NACE MR0175 / API 571 / NORSOK M-506
Understand steel grades, NACE MR0175 sour service, and material testing
NACE MR0175 (ISO 15156) specifies material requirements for equipment in sour (H₂S-containing) oil and gas service. This calculator helps determine appropriate materials based on H₂S partial pressure, temperature, and pH conditions.
The calculator evaluates operating conditions against NACE MR0175 sour service regions and API 571 damage mechanisms. It considers H₂S concentration, CO₂ partial pressure, chloride content, and temperature to recommend suitable materials.
Sulfide stress cracking (SSC) is caused by hydrogen embrittlement under tensile stress in sour environments. Stress-oriented hydrogen-induced cracking (SOHIC) occurs as stacked hydrogen blisters aligned with through-thickness stress, per NACE MR0175 and API 571.
Duplex stainless steels are considered when carbon steel is unsuitable due to high chloride levels, elevated temperatures, or combined CO₂/H₂S corrosion. Material selection depends on the specific NACE MR0175 environment classification.