Nnwale ihe akaebe bụ akụkụ dị mkpa nke mmezi nke iguzosi ike n'ezi ihe nchekwa nke sistemụ anyị nwere ngwaọrụ nchekwa (SIS) na sistemụ ndị metụtara nchekwa (dịka ọmụmaatụ mkpu dị mkpa, sistemụ ọkụ na gas, sistemụ mkpọchi ngwa ọrụ, wdg). Nnwale ihe akaebe bụ nnwale oge iji chọpụta ọdịda dị ize ndụ, nwalee ọrụ metụtara nchekwa (dịka ọmụmaatụ ịtọgharịa, gafere, mkpu, nchọpụta ihe, mmechi aka, wdg), ma hụ na sistemụ ahụ na-emezu ụkpụrụ ụlọ ọrụ na mpụga. Nsonaazụ nke nnwale ihe akaebe bụkwa ihe atụ nke irè nke mmemme iguzosi ike n'ezi ihe SIS na ntụkwasị obi ubi nke sistemụ ahụ.
Usoro nnwale akaebe na-ekpuchi usoro ule site n'inweta ikike, ime ọkwa na iwepụ sistemụ ahụ n'ọrụ maka nnwale ruo n'ịhụ na nnwale zuru oke, idekọ ule akaebe na nsonaazụ ya, itinye sistemụ ahụ n'ọrụ ọzọ, na inyocha nsonaazụ ule ugbu a na nsonaazụ ule akaebe gara aga.
ANSI/ISA/IEC 61511-1, Nkebi nke 16, na-ekpuchi nnwale SIS. Akụkọ teknụzụ ISA TR84.00.03 – “Nguzosi ike n'ezi ihe nke Sistemụ Nchekwa (SIS),” na-ekpuchi nnwale akaebe ma a na-eme mgbanwe ugbu a yana a na-atụ anya na a ga-ewepụta ụdị ọhụrụ n'oge na-adịghị anya. Akụkọ teknụzụ ISA TR96.05.02 – “Nnwale Nnwale Nnwale N'ime-ebe nke Valves Akpaaka” ka a na-emepụta ugbu a.
Akụkọ UK HSE CRR 428/2002 – “Ụkpụrụ maka nnwale akaebe nke sistemụ eji ngwaọrụ nchekwa eme ihe n'ụlọ ọrụ kemịkalụ” na-enye ozi gbasara nnwale akaebe na ihe ụlọ ọrụ na-eme na UK.
Usoro nnwale ihe akaebe dabere na nyocha nke ụdị ọdịda dị ize ndụ a maara maka akụkụ ọ bụla dị na ụzọ njem ọrụ nchekwa (SIF), ọrụ SIF dị ka sistemụ, na otu esi (na ma ọ bụrụ) nwalee maka ọnọdụ ọdịda dị ize ndụ. Mmepe usoro kwesịrị ịmalite na usoro nhazi SIF site na nhazi sistemụ, nhọrọ nke ihe mejupụtara, na mkpebi nke oge na otu esi egosi ule. Ngwaọrụ SIS nwere ogo dị iche iche nke nsogbu nnwale ihe akaebe nke a ga-atụle na nhazi, ọrụ na mmezi SIF. Dịka ọmụmaatụ, mita orifice na ndị na-ebufe nrụgide dị mfe ịnwale karịa mita Coriolis mass flowmeters, mita mag ma ọ bụ sensọ ọkwa radar site na ikuku. Ngwa na nhazi valvụ nwekwara ike imetụta oke nke ule ihe akaebe valvụ iji hụ na ọdịda dị ize ndụ na nke mbido n'ihi mmebi, nkwụnye ma ọ bụ ọdịda dabere na oge anaghị ebute ọdịda dị oke njọ n'ime oge nnwale ahọpụtara.
Ọ bụ ezie na a na-emepụta usoro nnwale n'oge usoro injinia SIF, saịtị SIS Technical Authority, Operations na ndị ọkachamara na ngwa ọrụ ga-eme nnwale ahụ kwesịkwara inyocha ha. Ekwesịrị ime nyocha nchekwa ọrụ (JSA). Ọ dị mkpa ka ụlọ ọrụ ahụ kwenye na ule a ga-eme na mgbe, yana ohere anụ ahụ na nchekwa ha. Dịka ọmụmaatụ, ọ baghị uru ịkọwapụta nnwale strok nke akụkụ mgbe otu ọrụ anaghị ekwenye ime ya. A na-atụkwa aro ka ọkachamara isiokwu nọọrọ onwe ya (SME) nyochaa usoro nnwale ahụ. E gosipụtara nnwale a na-achọkarị maka ule akaebe ọrụ zuru oke na Foto 1.
Ihe achọrọ maka ule nkwenye ọrụ zuru oke Foto nke 1: Nkọwapụta ule nkwenye ọrụ zuru oke maka ọrụ akụrụngwa nchekwa (SIF) na sistemụ ngwaọrụ nchekwa ya (SIS) kwesịrị ịkọwa ma ọ bụ zoo aka na usoro ndị dị n'usoro site na nkwadebe ule na usoro ule ruo na ọkwa na akwụkwọ.
Foto nke 1: Nkọwapụta ule zuru oke maka ọrụ nchekwa (SIF) na sistemụ nchekwa ya (SIS) kwesịrị ịkọwa ma ọ bụ zoo aka na usoro ndị dị n'usoro site na nkwadebe ule na usoro ule ruo na ọkwa na akwụkwọ.
Nnwale ihe akaebe bụ ihe a na-eme atụmatụ maka mmezi nke ndị ọrụ ruru eru a zụrụ azụ n'ule SIS, usoro ihe akaebe, na okirikiri SIS ha ga-anwale kwesịrị ime. E kwesịrị ịtụle usoro ahụ tupu emee ule ihe akaebe mbụ, ma nye nzaghachi na saịtị SIS Technical Authority maka mmezi ma ọ bụ ndozi.
E nwere ụzọ abụọ isi ọdịda (dị mma ma ọ bụ dị ize ndụ), nke kewara n'ime ụzọ anọ—nke dị ize ndụ nke a na-achọpụtaghị, nke dị ize ndụ nke a chọpụtara (site na nchọpụta), nke a na-achọpụtaghị na nke dị nchebe. A na-eji okwu ọdịda dị ize ndụ na nke dị ize ndụ nke a na-achọpụtaghị na-agbanwe agbanwe n'isiokwu a.
N'ule ihe akaebe SIF, anyị nwere mmasị na ụzọ ọdịda dị ize ndụ a na-achọpụtaghị, mana ọ bụrụ na enwere nchọpụta ihe njirimara nke onye ọrụ na-achọpụta ọdịda dị ize ndụ, a ga-anwale nchọpụta ihe akaebe ndị a. Mara na n'adịghị ka nchọpụta ihe njirimara nke onye ọrụ, onye ọrụ anaghị enyocha nchọpụta ihe mmetụta dị n'ime ngwaọrụ dị ka ọrụ, nke a nwekwara ike imetụta echiche ihe akaebe. Mgbe a na-ewere kredit maka nchọpụta ihe mgbaàmà na mgbakọ na mwepụ SIL, a ga-anwale mkpu nchọpụta ihe mgbaàmà (dịka ọmụmaatụ mkpu ndị na-adịghị anya) dị ka akụkụ nke nnwale ihe akaebe.
Enwere ike kewaa ụdị ọdịda ọzọ n'ime ndị a nwalere n'oge ule nnwale, ndị a na-anwaleghị maka ha, na ọdịda mmalite ma ọ bụ ọdịda dabere na oge. Enwere ike ọ gaghị anwale ụfọdụ ụdị ọdịda dị ize ndụ ozugbo maka ọtụtụ ihe kpatara ya (dịka ihe isi ike, mkpebi injinia ma ọ bụ ọrụ, amaghị ihe, enweghị ikike, mmejọ sistemụ na-apụ apụ ma ọ bụ iwu, obere ohere nke ihe omume, wdg). Ọ bụrụ na enwere ụdị ọdịda a maara nke a na-agaghị anwale maka ya, a ga-akwụghachi ụgwọ na nhazi ngwaọrụ, usoro nnwale, nnọchi ma ọ bụ iwughachi ngwaọrụ oge, na/ma ọ bụ nnwale inferential kwesịrị ime iji belata mmetụta na iguzosi ike n'ezi ihe SIF nke enweghị nnwale.
Ọdịda mmalite bụ ọnọdụ ma ọ bụ ọnọdụ na-emebi emebi nke na a pụrụ ịtụ anya na ọdịda dị oke njọ, dị ize ndụ ga-eme ma ọ bụrụ na emeghị ihe ndozi n'oge. A na-ahụkarị ha site na iji arụmọrụ tụnyere ule ihe akaebe nke mbụ ma ọ bụ nke mbụ (dịka ọmụmaatụ mbinye aka valvụ ma ọ bụ oge nzaghachi valvụ) ma ọ bụ site na nyocha (dịka ọdụ ụgbọ mmiri usoro arụnyere). Ọdịda mmalite na-adaberekarị na oge - ka ngwaọrụ ma ọ bụ mgbakọ ahụ na-arụ ọrụ ogologo oge, otú ahụ ka ọ na-emebiwanye; ọnọdụ ndị na-eme ka ọdịda enweghị usoro dịkwuo mfe, nhazi nkwụnye ọdụ ụgbọ mmiri ma ọ bụ nchịkọta sensọ ka oge na-aga, ndụ bara uru agwụla, wdg. Ya mere, ka oge nnwale ihe akaebe ahụ dị ogologo, otú ahụ ka o yikarịrị ka ọdịda mmalite ma ọ bụ nke dabere na oge ga-adị. A ga-anwalekwa ihe nchebe ọ bụla megide ọdịda mmalite (nhicha ọdụ ụgbọ mmiri, nchọpụta okpomọkụ, wdg).
A ga-ederịrị usoro ndị a n'ule ihe akaebe maka ọdịda dị ize ndụ (nke a na-achọpụtaghị). Usoro nyocha ọnọdụ ọdịda na mmetụta (FMEA) ma ọ bụ usoro nyocha ọnọdụ ọdịda, mmetụta na nchọpụta ọrịa (FMEDA) nwere ike inyere aka ịchọpụta ọdịda dị ize ndụ a na-achọpụtaghị, yana ebe a ga-emeziwanye mkpuchi nnwale ahụ.
Ọtụtụ usoro nnwale akaebe bụ ahụmịhe edere ede na ndebiri sitere na usoro ndị dị adị. Usoro ọhụrụ na SIF ndị ka sie ike na-achọ ụzọ e ji aka hazie nke ọma site na iji FMEA/FMEDA iji nyochaa ọdịda dị ize ndụ, chọpụta otu usoro nnwale ga-esi nwalee ma ọ bụ na ọ gaghị anwale ọdịda ndị ahụ, yana mkpuchi nke ule ndị ahụ. E gosiri eserese ngọngọ nyocha ọnọdụ ọdịda makro-ọkwa maka ihe mmetụta na Foto 2. FMEA na-achọkarị ime otu ugboro maka ụdị ngwaọrụ ụfọdụ ma jiri ya mee ihe ọzọ maka ngwaọrụ ndị yiri ya na-atụle ọrụ usoro ha, ntinye na ikike nnwale saịtị.
Nyocha ọdịda ọkwa macro Foto nke 2: Eserese ngọngọ nyocha ọnọdụ ọdịda macro-level a maka ihe mmetụta na onye na-ebufe nrụgide (PT) na-egosi ọrụ ndị bụ isi a ga-ekewa n'ime ọtụtụ nyocha ọdịda obere iji kọwaa nke ọma ọdịda nwere ike idozi na ule ọrụ.
Foto nke 2: Eserese ngọngọ nyocha ọnọdụ ọdịda macro-level a maka ihe mmetụta na onye na-ebufe nrụgide (PT) na-egosi ọrụ ndị bụ isi a ga-ekewa n'ime ọtụtụ nyocha ọdịda obere iji kọwaa nke ọma ọdịda nwere ike idozi na ule ọrụ.
A na-akpọ pasentị nke ọdịda a maara, dị ize ndụ, na nke a na-achọpụtaghị nke a nwalere ihe akaebe mkpuchi ule (PTC). A na-ejikarị PTC eme ihe na mgbakọ SIL iji "kwụọ" ụgwọ maka ọdịda ịnwale SIF nke ọma. Ndị mmadụ nwere nkwenye hiere ụzọ na n'ihi na ha atụlewo enweghị mkpuchi ule na mgbakọ SIL ha, ha emepụtala SIF a pụrụ ịtụkwasị obi. Eziokwu dị mfe bụ na, ọ bụrụ na mkpuchi ule gị bụ 75%, ọ bụrụkwa na i tinyere ọnụọgụ ahụ n'ime mgbakọ SIL gị ma nwalee ihe ị na-anwale ugboro ugboro, 25% nke ọdịda dị ize ndụ ka nwere ike ime na ọnụọgụgụ. Achọghị m ịnọ na 25% ahụ.
Akụkọ nkwado FMEDA na akwụkwọ ntuziaka nchekwa maka ngwaọrụ na-enyekarị usoro nnwale kacha nta na mkpuchi nnwale. Ndị a na-enye naanị nduzi, ọ bụghị usoro nnwale niile achọrọ maka usoro nnwale nnwale zuru oke. A na-ejikwa ụdị nyocha ọdịda ndị ọzọ, dị ka nyocha osisi mmejọ na mmezi nke dabere na ntụkwasị obi, iji nyochaa maka ọdịda dị ize ndụ.
Enwere ike kewaa ule nnwale n'ime ule ọrụ zuru oke (site na njedebe ruo na njedebe) ma ọ bụ nke akụkụ (Foto nke 3). A na-emekarị nnwale ọrụ nke akụkụ mgbe ihe ndị dị na SIF nwere oge ule dị iche iche na mgbakọ SIL nke na-adabaghị na mmechi ma ọ bụ mgbanwe atụmatụ. Ọ dị mkpa ka usoro ule ihe akaebe ọrụ nke akụkụ jikọtara ọnụ nke na ha na-anwale ọrụ nchekwa niile nke SIF. Site na nnwale ọrụ nke akụkụ, a ka na-atụ aro ka SIF nwee ule ihe akaebe mbụ site na njedebe ruo na njedebe, yana ndị na-esote n'oge mgbanwe.
Nnwale ihe akaebe nke akụkụ kwesịrị ịgbakọ Foto nke 3: Nnwale ihe akaebe nke akụkụ (ala) jikọtara kwesịrị ikpuchi ọrụ niile nke ule ihe akaebe zuru oke (n'elu).
Foto nke 3: Nnwale ihe akaebe nke akụkụ (ala) jikọtara ọnụ kwesịrị ikpuchi ọrụ niile nke ule ihe akaebe zuru oke (n'elu).
Nnwale ihe akaebe nke akụkụ na-anwale naanị pasentị nke ụdị ọdịda ngwaọrụ. Ihe atụ a na-ahụkarị bụ nnwale valvụ nke akụkụ na-akpata ọrịa strok, ebe a na-ebugharị valvụ ahụ obere ego (10-20%) iji hụ na ọ raparaghị. Nke a nwere mkpuchi ihe akaebe dị ala karịa ule ihe akaebe na oge nnwale mbụ.
Usoro nnwale akaebe nwere ike ịdị iche na mgbagwoju anya dịka SIF na usoro ule ụlọ ọrụ si dị. Ụfọdụ ụlọ ọrụ na-ede usoro nnwale zuru ezu site na nzọụkwụ, ebe ndị ọzọ nwere usoro dị mkpirikpi. Mgbe ụfọdụ, a na-eji ntụaka maka usoro ndị ọzọ, dị ka nhazi ọkọlọtọ, belata nha nke usoro nnwale akaebe ma nyere aka hụ na nnwale ahụ na-aga n'ihu. Usoro nnwale akaebe dị mma kwesịrị inye nkọwa zuru oke iji hụ na emechara ule niile nke ọma ma dekọọ ya, mana ọ bụghị nkọwa zuru oke iji mee ka ndị ọrụ teknụzụ chọọ ịgafe nzọụkwụ. Inwe onye ọrụ teknụzụ, onye bụ ọrụ maka ime usoro nnwale ahụ, mmalite nzọụkwụ nnwale emechara nwere ike inyere aka hụ na a ga-eme ule ahụ nke ọma. Mbinye aka nke ule akaebe emechara site n'aka onye nnọchi anya Ngwaọrụ na Ọrụ ga-emesi ike mkpa ọ dị ma hụ na ule akaebe emechara nke ọma.
A ga-agwa ndị ọkachamara okwu mgbe niile ka ha nyere aka melite usoro ahụ. Ọganiihu nke usoro nnwale akaebe dị n'aka ndị ọkachamara, yabụ a na-atụ aro nke ukwuu ka a mee mgbalị ọnụ.
A na-emekarị ọtụtụ nnwale ihe akaebe n'èzí n'oge mmechi ma ọ bụ ntụgharị. N'ọnọdụ ụfọdụ, a pụrụ ịchọ ka e mee nnwale ihe akaebe n'ịntanetị mgbe a na-agba ọsọ iji mezuo mgbakọ SIL ma ọ bụ ihe ndị ọzọ achọrọ. Nnwale n'ịntanetị chọrọ atụmatụ na nhazi na Ọrụ iji kwe ka e mee nnwale ihe akaebe ahụ n'enweghị nsogbu, na-enweghị nsogbu usoro, na-enweghịkwa ihe kpatara njem aghụghọ. Ọ na-ewe naanị otu njem aghụghọ iji jiri ndị mmegide gị niile mee ihe. N'oge ụdị ule a, mgbe SIF adịghị njikere ịrụ ọrụ nchekwa ya, 61511-1, Nkebi nke 11.8.5, na-ekwu na "A ga-enye usoro ịkwụghachi ụgwọ nke na-ahụ na ọrụ nchekwa na-aga n'ihu dịka 11.3 si dị mgbe SIS nọ na mgbochi (nrụzi ma ọ bụ nnwale)." Usoro njikwa ọnọdụ na-adịghị mma kwesịrị ịga na usoro nnwale ihe akaebe iji nyere aka hụ na emechara nke a nke ọma.
A na-ekewa SIF n'ime akụkụ atọ bụ isi: ihe mmetụta, ihe ngwọta mgbagha na ihe ikpeazụ. E nwekwara ngwaọrụ enyemaka nke enwere ike ijikọ n'ime akụkụ atọ a (dịka ihe mgbochi IS, amps trip, relays interposing, solenoids, wdg) nke a ga-anwalekwa. Akụkụ dị mkpa nke nnwale ihe akaebe nke teknụzụ ndị a nwere ike ịchọta na sidebar, "Nnwale ihe mmetụta, ihe ngwọta mgbagha na ihe ikpeazụ" (n'okpuru).
Ụfọdụ ihe dị mfe ịchọpụta karịa ndị ọzọ. Ọtụtụ teknụzụ ọgbara ọhụrụ na ole na ole ochie na-agba ọsọ na ọkwa dị n'ụdị siri ike karị. Ndị a gụnyere mita Coriolis, mita vortex, mita mag, radar ikuku, ọkwa ultrasonic, na mgbanwe usoro n'ime ebe, dịka ọmụmaatụ. Ọ dabara nke ọma, ọtụtụ n'ime ndị a nwere nchọpụta ka mma ugbu a nke na-enye ohere ka nnwale ka mma.
A ga-atụle ihe isi ike nke nnwale ihe akaebe dị otu a n'ọhịa na nhazi SIF. Ọ dị mfe maka injinia ịhọrọ ngwaọrụ SIF na-atụleghị ihe a ga-achọ iji nwalee ihe akaebe, ebe ọ bụ na ha agaghị abụ ndị na-anwale ha. Nke a bụkwa eziokwu maka nnwale akụkụ-stroke, nke bụ ụzọ a na-ahụkarị iji melite ohere nke ọdịda SIF nkezi na ọchịchọ (PFDavg), mana mgbe e mesịrị na ụlọ ọrụ ahụ, Ọrụ anaghị achọ ime ya, ọtụtụ mgbe ọ nwere ike ọ gaghị eme ya. Na-enye nlekọta osisi mgbe niile na injinịa SIFs gbasara nnwale ihe akaebe.
Nnwale ihe akaebe kwesịrị ịgụnye inyocha nrụnye na ndozi SIF dịka ọ dị mkpa iji mezuo 61511-1, Nkebi nke 16.3.2. Ekwesịrị ime nyocha ikpeazụ iji hụ na e tinyere ihe niile n'elu bọtịnụ, yana nlele ugboro abụọ na e tinyela SIF n'ọrụ nhazi nke ọma.
Ide na itinye usoro nnwale dị mma n'ọrụ bụ nzọụkwụ dị mkpa iji hụ na SIF bụ eziokwu n'oge ndụ ya niile. Usoro nnwale ahụ kwesịrị inye nkọwa zuru oke iji hụ na a na-eme ule ndị achọrọ mgbe niile na n'enweghị nsogbu ma dekọọ ha. A ga-akwụ ụgwọ maka ọdịda dị ize ndụ nke a na-anaghị anwale site na ule akaebe iji hụ na a na-edobe nchekwa SIF nke ọma n'oge ndụ ya niile.
Ide usoro nnwale dị mma chọrọ ụzọ ezi uche dị na ya iji nyochaa injinia nke ọdịda ndị nwere ike ịdị ize ndụ, ịhọrọ ụzọ, na ide usoro nnwale akaebe dị n'ime ikike nnwale nke ụlọ ọrụ ahụ. Ka ị na-aga, nweta nnabata n'ọrụ osisi n'ọkwa niile maka nnwale ahụ, ma zụọ ndị ọrụ teknụzụ ka ha mee ma dekọọ ule nnwale ahụ yana ịghọta mkpa nke ule ahụ. Dee ntuziaka dị ka a ga-asị na ị bụ onye ọrụ teknụzụ nke ga-arụ ọrụ ahụ, na ndụ dabere na ịnweta nnwale ahụ nke ọma, n'ihi na ha na-eme ya.
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
A na-ekewa SIF n'ime akụkụ atọ bụ isi, ihe mmetụta, ihe ngwọta echiche na ihe ndị ikpeazụ. E nwekwara ngwaọrụ enyemaka ndị enwere ike ijikọ n'ime akụkụ atọ a (dịka ihe mgbochi IS, amps trip, relays interposing, solenoids, wdg) nke a ga-anwalekwa.
Nnwale ihe akaebe nke sensọ: Nnwale ihe akaebe nke sensọ ga-ahụ na ihe mmetụta ahụ nwere ike ịchọpụta mgbanwe usoro ahụ n'ofe oke ya ma ziga akara kwesịrị ekwesị na ihe ngwọta SIS maka nyocha. Ọ bụ ezie na ọ bụghị nke gụnyere, ụfọdụ ihe ndị a ga-atụle n'ịmepụta akụkụ ihe mmetụta nke usoro nnwale ahụ dị na Tebụl 1.
Nnwale ihe akaebe nke ihe ngwọta mgbagwoju anya: Mgbe emechara nnwale ihe akaebe zuru oke, a na-anwale akụkụ nke onye na-edozi mgbagwoju anya n'imezu ihe nchekwa SIF na ihe ndị metụtara ya (dịka ọmụmaatụ mkpu, nrụpụta, gafere, nchọpụta onye ọrụ, mbelata arụmọrụ, HMI, wdg.). Nnwale ihe akaebe nke ọrụ akụkụ ma ọ bụ nke obere ga-emerịrị ule ndị a niile dị ka akụkụ nke ule ihe akaebe nke ọ bụla na-ekpuchi. Onye na-emepụta ihe ngwọta mgbagwoju anya kwesịrị inwe usoro nnwale ihe akaebe akwadoro na akwụkwọ ntuziaka nchekwa ngwaọrụ. Ọ bụrụ na ọ bụghị ma dịka opekempe, a ga-agbanye ike ihe ngwọta mgbagwoju anya, a ga-enyocha ndekọ nchọpụta ihe ngwọta mgbagwoju anya, ọkụ ọnọdụ, voltaji ọkọnọ ike, njikọ nkwukọrịta na mbelata arụmọrụ. A ga-eme nyocha ndị a tupu nnwale ihe akaebe zuru oke.
Ekwela ka a chee na ngwanrọ ahụ dị mma ruo mgbe ebighị ebi, a gaghịkwa anwale echiche ahụ mgbe ule mbụ gasịrị, n'ihi na mgbanwe ngwanrọ na ngwaike na-enweghị akwụkwọ, nke na-enweghị ikike na nke a na-anwaleghị na mmelite ngwanrọ nwere ike ịbanye na sistemụ ka oge na-aga, a ga-etinyerịrị ya na nkà ihe ọmụma ule gị niile. A ga-enyocha njikwa nke ndekọ mgbanwe, mmezi, na mgbanwe iji hụ na ha dị ọhụrụ ma na-edozi ha nke ọma, ọ bụrụkwa na ha nwere ike, a ga-atụnyere mmemme ngwa ahụ na nkwado ndabere kachasị ọhụrụ.
E kwesịkwara ịkpachara anya iji nwalee ọrụ enyemaka na nchọpụta nke onye ọrụ niile (dịka ọmụmaatụ, ndị nche, njikọ nkwukọrịta, ngwa nchekwa weebụ, wdg).
Nnwale ihe ikpeazụ: Ọtụtụ ihe ikpeazụ bụ valvụ, agbanyeghị, ihe mmalite moto akụrụngwa na-agbagharị agbagharị, draịva ọsọ na ihe ndị ọzọ eletriki dị ka kọntaktọ na ihe mgbawa sekit na-ejikwa dị ka ihe ikpeazụ, a ga-enyochakwa ụdị ọdịda ha ma nwalee ha.
Ụdị ọdịda mbụ maka valvụ na-arapara, oge nzaghachi dị nwayọ ma ọ bụ ọsọ ọsọ, yana ntapu mmiri, ihe niile a na-emetụta site na njikọ usoro ọrụ valvụ n'oge njem. Ọ bụ ezie na ịnwale valvụ ahụ n'ọnọdụ ọrụ bụ ihe kacha mma, ọrụ ga-emegidekarị ịda SIF mgbe osisi ahụ na-arụ ọrụ. A na-anwale ọtụtụ valvụ SIS mgbe osisi ahụ na-ada na enweghị nrụgide dị iche, nke bụ ọnọdụ ọrụ kacha sie ike. Onye ọrụ kwesịrị ịma maka nrụgide dị iche iche nke ọrụ kacha njọ na mmetụta mmebi valvụ na usoro, nke a ga-etinye na nhazi na nha valvụ na 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).
Okpomọkụ gburugburu ebe obibi nwekwara ike imetụta ibu esemokwu valvụ, nke mere na nnwale valvụ n'oge ihu igwe na-ekpo ọkụ ga-abụkarị ibu esemokwu kacha nta ma e jiri ya tụnyere ọrụ ihu igwe oyi. N'ihi ya, a ga-atụle nnwale akaebe nke valvụ na okpomọkụ na-agbanwe agbanwe iji nye data na-agbanwe agbanwe maka nnwale echiche maka mkpebi nke mmebi arụmọrụ valvụ.
Valvụ nwere ihe ndị nwere ike idobe ihe ma ọ bụ ihe njikwa valvụ dijitalụ nwere ike ịmepụta mbinye aka valvụ nke enwere ike iji nyochaa mmebi na arụmọrụ valvụ. Enwere ike ịrịọ mbinye aka valvụ ntọala dịka akụkụ nke iwu ịzụrụ ihe gị ma ọ bụ ị nwere ike ịmepụta otu n'oge ule nnwale mbụ iji jee ozi dị ka ntọala. Ekwesịrị ime mbinye aka valvụ maka imeghe na imechi valvụ ahụ. Ekwesịrị iji nchọpụta valvụ dị elu ma ọ bụrụ na ọ dị. Nke a nwere ike inyere gị aka ịgwa gị ma arụmọrụ valvụ gị na-aka njọ site na iji mbinye aka valvụ nnwale na nchọpụta na-esote tụnyere ntọala gị. Ụdị ule a nwere ike inye aka kwụọ ụgwọ maka anwaleghị valvụ ahụ n'ọnọdụ nrụgide ọrụ kacha njọ.
Mbinye aka valvụ n'oge ule ihe akaebe nwekwara ike idekọ oge nzaghachi site na stampụ oge, na-ewepụ mkpa maka elekere nkwụsị. Mmụba oge nzaghachi bụ ihe ịrịba ama nke mmebi valvụ na mmụba ibu esemokwu iji bugharịa valvụ ahụ. Ọ bụ ezie na enweghị ụkpụrụ gbasara mgbanwe na oge nzaghachi valvụ, ụkpụrụ na-adịghị mma nke mgbanwe site na ule ihe akaebe ruo na ule ihe akaebe na-egosi mfu nke oke nchekwa na arụmọrụ valvụ ahụ. Nnwale ihe akaebe valvụ SIS nke oge a kwesịrị ịgụnye mbinye aka valvụ dị ka ihe gbasara omume injinia dị mma.
A ga-atụ nrụgide ikuku nke ngwa valvụ ahụ n'oge nnwale ihe akaebe. Ọ bụ ezie na spring valvụ maka valvụ nloghachi mmiri bụ ihe na-emechi valvụ ahụ, a na-ekpebi ike ma ọ bụ torque metụtara ya site na oke spring valvụ ahụ si na nrụgide ihe nrịbama ahụ gbakọọ (dịka Iwu Hooke si dị, F = kX). Ọ bụrụ na nrụgide ihe nrịbama gị dị ala, spring agaghị agbakọta nke ukwuu, yabụ obere ike ga-adị iji bugharịa valvụ ahụ mgbe ọ dị mkpa. Ọ bụ ezie na ọ bụghị nke gụnyere, e nyere ụfọdụ ihe ị ga-atụle n'ịmepụta akụkụ valvụ nke usoro nnwale ihe nrịbama ahụ na Tebụl 2.
Oge ozi: Nọvemba-13-2019