The systematic studies to evaluate the corrosion resistance to Sulfide Stress Cracking (SSC) and crevice corrosion susceptibility of UNS S30400 and S31603 carcass material showed that serviceability limits to these materials can be extended to: 60°C, 1%H2S 99%CO2, pH>4.0, 60,000ppm Cl-. Notwithstanding, the present field conditions at Campos Basin is still less aggressive than the new serviceability limits just mentioned, but the oil production scenarios may change to more aggressive environments in a near future. Therefore, the test program was extended to lean duplex stainless steel, such as UNS S32101 and S32304. The aim of this test program is to provide technical data to support the replacement of austenitic flexible pipe carcass, at Campos Basin, by low cost materials with suitable mechanical properties and corrosion resistance when the field conditions turn too aggressive to carcass materials in operation. According to results presented herein, in the range of 70 to 90 °C, up to 4% H2S, 96%CO2, 120,000 ppm Cl- and pH>3.8 the UNS S32101 and UNS S32304 are not susceptible to SSC or any other type of localized corrosion, pits or crevice corrosion.

Subject
Pits, Materials, Piping, Materials performance, Microstructure, Acidity, Crevices, U bends, Immersion, Corrosion resistance, Localized corrosion, Pitting resistance equivalent number, Sulfide stress cracking
Keywords:
Lean Duplex carcass, corrosion, sour service, SSC
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2017
Association for Materials Protection and Performance (AMPP)
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