CRA 2550E (UNS N06255) is a premium melted, cold worked nickel-based alloy meeting the severe challenges of wells containing high chlorides, H2S and temperature. With a typical Pitting Resistance Equivalent Number of 52, it is highly resistant to pitting corrosion and chloride-induced stress corrosion cracking. For sour service applications, it is classified in MR0175/ISO15156 as a type 4d alloy, with no restrictions to partial pressure of H2S below 300°F and resistant to 300 psi H2S at 425°F.
CRA 2550E-140 C-rings tested at 100% AYS in 15.5 ppg ZnBr2/CaBr2/CaCl2 brine exhibited no evidence of cracking. Tests were performed under three conditions:
• 1.5 psi H2S / 500 psi CO2 / 350°F
• O2 saturated / 425°F
• 500 psi CO2 / 425°F
CRA 2550E has excellent hydrogen embrittlement resistance at all standard strength levels.