ʻOiai ke kūpaʻa ʻana o ka corrosion o nā paipu kila kila, ʻo nā paipu kila kila i hoʻokomo ʻia i loko o nā kai moana e pili ana i nā ʻano ʻino like ʻole i ka wā o ko lākou ola i manaʻo ʻia. ka ʻike a me ka ʻike ʻana i nā mea hana e hōʻoia ai ʻaʻole e hoʻoweliweli ka corrosion i ka pono o ka paipa i hoʻokomo ʻia a hoʻololi i ka palekana.
Hiki ke ʻike ʻia ka corrosion kūloko ma nā paepae he nui, nā moku, nā moku, a me nā paipu i nā hoʻonohonoho ʻana i waho.
ʻOi aku ka nui o ka pōʻino i ka wā e piʻi ai ka mahana hana o ka noi. Hiki i ka wela ke hoʻolalelale i ka luku ʻana i ke kiʻi ʻoniʻoni pasif o waho pale o ka paipu, a laila e hoʻoikaika i ka hoʻokumu ʻana o ka pitting corrosion.
ʻO ka mea pōʻino, hiki ke paʻakikī ka ʻike ʻana i kēia mau ʻano o ka corrosion, ʻoi aku ka paʻakikī o ka ʻike, wānana a me ka hoʻolālā ʻana. valent Number (PREN). ʻOi aku ke kiʻekiʻe o ka waiwai PREN o kahi metala, ʻoi aku ka kiʻekiʻe o kona kūʻē ʻana i ka corrosion kūloko.
E nānā ana kēia ʻatikala pehea e ʻike ai i ka ʻinoʻino o ka lua a me ka ʻāʻī a pehea e koho ai i nā mea paipu no nā noi aila a me nā kinoea waho ma muli o ka waiwai PREN o ka mea.
Loaʻa ka corrosion localized ma nā wahi liʻiliʻi i hoʻohālikelike ʻia me ka corrosion maʻamau, ʻoi aku ka ʻoi aku o ka ʻaʻahu ma luna o ka metala. ka hana ʻana o kēia kiʻiʻoniʻoni passivation.
Pitting.Pitting corrosion i ka wa e pau ai ka passivation film ma ka loihi o ka paipu, e hana ana i na lua liilii a i ole mau lua paha ma ka ili o ka paipu. E ulu paha ia mau lua e like me ka hana ana o ka electrochemical reactions, e hoopau ai ka hao i loko o ka hopena ma lalo o ka lua. The dissolved iron will then diffuse and iron pitrust oxide to pitrust or deep oxide. ʻO nā hopena kemika e hoʻokē ʻai, hoʻonui ʻia ka ʻino, a hiki ke alakaʻi i ka perforation o ka paia paipu a alakaʻi i nā leaka.
ʻOi aku ka maʻalahi o ka paipu ʻana i ka corrosion i ka wā i haumia ai kona ʻili o waho (Figure 1). No ka laʻana, hiki i ka hoʻohaumia ʻana mai ka wili a me ka wili ʻana i nā hana ke hōʻino i ka papa o ka paipa passivating o ka paipu, a laila e hana ai a wikiwiki i ka pitting corrosion. papa a hiki ke alakaʻi i ka ʻinoʻino. No ka pale ʻana i kēia mau ʻano ʻino, e hoʻomaʻemaʻe i kāu mau paipu ma ka holoi pinepine ʻana iā lākou me ka wai hou.
Kiʻi 1 - 316/316L paipu kila kila i hoʻohaumia ʻia me ka ʻakika, brine a me nā waihona ʻē aʻe e maʻalahi loa i ka luaʻi ʻana.
crevice corrosion.Ma ka hapanui o na hihia, hiki ke ike maʻalahi ka lua e ka mea hoʻohana. Akā naʻe, ʻaʻole maʻalahi ka ʻike ʻana i ka ʻino ʻana a ʻoi aku ka nui o ka pilikia i nā mea hana a me nā limahana. He mea maʻamau ia e hana ʻia ma nā paipu me nā wahi paʻa i waena o nā mea a puni, e like me nā paipu i hoʻopaʻa ʻia me nā kiʻi a i ʻole nā ​​paipu i hoʻopaʻa paʻa ʻia i ka ʻaoʻao. puka i loko o ka ʻāpana i ka manawa a hoʻoulu i ka ʻinoʻino o ka ʻāʻī (Figure 2).
Kiʻi 2 – Hiki ke hoʻoulu ʻia ka ʻino ma waena o ka paipu a me ke kākoʻo paipu (luna) a i ka wā e hoʻokomo ʻia ai ka paipu kokoke i nā ʻili ʻē aʻe (lalo) ma muli o ka hoʻokumu ʻia ʻana o kahi solution ferric chloride chemically aggressive acidified i loko o ka lua.
Hoʻohālikelike ka ʻino ʻo Crevice i ka corrosion ma mua o ka lua i hana ʻia ma waena o ka lōʻihi o ka paipu a me ke kākoʻo o ka paipu.
ʻO nā māwae paʻa ka pilikia nui loa o ka pala.
Hiki ke pale maikaʻi ʻia ka pōʻino o ka lua a me ka crevice ma ke koho ʻana i ka mea hoʻoheheʻe metala kūpono no ka noi. Pono nā mea kikoʻī e hoʻoikaika pono i ke koho ʻana i nā mea paipu maikaʻi loa e hōʻemi i ka hopena o ka corrosion ma muli o ke kaiapuni hana, nā kūlana kaʻina a me nā ʻano ʻē aʻe.
No ke kōkua ʻana i nā mea kikoʻī i ka koho ʻana i nā mea, hiki iā lākou ke hoʻohālikelike i nā metala 'PREN waiwai no ka hoʻoholo ʻana i ko lākou kūʻē ʻana i ka corrosion localized. Hiki ke helu ʻia ka PREN mai ka hui kemika o ka alloy, me kona chromium (Cr), molybdenum (Mo), a me ka nitrogen (N) maʻiʻo, penei:
Hoʻonui ka PREN me ka ʻike o ka corrosion-resistant elements chromium, molybdenum a me ka nitrogen i loko o ka hui. ka piʻi liʻiliʻi o ka CPT i hoʻohālikelike ʻia me ka alloy, akā ʻo ka piʻi nui ʻana o ka PREN e hōʻike ana i ka hoʻomaikaʻi ʻana i ka hana no ka CPT kiʻekiʻe loa.
Hoʻohālikelike ka Papa 1 i nā koina PREN o nā ʻāpana like ʻole i hoʻohana mau ʻia i nā noi aila a me nā kinoea waho.
ʻO nā kiʻekiʻe kiʻekiʻe o ka nickel (Ni) i loko o ke kila kila e hoʻoikaika i ka pale ʻana i ka corrosion. Akā naʻe, ʻaʻole ʻo ka nickel content o ke kila kila ʻaʻole ia he ʻāpana o ka equation PREN. I kēlā me kēia hihia, ʻoi aku ka maikaʻi o ke kuhikuhi ʻana i nā kila kila me nā kiʻekiʻe nickel kiʻekiʻe. ʻO ka tensite he māhele crystalline i makemake ʻole ʻia i nā metala e hoʻemi ana i ke kūpaʻa o ke kila kila i ka corrosion localized a me ka chloride-induced stress cracking.
Hiki ke ʻino ʻia ma nā wahi ʻē aʻe ma nā paipu i hoʻohana ʻia i nā kaiapuni moana. Akā naʻe, ʻoi aku ka nui o ka corrosion pitting ma nā wahi i haumia mua ʻia, ʻoiai ʻoi aku ka nui o ka corrosion crevice ma nā wahi me nā āwaha haiki ma waena o ka paipu a me ka lako paʻa.
Eia naʻe, e hoʻomanaʻo he mau ʻano ʻē aʻe e hiki ke hoʻopilikia i ka corrosion.
Hiki i nā mea nona ka paepae a me nā mea hoʻohana ke hana i nā hana e hōʻemi i ka hopena o ka ʻino ma hope o ke kau ʻana o ka paipu.
Ma muli o nā ʻanuʻu i hōʻike ʻia ma luna nei, hiki i nā mea nona ka paepae a me nā mea hoʻohana ke hōʻemi i ka hopena o ka hoʻoheheʻe ʻana o ka paipu a me nā leaks pili i loko o nā kaiapuni kai, hoʻomaikaʻi i ka palekana a me ka pono, ʻoiai e hōʻemi ana i ka manawa o ka nalowale o ka huahana a i ʻole ka hoʻokuʻu ʻana i nā mea mahuka.
Brad Bollinger is the Oil and Gas Marketing Manager for Swagelok Company.He can be reached at bradley.bollinger@swagelok.com.
ʻO ka Journal of Petroleum Technology ka makasina poʻokela o ka Society of Petroleum Engineers, e hāʻawi ana i nā puʻupuʻu mana a me nā hiʻohiʻona e pili ana i ka holomua o ka ʻimi ʻana a me ka ʻenehana hana, nā pilikia o ka ʻoihana aila a me ke kinoea, a me nā nūhou e pili ana iā SPE a me kona mau lālā.