Ahakoa te ātete ā-roto o ngā paipa kowiri tira, ka pāngia ngā paipa kowiri tira e whakauruhia ana ki ngā taiao moana e ngā momo waikura i roto i te roanga o te wā e hiahiatia ana. Ka taea e tēnei waikura te arahi ki ngā tukunga rere, ngā ngaronga hua me ngā mōrearea pea. Ka taea e ngā kaipupuri me ngā kaiwhakahaere papaaho moana te whakaiti i te mōrearea o te waikura mā te tohu i ngā rauemi paipa kaha ake e whakarato ana i te ātete waikura pai ake. Muri iho, me noho mataara tonu rātou i te wā e tirotirohia ana ngā raina weronga matū, ngā raina waipēhi me ngā raina whakatere, me ngā taputapu tukatuka me ngā taputapu kia kore ai te waikura e whakawehi i te kounga o ngā paipa kua whakauruhia, e whakararu rānei i te haumaru.
Ka kitea te waikura ā-rohe i runga i ngā papaaho maha, ngā kaipuke, ngā kaipuke me ngā paipa tai. Ka taea e tēnei waikura te puta i te āhua o te waikura poka, te waikura kapiti rānei, ka taea e ēnei te whakahoro i te pakitara o te paipa, ka puta ai te wai.
Ka piki ake te mōrearea o te waikura i te pikinga ake o te pāmahana whakahaere o te tono. Ka taea e te wera te whakateretere i te pirau o te kiriata waikura tiaki o waho o te ngongo, ā, ka puta ai te poka.
Engari, he uaua ki te kite i te waikura o te poka me te kapiti, ā, he uaua ki te tautuhi, ki te matapae, me te hoahoa i ēnei momo waikura. I runga i ēnei mōrearea, me tūpato ngā kaipupuri papaaho, ngā kaiwhakahaere me ngā kaiwhakarite i te whiriwhiri i te rauemi paipa pai rawa atu mō tā rātou tono. Ko te whiriwhiri rauemi te rārangi tuatahi o tā rātou parepare ki te waikura, nō reira he mea tino nui te tika. Waimarie, ka taea e rātou te whiriwhiri i tētahi inenga tino māmā engari tino whai hua mō te ātete waikura ā-rohe, ko te Tau Ātete Pitting (PREN). Ko te teitei ake o te uara PREN o tētahi konganuku, ko te teitei ake o tōna ātete ki te waikura ā-rohe.
Ka tirohia e tēnei tuhinga me pēhea te tautuhi i te waikura o ngā poka me ngā kapiti, me pēhea hoki te arotau i te kōwhiringa rauemi ngongo mō ngā tono hinu me te hau o tai i runga i te uara PREN o te rauemi.
Ka puta te waikura ā-rohe i ngā wāhi iti ki te waikura whānui, he rite tonu te āhua ki runga i te mata whakarewa. Ka tīmata te waikura poka me te kapiti ki runga i ngā ngongo maitai kore waikura 316 ina pakaru te kiriata waikura korehau o waho o te whakarewa nā te pānga ki ngā wai waikura, tae atu ki te wai tote. Ko ngā taiao moana he nui ngā pūhaumāota, me ngā pāmahana teitei me te poke o te mata ngongo, ka piki ake te tūponotanga o te pirau o tēnei kiriata korehau.
Te waikura o te waikura Ka puta te waikura o te waikura ina pakaru te kiriata whakakore i runga i tētahi wāhanga o te paipa, ka hanga he kōhao iti, he kōhao rānei i runga i te mata o te paipa. Tērā pea ka tipu ake aua kōhao i te haere tonu o ngā tauhohenga hiko, ā, ko te mutunga iho ka rewa te rino i roto i te konganuku ki roto i te wairewa i raro i te kōhao. Kātahi ka horapa te rino rewa ki te tihi o te kōhao ka waikura hei hanga waikura rino, waikura rānei. I te hohonu haere o te kōhao, ka tere ake ngā tauhohenga hiko, ka piki ake te waikura, ka arahi pea ki te poka o te pakitara o te paipa, ka arahi hoki ki ngā turuturu.
He ngāwari ake te pakaru o ngā ngongo mēnā he poke te mata o waho (Pikitia 1). Hei tauira, ka taea e ngā poke mai i ngā mahi whakarewa me te huri te kino i te paparanga waikura whakakore o te paipa, ā, ka hangaia, ka tere ake te pakaru. Pērā anō hoki mō te whakahaere noa i te parahanga mai i ngā paipa. Hei tāpiri, i te mimiti haere o ngā pata tote, ka tiakina e ngā tioata tote mākū e hanga ana i runga i ngā paipa te paparanga waikura, ā, ka arahi pea ki te pakaru. Hei ārai i ēnei momo parahanga, kia ma tonu ō paipa mā te horoi i a rātou ki te wai māori i ia wā.
Pikitia 1. He tino ngāwari te pakaru o te paipa maitai kore waikura 316/316L kua poke i te waikawa, te tote, me ētahi atu putunga.
te waikura o te kapiti. I te nuinga o te wā, ka kitea ngāwari e te kaiwhakahaere te waikura o te kapiti. Heoi, ehara i te mea ngāwari te kite i te waikura o te kapiti, ā, he nui ake te mōrearea ki ngā kaiwhakahaere me ngā kaimahi. Ka puta tēnei i ngā paipa he whaiti ngā āputa i waenga i ngā rauemi e karapoti ana, pērā i ngā paipa e puritia ana ki ngā rawhi, i ngā paipa rānei e piri pūmau ana tetahi ki tetahi. Ina mimiti te wai tote ki roto i te kapiti, i roto i te wā, ka puta he wairewa waikawa konupora (FeCl3) kaha ki tēnei wāhi, ka tere ake te waikura o te kapiti (Pikitia 2). Nā te mea ka whakanui ake te kapiti i te mōrearea o te waikura, ka puta te waikura o te kapiti i ngā pāmahana iti iho i te kapiti.
Pikitia 2 – Ka taea te whakawhanake i te waikura kapiti i waenganui i te paipa me te tautoko paipa (runga) me te wā e tāutahia ana te paipa tata ki ētahi atu mata (raro) nā te hanganga o te wairewa waikawa o te konupūmā ferric i roto i te āputa.
Ko te waikura o te kapiti he rite ki te pakaru tuatahi i roto i te āputa i waenganui i te wāhanga paipa me te kara tautoko paipa. Heoi, nā te pikinga ake o te kukū o te Fe++ i roto i te wai i roto i te whati, ka nui haere te hāneanea tuatahi kia kapi katoa te whati. Hei whakamutunga, ka taea e te waikura o te kapiti te arahi ki te pakaru o te paipa.
Ko ngā kapiti matotoru te mea nui rawa atu mō te waikura. Nō reira, ko ngā rawhi paipa e karapoti ana i te wāhanga nui ake o te porowhita o te paipa he nui ake te mōrearea i ngā rawhi tuwhera, e whakaiti ana i te mata pa i waenga i te paipa me te rawhi. Ka taea e ngā tohunga ratonga te āwhina ki te whakaiti i te tūponotanga o te kino, te pakaru rānei o te waikura o te kapiti mā te whakatuwhera i ngā rawhi me te tirotiro i te mata o te paipa mō te waikura.
Mā te whiriwhiri i te konukōre whakarewa tika mō te whakamahinga ka taea te ārai i te waikura o ngā rua me ngā kapiti. Me āta whakaaro ngā kaiwhakatakoto i te whiriwhiri i te rauemi paipa tino pai hei whakaiti i te tūponotanga o te waikura i runga i te taiao tukanga, ngā āhuatanga tukanga, me ētahi atu taurangi.
Hei āwhina i ngā kaiwhakatakoto whakaaro ki te arotau i te kōwhiringa rauemi, ka taea e rātou te whakataurite i ngā uara PREN o ngā konganuku hei whakatau i tō rātou ātete ki te waikura ā-rohe. Ka taea te tatau i te PREN mai i te matū o te koranu, tae atu ki tōna ihirangi chromium (Cr), molybdenum (Mo), me te hauota (N), penei:
Ka piki ake te PREN i te nui o ngā huānga ātete-waikura o te chromium, te molybdenum me te hauota i roto i te koranu. Ko te ōwehenga PREN e ahu mai ana i te pāmahana poka nui (CPT) – te pāmahana iti rawa e puta ai te poka – mō ngā momo maitai kore waikura i runga i te hanganga matū. Ko te tikanga, he ōrite te PREN ki te CPT. Nō reira, ko ngā uara PREN teitei ake e tohu ana i te ātete poka teitei ake. Ko te pikinga iti o te PREN he rite noa ki te pikinga iti o te CPT ki te whakataurite ki te koranu, ko te pikinga nui o te PREN e tohu ana i te whakapainga nui o te mahi ki te CPT teitei ake.
E whakataurite ana te Ripanga 1 i ngā uara PREN mō ngā momo koranu e whakamahia whānuitia ana i roto i te umanga hinu me te hau moana. E whakaatu ana me pēhea te whakapai ake i te ātete waikura mā te whiriwhiri i tētahi koranu paipa kounga teitei ake te whakatakotoranga. Ka piki ake te PREN mai i te 316 SS ki te 317 SS. He pai rawa atu ngā Super Austenitic 6 Mo SS, ngā Super Duplex 2507 SS rānei mō te whakanui ake i te mahi.
Ka whakanui ake hoki te nui o te nikara (Ni) i roto i te maitai kore waikura i te ātete ki te waikura. Heoi, kāore te nui o te nikara o te maitai kore waikura i roto i te whārite PREN. Ahakoa pēhea, he pai tonu te whiriwhiri i ngā maitai kore waikura he nui ake te nui o te nikara, nā te mea ka āwhina tēnei huānga ki te whakaora anō i ngā mata e whakaatu ana i ngā tohu o te waikura ā-rohe. Ka whakaū te nikara i te austenite, ā, ka ārai i te hanganga martensite i te piko, i te tō matao rānei i te 1/8 o te paipa pakari. Ko te martensite he wāhanga tioata kāore e hiahiatia ana i roto i ngā konganuku e whakaiti ana i te ātete o te maitai kore waikura ki te waikura ā-rohe me te pakaru ahotea i puta mai i te hauhāora. Ko te nui ake o te nikara o te 12% neke atu rānei i roto i te maitai 316/316L he mea e hiahiatia ana hoki mō ngā tono hau hauwai pēhanga teitei. Ko te iti rawa o te kukū nikara e hiahiatia ana mō te maitai kore waikura ASTM 316/316L he 10%.
Ka taea te waikura ā-rohe te puta i ngā paipa katoa e whakamahia ana i roto i ngā taiao moana. Heoi, he nui ake te tūponotanga o te pakaru i ngā wāhi kua poke kē, engari he nui ake te tūponotanga o te waikura kapiti i ngā wāhi he whaiti ngā āputa i waenganui i te paipa me ngā taputapu tāutanga. Mā te whakamahi i te PREN hei pūtake, ka taea e te kaiwhakatakoto whakaaro te kōranu paipa pai rawa atu hei whakaiti i te tūponotanga o tētahi momo waikura ā-rohe.
Heoi, kia maumahara kei reira ētahi atu taurangi ka pā ki te mōrearea o te waikura. Hei tauira, ka pā te pāmahana ki te ātete o te maitai kore waikura ki te pakaru. Mō ngā āhuarangi moana wera, me whai whakaaro nui ki ngā paipa maitai kore waikura super austenitic 6 molybdenum, ki ngā paipa maitai kore waikura super duplex 2507 rānei, nā te mea he tino ātete ēnei rauemi ki te waikura ā-rohe me te pakaru o te pūhaumāota. Mō ngā āhuarangi makariri, he rawaka pea he paipa 316/316L, inā koa mēnā he hītori whakamahinga angitu.
Ka taea hoki e ngā kaipupuri me ngā kaiwhakahaere o ngā papaaho moana te mahi i ngā mahi hei whakaiti i te tūponotanga o te waikura i muri i te tāutanga o ngā ngongo. Me pupuri e rātou ngā paipa kia ma, kia horoia hoki ki te wai māori i ia wā hei whakaiti i te tūponotanga o te pakaru. Me whakatūwhera hoki e ngā tohunga tiaki ngā rawhi paipa i ngā wā tirotiro auau hei tirotiro mēnā he waikura kei ngā kapiti.
Mā te whai i ngā kaupae o runga ake nei, ka taea e ngā kaipupuri me ngā kaiwhakahaere o ngā papaaho te whakaiti i te mōrearea o te waikura o ngā paipa me ngā turuturu e pā ana ki te taiao moana, te whakapai ake i te haumaru me te whai huatanga, me te whakaiti i te tūponotanga o te ngaronga o ngā hua, o ngā tukunga rere rānei.
Brad Bollinger is the Oil and Gas Marketing Manager for Swagelok. He can be contacted at bradley.bollinger@swagelok.com.
Ko te Journal of Petroleum Technology te hautaka matua o te Society of Petroleum Engineers, e whakaatu ana i ngā whakarāpopototanga me ngā tuhinga whai mana mō ngā whanaketanga o te hangarau o runga, ngā take o te umanga hinu me te hau, me ngā purongo mō SPE me ōna mema.