API 5CT misali ne akan rumbun mai ta Cibiyar Man Fetur ta Amurka, galibi don bututun mai, tubing da casing.

API 5CT cakulan man fetur da ake amfani da shi wajen hako rijiyoyin mai, wanda aka fi amfani da shi don hakowa da kuma kammala bangon dama na tallafi, don tabbatar da gudanar da aikin hakowa da kuma kammala aikin hakowa bayan aikin rijiyoyin na yau da kullun.Casing shine don kula da rijiyoyin suna tafiyar da layin rayuwa.Kamar yadda yanayi daban-daban na geological, yanayin yanayin damuwa na karkashin kasa, ja, latsawa, lankwasawa, damuwa na torsional yana aiki akan tasirin haɗin gwiwa na bututu, wanda casing kanta, ingancin mafi girman buƙatun.Da zarar kwandon kanta ya lalace saboda wasu dalilai, zai iya haifar da duk rijiyoyin da ake samarwa, ko ma a soke su.

Abubuwan injina na API 5CT API 5CTBututun ƙarfe mara nauyi: