Ukuhlolwa kobufakazi kuyingxenye ebalulekile yokugcinwa kobuqotho bokuphepha kwamasistimu ethu amathuluzi okuphepha (i-SIS) namasistimu ahlobene nokuphepha (isb. ama-alamu abalulekile, amasistimu omlilo nawegesi, amasistimu wokukhiya amathuluzi, njll.). Ukuhlolwa kobufakazi kuwukuhlola ezikhathini ezithile ukuze kutholwe ukwehluleka okuyingozi, ukuhlola ukusebenza okuhlobene nokuphepha (isb. ukusetha kabusha, ukudlula, ama-alamu, ukuxilongwa, ukuvala shaqa mathupha, njll.), kanye nokuqinisekisa ukuthi isistimu ihlangabezana nezindinganiso zenkampani nezangaphandle. Imiphumela yokuhlolwa kobufakazi nayo iyisilinganiso sokusebenza ngempumelelo kohlelo lobuqotho bemishini ye-SIS kanye nokwethenjwa kwensimu yesistimu.
Izinqubo zokuhlola ubufakazi zihlanganisa izinyathelo zokuhlola kusukela ekutholeni izimvume, ukwenza izaziso kanye nokukhipha isistimu emsebenzini ukuze ihlolwe ukuze kuqinisekiswe ukuhlolwa okuphelele, ukubhalwa kokuhlolwa kobufakazi nemiphumela yako, ukubuyisela isistimu emsebenzini, nokuhlola imiphumela yamanje yokuhlolwa kanye nobufakazi bangaphambilini. imiphumela yokuhlolwa.
I-ANSI/ISA/IEC 61511-1, Isigaba somthetho 16, sihlanganisa ukuhlolwa kobufakazi be-SIS. Umbiko wezobuchwepheshe we-ISA TR84.00.03 – “Mechanical Integrity of Safety Instrumented Systems (SIS),” uhlanganisa ukuhlolwa kobufakazi futhi okwamanje isabuyekezwa ngenguqulo entsha elindelwe ukuphuma maduze. Umbiko wezobuchwepheshe we-ISA TR96.05.02 – “In-situ Proof Testing of Automated Valves” okwamanje isathuthukiswa.
Umbiko we-UK HSE i-CRR 428/2002 - "Izimiso zokuhlola ubufakazi bezinhlelo zokuphepha ezisetshenziswa embonini yamakhemikhali" inikeza ulwazi mayelana nokuhlolwa kobufakazi kanye nalokho izinkampani ezikwenzayo e-UK.
Inqubo yokuhlola yokuqinisekisa isekelwe ekuhlaziyweni kwamamodi okuhluleka ayingozi aziwayo engxenyeni ngayinye yendlela yohambo yethuluzi lokuphepha (SIF), ukusebenza kwe-SIF njengesistimu, kanye nendlela (futhi uma) yokuhlola ukwehluleka okuyingozi. imodi. Ukuthuthukiswa kwenqubo kufanele kuqale esigabeni sokuklama kwe-SIF ngokuklanywa kwesistimu, ukukhethwa kwezingxenye, kanye nokunqunywa kokuthi kuhlolwa nini futhi kanjani. Amathuluzi e-SIS anamazinga ahlukahlukene obunzima bokuhlola ubufakazi okufanele bucatshangelwe ekwakhiweni kwe-SIF, ukusebenza nokunakekelwa. Isibonelo, amamitha we-orifice nama-pressure transmitters kulula ukuwahlola kune-Coriolis mass flowmeters, mag metres noma izinzwa zeleveli ye-radar yomoya. Uhlelo lokusebenza kanye nedizayini yevalvu nakho kungathinta ukuqonda kokuhlolwa kokuqinisekisa ama-valve ukuze kuqinisekiswe ukuthi ukwehluleka okuyingozi nokuqalayo ngenxa yokucekelwa phansi, ukuxhunywa noma ukwehluleka okuncike esikhathini akuholeli ekwehlulekeni okubalulekile phakathi nesikhawu sokuhlola esikhethiwe.
Nakuba izinqubo zokuhlola ubufakazi zivame ukuthuthukiswa phakathi nesigaba sobunjiniyela be-SIF, kufanele futhi zibuyekezwe isayithi le-SIS Technical Authority, Operations kanye nochwepheshe bezinsimbi abazobe benza ukuhlola. Ukuhlaziywa kokuphepha komsebenzi (JSA) kufanele futhi kwenziwe. Kubalulekile ukuthola ukuthi isitshalo sithenge ini ngokuthi yiziphi izivivinyo ezizokwenziwa futhi nini, kanye nokuba nokwenzeka kwazo ngokomzimba nokuphepha. Isibonelo, akusizi ukucacisa ukuhlola ingxenye ye-stroke lapho iqembu le-Operations lingeke livume ukukwenza. Kuphinde kunconywe ukuthi izinqubo zokuhlolwa kobufakazi zibuyekezwe uchwepheshe ozimele wendaba (i-SME). Ukuhlolwa okujwayelekile okudingekayo ukuze kuhlolwe ubufakazi bokusebenza okugcwele kuboniswe kuMfanekiso 1.
Izidingo ezigcwele zokuhlola ubufakazi bokusebenza Umfanekiso 1: Ukucaciswa okugcwele kokuhlolwa kobufakazi bokusebenza kwe-safety instrumented function (SIF) kanye nesistimu yayo ye-safety instrumented (SIS) kufanele kucacise noma kubhekisele ezinyathelweni ezilandelanayo kusukela kumalungiselelo okuhlola nezinqubo zokuhlola kuya kuzaziso nakumadokhumenti. .
Umfanekiso 1: Ukucaciswa okugcwele kokuhlolwa kobufakazi bokusebenza komsebenzi wethuluzi lokuphepha (SIF) kanye nesistimu yayo yensimbi yokuphepha (SIS) kufanele kucacise noma kubhekisele ezinyathelweni ezilandelanayo kusukela kumalungiselelo okuhlola nezinqubo zokuhlola kuya kuzaziso nakumadokhumenti.
Ukuhlola ubufakazi kuyisenzo sokunakekela esihleliwe okufanele senziwe izisebenzi ezinekhono eziqeqeshwe ekuhloleni kwe-SIS, inqubo yobufakazi, namaluphu e-SIS azowahlola. Kufanele kube nokuhamba kwenqubo ngaphambi kokwenza ukuhlolwa kobufakazi bokuqala, kanye nempendulo kusayithi le-SIS Technical Authority kamuva ukuze kuthuthukiswe noma kulungiswe.
Kunezindlela ezimbili zokuhluleka eziyinhloko (eziphephile noma eziyingozi), ezihlukaniswe ngezigaba ezine-eziyingozi ezingabonwa, ezitholwe eziyingozi (ngokuhlola), eziphephile zingabonwa futhi zitholakale ziphephile. Amagama okuhluleka ayingozi futhi ayingozi angabonwa asetshenziswa ngokushintshana kulesi sihloko.
Ekuhlolweni kobufakazi be-SIF, sinentshisekelo ngokuyinhloko ezindleleni eziyingozi zokuhluleka ezingabonwa, kodwa uma kukhona ukuxilonga komsebenzisi okuthola ukwehluleka okuyingozi, lokhu kuxilongwa kufanele kuhlolwe ubufakazi. Qaphela ukuthi ngokungafani nokuxilongwa komsebenzisi, ukuhlola kwangaphakathi kwedivayisi ngokuvamile akukwazi ukuqinisekiswa njengokusebenza komsebenzisi, futhi lokhu kungase kube nomthelela kufilosofi yokuhlola kobufakazi. Uma ikhredithi yokuxilonga ithathwa ezibalweni ze-SIL, ama-alamu okuxilonga (isb. ama-alamu angaphandle kwebanga) kufanele ahlolwe njengengxenye yokuhlola kobufakazi.
Izindlela zokwehluleka zingahlukaniswa zibe yilezo ezihlolelwe ngesikhathi sokuhlolwa kobufakazi, lezo ezingahlolelwanga, kanye nokwehluleka kwesiqalo noma ukwehluleka okuncike esikhathini. Amanye amamodi okuhluleka ayingozi angeke ahlolwe ngokuqondile ngenxa yezizathu ezehlukene (isb. ubunzima, ubunjiniyela noma isinqumo sokusebenza, ukungazi, ukungakwazi, ukweqiwa noma ukwenza amaphutha esistimu, amathuba amancane okwenzeka, njll.). Uma kukhona amamodi okuhluleka aziwayo angeke ahlolelwe, isinxephezelo kufanele senziwe ekwakhiweni kwedivayisi, inqubo yokuhlola, ukushintshwa kwedivayisi ngezikhathi ezithile noma ukwakha kabusha, kanye/noma ukuhlola okungenangqondo kufanele kwenziwe ukuze kuncishiswe umphumela wobuqotho be-SIF bokungahloli.
Ukwehluleka kokuqala yisimo esilulazayo noma isimo esingangokuthi ukwehluleka okubucayi, okuyingozi kungalindelwa ngokuphusile ukuthi kwenzeke uma izinyathelo zokulungisa zingenziwanga ngesikhathi. Ngokuvamile zitholwa ngokuqhathanisa ukusebenza nokuhlola kwakamuva noma kokuqala kobufakazi bebhentshimakhi (isb. amasiginesha evalvu noma izikhathi zokuphendula amavalvu) noma ngokuhlola (isb. imbobo yenqubo exhunyiwe). Ukwehluleka kokuqala kuvame ukuncika esikhathini—uma idivayisi noma ukuhlanganisa kunesikhathi eside kusevisi, kuyancipha kakhulu; izimo ezisiza ukwehluleka okungahleliwe ziba maningi amathuba okuba, kucubungula ukuxhuma kwembobo noma ukwakheka kwenzwa ngokuhamba kwesikhathi, impilo yokusebenziseka isiphelile, njll. Ngakho-ke, uma isikhathi sokuhlola sobufakazi siba side, maningi amathuba okuba kube nokwehluleka kokuqala noma okuncike esikhathini. Noma yikuphi ukuvikela ekuhlulekeni kwe-incipie kufanele futhi kuhlolwe ubufakazi (ukuhlanzwa kwechweba, ukulandelwa kokushisa, njll.).
Izinqubo kufanele zibhalwe ukuze kuhlolwe ubufakazi bokwehluleka okuyingozi (okungabonwa). Imodi yokwehluleka nokuhlaziywa komphumela (i-FMEA) noma imodi yokwehluleka, amasu okuhlaziya umphumela kanye nokuxilonga (i-FMEDA) angasiza ekuhlonzeni ukwehluleka okuyingozi okungabonwa, nalapho ukufakwa kokuhlola kobufakazi kufanele kuthuthukiswe.
Izinqubo eziningi zokuhlola ubufakazi zibhaliwe ekuhlangenwe nakho okusekelwe nezifanekiso ezivela ezinqubweni ezikhona. Izinqubo ezintsha kanye nama-SIF ayinkimbinkimbi adinga indlela enobunjiniyela kakhudlwana kusetshenziswa i-FMEA/FMEDA ukuze kuhlaziywe ukwehluleka okuyingozi, kunqume ukuthi inqubo yokuhlola izohlola kanjani noma ngeke ihlole kanjani lokho kwehluleka, kanye nokufakwa kwezivivinyo. Umdwebo webhulokhi yokuhlaziywa kwemodi yokwehluleka kweleveli enkulu yenzwa uboniswa kuMfanekiso 2. I-FMEA ngokuvamile idinga ukwenziwa kanye kuphela ohlotsheni oluthile lwedivayisi futhi iphinde isetshenziselwe amadivayisi afanayo ngokucabangela isevisi yawo yenqubo, ukufakwa kanye namandla okuhlola isayithi. .
Ukuhlaziywa kokwehluleka kwezinga elikhulu Umfanekiso 2: Lo mdwebo webhulokhi yokuhlaziya ukwehluleka kweleveli enkulu yenzwa ne-pressure transmitter (PT) ukhombisa imisebenzi emikhulu ezohlukaniswa ibe uhlaziyo lokuhluleka okuncane ukuze kuchazwe ngokugcwele ukwehluleka okungase kusingathwe. ekuhlolweni komsebenzi.
Umfanekiso 2: Lo mdwebo webhulokhi yokuhlaziywa kwemodi yokwehluleka kweleveli enkulu yenzwa ne-pressure transmitter (PT) ubonisa imisebenzi emikhulu ezohlukaniswa ibe ukuhlaziya kokuhluleka okuncane okuningi ukuze kuchazwe ngokugcwele ukwehluleka okungaba khona okuzobhekwana nakho ekuhlolweni komsebenzi.
Amaphesenti okwehluleka okwaziwayo, okuyingozi, okungakabonakali okuhloliwe kubizwa ngokuthi i-proof test coverage (PTC). I-PTC ivamise ukusetshenziswa ezibalweni ze-SIL “ukunxephezela” ngokwehluleka ukuhlola ngokugcwele i-SIF. Abantu banenkolelo eyiphutha yokuthi ngenxa yokuthi bacabangele ukushoda kokuhlolwa ekubaleni kwabo kwe-SIL, baklame i-SIF ethembekile. Iqiniso elimsulwa liwukuthi, uma ukuhlolwa kwakho kungama-75%, futhi uma ulinganise leyo nombolo ekubaleni kwakho kwe-SIL futhi uhlola izinto osuvele uzihlola kaningi, u-25% wokwehluleka okuyingozi kusengenzeka ngokwezibalo. Impela angifuni ukuba kulowo 25%.
Imibiko yokugunyazwa kwe-FMEDA kanye namamanuwali okuphepha kumadivayisi ngokuvamile ahlinzeka ngenqubo yokuhlola ubufakazi obuncane kanye nokufakwa kobufakazi bokuhlola. Lokhu kunikeza isiqondiso kuphela, akuzona zonke izinyathelo zokuhlola ezidingekayo ukuze kwenziwe inqubo yokuhlola ubufakazi obuphelele. Ezinye izinhlobo zokuhlaziya ukwehluleka, njengokuhlaziywa kwesihlahla esinephutha kanye nokunakekelwa okugxile ekuthembekeni, nazo zisetshenziselwa ukuhlaziya ukwehluleka okuyingozi.
Ukuhlolwa kobufakazi kungahlukaniswa ngokusebenza okugcwele (ekupheleni kuya ekupheleni) noma ukuhlola okuyingxenye (Umfanekiso 3). Ukuhlola ukusebenza kancane kuvamise ukwenziwa lapho izingxenye ze-SIF zinezikhathi zokuhlola ezihlukile ezibalweni ze-SIL ezingahambelani nokuvalwa okuhleliwe noma ukuguqulwa. Kubalulekile ukuthi izinqubo zokuhlola ubufakazi obungaphelele zidlulelane ukuze zihlole konke ukusebenza kokuphepha kwe-SIF. Ngokuhlolwa kokusebenza okuyingxenye, kusanconywa ukuthi i-SIF ibe nokuhlola kobufakazi bokuphela kokuphela, kanye nokulandelayo ngesikhathi sokuguqulwa.
Ukuhlolwa kobufakazi obuncane kufanele kuhlanganise Umfanekiso 3: Ukuhlolwa kobufakazi obuyingxenye okuhlanganisiwe (phansi) kufanele kufake yonke imisebenzi yokuhlolwa kobufakazi obusebenza ngokugcwele (phezulu).
Umfanekiso 3: Ukuhlolwa kobufakazi obuhlangene obuyingxenye (phansi) kufanele kufake yonke imisebenzi yokuhlolwa okugcwele kobufakazi (phezulu).
Ukuhlolwa kobufakazi obungaphelele kuhlola kuphela amaphesenti amamodi okuhluleka kwedivayisi. Isibonelo esivamile ukuhlola i-valve ye-stroke, lapho i-valve ihanjiswa khona inani elincane (10-20%) ukuze kuqinisekiswe ukuthi ayibambekile. Lokhu kunokufakwa kokuhlolwa kobufakazi obuphansi kunokuhlola kobufakazi ngesikhathi sokuhlolwa okuyisisekelo.
Izinqubo zokuhlola ubufakazi zingahlukahluka ngobunkimbinkimbi be-SIF kanye nefilosofi yenqubo yokuhlola yenkampani. Ezinye izinkampani zibhala izinqubo zokuhlola ezinemininingwane yesinyathelo nesinyathelo, kanti ezinye zinezinqubo ezimfushane. Ukubhekisela kwezinye izinqubo, njengokulinganisa okujwayelekile, ngezinye izikhathi kusetshenziswa ukunciphisa usayizi wenqubo yokuhlola ubufakazi nokusiza ukuqinisekisa ukuvumelana ekuhloleni. Inqubo yokuhlola ubufakazi obuhle kufanele inikeze imininingwane eyanele ukuze kuqinisekiswe ukuthi konke ukuhlola kufezwa kahle futhi kubhalwe phansi, kodwa hhayi imininingwane eminingi ukuze ibangele ochwepheshe bafune ukweqa izinyathelo. Ukuba nochwepheshe, onesibopho sokwenza isinyathelo sokuhlola, ukuqala kwesinyathelo sokuhlola esiqediwe kungasiza ekuqinisekiseni ukuthi ukuhlolwa kuzokwenziwa ngendlela efanele. Ukusayinwa kokuhlolwa kobufakazi obuqediwe yi-Instrument Supervisor kanye nabamele Imisebenzi nakho kuzogcizelela ukubaluleka futhi kuqinisekise ukuhlolwa kobufakazi obugcwaliswe kahle.
Impendulo yochwepheshe kufanele njalo imenywe ukusiza ukuthuthukisa inqubo. Impumelelo yenqubo yokuhlola ubufakazi ilele engxenyeni enkulu ezandleni zikachwepheshe, ngakho umzamo wokubambisana unconywa kakhulu.
Ukuhlolwa kobufakazi obuningi ngokuvamile kwenziwa ungaxhunyiwe ku-inthanethi ngesikhathi sokuvalwa noma ukuguqula. Kwezinye izimo, ukuhlolwa kobufakazi kungase kudingeke ukuthi kwenziwe ku-inthanethi ngenkathi kuqaliswa ukwanelisa izibalo ze-SIL noma ezinye izidingo. Ukuhlola ku-inthanethi kudinga ukuhlela nokuxhumana ne-Operations ukuvumela ukuhlolwa kobufakazi ukuthi kwenziwe ngokuphepha, ngaphandle kwenqubo ecasuliwe, futhi ngaphandle kokubangela uhambo oluyinkohliso. Kuthatha uhambo olulodwa kuphela lokusebenzisa wonke ama-attaboys akho. Phakathi nalolu hlobo lokuhlola, lapho i-SIF ingatholakali ngokugcwele ukwenza umsebenzi wayo wokuphepha, 61511-1, Isigaba somthetho 11.8.5, sithi “Izinyathelo zokunxephezela eziqinisekisa ukuqhubeka nokusebenza okuphephile zizohlinzekwa ngokuhambisana no-11.3 uma i-SIS ingaphakathi. bypass (ukulungisa noma ukuhlola).” Inqubo yokulawula isimo esingajwayelekile kufanele ihambisane nenqubo yokuhlola ubufakazi ukuze kuqinisekiswe ukuthi lokhu kwenziwa ngendlela efanele.
I-SIF ivamise ukuhlukaniswa ibe izingxenye ezintathu eziyinhloko: izinzwa, izixazululi ezinengqondo nezinto zokugcina. Kukhona futhi izisetshenziswa ezisizayo ezingahlotshaniswa ngaphakathi kwengxenye ngayinye kulezi zintathu (isb. Izithiyo ze-IS, ama-trip amps, ama-interposing relay, ama-solenoid, njll.) okumele nazo zihlolwe. Izici ezibalulekile zokuhlola ubufakazi ngakunye kwalokhu buchwepheshe kungase kutholakale kubha eseceleni, “Izinzwa zokuhlola, izixazululi ezinengqondo nezinto zokugcina” (ngezansi).
Ezinye izinto zilula ukufakazela ukuhlolwa kunezinye. Ubuchwepheshe obuningi besimanje kanye nobudala obuncane bokugeleza kanye neleveli busesigabeni esinzima kakhulu. Lokhu kufaka phakathi ama-flowmeters e-Coriolis, ama-vortex metres, ama-mag metres, i-radar yomoya, izinga le-ultrasonic, kanye namaswishi enqubo ye-in-situ, ukubala okumbalwa. Ngenhlanhla, eziningi zalezi manje sezinokuxilongwa okuthuthukisiwe okuvumela ukuhlolwa okuthuthukisiwe.
Ubunzima bokuhlola ubufakazi bomshini onjalo endaweni kufanele bucatshangelwe ekwakhiweni kwe-SIF. Kulula konjiniyela ukukhetha amadivayisi e-SIF ngaphandle kokucabangisisa ngalokho okungadingeka ukuze kuhlolwe idivayisi, njengoba ngeke kube abantu abawahlolayo. Lokhu kuyiqiniso futhi ngokuhlolwa kwengxenye yokushaywa unhlangothi, okuyindlela evamile yokuthuthukisa amathuba amaphakathi e-SIF okwehluleka uma kudingeka (PFDavg), kodwa kamuva endaweni yesikhungo Imisebenzi ayifuni ukukwenza, futhi izikhathi eziningi ingase ingakwenzi. Hlala njalo uhlinzeka ngokugada kwezitshalo kobunjiniyela bama-SIF ngokuphathelene nokuhlolwa kobufakazi.
Ukuhlolwa kobufakazi kufanele kuhlanganise nokuhlolwa kokufakwa nokulungiswa kwe-SIF njengoba kudingeka ukuze kuhlangatshezwane no-61511-1, Isigaba somthetho 16.3.2. Kufanele kube nokuhlolwa kokugcina ukuze kuqinisekiswe ukuthi yonke into ifakwe izinkinobho, futhi kuhlolwe kabili ukuthi i-SIF ibuyiselwe ngendlela efanele kusevisi yenqubo.
Ukubhala nokusebenzisa inqubo yokuhlola enhle kuyisinyathelo esibalulekile sokuqinisekisa ubuqotho be-SIF phakathi nokuphila kwayo konke. Inqubo yokuhlola kufanele inikeze imininingwane eyanele ukuze kuqinisekiswe ukuthi ukuhlolwa okudingekile kwenziwa ngokungaguquki nangokuphepha futhi kubhalwe phansi. Ukwehluleka okuyingozi okungahloliwe ukuhlolwa kobufakazi kufanele kunxeshezelwe ukuze kuqinisekiswe ukuthi ubuqotho bokuphepha be-SIF bugcinwa ngokwanele phakathi nokuphila kwayo.
Ukubhala inqubo yokuhlola ubufakazi obuhle kudinga indlela enengqondo yokuhlaziya ubunjiniyela bokuhluleka okungaba yingozi, ukukhetha izindlela, kanye nokubhala izinyathelo zokuhlola zobufakazi ezingaphakathi kwamandla okuhlola emboni. Endleleni, thola ukuthengwa kwezitshalo kuwo wonke amazinga ukuze zihlolwe, futhi uqeqeshe ochwepheshe ukuthi benze futhi babhale phansi ukuhlolwa kobufakazi kanye nokuqonda ukubaluleka kokuhlolwa. Bhala imiyalelo kube sengathi unguchwepheshe wezinsimbi okuzodingeka enze umsebenzi, futhi lokho ukuphila kuncike ekutholeni ukuhlolwa okufanele, ngoba bayakwenza.
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
I-SIF ivamise ukuhlukaniswa izingxenye ezintathu eziyinhloko, izinzwa, izixazululi ezinengqondo nezinto zokugcina. Kukhona futhi izisetshenziswa ezisizayo ezingahlotshaniswa ngaphakathi kwalezi zingxenye ezintathu (isb. Izithiyo ze-IS, ama-trip amps, ama-interposing relay, ama-solenoid, njll.) okumele nazo zihlolwe.
Ukuhlolwa kobufakazi benzwa: Ukuhlolwa kobufakazi benzwa kufanele kuqinisekise ukuthi inzwa ikwazi ukuzwa ukuhlukahluka kwenqubo phezu kobubanzi bayo obugcwele futhi idlulisele isignali efanele kusixazululi se-SIS esinengqondo ukuze sihlolwe. Nakuba zingabandakanyi, ezinye zezinto okufanele zicatshangelwe ekudaleni ingxenye yenzwa yenqubo yokuhlola ubufakazi inikezwe kuThebula 1.
Ukuhlolwa kobufakazi bokulungisa okunengqondo: Uma ukuhlolwa kobufakazi obugcwele kwenziwa, ingxenye yesixazululi esinengqondo ekufezeni isenzo sokuphepha se-SIF nezenzo ezihlobene (isb. ama-alamu, ukusetha kabusha, ama-bypass, ukuxilonga komsebenzisi, ukungafuneki, i-HMI, njll.) kuyahlolwa. Ukuhlolwa kobufakazi bokusebenza ingxenye noma ingxenye encane kufanele kufeze zonke lezi zivivinyo njengengxenye yokuhlolwa kobufakazi obudlulele. Umkhiqizi we-logic solver kufanele abe nenqubo yokuhlola yobufakazi enconyiwe kumanuwali wokuphepha wedivayisi. Uma kungenjalo futhi okungenani, amandla esixazululi esinengqondo kufanele ajikelezwe, futhi amarejista okuxilonga isixazululi se-logic, izibani zesimo, ama-voltage okunikezwa kwamandla kagesi, izixhumanisi zokuxhumana kanye nokungasasebenzi kufanele kuhlolwe. Lokhu kuhlola kufanele kwenziwe ngaphambi kokuhlolwa kobufakazi obugcwele.
Ungacabangi ukuthi isofthiwe yinhle kuze kube phakade futhi ingqondo akufanele ihlolwe ngemva kokuhlolwa kobufakazi bokuqala njengesofthiwe engabhaliwe, engagunyaziwe futhi engahloliwe kanye nezinguquko ze-hardware kanye nezibuyekezo zesofthiwe zingangena ohlelweni ngokuhamba kwesikhathi futhi kufanele zifakwe kuhlelo lwakho lonke. ifilosofi yokuhlola ubufakazi. Ukuphathwa koshintsho, ukugcinwa, nokubuyekezwa kwamalogu kufanele abuyekezwe ukuze kuqinisekiswe ukuthi asesikhathini futhi agcinwa kahle, futhi uma ekwazi, uhlelo lohlelo lokusebenza kufanele luqhathaniswe nesipele sakamuva.
Kufanele futhi kuqashelwe ukuze kuhlolwe yonke imisebenzi ewusizo yesixazululi se-logic yomsebenzisi neyokuhlola (isb. izinja eziqaphayo, izixhumanisi zokuxhumana, izinto zikagesi ze-cybersecurity, njll.).
Ukuhlolwa kobufakazi besici sokugcina: Izakhi eziningi zokugcina ama-valve, nokho, iziqalisi zemishini ezungezayo, amadrayivu ashintshashintshayo kanye nezinye izakhi zikagesi njengezixhumi nama-circuit breaker nazo zisetshenziswa njengezinto zokugcina futhi izindlela zokuhluleka kwazo kufanele zihlaziywe futhi kuhlolwe ubufakazi.
Izindlela eziyinhloko zokuhluleka kwamavalvu ziyabambeka, isikhathi sokuphendula sihamba kancane kakhulu noma sishesha kakhulu, nokuvuza, konke okuthintwa ukusebenzelana kwenqubo yokusebenza kwamavalvu ngesikhathi sohambo. Nakuba ukuhlola i-valve ezimeni zokusebenza kuyisimo esifiseleka kakhulu, Ukusebenza ngokuvamile kuzophikisana nokukhubeka i-SIF ngenkathi isikhungo sisebenza. Amavalvu amaningi e-SIS ngokuvamile ayahlolwa ngenkathi isitshalo singaphansi kokucindezela okungafani, okuyizimo zokusebenza ezingadingeki kakhulu. Umsebenzisi kufanele aqaphele ingcindezi embi kakhulu yokusebenza ehlukile kanye ne-valve nemiphumela yokuwohloka kwenqubo, okufanele ifakwe ku-valve ne-actuator design kanye nosayizi.
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).
Amazinga okushisa e-ambient angaphinda athinte imithwalo yokushayisana kwama-valve, ukuze ama-valve okuhlola esimweni sezulu esifudumele ngokuvamile abe umthwalo wokungqubuzana ongafuni kakhulu uma uqhathaniswa nokusebenza kwesimo sezulu esibandayo. Ngenxa yalokho, ukuhlolwa kobufakazi bama-valve ekushiseni okungaguquguquki kufanele kucatshangelwe ukunikeza idatha engaguquki yokuhlolwa kwe-inferential ukuze kunqunywe ukuwohloka kokusebenza kwama-valve.
Amavaluvu anezindawo ezihlakaniphile noma isilawuli se-valve yedijithali ngokuvamile anekhono lokudala isiginesha yamavalvu engasetshenziswa ukuqapha ukuwohloka ekusebenzeni kwamavalvu. Isiginesha yevalvu eyisisekelo ingacelwa njengengxenye ye-oda lakho lokuthenga noma ungadala elilodwa ngesikhathi sokuhlolwa kobufakazi bokuqala ukuze lisebenze njengesisekelo. Isignesha ye-valve kufanele yenziwe kokubili ukuvula nokuvala i-valve. Ukuxilongwa kwe-valve okuthuthukisiwe kufanele futhi kusetshenziswe uma kukhona. Lokhu kungakusiza ukukutshela ukuthi ukusebenza kwe-valve yakho kuyawohloka ngokuqhathanisa amasignesha alandelayo e-valve yokuhlola kanye nokuxilongwa nesisekelo sakho. Lolu hlobo lokuhlola lungasiza ukunxephezela ukungahloli i-valve ezimweni ezimbi kakhulu zokucindezela kokusebenza.
Isiginesha yevalvu ngesikhathi sokuhlolwa kobufakazi ingase futhi ikwazi ukurekhoda isikhathi sokuphendula ngezitembu zesikhathi, isuse isidingo sesitophuwashi. Ukwenyuka kwesikhathi sokuphendula kuwuphawu lokuwohloka kwe-valve nokwanda komthwalo wokungqubuzana ukuze uhambise i-valve. Nakuba zingekho izindinganiso eziphathelene nezinguquko zesikhathi sokuphendula i-valve, iphethini engeyinhle yezinguquko kusukela ekuhlolweni kobufakazi kuya ekuhlolweni kobufakazi kubonisa ukulahlekelwa okungase kube khona komkhawulo wokuphepha nokusebenza kwe-valve. Ukuhlolwa kobufakazi bevalvu ye-SIS yesimanje kufanele kufake isiginesha yevalvu njengendaba yokusebenza okuhle kobunjiniyela.
Umfutho wokunikezwa komoya wensimbi yevalvu kufanele ulinganiswe ngesikhathi sokuhlolwa kobufakazi. Nakuba i-valve spring yevalve yokubuyisela entwasahlobo kuyilokho okuvala i-valve, amandla noma i-torque ehilelekile inqunywa ukuthi isiphethu se-valve sicindezelwa kangakanani ukucindezela kokunikezwa kwamavalvu (ngoMthetho kaHooke, F = kX). Uma ingcindezi yakho yokuhlinzeka iphansi, isiphethu ngeke siminyanise kakhulu, ngakho-ke amandla amancane azotholakala ukuhambisa i-valve lapho kudingeka. Nakuba zingabandakanyi, ezinye zezinto okufanele zicatshangelwe ekudaleni ingxenye yevalvu yenqubo yokuhlola ubufakazi zinikezwe kuThebula 2.
Isikhathi sokuthumela: Nov-13-2019
