Amasu Okushisela Insimbi Ye-Nickel Embonini Ye-Petrochemical
Imboni yamakhemikhali kaphethiloli isebenza ngaphansi kwezimo ezinzima: amazinga okushisa aphezulu, ukucindezela okuphezulu, kanye nokuchayeka ezintweni ezigqwalisayo ezifana ne-chloride, i-sulfur, i-H₂S, i-CO₂, kanye namakhemikhali ahlukahlukene e-asidi. Kulezi zimo, ukukhethwa kwezinto kuyisici esinqumayo ekuthembekeni kwemishini yenqubo. Izinsimbi ezisekelwe ku-nickel (i-nickel kanye nama-alloy ayo) zisetshenziswa kabanzi ngenxa yokumelana kwazo nokugqwala okuphezulu, ukuqina kokushisa okuphezulu, kanye nekhono lokumelana nokuqhekeka kokugqwala kokucindezeleka. Kodwa-ke, lezi zinzuzo zingatholakala kuphela uma inqubo yokugqwala yenziwa kusetshenziswa indlela efanele, njengoba ukugqwala kungashintsha isakhiwo sezinto, kubangele ukuqhekeka okushisayo, ukubhoboka, noma ukunciphisa ukumelana nokugqwala endaweni yokugqwala.
1. Indima yama-alloy e-nickel kumakhemikhali e-petrochemicals
Ama-alloy e-nickel afana ne-Nickel 200/201, i-Monel (Ni-Cu), i-Inconel (Ni-Cr-Fe), i-Incoloy, kanye ne-Hastelloy (Ni-Mo-Cr) avame ukusetshenziswa kuma-heat exchanger, amakholomu okuhluza, ama-reactor, amapayipi okucubungula, imishini yokususa i-sulfurization, kanye nezinhlelo ezibhekana nama-acid nama-chloride. Isibonelo, ama-alloy e-Ni-Cr anokumelana okuhle kwe-oxidation emazingeni okushisa aphezulu, kuyilapho ama-alloy e-Ni-Mo ehamba phambili ekunciphiseni izindawo kanye nezixazululo ezithile ze-asidi. Ukushisela la ma-alloy kudinga ukugcina ukwakheka kwe-alloy okuyisisekelo ukuze kugcinwe ukumelana okuhle kokugqwala.
2. Izinselele ezikhethekile ekushiseni i-nickel
Ngokuvamile, ama-alloy e-nickel anokushisa okuphansi kune-carbon steel kanye ne-coefficient ephezulu yokwanda kokushisa. Lokhu kuhlanganiswa kuholela ekugxilweni okukhulu kokushisa endaweni yokushisela futhi kungandisa ukuphambuka. Ngaphezu kwalokho, amanye ama-alloy e-nickel azwela ku:
– Ukuqhekeka okushisayo (ukuqhekeka kokuqina) ngenxa yokuhlukaniswa kwezinto emingceleni yokusanhlamvu ngesikhathi sokuqina kwensimbi yokushisela.
– Ukubhoboka kwenhlabathi kuvame ukubangelwa ukungcola, umswakama, noma igesi evalelekile.
– Ukuzwela noma ukunciphisa ukumelana nokugqwala kwendawo uma inqubo yokushisela ingalungile, ikakhulukazi kuma-alloy athile.
– Ukungcoliswa kwensimbi/ikhabhoni okuvela kumathuluzi okusebenza ensimbi kungalimaza ukumelana nokugqwala, ikakhulukazi ezindaweni ezinolaka zamakhemikhali.
Ngakho-ke, ukulawula ukuhlanzeka, ukukhetha izigcwalisi, kanye nemingcele yokushisa kubalulekile.
3. Ukukhetha inqubo yokushisela: GTAW, GMAW, SMAW, kanye ne-SAW
Ezinye izinqubo ezivamile zokushisela ze-nickel alloys kumakhemikhali e-petrochemicals zifaka:
a) I-GTAW (TIG)
I-GTAW ivame ukuba yindlela ekhethwayo yokudlulisa izimpande zamapayipi, ukusebenza ngokunemba, kanye nezinto ezincane. Izinzuzo zayo zifaka phakathi ukulawula ukushisa okuhle kanye nokushisela okuhlanzekile. Ukuvikela igesi ye-argon emsulwa kuvame ukusetshenziswa; kwezinye izinhlelo zokusebenza, i-helium ingangezwa ukuthuthukisa ukungena.
b) I-GMAW (MIG) kanye ne-pulsed GMAW
I-GMAW ifaneleka ekukhiqizweni okusheshayo, ikakhulukazi ekwakhiweni kweshabhu. Imodi ye-pulsed isiza ukunciphisa ukufakwa kokushisa kanye nokuchitheka, kanye nokuthuthukisa ukulawula ezindaweni ezinzima zokushisela. Intambo yokushisela kumele igcinwe futhi iphathwe kahle ukuze kugwenywe ukungcola.
c) I-SMAW (ukushisela i-electrode)
I-SMAW isetshenziswa kabanzi ekulungiseni insimu ngenxa yemishini yayo elula. Kodwa-ke, izingozi zokuthathwa kwe-hydrogen kanye nokufakwa kwe-slag kumele zilawulwe ngokukhetha i-electrode efanele, izinqubo zokubhaka i-electrode, uma kudingeka, kanye namasu okuhlanza angaphakathi.
d) I-SAW
I-SAW iyasebenza kumapuleti aminyene kanye nama-weld amade, njengasemithonjeni yokucindezela noma amagobolondo. Ukukhetha i-flux kanye nentambo kumele kufaneleke ukuqinisekisa ukuthi ukwakheka kwensimbi ye-weld kugcina ukumelana nokugqwala okufiselekayo.
4. Ukulungiswa kwezinto kanye nokuhlanza indawo
Impumelelo yokushisela i-nickel alloy ithonywa kakhulu ukulungiswa kwendawo. Imikhuba evamile embonini ye-petrochemical ihlanganisa:
– Ukususa amafutha nge-solvent efanele ukususa uwoyela/amafutha.
– Hlanza i-oxide usebenzisa ibhulashi lensimbi engagqwali elikhethekile (ungasebenzisi ibhulashi lensimbi yekhabhoni).
– Ukusetshenziswa kwamathuluzi ahlukene: ama-grinder, ama-flap disc, namabhulashi kufanele anikezelwe ngqo ezintweni ze-nickel/stainless ukuze kuvinjelwe ukungcoliswa okuphambeneyo.
– Ukulungiswa okuqhubekayo kanye nokulawulwa kwezikhala ukuze kuncishiswe ingozi yokuntuleka kokuhlanganiswa noma ukushiswa.
Ngisho nezinto ezincane ezingcolisayo zingabangela ukubhoboka futhi zinciphise ikhwalithi yoboya obuhlanganisiwe.
5. Ukukhethwa kwensimbi yokugcwalisa kanye nokuhambisana kwayo
Ukukhethwa kwensimbi yokugcwalisa akufanele kusekelwe kuphela esimisweni esithi "izinto zilingana nezinto". Ekwenzeni kwe-petrochemical, ama-filler avame ukukhethwa ukuze kuthuthukiswe ukumelana nokuqhekeka nokugqwala. Izibonelo zezimiso ezijwayelekile:
– Sebenzisa i-filler enokumelana okuhle nokuqhekeka okushisayo kanye nokwakheka okusekela ukuqina okuzinzile.
– Ngokushisela okuhlukile (isb. i-nickel alloy kuya kwensimbi engagqwali noma i-alloy), kuvame ukukhethwa i-nickel filler ethile ekwazi ukubekezelela umehluko ekukhuleni kokushisa nokunciphisa izinkinga zokuxuba.
- Qinisekisa ukuthi umgcwalisi uhlangabezana nezindinganiso ezifanele ze-AWS/ASME futhi uhlangabezana nezimfuneko zephrojekthi.
Eziningi izinhlelo zokusebenza, isici sokugqwala sinamandla kakhulu kunamandla okudonseka ngakho-ke ukukhetha kokugcwalisa kubhekisela kokuhlangenwe nakho kwesevisi kanye nezincomo zekhodi.
6. Ukulawulwa kokufakwa kokushisa, ukushisa kusengaphambili, kanye nokushisa okuphakathi
Ama-alloy e-nickel ngokuvamile awadingi ukushisa okuphezulu njengezinsimbi ezithile ze-alloy, kodwa ukulawula izinga lokushisa kusabalulekile:
– Ukufakwa kokushisa okuningi kakhulu kungandisa i-HAZ (indawo ethintekile ekushiseni), kwandise ukuphambuka, futhi kwandise amathuba okuhlukaniswa okubangela ukuqhekeka kokushisa.
– Izinga lokushisa le-interpass kufanele ligcinwe lingabi phezulu kakhulu, ukuze ukuqina kwesakhiwo kanye nokumelana nokugqwala kulawulwe.
– Amasu okudlulisa okuningi anezilungiselelo zamandla kagesi/amandla kagesi ezizinzile avame ukusetshenziswa kumapuleti aqinile ukuze kugcinwe ikhwalithi.
Amapharamitha aqondile avame ukunqunywa nge-WPS (Welding Procedure Specification) futhi ahlolwe nge-PQR (Procedure Qualification Record).
7. Amasu okushisela ukunciphisa amaphutha
Amanye amasu asebenzayo avame ukusetshenziswa ekushiseni i-nickel kuma-petrochemicals:
– Ama-stringer bead ayathandwa kunokweluka okubanzi, ukuze kuncishiswe ukufakwa kokushisa nokunciphisa ukuhlukaniswa.
– Ukuhlanza izingqimba ezihlukene kubaluleke kakhulu, ikakhulukazi ku-SMAW kanye ne-SAW, ukuvimbela ukufakwa kwe-slag.
– Ukulawula ukuqala nokuma: imbobo kumele igcwaliswe kahle ukuze kuvinjelwe ukuqhekeka kwembobo.
– Ukuhlanza ingemuva ekushiseni kwepayipi le-GTAW (nge-argon) ukuze kugcinwe i-root bead ingena-oxidation.
– Ukusebenzisa igesi yokuvikela esezingeni eliphezulu nokuqinisekisa ukuthi akukho ukuvuza okubangela ukubola noma ukubola.
8. Ukwelashwa kokushisa ngemva kokushiswa (i-PWHT) kanye nokucatshangelwa kwensimbi
Akuzona zonke izinhlobo ze-nickel ezidinga i-PWHT. Ezimweni eziningi, i-PWHT ingadala ukuna kwezigaba ezithile, okunganciphisa ukumelana nokugqwala noma ukuqina, kuye ngohlobo lwe-alloy. Ngakho-ke:
– I-PWHT yenziwa kuphela uma kudingeka ikhodi (ASME) noma umklamo, noma uma into ethile iyidinga.
– Ukuhlolwa kwengozi yemvula yesigaba se-carbide/intermetallic kufanele kucabangele izinga lokushisa lesevisi kanye nendawo egqwalisayo.
– Kwezinye izinhlelo zokusebenza, kungadingeka ukuncibilikisa isixazululo noma ukwelashwa okushisa okukhethekile, kodwa lokhu kuvame ukwenziwa endaweni efanele futhi kusekelwe ezicini zezinto zokwakha.
9. Ukuhlolwa, ukuhlolwa kanye nezindinganiso ezisetshenziswayo
Kumakhemikhali e-petrochemicals, ukushisela ezintweni ze-nickel ngokuvamile kulandela i-ASME Section IX yezinqubo kanye neziqu zomshini wokushisela, kanye ne-ASME Section VIII (imikhumbi yokucindezela) noma i-B31.3 (ukucubungula amapayipi). Izindlela zokuhlola ezivamile zifaka:
– VT (Visual Testing) ukuhlola ukuma kobuhlalu, ukusika okungaphansi, ukugqagqana.
– I-PT (Ukuhlolwa Kokungena Koketshezi) iyasebenza ekutholeni imifantu engaphezulu ezintweni ezingezona eze-ferromagnetic.
– I-RT/UT ukuthola amaphutha angaphakathi njenge-porosity, ukuntuleka kwe-fusion, noma ukufakwa kwe-slag.
– Ukuhlolwa okwengeziwe njengokulinganisa i-ferrite (uma kufanele), ukuhlolwa kobulukhuni, noma ukuhlolwa kokugqwala kungadingeka kuye ngesevisi.
Ikhwalithi yemibhalo (i-WPS, i-PQR, i-WPQ, ukulandeleka kwezinto, inombolo yokushisa) nayo ibaluleke kakhulu kumaphrojekthi e-petrochemical.
10. Isiphetho
Amasu okushisela insimbi ye-nickel embonini yamakhemikhali kaphethroli adinga ukunamathela ngokuqinile ekuhlanzekeni, ekukhetheni inqubo kanye nokugcwalisa, kanye nokulawula okokufaka ukushisa. Ama-alloy e-nickel anikeza ukusebenza okuhle kakhulu ezindaweni ezigqwalisayo nezishisa kakhulu, kodwa ukuzwela kwawo ekungcoleni nasekuqhekekeni okushisayo kudinga ukwakheka okuqinile kanye nokwenza izinqubo zokushisela. Ngokusebenzisa i-WPS efanele, ukulawulwa kwamapharamitha, amasu okushisela afanele, kanye nokuhlolwa okuphelele ngokuhambisana nezindinganiso ze-ASME, amajoyinti ashiselwe asekelwe ku-nickel angafinyelela ukuthembeka kwesikhathi eside futhi anciphise ingozi yokwehluleka kwemishini ebalulekile ezindaweni ze-petrochemical.
Uma ufisa, ngingalungisa lesi sihloko sibe sezobuchwepheshe ngokwengeziwe ngokufaka izibonelo ze-WPS (ububanzi bamanje/bamandla kagesi, uhlobo lwegesi yokuvikela, i-interpass ephezulu), noma ukugxila ku-alloy eyodwa ethile njenge-Inconel 625 noma i-Hastelloy C-276.
