Nangona uxhathiso lwendalo lwemibhobho yensimbi engenasici, imibhobho yensimbi engenastainless efakwe kwiindawo zaselwandle ixhomekeke kwiintlobo ezahlukeneyo zomhlwa ngexesha lokuphila kwabo okulindelweyo.Le nkunkuma ingakhokelela ekukhutshweni kwezinto ezibalekayo, ilahleko yemveliso kunye nobungozi obunokubakho.Abanikazi beqonga le-offshore kunye nabaqhubi banokunciphisa umngcipheko wokuhlwa ngokuchaza izinto eziqinileyo zemibhobho, ukuchasana kwemibhobho eqinile, i-injection ye-injection yeekhemikhali kufuneka ibonelele kwi-injini ye-corrosion engcono. imigca ye-aulic kunye ne-impulse, kunye nenkqubo ye-instrumentation kunye nezixhobo zokuva ukuqinisekisa ukuba ukubola akusongeli ukunyaniseka kwemibhobho efakelweyo kunye nokhuseleko olulula.
I-corrosion yendawo inokufumaneka kumaqonga amaninzi, iinqanawa, iinqanawa, kunye nemibhobho kwi-offshore installs.
Umngcipheko we-corrosion mkhulu xa ubushushu bokusebenza besicelo bukhuphuka.Ubushushu bunokukhawuleza ukutshatyalaliswa kwefilimu ye-oxide yangaphandle ekhuselayo ye-tube, ngaloo ndlela ikhuthaza ukubunjwa kwe-corrosion ye-pitting.
Ngelishwa, i-pitting yendawo kunye ne-corrosion ye-crevice kunokuba nzima ukuyibona, okwenza ezi ntlobo ze-corrosion zibe nzima ngakumbi ukuchonga, ukuqikelela kunye nokuyila.Ngenxa yale mingcipheko, abanini beqonga, abaqhubi kunye nabaqulunqiweyo kufuneka balumke xa bekhetha izinto zombhobho ezifanelekileyo kwisicelo sabo.Ukukhethwa kwezinto ezibonakalayo ngumgca wabo wokuqala wokukhusela kwi-corrosion, ngoko ke ukuyifumana okulungileyo kubalulekile. ubuxhakaxhaka beNombolo eLinganayo (PREN) .Iphezulu ixabiso le-PREN lentsimbi, iphezulu ukuchasana kwayo kwi-corrosion yendawo.
Eli nqaku liza kuphonononga indlela yokuchonga i-pitting kunye ne-crevice corrosion kunye nendlela yokuphucula ukhetho lwezixhobo ze-tubing kwi-offshore oil kunye ne-gas applications ngokusekelwe kwixabiso le-PREN yezinto.
Umhlwa wendawo wenzeka kwiindawo ezincinci xa kuthelekiswa nomhlwa jikelele, ohambelana ngakumbi kumphezulu wesinyithi.I-Pitting kunye ne-crevice corrosion iqala ukwenza kwimibhobho yentsimbi engatyiwayo engama-316 xa ifilimu yentsimbi yekhromium-etyebileyo yeoksidi yesinyithi igqabhuka ngenxa yokuvezwa kulwelo oludlekayo, kuqukwa nemekobume yetyuwa elwandle kunye nonxweme olunobushushu obuphezulu kunye nonxweme olunxwemeni kunye nonxweme olunobushushu obuphezulu kunye nonxweme olunxwemeni lolwandle kunye nonxweme olunetyuwa. umphezulu we-bing, ukwandisa amandla okuthotywa kwale filimu ye-passivation.
pitting.Pitting corrosion kwenzeka xa ifilimu passivation kubude umbhobho kutshatyalaliswa, ukwenza imingxunya encinane okanye imingxuma phezu komhlaba umbhobho.Imingxuma enjalo kusenokwenzeka ukuba zikhule njengoko reactions electrochemical kwenzeka, okubangela intsimbi kwisinyithi ukunyibilika kwisisombululo emazantsi pit.Intsimbi enyibilikisiweyo iya kuthi ke diffuse ukuya phezulu emhadini tot i-iron oxidiz oxikside okanye electrochemical reaction. i-celerate, i-corrosion iqinisa, kwaye inokukhokelela ekubhobhozeni udonga lombhobho kwaye ikhokelele ekuvuzeni.
I-tubing ichaphazeleka ngakumbi kwi-pitting corrosion xa umphezulu wayo wangaphandle ungcolisekile (Umfanekiso 1) .Umzekelo, ungcoliseko oluvela kwi-welding kunye nemisebenzi yokusila inokonakalisa i-oxide ye-oxide edlulayo yombhobho, ngaloo ndlela iqulunqa kwaye ikhawuleze i-corrosion. ukukhusela i-oxide layer kwaye kunokukhokelela kwi-pitting corrosion.Ukuthintela ezi ntlobo zokungcola, gcina imibhobho yakho icocekile ngokuyigubungula rhoqo ngamanzi amnandi.
Umzobo 1 - 316 / 316L umbhobho wensimbi engenasici ongcolileyo nge-asidi, i-brine kunye nezinye iidiphozithi zithinteka kakhulu kwi-corrosion.
I-crevice corrosion.Kwiimeko ezininzi, i-pitting ingachongwa ngokulula ngumqhubi.Nangona kunjalo, i-crevice corrosion ayilula ukuyibona kwaye ibeka umngcipheko omkhulu kubaqhubi kunye nabasebenzi.Kuqhelekile ukwenzeka kwimibhobho enezithuba eziqinileyo phakathi kwezinto ezijikelezileyo, njengemibhobho ebanjwe kwindawo kunye neziqeshana okanye imibhobho efakwe ngokuqinileyo ecaleni. kwindawo ngokuhamba kwexesha kwaye ibangela ukubola kwemingxuma ngokukhawuleza (Umfanekiso 2) .Ngenxa yokuba iintanda ngokwazo zandisa umngcipheko wokuhlwa, ukubola kwemingxuma kunokwenzeka kumaqondo obushushu angaphantsi kakhulu kunomhlwa wokugoba.
Umzobo we-2 - I-Crevice corrosion ingaphuhliswa phakathi kombhobho kunye nenkxaso yombhobho (phezulu) kwaye xa umbhobho ufakwe kufuphi neminye imiphezulu (ezantsi) ngenxa yokwenziwa kwesisombululo se-acidified ferric chloride eyingozi kwi-crevice.
I-Crevice corrosion idla ngokufanisa i-pitting corrosion kuqala kwi-crevice eyenziwe phakathi kobude bombhobho kunye ne-clip yenkxaso yombhobho.Nangona kunjalo, ngenxa yokunyuka kwe-Fe ++ yoxinaniso kulwelo olungaphakathi kweqhekeza, i-crater yokuqala iba nkulu kwaye ibe nkulu de ivale yonke i-fracture.
Iintanda eziqinileyo zingowona mngcipheko mkhulu wokuthotywa.Ngoko ke, izithinteli zemibhobho ezisonga ubuninzi besangqa sombhobho zikholisa ukubonisa umngcipheko omkhulu kuneeclamps ezivulekileyo, ezinciphisa indawo yokudibanisa phakathi kombhobho kunye ne-clamp.
I-pitting kunye ne-crevice corrosion inokuthintelwa ngokufanelekileyo ngokukhetha i-alloy yensimbi efanelekileyo kwisicelo.Abachazi kufuneka basebenzise inkuthalo ukukhetha eyona imathiriyeli yombhobho ukunciphisa umngcipheko wokuhlwa ngokusekelwe kwimeko yokusebenza, iimeko zenkqubo kunye nezinye izinto eziguquguqukayo.
Ukunceda abacacisi baphucule ukhetho lwezixhobo, banokuthelekisa amaxabiso esinyithi e-PREN ukumisela ukuxhathisa kwabo kwi-corrosion yendawo.PREN ingabalwa kwimichiza ye-alloy, kubandakanywa ne-chromium (Cr), i-molybdenum (Mo), kunye nomxholo we-nitrogen (N), ngolu hlobo lulandelayo:
I-PREN iyanda kunye nomxholo wezinto ezichasene nokugqwala kwe-chromium, i-molybdenum kunye ne-nitrogen kwi-alloy.Ubudlelwane be-PREN busekelwe kwiqondo lokushisa elibalulekileyo (CPT) - iqondo lokushisa eliphantsi kakhulu apho i-pitting corrosion ibonwa - kwiindidi zensimbi ezingenasici ngokumalunga nokubunjwa kweekhemikhali. kwi-PREN ilingana kuphela nokunyuka okuncinci kwe-CPT xa kuthelekiswa ne-alloy, kanti ukunyuka okukhulu kwe-PREN kubonisa ukuphuculwa okuphawulekayo kwintsebenzo kwi-CPT ephezulu kakhulu.
Itheyibhile 1 ithelekisa amaxabiso e-PREN ee-alloys ezahlukeneyo ezisetyenziswa ngokuqhelekileyo kwi-oyile ye-offshore kunye ne-gas applications.Ibonisa indlela inkcazo inokuphucula ngokuphawulekayo ukuxhatshazwa kwe-corrosion ngokukhetha i-alloy yombhobho womgangatho ophezulu.PREN inyuka kuphela xa idlula kwi-316 ukuya kwi-317 yensimbi engenasici.
Uxinzelelo oluphezulu lwe-nickel (Ni) kwinsimbi engenasici lukwaphakamisa ukuxhathisa kwe-corrosion.Nangona kunjalo, umxholo we-nickel wensimbi engenasici awuyonxalenye ye-equation ye-PREN.Kuyo nayiphi na imeko, kudla ngokuba luncedo ukucacisa iintsimbi ezingenasici ezinogxininiso lwe-nickel ephezulu, njengoko le nto inceda ukuphinda idlulise iindawo ezibonisa iimpawu ze-corrosion ye-australia okanye i-cold corrobilizesten i-australia okanye i-cold corrobilizesten i-australia. I-8 ipayipi enzima.I-Martensite yinqanaba le-crystalline elingafunekiyo kwiintsimbi ezinciphisa ukuxhathisa kwensimbi engenasici kwi-corrosion yendawo kunye ne-chloride-induced stress cracking.Umxholo we-nickel ophezulu ubuncinane we-12% kwi-316 / 316L nayo iyanqweneleka kwizicelo ezibandakanya uxinzelelo oluphezulu lwe-gaseous i-concentration ye-3L TM 3 i-standard efunekayo ye-nickel TM6 i-AS6 ye-stainless staining encinci ye-stainless 31 TM 6. 10%.
I-corrosion yendawo ingenzeka naphi na kwimibhobho esetyenziswa kwiindawo zaselwandle.Nangona kunjalo, ukubola kwemingxuma kunokwenzeka ukuba kwenzeke kwiindawo esele zingcolisekile, ngelixa i-corrosion ye-crevice inokwenzeka ukuba yenzeke kwiindawo ezinezikhewu ezimxinwa phakathi kombhobho kunye ne-hardware ekhwelayo.
Nangona kunjalo, khumbula ukuba kukho ezinye izinto ezinokuchaphazela umngcipheko wokugqwala.Ngokomzekelo, ubushushu buchaphazela ukuchasana kwe-pitting yensimbi engenasici.Kwimozulu yaselwandle eshushu, i-6 molybdenum super austenitic okanye i-2507 super duplex ipayipi yensimbi engenasici kufuneka iqwalaselwe nzulu ngenxa yokuba ezi zixhobo zinokuchasana okugqwesileyo kwi-corrosion yendawo kunye ne-chloride ye-Cloride ye-16 Imbali epholileyo, i-Cloride ye-316 imbali epholileyo inokuba yi-3. yokusetyenziswa ngempumelelo kuye kwasekwa.
Abanini bamaqonga angaphandle konxweme kunye nabasebenzisi nabo banokuthatha amanyathelo okunciphisa umngcipheko wokuhlwa emva kokuba kufakwe iityhubhu. Kufuneka bagcine imibhobho icocekile kwaye igungxulwe ngamanzi amatsha rhoqo ukunciphisa umngcipheko wokurhwalala kwemingxuma.
Ukulandela amanyathelo achazwe ngasentla, abanikazi beqonga kunye nabaqhubi banokunciphisa umngcipheko wokubola kweetyhubhu kunye nokuvuza okuhambelanayo kwiindawo ezihlala elwandle, ukuphucula ukhuseleko kunye nokusebenza kakuhle, ngelixa kunciphisa ithuba lokulahleka kwemveliso okanye ukukhutshwa kokukhutshwa kwe-emissions.
Brad Bollinger is the Oil and Gas Marketing Manager for Swagelok Company.He can be reached at bradley.bollinger@swagelok.com.
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