A New High-Strength, Corrosion-Resistant Alloy for Oil and Gas Applications

HASTELLOY^® C-22HS^® alloy was introduced recently for applications requiring both corrosion resistance and high strength.  Being a C-type alloy (Ni-Cr-Mo), the new material has excellent resistance to uniform and localized corrosion in both reducing and oxidizing acids.  However, the new alloy is capable of being age-hardened to effectively double the yield strength over other C-type alloys.  More recently, C-22HS alloy has generated interest in the oil and gas industry due to its resistance to sour gas environments.  A considerable amount of testing has been performed to support the new alloy in this application.  In this paper, the properties of the new alloy relevant to the oil and gas industry will be presented.  These include the NACE standard room temperature tensile test for sulfide stress cracking and slow strain rate tensile testing at elevated temperatures (Level VII) both with and without the presence of elemental sulfur.  The alloy has shown excellent resistance in all test conditions.  Finally, efforts to develop alternate processing routes for C-22HS alloy for very high strength applications will be detailed.