NACE MR0175 / ISO 15156
Standard for materials resistant to sulfide stress cracking in H2S sour oil & gas environments.
NACE MR0175 (now ISO 15156) defines acceptable alloy compositions for sour service where hydrogen sulfide can cause sulfide stress cracking.
PMI programs verify that installed alloys (carbon steel, duplex, nickel alloys) match approved grades. Portable XRF confirms Cr, Ni, Mo, and Cu levels — critical for duplex 2205 and Inconel families in refineries and pipelines.