Kuyesa umboni ndi gawo lofunika kwambiri pakusunga chitetezo cha makina athu otetezedwa (SIS) ndi makina okhudzana ndi chitetezo (monga ma alarm ofunikira, makina ozimitsa moto ndi gasi, makina olumikizirana ndi zida, ndi zina zotero). Kuyesa umboni ndi kuyesa kwa nthawi ndi nthawi kuti mupeze kulephera koopsa, kuyesa magwiridwe antchito okhudzana ndi chitetezo (monga kubwezeretsanso, kutseka, ma alarm, kuzindikira, kuzimitsa pamanja, ndi zina zotero), ndikuwonetsetsa kuti makinawo akukwaniritsa miyezo ya kampani ndi yakunja. Zotsatira za kuyesa umboni ndi muyeso wa momwe pulogalamu ya SIS imagwirira ntchito bwino komanso kudalirika kwa makinawo.
Njira zoyesera umboni zimaphatikizapo njira zoyesera kuyambira kupeza zilolezo, kupereka zidziwitso ndikuchotsa makina kuti ayesedwe mpaka kuonetsetsa kuti mayeso athunthu ayesedwa, kulemba mayeso otsimikizira ndi zotsatira zake, kubwezeretsa makinawo pa ntchito, ndikuwunika zotsatira za mayeso omwe alipo komanso zotsatira za mayeso am'mbuyomu.
ANSI/ISA/IEC 61511-1, Gawo 16, likufotokoza za kuyesa kwa SIS. Lipoti laukadaulo la ISA TR84.00.03 – “Mechanical Integrity of Safety Instrumented Systems (SIS),” likufotokoza za kuyesa kwa umboni ndipo pakadali pano likukonzedwanso ndipo mtundu watsopano ukuyembekezeka kutulutsidwa posachedwa. Lipoti laukadaulo la ISA TR96.05.02 – “Kuyesa kwa Ma Valves Odziyimira Pawokha” kukupangidwa pakadali pano.
Lipoti la UK HSE CRR 428/2002 – “Mfundo zoyesera umboni wa makina otetezedwa mumakampani opanga mankhwala” zimapereka chidziwitso chokhudza kuyesa umboni ndi zomwe makampani akuchita ku UK.
Njira yoyesera umboni imachokera pa kusanthula kwa njira zodziwika bwino zolephera zoopsa za gawo lililonse mu njira yoyendera ya chitetezo (SIF), magwiridwe antchito a SIF ngati dongosolo, ndi momwe (ndi ngati) angayesere njira yolephera yoopsa. Kupanga njira kuyenera kuyamba mu gawo la kapangidwe ka SIF ndi kapangidwe ka dongosolo, kusankha zigawo, ndi kudziwa nthawi komanso momwe angayesere umboni. Zipangizo za SIS zili ndi zovuta zosiyanasiyana zoyesera umboni zomwe ziyenera kuganiziridwa pakupanga, kugwiritsa ntchito ndi kukonza kwa SIF. Mwachitsanzo, mita ya orifice ndi ma transmitter opanikizika ndizosavuta kuyesa kuposa mita ya Coriolis mass flowmeters, mita ya mag kapena masensa a radar omwe ali mumlengalenga. Kugwiritsa ntchito ndi kapangidwe ka valavu kumathanso kukhudza kukwanira kwa mayeso otsimikizira valavu kuti zitsimikizire kuti kulephera koopsa komanso koyambira chifukwa cha kuwonongeka, kutsekeka kapena kulephera kodalira nthawi sikubweretsa kulephera kwakukulu mkati mwa nthawi yosankhidwa yoyesera.
Ngakhale njira zoyesera umboni nthawi zambiri zimapangidwa panthawi ya uinjiniya wa SIF, ziyeneranso kuwunikidwanso ndi bungwe la SIS Technical Authority, Operations ndi akatswiri a zida omwe adzachite mayesowo. Kusanthula chitetezo cha ntchito (JSA) kuyeneranso kuchitika. Ndikofunikira kupeza chilolezo cha fakitale pa mayeso omwe adzachitike komanso nthawi yake, komanso kuthekera kwawo mwakuthupi komanso chitetezo. Mwachitsanzo, sikothandiza kunena mayeso a stroke pang'ono pomwe gulu la Operations silingavomereze kuchita izi. Tikulimbikitsanso kuti njira zoyesera umboni ziwunikidwanso ndi katswiri wodziyimira pawokha (SME). Kuyesa kwachizolowezi komwe kumafunika pa mayeso otsimikizira ntchito yonse kukuwonetsedwa mu Chithunzi 1.
Zofunikira pa mayeso otsimikizira magwiridwe antchito onse Chithunzi 1: Chidziwitso cha mayeso otsimikizira magwiridwe antchito onse a ntchito yotetezedwa (SIF) ndi makina ake otetezera (SIS) chiyenera kufotokoza kapena kutchula masitepe motsatizana kuyambira kukonzekera mayeso ndi njira zoyesera mpaka zidziwitso ndi zolemba.
Chithunzi 1: Chidziwitso chonse chotsimikizira ntchito ya chitetezo cha ntchito (SIF) ndi makina ake otetezera (SIS) chiyenera kufotokoza kapena kutchula masitepe motsatizana kuyambira kukonzekera mayeso ndi njira zoyesera mpaka zidziwitso ndi zolemba.
Kuyesa umboni ndi njira yokonzekera yokonza yomwe iyenera kuchitidwa ndi anthu oyenerera ophunzitsidwa mayeso a SIS, njira yowunikira, ndi ma SIS omwe adzayese. Payenera kukhala njira yowunikira momwe ntchitoyi ikuyendera musanayambe kuyesa koyamba kwa umboni, ndikupereka ndemanga ku bungwe la SIS Technical Authority pambuyo pake kuti akonze kapena kukonza.
Pali njira ziwiri zazikulu zolephera (zotetezeka kapena zoopsa), zomwe zagawidwa m'magulu anayi—zoopsa zosazindikirika, zowopsa zozindikirika (mwa kuzindikira), zotetezeka zosazindikirika ndi zotetezeka zozindikirika. Mawu oti kulephera koopsa ndi koopsa osazindikirika agwiritsidwa ntchito mosiyanasiyana m'nkhaniyi.
Mu kuyesa kwa umboni wa SIF, timakonda kwambiri njira zoopsa zolephera zomwe sizikudziwika, koma ngati pali njira zodziwira za ogwiritsa ntchito zomwe zimazindikira kulephera koopsa, njirazi ziyenera kuyesedwa umboni. Dziwani kuti mosiyana ndi njira zodziwira za ogwiritsa ntchito, njira zodziwira zamkati mwa chipangizo nthawi zambiri sizingatsimikizidwe ngati zikugwira ntchito ndi wogwiritsa ntchito, ndipo izi zitha kukhudza malingaliro a mayeso otsimikizira. Pamene kuyamikira kwa njira zodziwira matenda kutengedwa mu mawerengedwe a SIL, ma alamu ozindikira matenda (monga ma alamu akunja) ayenera kuyesedwa ngati gawo la mayeso otsimikizira.
Njira zolephera zitha kugawidwanso m'magulu awiri omwe adayesedwa panthawi yoyesa umboni, omwe sanayesedwe, ndi omwe adalephera koyamba kapena kulephera kutengera nthawi. Njira zina zowopsa zolephera sizingayesedwe mwachindunji pazifukwa zosiyanasiyana (monga zovuta, chisankho chaukadaulo kapena chogwirira ntchito, kusadziwa, kusachita bwino, kulephera kapena kulephera kuchita zolakwika m'dongosolo, mwayi wochepa woti zichitike, ndi zina zotero). Ngati pali njira zodziwika zolephera zomwe sizingayesedwe, malipiro ayenera kuchitidwa pakupanga chipangizo, njira zoyesera, kusintha chipangizo nthawi ndi nthawi kapena kumanganso, ndi/kapena kuyesa koganizira kuyenera kuchitidwa kuti muchepetse zotsatira za kusayesa kwa SIF.
Kulephera koyambira ndi mkhalidwe woipa kwambiri kotero kuti kulephera kwakukulu komanso koopsa kungayembekezeredwe kuchitika ngati njira zowongolera sizitengedwa munthawi yake. Nthawi zambiri zimazindikirika poyerekezera magwiridwe antchito ndi mayeso aposachedwa kapena oyamba (monga ma signature a valavu kapena nthawi yoyankhira valavu) kapena poyang'ana (monga plugged process port). Kulephera koyambira nthawi zambiri kumadalira nthawi—chipangizo kapena msonkhano ukakhala wogwira ntchito kwa nthawi yayitali, umakhala woipa kwambiri; zinthu zomwe zimapangitsa kuti kulephera mwachisawawa kukhale kofala, process port plugging kapena sensor building pakapita nthawi, nthawi yogwiritsira ntchito yatha, ndi zina zotero. Chifukwa chake, nthawi yayitali yoyesera umboni, nthawi yoyambira kapena kulephera kodalira nthawi ikakhala yayitali. Chitetezo chilichonse ku kulephera koyambira chiyeneranso kuyesedwa umboni (kutsuka madoko, kutsatira kutentha, ndi zina zotero).
Njira ziyenera kulembedwa kuti zitsimikizire kulephera koopsa (kosapezeka). Njira zoyesera ndi kusanthula zotsatira (FMEA) kapena njira zoyesera, kusanthula zotsatira ndi kuzindikira (FMEDA) zingathandize kuzindikira kulephera koopsa kosapezeka, komanso komwe kuyesa umboni kuyenera kukonzedwa.
Njira zambiri zoyesera umboni zimakhazikitsidwa pa zokumana nazo zolembedwa komanso ma tempuleti ochokera ku njira zomwe zilipo kale. Njira zatsopano ndi ma SIF ovuta kwambiri zimafuna njira yokonzedwa bwino pogwiritsa ntchito FMEA/FMEDA kuti ifufuze zolephera zoopsa, kudziwa momwe njira yoyesera idzayesere kapena ayi zolepherazo, komanso momwe mayesowo adzayezeredwere. Chithunzi cha block cha kusanthula kwa macro-level failure mode cha sensa chikuwonetsedwa mu Chithunzi 2. FMEA nthawi zambiri imafunika kuchitidwa kamodzi kokha pa chipangizo chamtundu winawake ndikugwiritsidwanso ntchito pazida zofanana poganizira ntchito zawo, kukhazikitsa ndi kuthekera koyesa malo.
Kusanthula kwa kulephera kwa macro-level Chithunzi 2: Chithunzichi cha block cha kusanthula kwa macro-level mode cha sensa ndi chotumizira mphamvu (PT) chikuwonetsa ntchito zazikulu zomwe nthawi zambiri zimagawidwa m'magawo angapo a micro failure analysis kuti zifotokoze bwino zolephera zomwe zingathetsedwe mu mayeso a ntchito.
Chithunzi 2: Chithunzichi cha macro-level failure mode analysis block cha sensa ndi pressure transmitter (PT) chikuwonetsa ntchito zazikulu zomwe nthawi zambiri zimagawidwa m'ma micro failure analysis angapo kuti zifotokoze bwino zolephera zomwe zingathetsedwe mu mayeso a functional.
Chiwerengero cha zolephera zodziwika, zoopsa, komanso zosazindikirika zomwe zimayesedwa umboni chimatchedwa proof test coverage (PTC). PTC imagwiritsidwa ntchito kwambiri pakuwerengera kwa SIL kuti "ipereke" kulephera kuyesa SIF mokwanira. Anthu ali ndi chikhulupiriro cholakwika chakuti chifukwa chakuti aganizira za kusowa kwa test coverage mu SIL calculation yawo, apanga SIF yodalirika. Chowonadi ndi chakuti, ngati test coverage yanu ndi 75%, ndipo ngati mwawerengera nambala imeneyo mu SIL calculation yanu ndi zinthu zomwe mukuyesera kale nthawi zambiri, 25% ya zolephera zoopsa zitha kuchitikabe. Sindikufuna kukhala mu 25%.
Malipoti ovomerezeka a FMEDA ndi mabuku oteteza zida nthawi zambiri amapereka njira yoyesera yotsimikizira komanso kuphimba mayeso otsimikizira. Izi zimangopereka chitsogozo chokha, osati njira zonse zoyesera zofunika kuti pakhale njira yonse yoyesera yotsimikizira. Mitundu ina ya kusanthula kulephera, monga kusanthula mtengo wolakwika ndi kukonza kokhazikika, imagwiritsidwanso ntchito kusanthula kulephera koopsa.
Mayeso otsimikizira akhoza kugawidwa m'magulu awiri: mayeso ogwirira ntchito (kuyambira kumapeto mpaka kumapeto) kapena mayeso ogwirira ntchito pang'ono (Chithunzi 3). Mayeso ogwirira ntchito pang'ono nthawi zambiri amachitidwa pamene zigawo za SIF zili ndi nthawi zosiyana zoyesera mu mawerengedwe a SIL zomwe sizikugwirizana ndi kutsekedwa kapena kutembenuka komwe kwakonzedwa. Ndikofunikira kuti njira zoyesera zotsimikizira zogwirira ntchito pang'ono zigwirizane kotero kuti pamodzi zimayesa magwiridwe antchito onse achitetezo a SIF. Ndi mayeso ogwirira ntchito pang'ono, akulangizidwabe kuti SIF ikhale ndi mayeso oyamba otsimikizira kuyambira kumapeto mpaka kumapeto, ndi ena otsatira panthawi yotembenuza.
Mayeso otsimikizira pang'ono ayenera kuwonjezeredwa Chithunzi 3: Mayeso otsimikizira pang'ono (pansi) ayenera kuphimba ntchito zonse za mayeso otsimikizira mokwanira (pamwamba).
Chithunzi 3: Mayeso ophatikizana a umboni wosakwanira (pansi) ayenera kuphimba ntchito zonse za mayeso ogwirira ntchito mokwanira (pamwamba).
Kuyesa kotsimikizira pang'ono kumayesa gawo limodzi lokha la njira zolephera kwa chipangizocho. Chitsanzo chodziwika bwino ndi kuyesa kwa valavu yopanda gawo, komwe valavu imasunthidwa pang'ono (10-20%) kuti itsimikizire kuti sinatseke. Izi zili ndi kuphimba kochepa kwa kuyesa kotsimikizira kuposa kuyesa kotsimikizira panthawi yoyesera yoyamba.
Njira zoyesera umboni zimatha kusiyana malinga ndi zovuta za SIF ndi njira zoyesera za kampani. Makampani ena amalemba njira zoyesera zatsatanetsatane pang'onopang'ono, pomwe ena ali ndi njira zazifupi. Maumboni okhudza njira zina, monga kuwerengera kokhazikika, nthawi zina amagwiritsidwa ntchito kuchepetsa kukula kwa njira yoyesera umboni ndikuthandizira kutsimikizira kusasinthasintha pakuyesa. Njira yabwino yoyesera umboni iyenera kupereka tsatanetsatane wokwanira kuti zitsimikizire kuti mayeso onse akwaniritsidwa bwino komanso olembedwa, koma osati tsatanetsatane wambiri kuti apangitse akatswiri kufuna kudumpha masitepe. Kukhala ndi katswiri, yemwe ali ndi udindo wochita gawo loyesa, kuyambitsa gawo loyesa lomalizidwa kungathandize kutsimikizira kuti mayeso achitika molondola. Kusaina mayeso omalizidwa ndi Woyang'anira Zida ndi Oimira Ntchito kudzagogomezeranso kufunika ndikutsimikizira mayeso omalizidwa bwino.
Ndemanga za akatswiri nthawi zonse ziyenera kupemphedwa kuti zithandize kukonza njira yoyezera. Kupambana kwa njira yoyesera umboni kumakhala m'manja mwa akatswiri, kotero kuyesetsa mogwirizana ndikofunikira kwambiri.
Kuyesa umboni nthawi zambiri kumachitika popanda intaneti panthawi yotseka kapena kutembenuka. Nthawi zina, kuyesa umboni kungafunike kuchitika pa intaneti pamene mukuchita kuti mukwaniritse mawerengedwe a SIL kapena zofunikira zina. Kuyesa pa intaneti kumafuna kukonzekera ndi kugwirizana ndi Opaleshoni kuti mayeso a umboni achitike mosamala, popanda kusokoneza njira, komanso popanda kuyambitsa ulendo wonyenga. Zimatengera ulendo umodzi wonyenga kuti mugwiritse ntchito zida zanu zonse. Pa mtundu uwu wa mayeso, pamene SIF sikupezeka mokwanira kuti igwire ntchito yake yotetezeka, 61511-1, Gawo 11.8.5, limati "Njira zolipirira zomwe zimatsimikizira kuti ntchito yotetezeka ipitirire ziyenera kuperekedwa motsatira 11.3 pamene SIS ikudutsa (kukonza kapena kuyesa)." Njira yosazolowereka yoyang'anira zochitika iyenera kupita ndi njira yoyesera umboni kuti izi zitheke bwino.
SIF nthawi zambiri imagawidwa m'magawo atatu akuluakulu: masensa, zotsukira logic ndi zinthu zomaliza. Palinso zida zothandizira zomwe zingagwirizanitsidwe mkati mwa gawo lililonse mwa magawo atatuwa (monga zotchinga za IS, ma trip amps, ma interposing relay, ma solenoids, ndi zina zotero) zomwe ziyeneranso kuyesedwa. Mbali zofunika kwambiri pakuyesa umboni uliwonse wa ukadaulo uwu zitha kupezeka mu sidebar, "Zotsukira zoyesera, zotsukira logic ndi zinthu zomaliza" (pansipa).
Zinthu zina n'zosavuta kuziyesa kuposa zina. Zipangizo zamakono zambiri komanso zakale zoyezera madzi ndi milingo zili m'gulu lovuta kwambiri. Izi zikuphatikizapo Coriolis flowmeters, vortex metres, mag metres, through-the-air radar, ultrasound level, ndi in-situ process switches, kungotchulapo zochepa. Mwamwayi, zambiri mwa izi tsopano zili ndi njira zodziwira matenda zomwe zimathandiza kuti mayeso akhale abwino.
Kuvuta kwa kuyesa umboni pa chipangizo choterechi kuyenera kuganiziridwa pa kapangidwe ka SIF. N'zosavuta kwa mainjiniya kusankha zipangizo za SIF popanda kuganizira mozama zomwe zingafunike poyesa umboni pa chipangizocho, chifukwa iwo sadzakhala anthu omwe amayesa. Izi ndi zoonanso pa kuyesa pang'ono kwa sitiroko, komwe ndi njira yodziwika bwino yowonjezerera mwayi wapakati wa SIF wolephera pakufunikira (PFDavg), koma pambuyo pake fakitaleyo sikufuna kuchita izi, ndipo nthawi zambiri sizingatero. Nthawi zonse perekani kuyang'anira mafakitale a mainjiniya a ma SIF pankhani yoyesa umboni.
Kuyesa kotsimikizira kuyenera kuphatikizapo kuyang'ana kukhazikitsa ndi kukonza kwa SIF ngati pakufunika kukwaniritsa 61511-1, Gawo 16.3.2. Payenera kukhala kuwunika komaliza kuti zitsimikizire kuti chilichonse chili ndi mabatani, ndikuwunikanso kawiri kuti SIF yabwezeretsedwa bwino mu ntchito yokonza.
Kulemba ndi kukhazikitsa njira yabwino yoyesera ndi gawo lofunika kwambiri kuti zitsimikizire kuti SIF ndi yodalirika pa moyo wake wonse. Njira yoyesera iyenera kupereka tsatanetsatane wokwanira kuti zitsimikizire kuti mayeso ofunikira akuchitika mosalekeza komanso mosamala komanso olembedwa. Kulephera koopsa komwe sikunayesedwe ndi mayeso otsimikizira kuyenera kulipidwa kuti zitsimikizire kuti chitetezo cha SIF chikusungidwa mokwanira pa moyo wake wonse.
Kulemba njira yabwino yoyesera umboni kumafuna njira yomveka bwino yowunikira zaukadaulo za kulephera koopsa komwe kungachitike, kusankha njira, ndikulemba njira zoyesera umboni zomwe zili mkati mwa luso la fakitale yoyesera. Panjira, pezani chilolezo cha chomera pamlingo uliwonse kuti chiyesedwe, ndikuphunzitsa akatswiri kuti achite ndikulemba mayeso otsimikizira komanso kumvetsetsa kufunika kwa mayesowo. Lembani malangizo ngati kuti ndinu katswiri wa zida zomwe adzayenera kugwira ntchitoyo, ndipo miyoyo imadalira kupeza mayesowo moyenera, chifukwa iwo amachita zimenezo.
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 nthawi zambiri imagawidwa m'magawo atatu akuluakulu, masensa, zothetsa nzeru, ndi zinthu zomaliza. Palinso zida zothandizira zomwe zingagwirizanitsidwe mkati mwa gawo lililonse mwa magawo atatuwa (monga zotchinga za IS, ma trip amps, ma interposing relay, ma solenoids, ndi zina zotero) zomwe ziyeneranso kuyesedwa.
Mayeso oletsa kutsekereza: Mayeso oletsa kutsekereza ayenera kuwonetsetsa kuti sensa ikhoza kumva kusintha kwa njira yonse ndikutumiza chizindikiro choyenera ku SIS logic solver kuti chiwunikidwe. Ngakhale kuti sizikuphatikizapo, zina mwa zinthu zofunika kuziganizira popanga gawo la sensa la njira yoyesera kutsekereza zaperekedwa mu Table 1.
Mayeso otsimikizira kutsimikiza kwa logic solver: Pamene mayeso otsimikizira kugwira ntchito mokwanira achitika, gawo la logic solver pokwaniritsa chitetezo cha SIF ndi zochita zina zokhudzana nazo (monga ma alarm, reset, bypasses, user diagnostics, redundancies, HMI, ndi zina zotero) zimayesedwa. Mayeso otsimikizira kugwira ntchito pang'ono kapena pang'ono ayenera kukwaniritsa mayeso onsewa ngati gawo la mayeso otsimikizira omwe amafanana. Wopanga logic solver ayenera kukhala ndi njira yoyesera umboni yomwe ikulangizidwa mu buku la chitetezo cha chipangizo. Ngati sichoncho, ndipo ngati sichoncho, mphamvu ya logic solver iyenera kuyendetsedwa, ndipo ma registers ozindikira logic solver, magetsi a status, magetsi amphamvu, maulalo olumikizirana ndi redundancy ayenera kuwonedwa. Macheke awa ayenera kuchitidwa mayeso asanayambe ntchito yonse proof proof.
Musaganize kuti pulogalamuyo ndi yabwino kwamuyaya ndipo mfundo zake siziyenera kuyesedwa pambuyo pa mayeso oyamba a umboni chifukwa zosintha za mapulogalamu ndi zida zosavomerezeka, zosavomerezeka komanso zosayesedwa zimatha kulowa m'makompyuta pakapita nthawi ndipo ziyenera kuganiziridwa mu lingaliro lanu lonse la mayeso a umboni. Kuyang'anira zolemba zosintha, kukonza, ndi kukonzanso kuyenera kuwunikidwanso kuti zitsimikizire kuti zasinthidwa komanso zikusamalidwa bwino, ndipo ngati zingatheke, pulogalamu ya pulogalamuyi iyenera kuyerekezeredwa ndi zosunga zobwezeretsera zaposachedwa.
Muyeneranso kusamala poyesa ntchito zonse zothandizira komanso zowunikira zomwe ogwiritsa ntchito angagwiritse ntchito (monga oyang'anira, maulalo olumikizirana, zida zachitetezo cha pa intaneti, ndi zina zotero).
Mayeso omaliza oletsa zinthu: Zinthu zambiri zomaliza ndi ma valve, komabe, zoyambira zamagalimoto zamagetsi zozungulira, ma drive osinthasintha ndi zida zina zamagetsi monga ma contactor ndi ma circuit breaker zimagwiritsidwanso ntchito ngati zinthu zomaliza ndipo njira zawo zolephera ziyenera kufufuzidwa ndikuyesedwa kuti zitsimikizidwe.
Njira zazikulu zolephera kwa ma valve ndi kutsekedwa, nthawi yoyankha imakhala yochedwa kwambiri kapena yothamanga kwambiri, komanso kutuluka kwa madzi, zomwe zonse zimakhudzidwa ndi mawonekedwe a njira yogwirira ntchito ya valve panthawi yoyenda. Ngakhale kuyesa valavu pamikhalidwe yogwirira ntchito ndi nkhani yabwino kwambiri, Ntchito nthawi zambiri sizingalepheretse kugwetsa SIF pamene fakitale ikugwira ntchito. Ma valve ambiri a SIS nthawi zambiri amayesedwa pomwe fakitale ili pansi pa zero differential pressure, zomwe ndi zovuta kwambiri pamikhalidwe yogwirira ntchito. Wogwiritsa ntchito ayenera kudziwa za kuthamanga kwambiri kwa magwiridwe antchito komanso zotsatira za kuwonongeka kwa valavu ndi njira, zomwe ziyenera kuganiziridwa mu kapangidwe ndi kukula kwa valavu ndi 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).
Kutentha kwa malo ozungulira kungakhudzenso kuchuluka kwa ma valve friction, kotero kuti ma valve oyesera nthawi yotentha nthawi zambiri amakhala otsika kwambiri poyerekeza ndi momwe amagwirira ntchito nthawi yozizira. Chifukwa chake, kuyesa ma valve pa kutentha kofanana kuyenera kuganiziridwa kuti kupereke deta yokhazikika yoyesera kuti mudziwe kuwonongeka kwa magwiridwe antchito a ma valve.
Ma valve okhala ndi ma positioners anzeru kapena chowongolera ma valve a digito nthawi zambiri amatha kupanga siginecha ya valve yomwe ingagwiritsidwe ntchito kuyang'anira kuwonongeka kwa magwiridwe antchito a valve. Siginecha ya valve yoyambira ikhoza kupemphedwa ngati gawo la oda yanu yogula kapena mutha kupanga imodzi panthawi yoyesa koyamba kuti ikhale ngati maziko. Siginecha ya valve iyenera kuchitidwa potsegula ndi kutseka valavu. Kuzindikira ma valve apamwamba kuyeneranso kugwiritsidwa ntchito ngati kulipo. Izi zingakuthandizeni kudziwa ngati magwiridwe antchito a valavu yanu akuchepa poyerekeza ma siginecha a valavu yoyesera umboni ndi matenda ndi maziko anu. Mtundu uwu wa mayeso ungathandize kubweza kusayesa valavu pakakhala zovuta kwambiri zogwirira ntchito.
Chizindikiro cha valavu panthawi yoyesa umboni chingathenso kulemba nthawi yoyankha ndi zizindikiro za nthawi, kuchotsa kufunikira kwa wotchi yoyimitsa. Kuwonjezeka kwa nthawi yoyankha ndi chizindikiro cha kuwonongeka kwa valavu ndi kuchuluka kwa katundu wokangana kuti valavu isunthe. Ngakhale palibe miyezo yokhudza kusintha kwa nthawi yoyankhira valavu, kusintha koyipa kuchokera ku mayeso oyesa umboni kupita ku mayeso oyesa umboni kumasonyeza kutayika kwa chitetezo cha valavu ndi magwiridwe antchito ake. Kuyesa kwamakono kwa valavu yoyesera valavu kuyenera kuphatikizapo chizindikiro cha valavu ngati nkhani yabwino yaukadaulo.
Kuthamanga kwa mpweya wa chipangizo cha valavu kuyenera kuyezedwa panthawi yoyesa kutsimikizira. Ngakhale kuti kasupe wa valavu ya valavu yobwerera ndi kasupe ndiye amene amatseka valavu, mphamvu kapena mphamvu yomwe ikukhudzidwa imatsimikiziridwa ndi kuchuluka kwa kasupe wa valavu komwe kakanikizidwa ndi kuthamanga kwa valavu (malinga ndi lamulo la Hooke, F = kX). Ngati kuthamanga kwanu kwamagetsi kuli kochepa, kasupeyo sadzakanikizidwa kwambiri, motero mphamvu yochepa idzapezeka kuti isunthe valavu ikafunika. Ngakhale sizikuphatikizapo, zina mwazinthu zomwe muyenera kuganizira popanga gawo la valavu ya njira yoyesera kutsimikizira zaperekedwa mu Gome 2.
Nthawi yotumizira: Novembala-13-2019