Materials · Hydrogen-induced cracking · NACE TM0284 / ISO 15156
HIC / Sour-Service Screening
H₂S partial pressure & sour classification, indicative ISO 15156-2 SSC severity region (SSC, not HIC — HIC applies for any sour service), NACE TM0284 HIC acceptance (CLR/CTR/CSR), and a material recommendation.
Sour Service
mol%
psia
Material
%
HIC Coupon (optional, TM0284)
%
%
%
Engineering Basis
pH₂S = yH₂S·Ptotal; sour when ≥0.3 kPa (0.05 psia) per NACE/ISO 15156.
Indicative ISO 15156-2 region from pH₂S (0.3 / 10 / 100 kPa) adjusted by in-situ pH.
NACE TM0284 acceptance: CLR ≤15%, CTR ≤5%, CSR ≤2% on the test coupon.
HIC-resistant material: low S (≤0.002-0.003%), calcium inclusion-shape control.
Standards: NACE TM0284, NACE MR0175 / ISO 15156-2 (2020+).