For the first phase of the Project solution has been developed to overcome sulfide stress corrosion problems in high strength steel armors in H2S/CO2 containing environment. The solution consists of protecting high strength steel armor elements with an aluminum cladding produced by method of Conform. This cladding has been shown to be fully H2S tolerant and capable to maintain bare steel in condition of electrochemical immunity (cathodic protection). The present paper summarizes the theoretical framework and the test programs worked out to validate the aluminum cladding solution.
Results of the First Phase of the Project: The test coupons made of metallic armor material for each category were also exposed individually to corrosive environment for corrosion rate test. H2S has been proven to be not reactive with the aluminum coating in water environment up to 1 bar partial pressure. Aluminum clad high strength steel strips (Y 0,2%~1000MPa and ~ 200 <m cladding thickness) passes NACE TM0177 sulfide stress corrosion cracking (SSCC) test purged with 0,9 bar CO2 - 0,1 bar H2S gas mixture (720 hours, pH 4, four point bending at 90% Y0,2%,). The same high strength steel strips without aluminum cladding doesn’t pass the test. Al clad high strength steel strips passes the extension of NACE TM0177 test to 1440 , 2160 and 3000 hours. In case of mechanical damage of the cladding, the remaining aluminum cladding is capable to cathodically protect the exposed steel
Key words: H2S, CO2, Sour Service, Hydrogen Embrittlement, Sulfide Stress Cracking, Hydrogen induced cracking, High Strength Steels