Pasinei nemararamiro ekuramba kwemarara epombi dzesimbi isina tsvina, pombi dzesimbi dzisina tsvina dzakaiswa munzvimbo dzegungwa dzinotarisana nemhando dzakasiyana-siyana dzekuora panguva yehupenyu hwavo hunotarisirwa.Kuora uku kunogona kutungamirira kune utsi hwekutiza, kurasikirwa kwechigadzirwa uye njodzi dzinogona kuitika.Varidzi vepapuratifomu yeOffshore uye vashandi vanogona kuderedza dambudziko rekuora nekutsanangura zvakasimba pombi zvinhu, zvinoramba zviri nani. kemikari jekiseni, hydraulic uye impulse mitsara, uye mashandiro ekushandisa uye yekunzwa midziyo yekuona kuti corrosion haityisidzire kuvimbika kwepombi yakaiswa uye kukanganisa kuchengetedza.
Localized corrosion inogona kuwanikwa pamapuratifomu akawanda, ngarava, zvikepe, uye pombi munzvimbo dzekunze kwemahombekombe.Kuora uku kunogona kuva muchimiro chegomba kana kukoromoka kwegomba, izvo zvinogona kukanganisa mudhuri wepombi uye kukonzera kubuda kwemvura.
Ngozi yekuora yakakura kana kupisa kwekushanda kwechikumbiro kunowedzera.Kupisa kunogona kukurumidza kuparadzwa kwekudzivirira kwekunze passive oxide firimu yechubhu, nokudaro kukurudzira kuumbwa kwepitting corrosion.
Sezvineiwo, gomba renzvimbo uye kukoromoka kwegora kunogona kunetsa kuona, zvichiita kuti mhando idzi dzekuora dzinyanye kuoma kuziva, kufanotaura uye kugadzira. Zvichipa njodzi idzi, varidzi vepuratifomu, vashandisi uye vagadziri vanofanira kungwarira pakusarudza iyo yakanakisa pombi yekushandisa kwavo.Kusarudzwa kwezvinhu ndiwo mutsara wavo wekutanga wekudzivirira kubva mukuora, saka kuiwana zvakanaka kunokosha. kushorwa, iyo Pitting Resistance Equivalent Number (PREN) .Iyo yakakwirira kukosha kwePREN yesimbi, kunowedzera kupikisa kwayo kune imwe nzvimbo.
Ichi chinyorwa chichaongorora maitiro ekuziva gomba uye crevice corrosion uye maitiro ekugadzirisa tubing zvinhu kusarudzwa kweiyo offshore mafuta uye gasi mashandisirwo zvichienderana neiyo PREN kukosha kwezvinhu.
Localized corrosion inoitika munzvimbo diki kana ichienzaniswa neyakaomeswa ngura, inova yakafanana pamusoro pesimbi. Pitting and crevice corrosion inotanga kuumbwa pa316 Stainless steel pombi apo simbi yekunze yechromium-rich passive oxide film inoputika nekuda kwekusangana nemvura inoparadza, kusanganisira mvura yemunyu. kusvibiswa kwetubhing pamusoro, kuwedzera mukana wekuderedzwa kweiyi passivation firimu.
pitting.Pitting corrosion inoitika apo passivation film iri pahurefu hwepombi inoparadzwa, ichiita makomba maduku kana makomba pamusoro pepombi.Makomba akadaro anogona kukura se electrochemical reactions inoitika, zvichiita kuti simbi iri musimbi inyunguduke mumushonga uri pasi pegomba.Simbi yakanyungudutswa inobva yapararira yakananga kumusoro kwegomba kuti gomba riite simbi yakadzika uye oxidi oxidi. electrochemical reactions inomhanyisa, ngura inowedzera, uye inogona kutungamira mukupwanya kwepombi madziro uye kutungamirira mukudonha.
Tubing inonyanya kukanganiswa negomba rekuora kana nzvimbo yayo yekunze yakasvibiswa (Mufananidzo 1) .Somuenzaniso, kusvibiswa kubva kune welding uye kugaya mabasa kunogona kukuvadza passivating oxide layer yepombi, nokudaro kuumba uye kukurumidza kwegomba. mapaipi anoita zvimwe chetezvo kuchengetedza oxide layer uye zvinogona kutungamirira mukuora kwegomba.Kudzivirira marudzi aya ekusvibiswa, chengeta pombi dzako dzakachena nekugara uchidzipukuta nemvura yakachena.
Mufananidzo 1 - 316/316L pombi yesimbi isina tsvina yakasvibiswa neasidhi, brine uye mamwe madhipoziti inobatwa zvakanyanya negomba rekuora.
Kakawanda, gomba rinogona kuonekwa nyore nyore nemushandisi.Zvisinei, kukoromoka hakusi nyore kuona uye kunopa njodzi huru kune vanoishandisa nevashandi.Kazhinji kacho papombi dzine nzvimbo dzakasimba pakati pezvinhu zvakapoteredzwa, semapombi akaiswa panzvimbo ane zvikwambo kana pombi dzakanyatsoiswa padivi nepadivi. (FeCl3) mhinduro mafomu munzvimbo nekufamba kwenguva uye inokonzera kukoromoka kwemukova kuti ikurumidze (Mufananidzo 2) .Nekuti mitswe pachayo inowedzera njodzi yekuora, kukoromoka kwemukova kunogona kuitika pakudziya kwakadzikira zvakanyanya pane gomba.
Figure 2 - Crevice corrosion inogona kukura pakati pepombi nepombi inotsigira (kumusoro) uye kana pombi yakaiswa pedyo nedzimwe nzvimbo (pasi) nekuda kwekuumbwa kwemakemikari ane hukasha acidified ferric chloride solution mumukaha.
Crevice corrosion inowanzofananidzira pitting corrosion kutanga mugomba rakagadzirwa pakati pehurefu hwepombi uye pombi yekutsigira clip.Zvisinei, nekuda kwekuwedzera kweFe ++ concentration mumvura mukati mekutsemuka, iyo yekutanga crater inova yakakura uye yakakura kusvika yavhara iyo yese kuputsika.
Kutsemuka kwakasimba ndiyo ngozi huru yekuora. Naizvozvo, zvisungiso zvepombi zvinoputira chikamu chikuru chedenderedzwa repombi zvinowanzopa njodzi huru pane yakavhurika mabhanhire, izvo zvinoderedza kudhumhana kwenzvimbo pakati pepombi nembambo. Vanamazvikokota vekuchengetedza vanogona kubatsira kuderedza mukana wekukoromoka kunokonzera kukuvadzwa kana kutadza kuburikidza nekugarovhura machirambi uye pombi yekuongorora pamusoro peiyo corrosion.
Pitting uye crevice corrosion inogona kudzivirirwa zvakanakisisa nekusarudza simbi yesimbi yakakodzera yekushandiswa.Vatauri vanofanira kunyatsochenjerera kuti vasarudze iyo yakakwana yepombi zvinhu kuti kuderedze njodzi yekuora zvichienderana nemamiriro ekushanda, maitiro ekugadzirisa uye zvimwe zvakasiyana.
Kubatsira vanotsanangura kukwidziridza kusarudzwa kwezvinhu, vanogona kuenzanisa masimbi 'PREN kukosha kuona kuramba kwavo kune corrosion yenzvimbo.PREN inogona kuverengerwa kubva mumakemikari emusanganiswa, kusanganisira ayo chromium (Cr), molybdenum (Mo), uye nitrogen (N) zvirimo, sezvinotevera:
PREN inowedzera nezviri mukati meiyo corrosion-resistant elements chromium, molybdenum and nitrogen in the alloy.The PREN relationship is based on the critical pitting temperature (CPT) - tembiricha yakaderera pane iyo pitting corrosion inoonekwa - yemhando dzakasiyana-siyana dzesimbi maererano nemakemikari ekuumbwa. kushorwa.Kuwedzera kuduku kwePREN kunongofanana nekuwedzera kuduku kweCPT kana ichienzaniswa nealloy, asi kuwedzera kukuru kwePREN kunoratidza kuwedzera kukuru kwekushanda kune CPT yakakwirira zvikuru.
Tafura 1 inofananidza kukosha kwePREN yealloys akasiyana-siyana anowanzoshandiswa mumafuta ekumahombekombe egungwa uye gasi kushandiswa.Inoratidza kuti tsanangudzo yacho inogona sei kuvandudza corrosion resistance nekusarudza yepamusoro giredhi pombi alloy.PREN inongowedzera zvishoma kana uchichinja kubva 316 kusvika 317 Stainless simbi.Nekuda kwekuwedzera kwakakura kwekuita, 6 Moinless 7 simbi super austenitic simbi yesimbi 25 yesimbi isina tsvina kushandiswa zvakanaka.
Kuwedzerwa kwepamusoro kwe nickel (Ni) musimbi isina tsvina kunowedzerawo corrosion resistance.Zvisinei, nickel yemukati yesimbi isina tsvina haisi chikamu chePREN equation.Kune chero mamiriro ezvinhu, zvinowanzobatsira kutsanangura simbi dzisina tsvina dzine nickel dzakakwirira, sezvo chinhu ichi chinobatsira kudzorerazve nzvimbo dzinoratidza zviratidzo zve localized corrobilizes corrobilizesten corrobilizesten corrobilizesten. inotonhora kudhirowa 1/8 pombi yakaoma.Martensite chikamu chekristaro chisingadiwe mumasimbi chinoderedza kushorwa kwesimbi isina tsvina kune ngura yenzvimbo pamwe nekupwanya kwechloride-induced stress cracking.A nickel yakakwira inokwana 12% mu316/316L inodiwawo pamaapplications anosanganisira high pressure concentration/31L yehydrogen nickel inodiwa 61L simbi isina tsvina muASTM yakajairwa yakatarwa i10%.
Localized corrosion inogona kuitika chero papi papombi dzinoshandiswa munzvimbo dzemugungwa.Zvisinei, kukora kwegomba kunowanzoitika munzvimbo dzinenge dzatosvibiswa, ukuwo kukoromoka kunowanzoitika munzvimbo dzine mikaha yakatetepa pakati pepombi nehardware inokwira. Uchishandisa PREN sehwaro, mutauri anogona kusarudza akanakisa pombi alloy kuderedza chero njodzi yenharaunda.
Zvisinei, yeuka kuti kune zvimwe zvinoshanduka zvinogona kukanganisa njodzi yekuora.Semuenzaniso, tembiricha inokanganisa kumira kwegomba resimbi isina tsvina.Kumamiriro ekunze anopisa emugungwa, 6 molybdenum super austenitic kana 2507 super duplex stainless simbi pombi inofanira kutariswa zvakanyanya nekuti zvinhu izvi zvine hunyanzvi hwekudzivirira kukoromoka kwenzvimbo uye chloride 3616 kutsemuka kwepaipi inotonhorera,3L inotonhorera inoputika / 16L inoputika. zvakakwana, kunyanya kana nhoroondo yekushandiswa kwakabudirira yakasimbiswa.
Varidzi vepuratifomu yepamhenderekedzo yegungwa nevashandisi vanogonawo kutora matanho ekudzikisa njodzi yekuora mushure mekunge tubing yaiswa. Vanofanira kuchengetedza pombi dzakachena uye dzichiyerera nemvura yakachena nguva nenguva kuitira kuderedza njodzi yekuora kwegomba.
Kutevera matanho ataurwa pamusoro apa, varidzi vepuratifomu nevashandisi vanogona kuderedza njodzi yekuora kwechubhu uye kudonha kwakabatana munzvimbo dzemugungwa, kuvandudza kuchengetedzeka uye kushanda nesimba, uku vachideredza mukana wekurasikirwa nechigadzirwa kana kuburitswa kwehupoteri.
Brad Bollinger is the Oil and Gas Marketing Manager for Swagelok Company.He can be reached at bradley.bollinger@swagelok.com.
The Journal of Petroleum Technology ndiyo magazini yepamusoro yeSosaiti yePetroleum Injiniya, ichipa mapfupi ane chiremera uye maficha ekufambira mberi mukuongorora nekugadzira tekinoroji, nyaya dzeindasitiri yemafuta negesi, uye nhau nezve SPE nenhengo dzayo.