ea bopaki bo sebetsang (holimo).
Setšoantšo sa 3: Liteko tse kopaneng tsa bopaki bo sa fellang (tlase) li lokela ho akaretsa mesebetsi eohle ea teko e felletseng ea bopaki bo sebetsang (holimo).
Teko ea bopaki bo sa fellang e leka peresente feela ea mekhoa ea ho hloleha ha sesebelisoa. Mohlala o tloaelehileng ke teko ea valve ea stroke e sa fellang, moo valve e tsamaisoang ka tekanyo e nyane (10-20%) ho netefatsa hore ha ea khomarela. Sena se na le tšireletso e tlase ea teko ea bopaki ho feta teko ea bopaki nakong ea teko ea mantlha.
Mekhoa ea tlhahlobo ea bopaki e ka fapana ka ho rarahana ka lebaka la ho rarahana ha SIF le filosofi ea mokhoa oa tlhahlobo ea k'hamphani. Likhamphani tse ling li ngola mekhoa e qaqileng ea tlhahlobo ea mohato ka mohato, ha tse ling li na le mekhoa e khutšoanyane haholo. Litšupiso tsa mekhoa e meng, joalo ka tlhahlobo e tloaelehileng, ka linako tse ling li sebelisoa ho fokotsa boholo ba mokhoa oa tlhahlobo ea bopaki le ho thusa ho netefatsa botsitso litekong. Mokhoa o motle oa tlhahlobo ea bopaki o lokela ho fana ka lintlha tse lekaneng ho netefatsa hore liteko tsohle li phethiloe hantle ebile li ngotsoe, empa eseng lintlha tse ngata ho etsa hore litsebi li batle ho tlola mehato. Ho ba le setsebi, ea ikarabellang bakeng sa ho etsa mohato oa teko, ho qala mohato oa teko o phethiloeng ho ka thusa ho netefatsa hore tlhahlobo e tla etsoa ka nepo. Ho saena tlhahlobo ea bopaki e phethiloeng ke Mookameli oa Lisebelisoa le baemeli ba Ts'ebetso ho tla boela ho hatise bohlokoa le ho netefatsa tlhahlobo ea bopaki e phethiloeng hantle.
Maikutlo a setsebi a lokela ho mengoa kamehla ho thusa ho ntlafatsa mokhoa ona. Katleho ea mokhoa oa teko ea bopaki e matsohong a setsebi, kahoo boiteko ba tšebelisano-'moho bo khothaletsoa haholo.
Bongata ba liteko tsa bopaki hangata li etsoa kantle ho inthanete nakong ea ho koaloa kapa ho fetoloa ha sesebelisoa. Maemong a mang, liteko tsa bopaki li ka 'na tsa hlokahala hore li etsoe inthaneteng ha li ntse li sebetsa ho fihlela lipalo tsa SIL kapa litlhoko tse ling. Teko ea inthanete e hloka ho rala le ho sebelisana le Ts'ebetso ho lumella teko ea bopaki hore e etsoe ka mokhoa o sireletsehileng, ntle le ho sitisoa ha ts'ebetso, le ntle le ho baka leeto la bohata. Ho nka leeto le le leng feela la bohata ho sebelisa li-attaboy tsohle tsa hau. Nakong ea mofuta ona oa teko, ha SIF e sa fumanehe ka botlalo ho etsa mosebetsi oa eona oa polokeho, 61511-1, Karolo ea 11.8.5, e re "Mehato ea puseletso e netefatsang ts'ebetso e tsoelang pele e sireletsehileng e tla fanoa ho latela 11.3 ha SIS e le tseleng (tokiso kapa tlhahlobo)." Mokhoa o sa tloaelehang oa taolo ea boemo o lokela ho tsamaea le mokhoa oa teko ea bopaki ho thusa ho netefatsa hore sena se etsoa hantle.
SIF hangata e aroloa ka likarolo tse tharo tse kholo: li-sensor, li-logic solver le likarolo tsa ho qetela. Hangata ho na le lisebelisoa tse thusang tse ka amanang le karolo ka 'ngoe ea tsena tse tharo (mohlala, li-IS barriers, li-trip amps, li-interposing relay, li-solenoids, jj.) tseo le tsona li lokelang ho lekoa. Likarolo tsa bohlokoa tsa ho leka bopaki theknoloji ka 'ngoe ea tsena li ka fumanoa lehlakoreng le ka thoko, "Li-testing sensors, li-logic solver le likarolo tsa ho qetela" (ka tlase).
Lintho tse ling li bonolo ho li leka ho paka ho feta tse ling. Mahlale a mangata a sejoale-joale le a khale a phallo le maemo a 'mele a sehlopheng se thata haholo. Tsena li kenyelletsa li-flowmeter tsa Coriolis, li-vortex metres, li-mag metres, radar ea moea, boemo ba ultrasound, le li-switch tsa ts'ebetso ea in-situ, ho bolela tse 'maloa. Ka lehlohonolo, tse ngata tsa tsena joale li na le litlhahlobo tse ntlafalitsoeng tse lumellang liteko tse ntlafalitsoeng.
Bothata ba ho leka bopaki ba sesebediswa se jwalo tshimong bo lokela ho nahanelwa moralong wa SIF. Ho bonolo hore boenjiniere bo kgethe disebediswa tsa SIF ntle le ho nahana ka botebo ka se tla hlokahala ho leka bopaki ba sesebediswa, kaha e ke ke ya ba bona ba di lekang. Sena se boetse se etsahala ka teko ya karolo ya stroke, e leng tsela e tlwaelehileng ya ho ntlafatsa kgonahalo ya karolelano ya SIF ya ho hloleha ha ho hlokahala (PFDavg), empa hamorao fektheri ya Tshebetso ha e batle ho e etsa, mme hangata e kanna ya se ke ya etsa jwalo. Kamehla fana ka tlhokomelo ya fektheri ya boenjiniere ba SIF mabapi le teko ya bopaki.
Teko ea bopaki e lokela ho kenyelletsa tlhahlobo ea ho kenya le ho lokisa SIF ha ho hlokahala ho fihlela 61511-1, Karolo ea 16.3.2. Ho lokela ho ba le tlhahlobo ea ho qetela ho netefatsa hore ntho e 'ngoe le e 'ngoe e koetsoe ka likonopo, le tlhahlobo e habeli ea hore SIF e khutliselitsoe ts'ebetsong ea ts'ebetso hantle.
Ho ngola le ho kenya tshebetsong mokhoa o motle wa teko ke kgato ya bohlokwa ho netefatsa botshepehi ba SIF bophelong bohle ba yona. Mokgwa wa teko o lokela ho fana ka dintlha tse lekaneng ho netefatsa hore diteko tse hlokahalang di etswa ka ho tsitsitseng le ka polokeho le ho ngolwa. Ho hloleha ho kotsi ho sa lekoang ka diteko tsa bopaki ho lokela ho lefellwa ho netefatsa hore botshepehi ba polokeho ba SIF bo bolokwa ka ho lekaneng bophelong bohle ba yona.
Ho ngola mokhoa o motle oa tlhahlobo ea bopaki ho hloka mokhoa o utloahalang oa tlhahlobo ea boenjiniere ea ho hloleha ho ka bang kotsi, ho khetha mekhoa, le ho ngola mehato ea tlhahlobo ea bopaki e ka har'a bokhoni ba tlhahlobo ea fektheri. Tseleng, fumana tumello ea fektheri maemong 'ohle bakeng sa tlhahlobo, 'me u koetlise litsebi ho etsa le ho ngola tlhahlobo ea bopaki hammoho le ho utloisisa bohlokoa ba teko. Ngola litaelo joalokaha eka u setsebi sa lisebelisoa se tla tlameha ho etsa mosebetsi, 'me maphelo a itšetlehile ka ho etsa tlhahlobo hantle, hobane ke bona ba etsang joalo.
Testing sensors, logic solvers and final elements A SIF is typically divided up into three main parts, sensors, logic solvers and final elements. There also typically are auxiliary devices that can be associated within each of these three parts (e.g. I.S. barriers, trip amps, interposing relays, solenoids, etc.) that must also be tested.Sensor proof tests: The sensor proof test must ensure that the sensor can sense the process variable over its full range and transmit the proper signal to the SIS logic solver for evaluation. While not inclusive, some of the things to consider in creating the sensor portion of the proof test procedure are given in Table 1. Table 1: Sensor proof test considerations Process ports clean/process interface check, significant buildup noted Internal diagnostics check, run extended diagnostics if available Sensor calibration (5 point) with simulated process input to sensor, verified through to the DCS, drift check Trip point check High/High-High/Low/Low-Low alarms Redundancy, voting degradation Out of range, deviation, diagnostic alarms Bypass and alarms, restrike User diagnostics Transmitter Fail Safe configuration verified Test associated systems (e.g. purge, heat tracing, etc.) and auxiliary components Physical inspection Complete as-found and as-left documentation Logic solver proof test: When full-function proof testing is done, the logic solver’s part in accomplishing the SIF’s safety action and related actions (e.g. alarms, reset, bypasses, user diagnostics, redundancies, HMI, etc.) are tested. Partial or piecemeal function proof tests must accomplish all these tests as part of the individual overlapping proof tests. The logic solver manufacturer should have a recommended proof test procedure in the device safety manual. If not and as a minimum, the logic solver power should be cycled, and the logic solver diagnostic registers, status lights, power supply voltages, communication links and redundancy should be checked. These checks should be done prior to the full-function proof test.Don’t make the assumption that the software is good forever and the logic need not be tested after the initial proof test as undocumented, unauthorized and untested software and hardware changes and software updates can creep into systems over time and must be factored into your overall proof test philosophy. The management of change, maintenance, and revision logs should be reviewed to ensure they are up to date and properly maintained, and if capable, the application program should be compared to the latest backup.Care should also be taken to test all the user logic solver auxiliary and diagnostic functions (e.g. watchdogs, communication links, cybersecurity appliances, etc.).Final element proof test: Most final elements are valves, however, rotating equipment motor starters, variable-speed drives and other electrical components such as contactors and circuit breakers are also used as final elements and their failure modes must be analyzed and proof tested.The primary failure modes for valves are being stuck, response time too slow or too fast, and leakage, all of which are affected by the valve’s operating process interface at trip time. While testing the valve at operating conditions is the most desirable case, Operations would generally be opposed to tripping the SIF while the plant is operating. Most SIS valves are typically tested while the plant is down at zero differential pressure, which is the least demanding of operating conditions. The user should be aware of the worst-case operational differential pressure and the valve and process degradation effects, which should be factored into the valve and actuator design and sizing.Commonly, to compensate for not testing at process operating conditions, additional safety pressure/thrust/torque margin is added to the valve actuator and inferential performance testing is done utilizing baseline testing. Examples of these inferential tests are where the valve response time is timed, a smart positioner or digital valve controller is used to record a valve pressure/position curve or signature, or advance diagnostics are done during the proof test and compared with previous test results or baselines to detect valve performance degradation, indicating a potential incipient failure. Also, if tight shut off (TSO) is a requirement, simply stroking the valve will not test for leakage and a periodic valve leak test will have to be performed. ISA TR96.05.02 is intended to provide guidance on four different levels of testing of SIS valves and their typical proof test coverage, based on how the test is instrumented. People (particularly users) are encouraged to participate in the development of this technical report (contact crobinson@isa.org).Ambient temperatures can also affect valve friction loads, so that testing valves in warm weather will generally be the least demanding friction load when compared to cold weather operation. As a result, proof testing of valves at a consistent temperature should be considered to provide consistent data for inferential testing for the determination of valve performance degradation.Valves with smart positioners or a digital valve controller generally have capability to create a valve signature that can be used to monitor degradation in valve performance. A baseline valve signature can be requested as part of your purchase order or you can create one during the initial proof test to serve as a baseline. The valve signature should be done for both opening and closing of the valve. Advanced valve diagnostic should also be used if available. This can help tell you if your valve performance is deteriorating by comparing subsequent proof test valve signatures and diagnostics with your baseline. This type of test can help compensate for not testing the valve at worst case operating pressures.The valve signature during a proof test may also be able to record the response time with time stamps, removing the need for a stopwatch. Increased response time is a sign of valve deterioration and increased friction load to move the valve. While there are no standards regarding changes in valve response time, a negative pattern of changes from proof test to proof test is indicative of the potential loss of the valve’s safety margin and performance. Modern SIS valve proof testing should include a valve signature as a matter of good engineering practice.The valve instrument air supply pressure should be measured during a proof test. While the valve spring for a spring-return valve is what closes the valve, the force or torque involved is determined by how much the valve spring is compressed by the valve supply pressure (per Hooke’s Law, F = kX). If your supply pressure is low, the spring will not compress as much, hence less force will be available to move the valve when needed. While not inclusive, some of the things to consider in creating the valve portion of the proof test procedure are given in Table 2. Table 2: Final element valve assembly considerations Test valve safety action at process operating pressure (best but typically not done), and time the valve’s response time. Verify redundancy Test valve safety action at zero differential pressure and time valve’s response time. Verify redundancy Run valve signature and diagnostics as part of proof test and compare to baseline and previous test Visually observe valve action (proper action without unusual vibration or noise, etc.). Verify the valve field and position indication on the DCS Fully stroke the valve a minimum of five times during the proof test to help ensure valve reliability. (This is not intended to fix significant degradation effects or incipient failures). Review valve maintenance records to ensure any changes meet the required valve SRS specifications Test diagnostics for energize-to-trip systems Leak test if Tight Shut Off (TSO) is required Verify the command disagree alarm functionality Inspect valve assembly and internals Remove, test and rebuild as necessary Complete as-found and as-left documentation Solenoids Evaluate venting to provide required response time Evaluate solenoid performance by a digital valve controller or smart positioner Verify redundant solenoid performance (e.g. 1oo2, 2oo3) Interposing Relays Verify correct operation, redundancy Device inspection
SIF hangata e aroloa ka likarolo tse tharo tse kholo, li-sensor, li-logic solver le likarolo tsa ho qetela. Hangata ho na le lisebelisoa tse thusang tse ka amanang le karolo ka 'ngoe ea tsena tse tharo (mohlala, li-IS barriers, li-trip amps, li-interposing relay, li-solenoids, jj.) tseo le tsona li lokelang ho lekoa.
Liteko tsa ho thibela kutlo: Teko ea ho thibela kutlo e tlameha ho netefatsa hore sensor e khona ho utloa phetoho ea ts'ebetso ho pholletsa le sebaka sa eona se felletseng le ho fetisetsa lets'oao le nepahetseng ho tharollo ea logic ea SIS bakeng sa tlhahlobo. Leha e sa kenyeletse, tse ling tsa lintho tseo u lokelang ho li nahana ha u theha karolo ea sensor ea ts'ebetso ea teko ea bopaki li fanoe ho Tafole ea 1.
Teko ea ho netefatsa tharollo ea logic: Ha ho etsoa teko ea bopaki ba ts'ebetso e felletseng, karolo ea tharollo ea logic ho phetheng ketso ea polokeho ea SIF le liketso tse amanang le eona (mohlala, lialamo, ho seta bocha, ho palama li-passpasses, tlhahlobo ea basebelisi, ho fokotsa ts'ebetso, HMI, jj.) lia lekoa. Liteko tsa ho netefatsa ts'ebetso tse sa fellang kapa tse nyenyane li tlameha ho phethahatsa liteko tsena kaofela e le karolo ea liteko tse kopaneng tsa bopaki. Moetsi oa tharollo ea logic o lokela ho ba le ts'ebetso e khothaletsoang ea teko ea bopaki bukaneng ea polokeho ea sesebelisoa. Haeba ho se joalo le bonyane, matla a tharollo ea logic a lokela ho tsamaisoa ka potoloho, 'me lirejistara tsa tlhahlobo ea tharollo ea logic, mabone a boemo, li-voltage tsa phepelo ea motlakase, lihokelo tsa puisano le ho fokotsa ts'ebetso li lokela ho hlahlojoa. Liteko tsena li lokela ho etsoa pele ho teko ea bopaki ba ts'ebetso e felletseng.
O se ke wa nahana hore software e ntle ka ho sa feleng mme mohopolo ha o hloke ho lekoa kamora teko ya pele ya bopaki kaha diphetoho tsa software le hardware tse sa ngolwang, tse sa dumellwang le tse sa lekoang le dintlafatso tsa software di ka kenella ditsamaisong ha nako e ntse e ya mme di lokela ho kenyeletswa filosofing ya hao ya teko ya bopaki ka kakaretso. Tsamaiso ya di-log tsa phetoho, tlhokomelo le ntlafatso e lokela ho hlahlojwa ho netefatsa hore di nakong mme di hlokometswe hantle, mme haeba di kgona, lenaneo la kopo le lokela ho bapiswa le bekapo ya moraorao.
Hape ho lokela ho elwa hloko ho leka mesebetsi yohle e thusang le e hlahlobang ya tharollo ya logic ya mosebedisi (mohlala, dintja tse lebelang, dihokelo tsa puisano, disebediswa tsa tshireletso ya inthanete, jj.).
Teko ea ho qetela ea ho thibela likarolo: Bongata ba likarolo tsa ho qetela ke li-valve, leha ho le joalo, li-starter tsa li-motor tsa lisebelisoa tse potolohang, li-drive tsa lebelo le feto-fetohang le likarolo tse ling tsa motlakase tse kang li-contactor le li-circuit breaker le tsona li sebelisoa e le likarolo tsa ho qetela 'me mekhoa ea tsona ea ho hloleha e tlameha ho hlahlojoa le ho hlahlojoa ka bopaki.
Mekhoa ea mantlha ea ho hloleha ha li-valve e ntse e emisoa, nako ea karabelo e lieha haholo kapa e potlakile haholo, le ho lutla, tseo kaofela li angoang ke sebopeho sa ts'ebetso ea valve nakong ea leeto. Leha ho le joalo ho leka valve maemong a ts'ebetso ke nyeoe e lakatsehang ka ho fetisisa, Ts'ebetso ka kakaretso e tla hanyetsa ho khoptjoa ha SIF ha fektheri e ntse e sebetsa. Li-valve tse ngata tsa SIS hangata li lekoa ha fektheri e le tlase khatellong ea phapang ea lefela, e leng se sa hlokeng letho maemong a ts'ebetso. Mosebelisi o lokela ho tseba ka khatello e mpe ka ho fetisisa ea phapang ea ts'ebetso le litlamorao tsa ho senyeha ha valve le ts'ebetso, tse lokelang ho kenyelletsoa moralo le boholo ba valve le actuator.
Commonly, to compensate for not testing at process operating conditions, additional safety pressure/thrust/torque margin is added to the valve actuator and inferential performance testing is done utilizing baseline testing. Examples of these inferential tests are where the valve response time is timed, a smart positioner or digital valve controller is used to record a valve pressure/position curve or signature, or advance diagnostics are done during the proof test and compared with previous test results or baselines to detect valve performance degradation, indicating a potential incipient failure. Also, if tight shut off (TSO) is a requirement, simply stroking the valve will not test for leakage and a periodic valve leak test will have to be performed. ISA TR96.05.02 is intended to provide guidance on four different levels of testing of SIS valves and their typical proof test coverage, based on how the test is instrumented. People (particularly users) are encouraged to participate in the development of this technical report (contact crobinson@isa.org).
Lithempereichara tse sebakeng se mofuthu li ka boela tsa ama meroalo ea khohlano ea li-valve, hoo li-valve tsa liteko maemong a leholimo a futhumetseng ka kakaretso e tla ba mojaro o sa hlokeng ho feta oa khohlano ha li bapisoa le ts'ebetso ea boemo ba leholimo bo batang. Ka lebaka leo, tlhahlobo ea bopaki ea li-valve mochesong o tsitsitseng e lokela ho nahanoa ho fana ka lintlha tse tsitsitseng bakeng sa tlhahlobo ea ho nahana bakeng sa ho fumana ho senyeha ha ts'ebetso ea li-valve.
Li-valve tse nang le li-positioner tse bohlale kapa molaoli oa li-valve tsa dijithale hangata li na le bokhoni ba ho theha tshaeno ea valve e ka sebelisoang ho lekola ho senyeha ha ts'ebetso ea li-valve. Tshaeno ea valve ea motheo e ka kopuoa e le karolo ea odara ea hau ea theko kapa u ka e etsa nakong ea teko ea pele ea bopaki ho sebetsa e le motheo. Tshaeno ea valve e lokela ho etsoa bakeng sa ho buloa le ho koaloa ha valve. Tlhahlobo e tsoetseng pele ea li-valve le eona e lokela ho sebelisoa haeba e fumaneha. Sena se ka u thusa ho u joetsa hore na ts'ebetso ea li-valve ea hau e ntse e mpefala ka ho bapisa tshaeno ea li-valve tsa tlhahlobo ea bopaki le tlhahlobo le motheo oa hau. Mofuta ona oa teko o ka thusa ho lefella ho se leke valve ha ho lekoa khatello e mpe ka ho fetisisa ea ts'ebetso.
Tšhaeno ea valve nakong ea teko ea bopaki e ka boela ea khona ho rekota nako ea karabelo ka litempe tsa nako, e leng se tlosang tlhoko ea stopwatch. Nako e eketsehileng ea karabelo ke pontšo ea ho senyeha ha valve le mojaro o eketsehileng oa khohlano ho tsamaisa valve. Leha ho se na maemo a mabapi le liphetoho nakong ea karabelo ea valve, mokhoa o mobe oa liphetoho ho tloha tekong ea bopaki ho ea tekong ea bopaki o bontša tahlehelo e ka bang teng ea moeli oa polokeho ea valve le ts'ebetso. Teko ea sejoale-joale ea bopaki ba valve ea SIS e lokela ho kenyelletsa letšoao la valve e le taba ea mokhoa o motle oa boenjiniere.
Khatello ea moea ea sesebelisoa sa valve e lokela ho lekanyetsoa nakong ea teko ea bopaki. Le hoja selemo sa valve bakeng sa valve ea ho khutlisa selemo ke sona se koalang valve, matla kapa torque e amehang e khethoa ke hore na selemo sa valve se hatelloa hakae ke khatello ea phepelo ea valve (ho ea ka Molao oa Hooke, F = kX). Haeba khatello ea hau ea phepelo e le tlase, selemo se ke ke sa hatelloa haholo, ka hona matla a fokolang a tla fumaneha ho tsamaisa valve ha ho hlokahala. Le ha e sa kenyeletsoa, tse ling tsa lintho tseo u lokelang ho li nahana ha ho etsoa karolo ea valve ea ts'ebetso ea teko ea bopaki li fanoe ho Tafole ea 2.
Nako ea poso: Pulungoana-13-2019