Kev kuaj pov thawj yog ib feem tseem ceeb ntawm kev tswj hwm kev ruaj ntseg ntawm peb cov txheej txheem kev nyab xeeb (SIS) thiab cov txheej txheem kev nyab xeeb (piv txwv li lub tswb ceeb toom tseem ceeb, hluav taws thiab roj systems, instrumented interlock systems, thiab lwm yam). Kev kuaj pov thawj yog kev kuaj xyuas tsis tu ncua los nrhiav kev ua tsis tiav txaus ntshai, kuaj kev ua haujlwm ntsig txog kev nyab xeeb (piv txwv li rov pib dua, bypasses, alarms, diagnostics, manual shutdown, thiab lwm yam), thiab xyuas kom meej tias lub kaw lus ua tau raws li lub tuam txhab thiab cov qauv sab nraud. Cov txiaj ntsig ntawm kev kuaj pov thawj kuj yog qhov ntsuas ntawm qhov ua tau zoo ntawm SIS mechanical integrity program thiab kev ntseeg tau ntawm lub kaw lus.
Cov txheej txheem kuaj pov thawj suav nrog cov kauj ruam kuaj los ntawm kev tau txais daim ntawv tso cai, ua kev ceeb toom thiab tshem tawm lub kaw lus tsis pub siv rau kev kuaj mus rau kev ua kom muaj kev kuaj xyuas tiav, sau cov ntaub ntawv kuaj pov thawj thiab nws cov txiaj ntsig, muab lub kaw lus rov qab siv tau, thiab soj ntsuam cov txiaj ntsig kuaj tam sim no thiab cov txiaj ntsig kuaj pov thawj yav dhau los.
ANSI/ISA/IEC 61511-1, Kab Lus 16, hais txog kev sim pov thawj SIS. Daim ntawv qhia txog kev siv ISA TR84.00.03 – “Kev Ncaj Ncees ntawm Cov Txheej Txheem Kev Nyab Xeeb (SIS),” hais txog kev sim pov thawj thiab tam sim no tab tom kho dua tshiab nrog rau qhov version tshiab uas yuav tawm sai sai no. Daim ntawv qhia txog kev siv ISA TR96.05.02 – “Kev Sim Pov Thawj Hauv Qhov Chaw Ntawm Cov Valve Uas Tsis Siv Neeg” tam sim no tab tom tsim kho.
Daim ntawv qhia txog UK HSE CRR 428/2002 - "Cov Ntsiab Cai rau kev sim ua pov thawj ntawm cov txheej txheem kev nyab xeeb hauv kev lag luam tshuaj lom neeg" muab cov ntaub ntawv hais txog kev sim ua pov thawj thiab cov tuam txhab ua dab tsi hauv UK.
Ib qho txheej txheem kuaj pov thawj yog raws li kev tshuaj xyuas ntawm cov hom kev ua tsis tiav txaus ntshai rau txhua yam khoom hauv txoj kev taug kev ntawm kev nyab xeeb (SIF), kev ua haujlwm ntawm SIF ua ib lub kaw lus, thiab yuav ua li cas (thiab yog tias) los kuaj rau hom kev ua tsis tiav txaus ntshai. Kev tsim cov txheej txheem yuav tsum pib hauv theem tsim SIF nrog kev tsim qauv, kev xaiv cov khoom, thiab kev txiav txim siab thaum twg thiab yuav ua li cas los kuaj pov thawj. Cov cuab yeej SIS muaj ntau qib ntawm qhov nyuaj ntawm kev kuaj pov thawj uas yuav tsum tau xav txog hauv kev tsim SIF, kev ua haujlwm thiab kev saib xyuas. Piv txwv li, cov ntsuas qhov orifice thiab cov khoom xa tawm siab yooj yim dua los kuaj dua li Coriolis cov ntsuas dej ntws, cov ntsuas mag lossis cov ntsuas qib radar los ntawm huab cua. Daim ntawv thov thiab kev tsim lub valve kuj tseem tuaj yeem cuam tshuam rau qhov kev ua tiav ntawm kev kuaj lub valve kom ntseeg tau tias qhov ua tsis tiav txaus ntshai thiab pib ua tsis tiav vim kev puas tsuaj, kev ntsaws lossis kev ua tsis tiav raws sijhawm tsis ua rau muaj kev ua tsis tiav loj hauv lub sijhawm kuaj xaiv.
Txawm hais tias cov txheej txheem kuaj pov thawj feem ntau yog tsim thaum lub sijhawm SIF engineering, lawv kuj yuav tsum tau saib xyuas los ntawm lub chaw SIS Technical Authority, Operations thiab cov kws kho cov cuab yeej uas yuav ua qhov kev sim. Yuav tsum tau ua ib qho kev tshuaj xyuas kev nyab xeeb ntawm txoj haujlwm (JSA). Nws yog ib qho tseem ceeb kom tau txais kev pom zoo ntawm lub Hoobkas txog qhov kev sim twg yuav ua thiab thaum twg, thiab lawv qhov ua tau ntawm lub cev thiab kev nyab xeeb. Piv txwv li, nws tsis zoo los qhia meej txog kev sim ib nrab thaum pawg Operations tsis pom zoo ua nws. Nws kuj tseem pom zoo kom cov txheej txheem kuaj pov thawj yuav tsum tau saib xyuas los ntawm tus kws tshaj lij ywj pheej (SME). Kev sim ib txwm xav tau rau kev sim pov thawj tag nrho tau piav qhia hauv Daim Duab 1.
Cov kev cai xeem ua pov thawj tag nrho Daim duab 1: Cov lus qhia txog kev xeem ua pov thawj tag nrho rau kev ua haujlwm ntsuas kev nyab xeeb (SIF) thiab nws lub kaw lus ntsuas kev nyab xeeb (SIS) yuav tsum sau lossis xa mus rau cov kauj ruam ua ntu zus los ntawm kev npaj xeem thiab cov txheej txheem xeem mus rau kev ceeb toom thiab cov ntaub ntawv.
Daim Duab 1: Cov lus qhia txog kev sim ua haujlwm tag nrho rau kev ua haujlwm ntsuas kev nyab xeeb (SIF) thiab nws lub kaw lus ntsuas kev nyab xeeb (SIS) yuav tsum sau lossis xa mus rau cov kauj ruam ua ntu zus los ntawm kev npaj xeem thiab cov txheej txheem xeem mus rau kev ceeb toom thiab cov ntaub ntawv.
Kev kuaj pov thawj yog ib qho kev npaj kho uas yuav tsum tau ua los ntawm cov neeg ua haujlwm txawj ntse uas tau kawm txog kev kuaj SIS, cov txheej txheem pov thawj, thiab cov voj voog SIS uas lawv yuav kuaj. Yuav tsum muaj kev qhia txog cov txheej txheem ua ntej ua qhov kev kuaj pov thawj thawj zaug, thiab xa rov qab rau SIS Technical Authority tom qab ntawd kom txhim kho lossis kho.
Muaj ob hom kev ua tsis tiav tseem ceeb (muaj kev nyab xeeb lossis txaus ntshai), uas muab faib ua plaub hom—txaus ntshai tsis pom, txaus ntshai pom (los ntawm kev kuaj mob), muaj kev nyab xeeb tsis pom thiab muaj kev nyab xeeb pom. Cov lus txaus ntshai thiab cov lus txaus ntshai tsis pom kev siv tau siv hloov pauv hauv tsab xov xwm no.
Hauv kev sim ua pov thawj SIF, peb feem ntau xav paub txog cov hom kev ua tsis tiav uas tsis tau pom, tab sis yog tias muaj cov neeg siv kuaj mob uas pom cov kev ua tsis tiav uas txaus ntshai, cov kev kuaj mob no yuav tsum tau kuaj ua pov thawj. Nco ntsoov tias tsis zoo li cov neeg siv kuaj mob, cov kev kuaj mob sab hauv ntawm lub cuab yeej feem ntau tsis tuaj yeem lees paub tias ua haujlwm tau los ntawm tus neeg siv, thiab qhov no tuaj yeem cuam tshuam rau lub tswv yim ntawm kev sim ua pov thawj. Thaum muab qhab nia rau kev kuaj mob hauv kev suav SIL, cov tswb ceeb toom kuaj mob (piv txwv li cov tswb ceeb toom sab nraud) yuav tsum tau kuaj ua ib feem ntawm kev sim ua pov thawj.
Cov hom kev ua tsis tiav muaj peev xwm muab faib ua cov uas tau sim thaum lub sijhawm sim ua pov thawj, cov uas tsis tau sim, thiab cov uas pib ua tsis tiav lossis cov uas nyob ntawm lub sijhawm. Qee hom kev ua tsis tiav txaus ntshai yuav tsis raug sim ncaj qha rau ntau yam laj thawj (piv txwv li qhov nyuaj, kev txiav txim siab txog kev tsim vaj tsev lossis kev ua haujlwm, kev tsis paub, kev tsis muaj peev xwm, kev tsis ua tiav lossis kev ua yuam kev tsis tu ncua, qhov muaj feem yuav tshwm sim tsawg, thiab lwm yam). Yog tias muaj cov hom kev ua tsis tiav uas paub tias yuav tsis raug sim, yuav tsum tau them nyiaj rau kev tsim khoom siv, cov txheej txheem sim, kev hloov khoom siv lossis kev tsim kho dua tshiab, thiab/lossis kev sim ua ntej yuav tsum tau ua kom txo qhov cuam tshuam rau kev ncaj ncees ntawm SIF ntawm kev tsis sim.
Kev ua tsis tiav thaum pib yog ib qho xwm txheej lossis ib qho xwm txheej uas ua rau muaj kev ua tsis tiav loj heev, txaus ntshai yog tias tsis ua raws li lub sijhawm. Feem ntau lawv raug kuaj pom los ntawm kev sib piv kev ua tau zoo rau cov kev sim pov thawj tsis ntev los no lossis thawj zaug (piv txwv li cov cim valve lossis lub sijhawm teb valve) lossis los ntawm kev tshuaj xyuas (piv txwv li lub qhov rooj ua haujlwm txhaws). Kev ua tsis tiav thaum pib feem ntau yog nyob ntawm lub sijhawm - lub cuab yeej lossis lub rooj sib dhos ua haujlwm ntev npaum li cas, nws yuav ua rau puas tsuaj ntau dua; cov xwm txheej uas ua rau muaj kev ua tsis tiav random yuav tshwm sim ntau dua, qhov chaw nres nkoj ua haujlwm txhaws lossis lub sensor tsim ntau dhau sijhawm, lub neej siv tau tas, thiab lwm yam. Yog li ntawd, lub sijhawm sim pov thawj ntev dua, qhov yuav tshwm sim ntau dua lossis ua tsis tiav raws sijhawm. Txhua yam kev tiv thaiv tiv thaiv kev ua tsis tiav thaum pib kuj yuav tsum tau kuaj pov thawj (kev ntxuav qhov chaw nres nkoj, kev taug qab cua sov, thiab lwm yam).
Cov txheej txheem yuav tsum tau sau los ua pov thawj rau kev sim rau qhov ua tsis tiav uas txaus ntshai (tsis pom). Kev tshuaj xyuas hom kev ua tsis tiav thiab cov txiaj ntsig (FMEA) lossis hom kev ua tsis tiav, cov txiaj ntsig thiab kev tshuaj xyuas kev kuaj mob (FMEDA) cov txheej txheem tuaj yeem pab txheeb xyuas cov kev ua tsis tiav uas txaus ntshai uas tsis pom, thiab qhov twg yuav tsum tau txhim kho kev them nqi ntawm kev sim pov thawj.
Ntau cov txheej txheem xeem pov thawj yog sau raws li kev paub dhau los thiab cov qauv los ntawm cov txheej txheem uas twb muaj lawm. Cov txheej txheem tshiab thiab SIFs nyuaj dua xav tau txoj hauv kev tsim kho dua tshiab siv FMEA/FMEDA los tshuaj xyuas cov kev ua tsis tiav txaus ntshai, txiav txim siab seb cov txheej txheem xeem yuav lossis tsis kuaj cov kev ua tsis tiav ntawd li cas, thiab kev npog ntawm cov kev xeem. Daim duab qhia txog kev tshuaj xyuas hom kev ua tsis tiav ntawm qib macro rau lub sensor tau pom hauv Daim Duab 2. FMEA feem ntau tsuas yog yuav tsum tau ua ib zaug rau ib hom khoom siv tshwj xeeb thiab rov siv dua rau cov khoom siv zoo sib xws nrog kev xav txog lawv cov txheej txheem kev pabcuam, kev teeb tsa thiab qhov chaw kuaj xyuas.
Kev tshuaj xyuas qhov ua tsis tiav ntawm theem macro Daim Duab 2: Daim duab thaiv kev tshuaj xyuas hom kev ua tsis tiav ntawm theem macro rau lub sensor thiab lub tshuab xa siab (PT) qhia txog cov haujlwm tseem ceeb uas feem ntau yuav raug muab faib ua ntau qhov kev tshuaj xyuas qhov ua tsis tiav me me kom txhais tau tag nrho cov kev ua tsis tiav uas yuav tsum tau hais txog hauv kev sim ua haujlwm.
Daim Duab 2: Daim duab qhia txog kev tshuaj xyuas hom kev ua tsis tiav ntawm qib macro rau lub sensor thiab lub tshuab xa siab (PT) qhia txog cov haujlwm tseem ceeb uas feem ntau yuav raug muab faib ua ntau qhov kev tshuaj xyuas kev ua tsis tiav me me kom txhais tau tag nrho cov kev ua tsis tiav uas yuav tsum tau hais txog hauv kev sim ua haujlwm.
Feem pua ntawm cov kev ua tsis tiav uas paub, txaus ntshai, thiab tsis pom uas tau kuaj pom hu ua kev pov thawj kuaj xyuas (PTC). PTC feem ntau siv rau hauv kev suav SIL los "them rov qab" rau qhov ua tsis tiav los kuaj SIF kom tiav. Cov neeg muaj kev ntseeg yuam kev tias vim lawv tau xav txog qhov tsis muaj kev pab them nqi kuaj hauv lawv qhov kev suav SIL, lawv tau tsim SIF txhim khu kev qha. Qhov tseeb yooj yim yog, yog tias koj qhov kev pab them nqi kuaj yog 75%, thiab yog tias koj suav tus lej ntawd rau hauv koj qhov kev suav SIL thiab cov khoom kuaj uas koj twb kuaj ntau zaus lawm, 25% ntawm cov kev ua tsis tiav txaus ntshai tseem tuaj yeem tshwm sim los ntawm kev suav lej. Kuv yeej tsis xav nyob hauv 25% ntawd.
Cov ntawv qhia txog kev pom zoo ntawm FMEDA thiab cov ntawv qhia kev nyab xeeb rau cov khoom siv feem ntau muab cov txheej txheem sim ua pov thawj tsawg kawg nkaus thiab kev them nqi sim ua pov thawj. Cov no tsuas yog muab cov lus qhia xwb, tsis yog txhua kauj ruam sim uas xav tau rau cov txheej txheem sim ua pov thawj. Lwm hom kev tshuaj xyuas qhov tsis ua haujlwm, xws li kev tshuaj xyuas tsob ntoo txhaum thiab kev saib xyuas qhov kev ntseeg siab, kuj siv los tshuaj xyuas qhov tsis ua haujlwm txaus ntshai.
Kev ntsuam xyuas pov thawj muaj peev xwm muab faib ua kev ntsuam xyuas kev ua haujlwm tag nrho (kawg-rau-kawg) lossis kev ntsuam xyuas kev ua haujlwm ib nrab (Daim Duab 3). Kev ntsuam xyuas kev ua haujlwm ib nrab feem ntau ua thaum cov khoom ntawm SIF muaj cov sijhawm xeem sib txawv hauv kev suav SIL uas tsis sib haum nrog kev kaw lossis kev hloov pauv uas tau npaj tseg. Nws yog ib qho tseem ceeb uas cov txheej txheem ntsuam xyuas kev ua haujlwm ib nrab yuav tsum sib tshooj kom lawv ua ke sim txhua qhov kev ua haujlwm kev nyab xeeb ntawm SIF. Nrog rau kev ntsuam xyuas kev ua haujlwm ib nrab, nws tseem pom zoo kom SIF muaj kev ntsuam xyuas pov thawj pib txij thaum kawg mus txog thaum kawg, thiab tom qab ntawd thaum lub sijhawm hloov pauv.
Cov kev ntsuam xyuas pov thawj ib nrab yuav tsum sib ntxiv Daim Duab 3: Cov kev ntsuam xyuas pov thawj ib nrab ua ke (hauv qab) yuav tsum npog tag nrho cov haujlwm ntawm kev ntsuam xyuas pov thawj ua haujlwm tag nrho (sab saum toj).
Daim Duab 3: Cov kev xeem pov thawj ib nrab ua ke (hauv qab) yuav tsum npog tag nrho cov haujlwm ntawm kev xeem pov thawj ua haujlwm tag nrho (sab saum toj).
Kev sim ua pov thawj ib nrab tsuas yog sim ib feem pua ntawm cov hom kev ua tsis tiav ntawm lub cuab yeej xwb. Ib qho piv txwv feem ntau yog kev sim lub valve ib nrab, qhov twg lub valve raug txav me ntsis (10-20%) los xyuas kom meej tias nws tsis daig. Qhov no muaj kev pab them nqi sim ua pov thawj qis dua li kev sim ua pov thawj ntawm lub sijhawm sim thawj zaug.
Cov txheej txheem kuaj pov thawj tuaj yeem sib txawv ntawm qhov nyuaj nrog rau qhov nyuaj ntawm SIF thiab lub tswv yim ntawm cov txheej txheem kuaj ntawm lub tuam txhab. Qee lub tuam txhab sau cov txheej txheem kuaj ntxaws ntxaws, thaum lwm tus muaj cov txheej txheem luv luv. Cov lus hais txog lwm cov txheej txheem, xws li kev ntsuas tus qauv, qee zaum siv los txo qhov loj ntawm cov txheej txheem kuaj pov thawj thiab los pab kom ntseeg tau tias muaj kev sib xws hauv kev kuaj. Cov txheej txheem kuaj pov thawj zoo yuav tsum muab cov ntsiab lus txaus kom ntseeg tau tias tag nrho cov kev kuaj tau ua tiav thiab sau tseg, tab sis tsis txhob muaj ntau cov ntsiab lus kom ua rau cov kws kho tshuab xav hla cov kauj ruam. Muaj tus kws kho tshuab, uas yog tus saib xyuas kev ua cov kauj ruam kuaj, pib cov kauj ruam kuaj tiav tuaj yeem pab kom ntseeg tau tias qhov kev xeem yuav ua tiav kom raug. Kev kos npe ntawm qhov kev xeem pov thawj tiav los ntawm Tus Saib Xyuas Cov Cuab Yeej thiab Cov Neeg Sawv Cev Ua Haujlwm kuj tseem yuav hais txog qhov tseem ceeb thiab ua kom ntseeg tau tias qhov kev xeem pov thawj tiav kom raug.
Yuav tsum tau caw cov lus taw qhia los ntawm cov kws kho tshuab kom pab txhim kho cov txheej txheem. Kev ua tiav ntawm cov txheej txheem kuaj pov thawj feem ntau yog nyob ntawm cov kws kho tshuab txhais tes, yog li ntawd kev sib koom tes yog qhov pom zoo heev.
Feem ntau kev kuaj pov thawj feem ntau ua offline thaum lub sijhawm kaw lossis tig rov qab. Qee zaum, kev kuaj pov thawj yuav tsum tau ua online thaum khiav kom ua tiav cov kev suav SIL lossis lwm yam kev cai. Kev kuaj online xav tau kev npaj thiab kev sib koom tes nrog Kev Ua Haujlwm kom tso cai rau kev kuaj pov thawj kom ua tau zoo, tsis muaj kev cuam tshuam, thiab tsis ua rau muaj kev mus ncig tsis raug. Nws tsuas yog siv ib qho kev mus ncig tsis raug kom siv tag nrho koj cov neeg ua haujlwm. Thaum lub sijhawm kuaj no, thaum SIF tsis muaj sijhawm ua tiav nws txoj haujlwm kev nyab xeeb, 61511-1, Kab Lus 11.8.5, hais tias "Kev ntsuas them nyiaj uas ua kom muaj kev ua haujlwm nyab xeeb txuas ntxiv yuav tsum tau muab raws li 11.3 thaum SIS nyob hauv kev hla (kho lossis sim)." Cov txheej txheem tswj hwm qhov xwm txheej tsis zoo yuav tsum mus nrog cov txheej txheem kuaj pov thawj kom pab ua kom qhov no ua tiav.
Ib qho SIF feem ntau muab faib ua peb ntu tseem ceeb: cov sensors, cov logic solvers thiab cov ntsiab lus kawg. Kuj tseem muaj cov khoom siv pabcuam uas tuaj yeem koom nrog hauv txhua ntu ntawm peb ntu no (piv txwv li IS barriers, trip amps, interposing relays, solenoids, thiab lwm yam) uas yuav tsum tau kuaj xyuas. Cov ntsiab lus tseem ceeb ntawm kev kuaj pov thawj txhua yam ntawm cov thev naus laus zis no tuaj yeem pom nyob rau hauv cov sidebar, "Kev kuaj cov sensors, logic solvers thiab cov ntsiab lus kawg" (hauv qab no).
Muaj tej yam yooj yim dua los ua pov thawj dua li lwm yam. Ntau yam thev naus laus zis niaj hnub thiab ob peb yam thev naus laus zis qub dua yog nyob rau hauv qeb nyuaj dua. Cov no suav nrog Coriolis flowmeters, vortex meters, mag meters, through-the-air radar, ultrasonic level, thiab in-situ process switches, yog qee yam piv txwv. Hmoov zoo, ntau yam ntawm cov no tam sim no muaj kev kuaj mob zoo dua uas tso cai rau kev kuaj mob zoo dua.
Qhov nyuaj ntawm kev sim ua pov thawj xws li cov cuab yeej hauv daim teb yuav tsum tau xav txog hauv SIF tsim. Nws yooj yim rau cov kws ua vaj tse xaiv cov cuab yeej SIF yam tsis tau xav txog qhov yuav tsum tau ua los sim ua pov thawj cov cuab yeej, vim lawv yuav tsis yog cov neeg sim lawv. Qhov no kuj muaj tseeb rau kev sim ib nrab-stroke, uas yog ib txoj hauv kev los txhim kho qhov nruab nrab ntawm SIF qhov ua tsis tiav raws li qhov xav tau (PFDavg), tab sis tom qab ntawd cov haujlwm ntawm lub Hoobkas tsis xav ua nws, thiab ntau zaus yuav tsis ua. Ib txwm muab kev saib xyuas ntawm lub Hoobkas ntawm kev tsim kho ntawm SIFs hauv kev hais txog kev sim ua pov thawj.
Qhov kev sim ua pov thawj yuav tsum suav nrog kev tshuaj xyuas qhov kev teeb tsa thiab kho SIF raws li qhov xav tau kom ua tau raws li 61511-1, Kab Lus 16.3.2. Yuav tsum muaj kev tshuaj xyuas zaum kawg kom ntseeg tau tias txhua yam tau khawm, thiab kev kuaj xyuas ob zaug tias SIF tau raug muab tso rov qab rau hauv kev pabcuam txheej txheem.
Kev sau thiab siv cov txheej txheem xeem zoo yog ib kauj ruam tseem ceeb kom ntseeg tau tias SIF muaj kev ncaj ncees thoob plaws nws lub neej. Cov txheej txheem xeem yuav tsum muab cov ntsiab lus txaus kom ntseeg tau tias cov kev xeem uas xav tau raug ua tiav thiab sau tseg tas li thiab muaj kev nyab xeeb. Cov kev ua tsis tiav txaus ntshai uas tsis tau kuaj los ntawm cov kev xeem pov thawj yuav tsum tau them rov qab kom ntseeg tau tias SIF muaj kev nyab xeeb txaus thoob plaws nws lub neej.
Kev sau ib txoj kev kuaj pov thawj zoo yuav tsum muaj ib txoj kev xav txog kev tshuaj xyuas kev tsim kho ntawm qhov ua tsis tiav uas yuav tshwm sim, xaiv cov hau kev, thiab sau cov kauj ruam kuaj pov thawj uas nyob hauv lub Hoobkas lub peev xwm kuaj. Ntawm txoj kev, kom cov Hoobkas pom zoo rau txhua qib rau kev kuaj, thiab cob qhia cov kws kho tshuab kom ua thiab sau cov ntaub ntawv kuaj pov thawj nrog rau kev nkag siab txog qhov tseem ceeb ntawm kev kuaj. Sau cov lus qhia zoo li koj yog tus kws kho tshuab uas yuav tsum ua haujlwm, thiab tias lub neej nyob ntawm kev ua kom raug kev kuaj, vim lawv ua.
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
Ib qho SIF feem ntau muab faib ua peb ntu tseem ceeb, cov sensors, cov logic solvers thiab cov ntsiab lus kawg. Kuj tseem muaj cov khoom siv pabcuam uas tuaj yeem koom nrog hauv txhua ntu ntawm peb ntu no (piv txwv li IS barriers, trip amps, interposing relays, solenoids, thiab lwm yam) uas yuav tsum tau kuaj xyuas.
Kev ntsuam xyuas pov thawj sensor: Kev ntsuam xyuas pov thawj sensor yuav tsum xyuas kom meej tias lub sensor tuaj yeem hnov qhov hloov pauv ntawm cov txheej txheem thoob plaws nws qhov ntau thiab xa cov teeb liab kom raug rau SIS logic solver rau kev ntsuam xyuas. Txawm hais tias tsis suav nrog, qee yam uas yuav tsum xav txog hauv kev tsim cov ntu sensor ntawm cov txheej txheem xeem pov thawj tau muab rau hauv Rooj 1.
Kev sim ua pov thawj ntawm tus neeg daws teeb meem logic: Thaum ua tiav kev sim ua pov thawj tag nrho, tus neeg daws teeb meem lub luag haujlwm hauv kev ua tiav SIF kev nyab xeeb thiab lwm yam kev ua (piv txwv li kev ceeb toom, kev pib dua, kev hla mus, kev kuaj mob ntawm tus neeg siv, kev rov ua dua, HMI, thiab lwm yam) raug sim. Kev sim ua pov thawj ib nrab lossis ib feem ntawm kev ua haujlwm yuav tsum ua tiav tag nrho cov kev sim no ua ib feem ntawm kev sim ua pov thawj sib tshooj. Tus neeg tsim khoom daws teeb meem logic yuav tsum muaj cov txheej txheem sim ua pov thawj pom zoo hauv phau ntawv qhia kev nyab xeeb ntawm lub cuab yeej. Yog tias tsis yog thiab tsawg kawg, lub zog ntawm tus neeg daws teeb meem logic yuav tsum tau hloov pauv, thiab cov ntaub ntawv sau npe ntawm tus neeg daws teeb meem, teeb pom kev zoo, cov hluav taws xob fais fab, cov kev sib txuas lus thiab kev rov ua dua yuav tsum tau kuaj xyuas. Cov kev kuaj xyuas no yuav tsum tau ua ua ntej kev sim ua pov thawj tag nrho.
Tsis txhob xav tias cov software zoo mus ib txhis thiab cov logic tsis tas yuav kuaj tom qab thawj qhov kev sim pov thawj vim tias cov software thiab kho vajtse tsis muaj ntaub ntawv pov thawj, tsis raug cai thiab tsis tau sim thiab cov kev hloov kho software tuaj yeem nkag mus rau hauv cov kab ke dhau sijhawm thiab yuav tsum tau suav nrog hauv koj lub tswv yim kev sim pov thawj tag nrho. Kev tswj hwm kev hloov pauv, kev saib xyuas, thiab cov ntawv teev cia kho dua tshiab yuav tsum tau saib xyuas kom ntseeg tau tias lawv hloov tshiab thiab tswj hwm zoo, thiab yog tias ua tau, qhov kev pab cuam daim ntawv thov yuav tsum tau piv rau qhov thaub qab tshiab tshaj plaws.
Yuav tsum tau ceev faj sim txhua yam kev pabcuam thiab kev kuaj mob ntawm tus neeg siv logic solver (piv txwv li cov neeg saib xyuas, cov kev sib txuas lus, cov khoom siv kev ruaj ntseg hauv cyber, thiab lwm yam).
Kev sim ua pov thawj kawg: Feem ntau cov khoom kawg yog cov li qub, txawm li cas los xij, cov khoom siv tig lub cev muaj zog pib, cov tsav tsheb hloov pauv ceev thiab lwm yam khoom siv hluav taws xob xws li cov contactors thiab cov hluav taws xob breakers kuj siv ua cov khoom kawg thiab lawv cov hom kev ua tsis tiav yuav tsum tau soj ntsuam thiab kuaj pov thawj.
Cov hom kev ua tsis tiav tseem ceeb rau cov li qub yog raug daig, lub sijhawm teb qeeb dhau lossis sai dhau, thiab xau, tag nrho cov no raug cuam tshuam los ntawm lub valve qhov kev ua haujlwm interface thaum lub sijhawm mus ncig. Thaum kuaj lub valve ntawm cov xwm txheej ua haujlwm yog qhov xwm txheej xav tau tshaj plaws, Kev Ua Haujlwm feem ntau yuav tsis zoo rau kev tripping SIF thaum lub Hoobkas ua haujlwm. Feem ntau cov li qub SIS feem ntau raug kuaj thaum lub Hoobkas poob qis ntawm xoom qhov siab sib txawv, uas yog qhov tsawg tshaj plaws ntawm cov xwm txheej ua haujlwm. Tus neeg siv yuav tsum paub txog qhov phem tshaj plaws ntawm qhov siab sib txawv ua haujlwm thiab cov teebmeem ntawm lub valve thiab cov txheej txheem puas tsuaj, uas yuav tsum tau suav nrog rau hauv lub valve thiab actuator tsim thiab qhov loj me.
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).
Qhov kub thiab txias ib puag ncig kuj tseem tuaj yeem cuam tshuam rau qhov kev sib txhuam ntawm lub valve, yog li ntawd kev sim cov valve hauv huab cua sov feem ntau yuav yog qhov kev sib txhuam tsawg tshaj plaws thaum piv rau kev ua haujlwm hauv huab cua txias. Yog li ntawd, kev sim pov thawj ntawm cov valve ntawm qhov kub thiab txias sib xws yuav tsum tau txiav txim siab los muab cov ntaub ntawv sib xws rau kev sim ua piv txwv rau kev txiav txim siab ntawm kev ua haujlwm ntawm lub valve poob qis.
Cov li qub uas muaj cov cuab yeej ntse lossis lub tshuab tswj hwm lub li qub digital feem ntau muaj peev xwm tsim cov cim qhia lub li qub uas siv tau los saib xyuas kev ua haujlwm ntawm lub li qub. Koj tuaj yeem thov kom muaj cov cim qhia lub li qub ua ib feem ntawm koj daim ntawv yuav khoom lossis koj tuaj yeem tsim ib qho thaum lub sijhawm sim ua pov thawj thawj zaug los ua lub cim qhia. Yuav tsum tau ua cov cim qhia lub li qub rau ob qho tib si qhib thiab kaw lub li qub. Yuav tsum siv kev kuaj mob siab heev yog tias muaj. Qhov no tuaj yeem pab qhia koj yog tias koj qhov kev ua haujlwm ntawm lub li qub puas tsuaj los ntawm kev sib piv cov cim qhia lub li qub thiab kev kuaj mob tom qab nrog koj cov cim qhia. Hom kev sim no tuaj yeem pab them rau kev tsis kuaj lub li qub ntawm qhov siab tshaj plaws.
Lub cim kos npe ntawm lub valve thaum lub sijhawm sim ua pov thawj kuj tseem yuav sau tau lub sijhawm teb nrog cov cim sijhawm, tshem tawm qhov xav tau lub moos nres. Lub sijhawm teb ntxiv yog ib qho cim ntawm lub valve puas tsuaj thiab kev sib txhuam ntau ntxiv los txav lub valve. Txawm hais tias tsis muaj cov qauv hais txog kev hloov pauv ntawm lub sijhawm teb ntawm lub valve, tus qauv tsis zoo ntawm kev hloov pauv ntawm kev sim ua pov thawj mus rau kev sim ua pov thawj yog qhia txog qhov kev poob ntawm qhov kev nyab xeeb ntawm lub valve thiab kev ua tau zoo. Kev sim ua pov thawj ntawm lub valve SIS niaj hnub no yuav tsum suav nrog lub cim kos npe ntawm lub valve ua ib qho kev xyaum ua haujlwm zoo.
Yuav tsum ntsuas qhov siab ntawm cov cua ntawm lub twj tso kua mis thaum lub sijhawm sim ua pov thawj. Txawm hais tias lub caij nplooj ntoos hlav rau lub caij nplooj ntoos hlav rov qab yog qhov kaw lub valve, lub zog lossis lub zog torque uas cuam tshuam yog txiav txim siab los ntawm qhov ntau npaum li cas lub caij nplooj ntoos hlav raug nias los ntawm lub zog ntawm lub valve (raws li Hooke's Law, F = kX). Yog tias koj qhov siab ntawm cov khoom siv qis, lub caij nplooj ntoos hlav yuav tsis nias ntau, yog li ntawd yuav muaj zog tsawg dua los txav lub valve thaum xav tau. Txawm hais tias tsis suav nrog, qee yam uas yuav tsum xav txog hauv kev tsim qhov seem ntawm lub valve ntawm cov txheej txheem sim ua pov thawj tau muab rau hauv Rooj 2.
Lub sijhawm tshaj tawm: Kaum Ib Hlis-13-2019