Ngakhale kuti mipope yachitsulo chosapanga dzimbiri imakhala yolimba kwambiri, mapaipi achitsulo osapanga dzimbiri omwe amaikidwa m'malo am'madzi amatha kuwononga mitundu yosiyanasiyana pazaka zomwe amayembekezera.Kuwonongeka kumeneku kungayambitse kutulutsa mpweya, kutayika kwazinthu komanso zoopsa zomwe zingatheke.Eni ake ndi ogwiritsa ntchito nsanja amatha kuchepetsa chiwopsezo cha dzimbiri pofotokoza zida zamphamvu zamapaipi zomwe zimapereka kukana kwa dzimbiri.Pambuyo pake, ayenera kukhala tcheru poyang'ana mizere ya jakisoni wa mankhwala, mizere ya hydraulic ndi impulse, ndi kukonza zida ndi zida kuti zitsimikizire kuti dzimbiri sizikuwopseza kukhulupirika kwa mapaipi oyikapo kapena kusokoneza chitetezo.
Zimbiri zamaloko zitha kupezeka pamapulatifomu ambiri, zombo, zombo ndi mapaipi akunyanja.Zimbirizi zimatha kukhala ngati zibowo kapena mng'oma, zomwe zimatha kuwononga khoma la chitoliro ndikupangitsa kuti madzi atuluke.
Kuopsa kwa dzimbiri kumawonjezeka pamene kutentha kwa ntchito kumawonjezeka.Kutentha kumatha kufulumizitsa kuwonongeka kwa filimu ya chubu yoteteza ku passive oxide filimuyo, potero kulimbikitsa kupindika.
Tsoka ilo, ming'alu ndi ming'alu ndizovuta kuzizindikira, zomwe zimapangitsa kuti zikhale zovuta kuzindikira, kulosera, ndikupanga mitundu iyi ya dzimbiri.Poganizira zoopsazi, eni nsanja, oyendetsa ntchito ndi omwe asankhidwa ayenera kusamala posankha zida zabwino kwambiri zamapaipi zomwe azigwiritsa ntchito.Kusankha zinthu zakuthupi ndiye njira yawo yoyamba yodzitetezera ku dzimbiri, kotero kuzikonza ndikofunikira kwambiri.Mwamwayi, amatha kusankha njira yosavuta koma yothandiza kwambiri yolimbana ndi dzimbiri, Pitting Resistance Equivalent Number (PREN).Kukwera kwamtengo wa PREN wachitsulo, kumapangitsa kuti chitsulo chisawonongeke.
Nkhaniyi iwona momwe mungadziwire kuwonongeka kwa maenje ndi ming'alu, komanso momwe mungakwaniritsire kusankha kwazinthu zamachubu kumafuta akunyanja ndi gasi kutengera mtengo wa PREN wazinthuzo.
Kuwonongeka kwamaloko kumachitika m'madera ang'onoang'ono poyerekeza ndi zowonongeka, zomwe zimakhala zofanana kwambiri pazitsulo.Kudzimbirira kwa dzenje kumayamba kupangika pachubu lachitsulo chosapanga dzimbiri la 316 pomwe filimu yakunja yachitsulo yokhala ndi chromium passive oxide imasweka chifukwa chokumana ndi zinthu zamadzimadzi zowononga, kuphatikiza madzi amchere.Malo okhala m'madzi odzaza ndi ma chloride, komanso kutentha kwambiri komanso kuipitsidwa kwa machubu, kumawonjezera mwayi wowonongeka kwa filimuyi.
pitting Pitting dzimbiri kumachitika pamene passivation filimu pa chigawo cha chitoliro akuphwasula, kupanga mabowo ang'onoang'ono kapena maenje pamwamba pa chitoliro.Maenje oterowo amatha kukula pamene machitidwe a electrochemical amapitilira, chifukwa chake chitsulo muzitsulo chimasungunuka mu njira pansi pa dzenje.Chitsulo chosungunukacho chidzafalikira pamwamba pa dzenje ndikutulutsa oxidize kupanga iron oxide kapena dzimbiri.Pamene dzenje likukulirakulira, machitidwe a electrochemical amathamanga, dzimbiri zimawonjezeka, zomwe zingayambitse kuphulika kwa khoma la chitoliro ndikuyambitsa kutayikira.
Machubu amatha kuponyedwa ngati kunja kwawo kuli ndi kachilombo (Chithunzi 1).Mwachitsanzo, zodetsa kuchokera kuwotcherera ndi kukupera ntchito zimatha kuwononga passivation oxide wosanjikiza wa chitoliro, potero kupanga ndi kufulumizitsa pitting.N'chimodzimodzinso ndi kungolimbana ndi kuipitsa mapaipi.Kuphatikiza apo, madontho amchere akamatuluka, makhiristo a mchere wonyowa omwe amapangidwa pamipope amateteza wosanjikiza wa oxide ndipo angayambitse kupindika.Pofuna kupewa kuipitsidwa kwa mitundu imeneyi, sungani mapaipi anu aukhondo mwa kuwatsuka ndi madzi abwino nthawi zonse.
Chithunzi 1. 316 / 316L chitoliro chachitsulo chosapanga dzimbiri choyipitsidwa ndi asidi, saline, ndi madipoziti ena amakhudzidwa kwambiri ndi pitting.
ming'alu dzimbiri.Nthawi zambiri, kubowola kumatha kuzindikirika mosavuta ndi wogwiritsa ntchito.Komabe, kuwonongeka kwa mpata sikophweka kuzindikira ndipo kumabweretsa chiopsezo chachikulu kwa ogwira ntchito ndi ogwira ntchito.Izi nthawi zambiri zimachitika pamapaipi omwe ali ndi mipata yopapatiza pakati pa zinthu zozungulira, monga mapaipi omwe amakhala ndi zingwe kapena mapaipi omwe amalumikizidwa mwamphamvu moyandikana.Pamene brine imalowa mu mng'alu, pakapita nthawi, madzi amtundu wa acidified ferric chloride solution (FeCl3) amapangidwa m'derali, zomwe zimapangitsa kuti ziphuphu ziwonongeke (mkuyu 2).Popeza kuti ming'alu payokha imapangitsa kuti pakhale dzimbiri, dzimbiri la mng'alu limatha kuchitika pa kutentha kocheperapo kusiyana ndi kupindika.
Chithunzi 2 - Kuwonongeka kwa chitoliro kumatha kukhala pakati pa chitoliro ndi chithandizo cha chitoliro (pamwamba) ndipo chitolirocho chikayikidwa pafupi ndi malo ena (pansi) chifukwa chopanga njira yowopsa ya acidified ya ferric chloride mumpata.
Kuwonongeka kwa zitoliro nthawi zambiri kumatengera kutsekera koyamba pakati pa gawo la chitoliro ndi kolala yothandizira chitoliro.Komabe, chifukwa cha kuwonjezeka kwa chiwerengero cha Fe ++ m'madzimadzi mkati mwa fracture, fupa loyamba limakhala lalikulu komanso lokulirapo mpaka likuphimba fracture yonse.Pamapeto pake, dzimbiri zingayambitse kuphulika kwa chitoliro.
Ming'alu yowirira imayimira chiopsezo chachikulu cha dzimbiri.Chifukwa chake, zingwe zotsekera mapaipi zomwe zimazungulira gawo lalikulu la chitolirocho zimakhala zowopsa kuposa zotsekera zotseguka, zomwe zimachepetsa kulumikizana pakati pa chitoliro ndi chotsekera.Akatswiri odziwa ntchito atha kuthandiza kuchepetsa kuwonongeka kwa mng'alu kapena kulephera potsegula zikhomo pafupipafupi ndikuyang'ana kuti chitoliro chachita dzimbiri.
Pitting ndi mpata dzimbiri akhoza kupewedwa posankha zitsulo aloyi yoyenera ntchito.Ofotokozera ayenera kuchita khama posankha zida zoyenera zopopera kuti achepetse chiwopsezo cha dzimbiri kutengera malo opangira, momwe zimapangidwira, ndi zina.
Kuthandizira ofotokozera kukhathamiritsa kusankha kwazinthu, amatha kufananiza zitsulo za PREN kuti zitsimikizire kukana kwawo ku dzimbiri komweko.PREN ikhoza kuwerengedwa kuchokera ku chemistry ya alloy, kuphatikizapo chromium (Cr), molybdenum (Mo), ndi nitrogen (N) motere:
PREN imawonjezeka ndi zomwe zili ndi zinthu zosagwirizana ndi dzimbiri za chromium, molybdenum ndi nayitrogeni mu aloyi.Chiŵerengero cha PREN chimachokera ku kutentha kwakukulu kwa pitting (CPT) - kutentha kochepa kwambiri komwe kuphulika kumachitika - kwazitsulo zosiyanasiyana zosapanga dzimbiri malingana ndi mankhwala.Kwenikweni, PREN ndiyofanana ndi CPT.Chifukwa chake, zikhalidwe zapamwamba za PREN zikuwonetsa kukana kwapang'onopang'ono.Kuwonjezeka pang'ono kwa PREN kumangofanana ndi kuwonjezeka kochepa kwa CPT poyerekeza ndi alloy, pamene kuwonjezeka kwakukulu kwa PREN kumasonyeza kusintha kwakukulu kwa ntchito pa CPT yapamwamba kwambiri.
Gome 1 limafanizira ma PREN ma alloys osiyanasiyana omwe amagwiritsidwa ntchito m'makampani amafuta ndi gasi akunyanja.Imawonetsa momwe mafotokozedwe angathandizire kwambiri kukana dzimbiri posankha aloyi yapaipi yapamwamba kwambiri.PREN imakwera pang'ono kuchokera ku 316 SS kufika ku 317 SS.Super Austenitic 6 Mo SS kapena Super Duplex 2507 SS ndi yabwino pakuwonjezeka kwakukulu kwa magwiridwe antchito.
Kuchuluka kwa nickel (Ni) muzitsulo zosapanga dzimbiri kumawonjezera kukana kwa dzimbiri.Komabe, kuchuluka kwa nickel mu chitsulo chosapanga dzimbiri si gawo la equation ya PREN.Mulimonsemo, nthawi zambiri zimakhala zopindulitsa kusankha zitsulo zosapanga dzimbiri zomwe zili ndi nickel yapamwamba, chifukwa chinthuchi chimathandiza kubwezeretsanso malo omwe amasonyeza zizindikiro za dzimbiri.Nickel imakhazikika pa austenite ndikuletsa mapangidwe a martensite popinda kapena kuzizira pojambula chitoliro cholimba cha 1/8.Martensite ndi gawo losafunikira la crystalline muzitsulo lomwe limachepetsa kukana kwa chitsulo chosapanga dzimbiri kuti zisawonongeke komweko komanso kusweka kwamphamvu kwa kloridi.Mafuta a faifi okwera osachepera 12% muzitsulo za 316/316L ndizofunikanso pakugwiritsa ntchito gasi wa hydrogen.Kuchuluka kwa nickel kocheperako komwe kumafunikira ASTM 316/316L chitsulo chosapanga dzimbiri ndi 10%.
Kuwonongeka kokhazikika kumatha kuchitika paliponse pamapaipi omwe amagwiritsidwa ntchito m'madzi am'madzi.Komabe, pobowola amatha kuchitika m'malo omwe aipitsidwa kale, pomwe dzimbiri la ming'alu nthawi zambiri limapezeka m'malo okhala ndi mipata yopapatiza pakati pa chitoliro ndi zida zoyikapo.Pogwiritsa ntchito PREN monga maziko, wofotokozera amatha kusankha chitoliro chabwino kwambiri chochepetsera chiwopsezo cha mtundu uliwonse wa dzimbiri.
Komabe, kumbukirani kuti pali zosintha zina zomwe zingakhudze chiopsezo cha dzimbiri.Mwachitsanzo, kutentha kumakhudza kukana kwa zitsulo zosapanga dzimbiri kuti zibowole.Kwa nyengo zotentha zam'madzi, chitsulo cha super austenitic 6 molybdenum kapena super duplex 2507 mapaipi achitsulo chosapanga dzimbiri amayenera kuganiziridwa mozama chifukwa zidazi zimalimbana bwino ndi dzimbiri komanso kusweka kwa kloridi.Kwa nyengo yozizira, chitoliro cha 316/316L chingakhale chokwanira, makamaka ngati pali mbiri yogwiritsira ntchito bwino.
Eni ake ndi ogwiritsa ntchito nsanja amathanso kuchitapo kanthu kuti achepetse chiwopsezo cha dzimbiri atayikidwa machubu.Ayenera kusunga mapaipi aukhondo komanso kuthiridwa ndi madzi abwino nthawi zonse kuti achepetse ngozi yoboola.Ayeneranso kukhala ndi akatswiri okonza zotsekera mapaipi otsegula poyang'ana makonda kuti awone ngati ming'alu yawonongeka.
Potsatira njira zomwe zili pamwambazi, eni nsanja ndi ogwiritsira ntchito amatha kuchepetsa chiwopsezo cha kuwonongeka kwa mipope ndi kudontha kofananako m'malo am'madzi, kuwongolera chitetezo ndi magwiridwe antchito, ndikuchepetsa mwayi wotayika kwazinthu kapena kutulutsa mpweya wothawa.
Brad Bollinger is the Oil and Gas Marketing Manager for Swagelok. He can be contacted at bradley.bollinger@swagelok.com.
Journal of Petroleum Technology ndiye magazini otsogola a Society of Petroleum Engineers, okhala ndi zidule zovomerezeka ndi zolemba zakupita patsogolo kwaukadaulo, nkhani zamakampani amafuta ndi gasi, komanso nkhani za SPE ndi mamembala ake.