An S31803 (22-05 alloy) duplex stainless steel flow-cross in service in the H2S-containing Saint-Faust gas field near Lacq was almost broken in two by a corrosion crack resulting from improper heat treatment.
Sensitization had occurred much more rapidly than expected from the kinetics of sigma phase formation generally considered in the literature. None of the inspection techniques routinely employed in the oil and gas
industry would have been capable of detecting this manufacturing defect. More stringent quality acceptance critetia are therefore necessary
Key worde: Duplex stainless steel, UNS S31803, H2S, Uranus 50, waterflood, sigma phase, sensitization, stigmatization