THE APPLICATION LIMITS OF ALLOYED 13 Cr TUBULAR STEELS FOR DOWNHOLE DUTIES

摘要

In the past few years, a new family of materials has entered the downhole tubular market, known as the "alloyed 13%Cr steels". These are a development of the conventional API 5CT grade 13%Cr steels to which alloying elements of Ni, Mo and Cu have been added, hence offering a number of advantages. In the present paper, domains of application for the 95ksi grade alloyed 13%Cr steels with respect to sour service conditions have been denned on pH vs. H_2S partial pressure plots. Corrosion properties have also been determined for two other aspects; chloride stress corrosion cracking (CISCO and high temperature corrosion resistance. The results have reiterated the importance of solution chemistry, pH and H_2S partial pressure in defining the corrosion properties of steels.