Pasinei nemararamiro ekuramba kwemarara epombi dzesimbi isina tsvina, pombi dzesimbi dzisina tsvina dzakaiswa munzvimbo dzegungwa dzinosangana nemhando dzakasiyana-siyana dzekuora panguva yehupenyu hwavo hunotarisirwa.Kuora uku kunogona kutungamirira kumhepo inoputika, kurasikirwa kwechigadzirwa uye njodzi dzinogona kuitika.Offshore chikuva varidzi nevashandisi vanogona kuderedza njodzi yekuora nekutsanangura yakasimba pombi zvinhu izvo zvinopa zviri nani hydrauspect resistance, hydrauspect resistance. uye mitsara yekumanikidza, uye kugadzira chiridzwa uye midziyo yekunzwa kuti ive nechokwadi chekuti ngura haityisidzire kutendeseka 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, nzvimbo yepitting uye crevice corrosion inogona 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 zvinhu zvekushandisa kwavo.Kusarudzwa kwezvinhu ndiwo mutsara wavo wekutanga wekudzivirira kubva mukuora, saka kuiwana kwayo kwakarurama kunokosha. Sistance Equivalent Number (PREN) .Pakakwirira kukosha kwePREN kwesimbi, 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 neyakawora, inova yakafanana pamusoro pesimbi. Pitting and crevice corrosion inotanga kuumbwa papombi 316 Stainless simbi apo kunze kwesimbi chromium-rich passive oxide film inoputika nekuda kwekusangana nemvura inoparadza, kusanganisira mvura inoparadza, kusanganisira nharaunda uye tembiricha yemvura yemunyu. bing pamusoro, wedzera mukana wekushatisa iyi passivation firimu.
pitting.Pitting corrosion inoitika apo passivation film iri pahurefu hwepombi inoparadzwa, ichiita makomba madiki 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 iite ironscAxidix reaction, electrochemical reaction, electrochemical reaction. celerate, ngura inowedzera, uye inogona kutungamira mukupwanya kwemadziro epombi uye kutungamirira mukudonha.
Tubing inonyanya kubatwa nekuora kwegomba kana nzvimbo yayo yekunze yakasvibiswa (Mufananidzo 1) .Somuenzaniso, kusvibiswa kubva kune welding uye kugaya mabasa kunogona kukuvadza passivating oxide layer yepombi, nokudaro kugadzira uye kukurumidza kwegomba. kuchengetedza oxide layer uye inogona kutungamirira kugomba corrosion.Kudzivirira marudzi aya ekusvibiswa, chengeta mapaipi ako akachena nekugara uchiapisa 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 kunoisa njodzi huru kune vanoishandisa nevashandi.Inowanzoitika pamapombi ane nzvimbo dzakasimba pakati pezvinhu zvakapoteredzwa, semapombi anobatwa ane zvikwambo kana mapaipi akaiswa zvakasimba parutivi. munzvimbo nekufamba kwenguva uye inokonzera kukurumidza kukoromoka kwekacheka (Figure 2) .Nekuti mitswe pachayo inowedzera njodzi yekuora, kukoromoka kunogona kuitika patembiricha yakaderera zvakanyanya pane gomba.
Figure 2 - Crevice corrosion inogona kukura pakati pepombi nepombi inotsigira (pamusoro) uye kana pombi yakaiswa pedyo nedzimwe nzvimbo (pasi) nekuda kwekugadzirwa 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 uye 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.Zvinonyanya kukosha, PREN kukwira kumusoro kunowedzera kuderera. muPREN inongoenzana 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 anowanzo shandiswa muoffshore oiri uye gasi application.Inoratidza kuti iyo yakatarwa inogona zvakanyanya kuvandudza corrosion resistance nekusarudza yepamusoro giredhi pombi alloy.PREN inongowedzera zvishoma kana ichichinja kubva 316 kusvika 317 Stainless simbi.Nekuda kwekuwedzera kwakakosha kwekuita, 6 Moinless simbi 7 simbi yakashongedzwa kana 2 yakanakisa stainless simbi 2.
Kuwedzera kwenickel (Ni) musimbi isina tsvina kunowedzerawo kuramba.Zvisinei, nickel yemukati yesimbi isina tsvina haisi chikamu chePREN equation. Chero zvazvingava, zvinowanzobatsira kutsanangura simbi dzisina tsvina dzine nickel dzakakwirira, sezvo chinhu ichi chinobatsira kupfuudza zvakare nzvimbo dzinoratidza zviratidzo zve localized corrosional corrosion uye kutonhora kwenickel kana kutonhora kunodzivirira. 8 pombi yakaoma.Martensite is an udised crystalline phase in metals that reduces stainless steel resistance to localized corrosion as well as chloride-induced stress cracking.A nickel yakakwirira yeinenge 12% mu 316 / 316L inodiwawo kune zvikumbiro zvinosanganisira high pressure gaseous corrosion uye ASM6161 simbi inodiwa inonzi nickel TM616166 yesimbi inodiwa. 10%.
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 zvakasiyana zvinogona kukanganisa njodzi yekuora.Somuenzaniso, 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 hwekupikisa corrosion yenzvimbo uye chloride 16 pombi inoputika kana chloride inoputika 16 nhoroondo yakakwana, 36L inotonhorera inoputika. yekubudirira kushandiswa 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.