Bututun ƙarfe shine aikin bututun iskar gas da aka fi amfani dashi. Babban fa'idodinsa shine: ƙarfin ƙarfi, ƙaƙƙarfan ƙarfi, ɗaukar damuwa, juriya mai ƙarfi da ƙarfi, filastik mai kyau, walƙiya mai sauƙin walda da sarrafa zafin jiki, kauri na bango yana da ƙarfi, ceton ƙarfe. Amma rashin juriya na lalata, yana buƙatar samun matakan kariya masu dacewa.

Bututun ƙarfe na bututun iskar gas a babban birnin na bututun ƙarfe maras sumul da waldadden bututun ƙarfe biyu. High ƙarfi sumul karfe bututu, amma iyakance samar tsari da kuma halin kaka da kullum kananan diamita karfe bututu DN200 kasa. More iri welded karfe bututu, waldi za a iya raba ta madaidaiciya kabu welded karfe bututu da karkace welded karfe bututu iri. Daga cikin su, madaidaiciyar bututun ƙarfe mai walƙiya (daga nan ana kiranta da bututun madaidaiciya) kuma ya haɗa da bututun ƙarfe na LSAW da babban bututun ƙarfe na juriya (ERW) da sauran nau'ikan. Karfe welded bututu (ssaw karfe bututu) ne karkace kabu biyu submerged baka welded (HSAW) bututu.

An kwatanta tsarin samar da bututu madaidaiciya da karkace, na farko yana da fa'ida:
① karkace bututu masana'antu tsari domin sanin su saura danniya ne mafi girma daga madaidaiciya kabu bututu, madaidaiciya kabu bututu tare da overall sakamakon fadada tsari, saura danniya kusa da sifili, yayin da karkace ba zai iya yin wannan;

② karkace weld gefen kuskure mafi yawa a cikin kewayon 1.1 ~ 1.2mm, ma'aunin yana buƙatar adadin kuskuren gefen bangon kauri zuwa ƙasa da 10% don bututun bangon bakin ciki, gefen da ba daidai ba yana da wahalar saduwa da daidaitattun buƙatun, kuma madaidaiciyar bututun kabu babu Wannan matsalar;

③ Idan aka kwatanta da madaidaiciyar bututun kabu, karkatacciyar layin walda ba ta da kyau, matsananciyar damuwa;

④ nada zafi shafi yankin ne mafi girma fiye da madaidaiciya kabu bututu, da bututu zafi shafi yankin ne mabuɗin zuwa inganci;

⑤ karkace daidaitattun lissafi, zuwa wurin ginin, a matsayin takwaransa, walda yana kawo wasu matsaloli.