Uji bukti minangka bagean integral saka pangopènan integritas keamanan sistem instrumentasi keamanan (SIS) lan sistem sing ana gandhengane karo keamanan (kayata alarm kritis, sistem geni & gas, sistem interlock instrumentasi, lan liya-liyane). Uji bukti minangka uji periodik kanggo ndeteksi kegagalan sing mbebayani, nguji fungsi sing ana gandhengane karo keamanan (kayata reset, bypass, alarm, diagnostik, shutdown manual, lan liya-liyane), lan mesthekake yen sistem kasebut memenuhi standar perusahaan lan eksternal. Asil uji bukti uga minangka ukuran efektifitas program integritas mekanik SIS lan keandalan lapangan sistem kasebut.
Prosedur uji coba bukti nyakup langkah-langkah uji coba wiwit saka njupuk ijin, nggawe kabar, lan mbusak sistem saka layanan kanggo diuji nganti njamin uji coba sing komprehensif, ndokumentasikake uji coba bukti lan asile, masang maneh sistem menyang layanan, lan ngevaluasi asil uji coba saiki lan asil uji coba bukti sadurunge.
ANSI/ISA/IEC 61511-1, Klausul 16, nyakup uji coba bukti SIS. Laporan teknis ISA TR84.00.03 – “Integritas Mekanis Sistem Instrumentasi Keselamatan (SIS),” nyakup uji coba bukti lan saiki lagi direvisi kanthi versi anyar sing diarepake bakal metu rauh. Laporan teknis ISA TR96.05.02 – “Uji Coba Bukti In-situ Katup Otomatis” saiki lagi dikembangake.
Laporan HSE Inggris CRR 428/2002 – “Prinsip-prinsip kanggo uji coba bukti sistem instrumentasi keamanan ing industri kimia” nyedhiyakake informasi babagan uji coba bukti lan apa sing ditindakake perusahaan ing Inggris.
Prosedur uji coba bukti adhedhasar analisis mode kegagalan mbebayani sing dikenal kanggo saben komponen ing jalur trip fungsi instrumentasi keamanan (SIF), fungsi SIF minangka sistem, lan kepiye (lan yen) nguji mode kegagalan mbebayani. Pengembangan prosedur kudu diwiwiti ing fase desain SIF kanthi desain sistem, pemilihan komponen, lan nemtokake kapan lan kepiye uji coba bukti. Instrumen SIS duwe macem-macem tingkat kesulitan uji coba bukti sing kudu ditimbang ing desain, operasi, lan pangopènan SIF. Contone, meter orifice lan pemancar tekanan luwih gampang diuji tinimbang meter aliran massa Coriolis, meter mag, utawa sensor tingkat radar liwat udara. Aplikasi lan desain katup uga bisa mengaruhi kelengkapan uji coba bukti katup kanggo mesthekake yen kegagalan mbebayani lan wiwitan amarga degradasi, penyumbatan, utawa kegagalan sing gumantung wektu ora nyebabake kegagalan kritis sajrone interval uji sing dipilih.
Sanajan prosedur uji coba bukti biasane dikembangake sajrone fase teknik SIF, prosedur kasebut uga kudu ditinjau dening Otoritas Teknis SIS situs, Operasi, lan teknisi instrumen sing bakal nindakake uji coba. Analisis keamanan kerja (JSA) uga kudu ditindakake. Penting kanggo entuk persetujuan pabrik babagan uji coba apa sing bakal ditindakake lan kapan, lan kelayakan fisik lan keamanane. Contone, ora ana gunane kanggo nemtokake uji coba partial-stroke nalika klompok Operasi ora setuju kanggo nindakake. Uga disaranake supaya prosedur uji coba bukti ditinjau dening pakar subjek independen (SME). Uji coba khas sing dibutuhake kanggo uji coba fungsi lengkap digambarake ing Gambar 1.
Persyaratan uji bukti fungsi lengkap Gambar 1: Spesifikasi uji bukti fungsi lengkap kanggo fungsi instrumentasi keamanan (SIF) lan sistem instrumentasi keamanan (SIS) kudu njlentrehake utawa ngrujuk langkah-langkah kanthi urutan wiwit saka persiapan uji lan prosedur uji nganti notifikasi lan dokumentasi.
Gambar 1: Spesifikasi uji coba bukti fungsi lengkap kanggo fungsi instrumentasi keamanan (SIF) lan sistem instrumentasi keamanan (SIS) kudu njlentrehake utawa ngrujuk langkah-langkah kanthi urutan wiwit saka persiapan uji coba lan prosedur uji coba nganti notifikasi lan dokumentasi.
Uji coba bukti minangka tindakan perawatan sing direncanakake sing kudu ditindakake dening personel sing kompeten sing wis dilatih babagan uji coba SIS, prosedur uji coba, lan puteran SIS sing bakal diuji. Kudu ana tinjauan prosedur sadurunge nindakake uji coba bukti awal, lan umpan balik menyang Otoritas Teknis SIS situs sawise iku kanggo perbaikan utawa koreksi.
Ana rong mode kegagalan utama (aman utawa mbebayani), sing dipérang dadi patang mode—mbebayani ora terdeteksi, mbebayani dideteksi (dening diagnostik), aman ora terdeteksi lan aman dideteksi. Istilah kegagalan mbebayani lan mbebayani ora terdeteksi digunakake kanthi genti-genten ing artikel iki.
Ing uji coba bukti SIF, kita utamane kasengsem ing mode kegagalan sing mbebayani lan ora terdeteksi, nanging yen ana diagnostik pangguna sing ndeteksi kegagalan sing mbebayani, diagnostik kasebut kudu diuji bukti. Elinga yen ora kaya diagnostik pangguna, diagnostik internal piranti biasane ora bisa divalidasi minangka fungsional dening pangguna, lan iki bisa mengaruhi filosofi uji bukti. Nalika kredit kanggo diagnostik dijupuk ing pitungan SIL, alarm diagnostik (kayata alarm njaba jangkauan) kudu diuji minangka bagean saka uji bukti.
Mode kegagalan bisa dipérang manèh dadi mode kegagalan sing diuji sajrone uji bukti, mode sing ora diuji, lan mode kegagalan sing lagi diwiwiti utawa kegagalan sing gumantung wektu. Sawetara mode kegagalan sing mbebayani bisa uga ora diuji langsung amarga macem-macem alasan (kayata kangelan, keputusan teknik utawa operasional, ora ngerti, ora kompeten, kesalahan sistematis sing ora digatekake utawa ditindakake, kemungkinan kedadeyan sing sithik, lan liya-liyane). Yen ana mode kegagalan sing dikenal sing ora bakal diuji, kompensasi kudu ditindakake ing desain piranti, prosedur uji coba, panggantos utawa pembangunan maneh piranti kanthi periodik, lan/utawa uji coba inferensial kudu ditindakake kanggo nyuda efek ing integritas SIF saka ora nguji.
Kegagalan awal yaiku kahanan utawa kondisi sing mudhun saengga kegagalan kritis lan mbebayani bisa diarepake kedadeyan yen tindakan korektif ora ditindakake kanthi tepat wektu. Biasane dideteksi kanthi mbandhingake kinerja karo tes bukti patokan anyar utawa awal (kayata tandha tangan katup utawa wektu respon katup) utawa kanthi inspeksi (kayata port proses sing dipasang). Kegagalan awal biasane gumantung karo wektu—luwih suwe piranti utawa perakitan digunakake, luwih rusak; kahanan sing nggampangake kegagalan acak dadi luwih mungkin, port proses dipasang utawa sensor sing numpuk sajrone wektu, umur manfaat wis entek, lan liya-liyane. Mulane, luwih suwe interval uji bukti, luwih mungkin kegagalan awal utawa gumantung karo wektu. Proteksi apa wae marang kegagalan awal uga kudu diuji bukti (pembersihan port, pelacakan panas, lan liya-liyane).
Prosedur kudu ditulis kanggo nguji bukti kegagalan sing mbebayani (ora dideteksi). Teknik analisis mode kegagalan lan efek (FMEA) utawa analisis mode kegagalan, efek lan diagnostik (FMEDA) bisa mbantu ngenali kegagalan sing mbebayani lan ora dideteksi, lan ing ngendi jangkoan uji bukti kudu ditingkatake.
Akeh prosedur uji coba bukti sing ditulis adhedhasar pengalaman lan cithakan saka prosedur sing wis ana. Prosedur anyar lan SIF sing luwih rumit mbutuhake pendekatan sing luwih direkayasa nggunakake FMEA/FMEDA kanggo nganalisis kegagalan sing mbebayani, nemtokake kepiye prosedur uji coba bakal utawa ora bakal nguji kegagalan kasebut, lan jangkoan uji coba kasebut. Diagram blok analisis mode kegagalan tingkat makro kanggo sensor dituduhake ing Gambar 2. FMEA biasane mung kudu ditindakake sapisan kanggo jinis piranti tartamtu lan digunakake maneh kanggo piranti sing padha kanthi nimbang layanan proses, instalasi, lan kemampuan uji coba situs.
Analisis kegagalan tingkat makro Gambar 2: Diagram blok analisis mode kegagalan tingkat makro kanggo sensor lan pemancar tekanan (PT) iki nuduhake fungsi utama sing biasane bakal dipérang dadi pirang-pirang analisis kegagalan mikro kanggo nemtokake kanthi lengkap potensi kegagalan sing kudu ditangani ing tes fungsi.
Gambar 2: Diagram blok analisis mode kegagalan tingkat makro kanggo sensor lan pemancar tekanan (PT) iki nuduhake fungsi utama sing biasane bakal dipérang dadi pirang-pirang analisis kegagalan mikro kanggo nemtokake kanthi lengkap potensi kegagalan sing kudu ditangani ing tes fungsi.
Persentase kegagalan sing dikenal, mbebayani, lan ora dideteksi sing diuji buktine diarani jangkoan uji bukti (PTC). PTC umume digunakake ing pitungan SIL kanggo "ngimbangi" kegagalan kanggo nguji SIF kanthi luwih lengkap. Wong-wong duwe kapercayan sing salah yen amarga dheweke wis nimbang kekurangan jangkoan uji ing pitungan SIL, dheweke wis ngrancang SIF sing bisa dipercaya. Kasunyatan sing prasaja yaiku, yen jangkoan uji sampeyan 75%, lan yen sampeyan ngfaktorake angka kasebut menyang pitungan SIL lan nguji bab-bab sing wis sampeyan uji luwih asring, 25% saka kegagalan mbebayani isih bisa kedadeyan sacara statistik. Aku mesthi ora pengin ana ing 25% kasebut.
Laporan persetujuan FMEDA lan manual keamanan kanggo piranti biasane nyedhiyakake prosedur uji coba bukti minimal lan jangkoan uji coba bukti. Iki mung nyedhiyakake pandhuan, ora kabeh langkah uji sing dibutuhake kanggo prosedur uji coba bukti sing komprehensif. Jinis analisis kegagalan liyane, kayata analisis wit kesalahan lan perawatan sing fokus ing keandalan, uga digunakake kanggo nganalisis kegagalan sing mbebayani.
Tes bukti bisa dipérang dadi uji fungsional lengkap (end-to-end) utawa uji fungsional parsial (Gambar 3). Uji fungsional parsial umumé ditindakake nalika komponen SIF duwé interval uji sing béda ing itungan SIL sing ora cocog karo rencana penutupan utawa turnaround. Penting banget yen prosedur uji bukti fungsional parsial tumpang tindih supaya bebarengan nguji kabeh fungsi keamanan SIF. Kanthi uji fungsional parsial, isih disaranake SIF duwé uji bukti awal end-to-end, lan uji bukti sabanjuré sajrone turnaround.
Tes bukti parsial kudune jumlahe padha Gambar 3: Tes bukti parsial gabungan (ngisor) kudune nutupi kabeh fungsi saka tes bukti fungsional lengkap (ndhuwur).
Gambar 3: Tes bukti parsial gabungan (ngisor) kudune nutupi kabeh fungsi saka tes bukti fungsional lengkap (ndhuwur).
Tes bukti parsial mung nguji persentase mode kegagalan piranti. Conto umum yaiku uji katup partial-stroke, ing ngendi katup dipindhah sithik (10-20%) kanggo verifikasi manawa ora macet. Iki nduweni jangkoan uji bukti sing luwih murah tinimbang uji bukti ing interval uji utama.
Prosedur uji bukti bisa beda-beda kerumitané miturut kerumitan SIF lan filosofi prosedur uji perusahaan. Sawetara perusahaan nulis prosedur uji langkah demi langkah sing rinci, dene perusahaan liyané duwé prosedur sing cukup ringkes. Referensi menyang prosedur liyané, kayata kalibrasi standar, kadhangkala digunakaké kanggo nyuda ukuran prosedur uji bukti lan kanggo mbantu njamin konsistensi ing uji coba. Prosedur uji bukti sing apik kudu nyedhiyakake rincian sing cukup kanggo mesthekake yen kabeh uji coba wis dirampungake lan didokumentasikake kanthi bener, nanging ora pati rinci nganti teknisi pengin nglewati langkah-langkah kasebut. Ndhuweni teknisi, sing tanggung jawab kanggo nindakake langkah uji coba, sing miwiti langkah uji coba sing wis rampung bisa mbantu njamin manawa uji coba bakal ditindakake kanthi bener. Penandatanganan uji bukti sing wis rampung dening Pengawas Instrumen lan wakil Operasi uga bakal nandheske pentinge lan njamin uji bukti sing wis rampung kanthi bener.
Umpan balik saka teknisi kudu tansah diundang kanggo mbantu ningkatake prosedur kasebut. Kasuksesan prosedur uji bukti sebagian besar ana ing tangan teknisi, mula upaya kolaboratif banget dianjurake.
Umume uji coba bukti biasane ditindakake kanthi offline sajrone shutdown utawa turnaround. Ing sawetara kasus, uji coba bukti bisa uga dibutuhake kanthi online nalika mlaku kanggo nyukupi pitungan SIL utawa syarat liyane. Uji coba online mbutuhake perencanaan lan koordinasi karo Operasi supaya uji coba bukti bisa ditindakake kanthi aman, tanpa proses sing ngganggu, lan tanpa nyebabake spurious trip. Mung butuh siji spurious trip kanggo nggunakake kabeh attaboy sampeyan. Sajrone jinis uji coba iki, nalika SIF ora kasedhiya kanthi lengkap kanggo nindakake tugas keamanane, 61511-1, Klausul 11.8.5, nyatakake yen "Langkah-langkah kompensasi sing njamin operasi sing aman terus kudu diwenehake miturut 11.3 nalika SIS ana ing bypass (ndandani utawa nguji)." Prosedur manajemen kahanan sing ora normal kudu digabung karo prosedur uji coba bukti kanggo mbantu mesthekake iki ditindakake kanthi bener.
SIF biasane dipérang dadi telung bagean utama: sensor, pemecah logika, lan elemen pungkasan. Ana uga piranti tambahan sing bisa digandhengake ing saben telung bagean iki (kayata alangan IS, amp trip, relay interposing, solenoid, lan liya-liyane) sing uga kudu diuji. Aspek penting saka uji coba bukti saben teknologi iki bisa ditemokake ing sidebar, "Nguji sensor, pemecah logika, lan elemen pungkasan" (ing ngisor).
Ana sawetara perkara sing luwih gampang diuji tinimbang liyane. Akeh teknologi aliran lan level modern lan sawetara sing luwih lawas kalebu kategori sing luwih angel. Iki kalebu flowmeter Coriolis, vortex meter, mag meter, radar liwat udara, level ultrasonik, lan saklar proses in-situ, lan liya-liyane. Untunge, akeh sing saiki duwe diagnostik sing luwih apik sing ngidini pengujian sing luwih apik.
Kesulitan nguji bukti piranti kasebut ing lapangan kudu ditimbang ing desain SIF. Gampang banget kanggo teknik milih piranti SIF tanpa nimbang kanthi serius apa sing dibutuhake kanggo nguji bukti piranti kasebut, amarga piranti kasebut dudu wong sing nguji. Iki uga bener kanggo uji coba partial-stroke, sing minangka cara umum kanggo nambah kemungkinan rata-rata SIF saka kegagalan nalika dibutuhake (PFDavg), nanging mengko Operasi pabrik ora pengin nindakake, lan asring ora bisa. Tansah menehi pengawasan pabrik babagan teknik SIF babagan uji coba bukti.
Tes bukti kudu kalebu inspeksi instalasi lan perbaikan SIF sing dibutuhake kanggo nyukupi 61511-1, Klausul 16.3.2. Kudu ana inspeksi pungkasan kanggo mesthekake kabeh wis dipasang kanthi bener, lan priksa maneh manawa SIF wis diselehake maneh kanthi bener menyang layanan proses.
Nulis lan ngetrapake prosedur tes sing apik minangka langkah penting kanggo njamin integritas SIF sajrone umure. Prosedur tes kudu menehi rincian sing cukup kanggo mesthekake yen tes sing dibutuhake ditindakake lan didokumentasikake kanthi konsisten lan aman. Kegagalan mbebayani sing ora diuji dening tes bukti kudu diimbangi kanggo mesthekake yen integritas keamanan SIF dijaga kanthi cukup sajrone umure.
Nulis prosedur uji coba bukti sing apik mbutuhake pendekatan logis kanggo analisis teknik babagan potensi kegagalan sing mbebayani, milih sarana, lan nulis langkah-langkah uji coba bukti sing ana ing kemampuan uji coba pabrik. Sajrone proses kasebut, entuk dukungan saka pabrik ing kabeh tingkat kanggo uji coba kasebut, lan latih teknisi kanggo nindakake lan ndokumentasikake uji coba bukti kasebut uga ngerti pentinge uji coba kasebut. Tulis pandhuan kaya-kaya sampeyan minangka teknisi instrumen sing kudu nindakake pakaryan kasebut, lan urip gumantung saka entuk uji coba sing bener, amarga pancen bener.
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 biasane dipérang dadi telung bagean utama, sensor, pemecah logika, lan unsur pungkasan. Biasane uga ana piranti tambahan sing bisa digandhengake ing saben telung bagean iki (kayata alangan IS, amp trip, relay interposing, solenoid, lan liya-liyane) sing uga kudu diuji.
Tes bukti sensor: Tes bukti sensor kudu njamin manawa sensor bisa ngrasakake variabel proses ing jangkauan lengkap lan ngirim sinyal sing tepat menyang pemecah logika SIS kanggo evaluasi. Sanajan ora kalebu, sawetara perkara sing kudu ditimbang nalika nggawe bagean sensor saka prosedur uji bukti diwenehake ing Tabel 1.
Tes bukti pemecah logika: Nalika uji coba bukti fungsi lengkap ditindakake, peran pemecah logika ing ngrampungake tindakan keamanan SIF lan tindakan sing gegandhengan (kayata alarm, reset, bypass, diagnostik pangguna, redundansi, HMI, lan liya-liyane) diuji. Tes bukti fungsi sebagian utawa sebagian kudu ngrampungake kabeh tes kasebut minangka bagean saka tes bukti tumpang tindih individu. Produsen pemecah logika kudu duwe prosedur uji bukti sing disaranake ing manual keamanan piranti. Yen ora lan paling ora, daya pemecah logika kudu didaur ulang, lan register diagnostik pemecah logika, lampu status, voltase catu daya, pranala komunikasi lan redundansi kudu dicenthang. Pamriksaan kasebut kudu ditindakake sadurunge tes bukti fungsi lengkap.
Aja nganggep yen piranti lunak kasebut apik selawase lan logika kasebut ora perlu diuji sawise uji coba awal amarga owah-owahan piranti lunak lan perangkat keras sing ora didokumentasikake, ora sah, lan durung diuji, sarta pembaruan piranti lunak bisa mlebu ing sistem sajrone wektu lan kudu difaktorake ing filosofi uji coba bukti sakabèhé. Manajemen log owah-owahan, pangopènan, lan revisi kudu ditinjau kanggo mesthekake yen wis dianyari lan dijaga kanthi bener, lan yen bisa, program aplikasi kudu dibandhingake karo serep paling anyar.
Uga kudu ati-ati kanggo nguji kabeh fungsi bantu lan diagnostik pemecah logika pangguna (kayata pengawas, pranala komunikasi, piranti keamanan siber, lan liya-liyane).
Uji bukti elemen pungkasan: Umume elemen pungkasan yaiku katup, nanging, starter motor peralatan sing muter, penggerak kecepatan variabel, lan komponen listrik liyane kayata kontaktor lan pemutus sirkuit uga digunakake minangka elemen pungkasan lan mode kegagalane kudu dianalisis lan diuji buktine.
Mode kegagalan utama kanggo katup yaiku macet, wektu respon alon banget utawa cepet banget, lan bocor, kabeh mau kena pengaruh antarmuka proses operasi katup nalika wektu trip. Sanajan nguji katup ing kondisi operasi minangka kasus sing paling disenengi, Operasi umume ora bakal ngganggu trip SIF nalika pabrik lagi beroperasi. Umume katup SIS biasane diuji nalika pabrik mudhun ing tekanan diferensial nol, sing minangka kondisi operasi sing paling ora nuntut. Pangguna kudu ngerti tekanan diferensial operasional paling awon lan efek degradasi katup lan proses, sing kudu difaktorake ing desain lan ukuran katup lan aktuator.
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).
Suhu sekitar uga bisa mengaruhi beban gesekan katup, saengga katup uji coba ing cuaca panas umume bakal dadi beban gesekan sing paling ora mbutuhake beban yen dibandhingake karo operasi cuaca adhem. Akibate, uji coba bukti katup ing suhu sing konsisten kudu dianggep kanggo nyedhiyakake data sing konsisten kanggo uji inferensial kanggo nemtokake degradasi kinerja katup.
Katup nganggo posisi cerdas utawa pengontrol katup digital umume duwe kemampuan kanggo nggawe tandha tangan katup sing bisa digunakake kanggo ngawasi degradasi kinerja katup. Tandha tangan katup dhasar bisa dijaluk minangka bagean saka pesenan tuku utawa sampeyan bisa nggawe nalika tes bukti awal kanggo dadi garis dasar. Tandha tangan katup kudu ditindakake kanggo mbukak lan nutup katup. Diagnostik katup tingkat lanjut uga kudu digunakake yen kasedhiya. Iki bisa mbantu ngandhani sampeyan yen kinerja katup sampeyan saya mudhun kanthi mbandhingake tandha tangan lan diagnostik katup tes bukti sabanjure karo garis dasar sampeyan. Jinis tes iki bisa mbantu ngimbangi ora nguji katup ing tekanan operasi paling awon.
Tandha tangan klep sajrone uji coba uga bisa ngrekam wektu respon nganggo cap wektu, saengga ora perlu stopwatch. Tambah wektu respon minangka tandha kerusakan klep lan tambah beban gesekan kanggo mindhah klep. Sanajan ora ana standar babagan owah-owahan wektu respon klep, pola owah-owahan negatif saka uji coba menyang uji coba nuduhake potensi kerugian margin keamanan lan kinerja klep. Uji coba uji coba klep SIS modern kudu kalebu tandha tangan klep minangka praktik teknik sing apik.
Tekanan pasokan udara instrumen katup kudu diukur sajrone uji coba bukti. Sanajan pegas katup kanggo katup bali pegas sing nutup katup, gaya utawa torsi sing digunakake ditemtokake dening sepira pegas katup dikompres dening tekanan pasokan katup (miturut Hukum Hooke, F = kX). Yen tekanan pasokan sampeyan kurang, pegas ora bakal kompres akeh, mula gaya sing kasedhiya kanggo mindhah katup nalika dibutuhake luwih sithik. Sanajan ora kalebu, sawetara perkara sing kudu ditimbang nalika nggawe bagean katup saka prosedur uji coba bukti diwenehake ing Tabel 2.
Wektu kiriman: 13-Nov-2019