ASTM A351 CK3MCuN is a 6% Mo Super Austenitic Grade of Stainless Steel. For the Gas flowline service with 5.22% mole H2S, is this material is suitable for the service? How can we interpret this with ISO 15156-3 Standard. Please suggest
By consulting Table A.8 and confirming that the heat treatment conditions and 100 HRB hardness maximum criteria are met whilst assessing whether:
a) there is less than 50 ppm of chloride in the fluid stream
or failing that
b) that the temperature does not exceed 60 deg C and that the partial pressure of H2S, calculated in accordance with Annex C of ISO 15156-2 and Technical Circular 1 Link does not exceed 100 kPa
But, as per table A.8 ISO 15156-3 it is mentioned as "Material have been used without restriction on P H2S, temperature , pH in production environment. Only Chloride Conc. Max 50 mg/l to be checked. If the temperature is exceeding on the 60 Deg C, can we interpret second row of Table A.8. Please advice.
It's either a) or b). So, if you exceed 60 deg C and/or 100 kPa pH2S, then you will either have to have up to 50 ppm chloride, or, if not, you will have to undertake qualification corrosion testing.