Nace Rp0472 Pdf [better] Jun 2026

NACE RP0472 (now updated to NACE SP0472 ) is the essential standard for preventing environmental cracking in carbon steel weldments used in petroleum refining. It specifically targets "P-1" steels (those with a tensile strength ≤ 70,000 psi). The standard focuses on two primary cracking mechanisms: Hydrogen Stress Cracking (HSC): Controlled by limiting the of the weld deposit and the heat-affected zone (HAZ). Alkaline Stress Corrosion Cracking (ASCC): Prevented primarily through Post-Weld Heat Treatment (PWHT) to reduce residual tensile stresses. Key Technical Requirements Hardness Limit: The standard specifies a maximum weld deposit hardness of (Brinell). HAZ Control:

: Hardness must not exceed 248 Hv10 (Vickers). Since production testing of the HAZ is difficult, it is controlled through base metal chemistry (limiting carbon equivalent), post-weld heat treatment (PWHT), or specific "thermal methods" like cooling time control. Residual Stress Reduction for ASCC : nace rp0472 pdf

), high-hardness welds are susceptible to brittle cracking. By following this guide, engineers ensure that welds remain ductile enough to withstand sour service. Key Requirements of the Standard NACE RP0472 (now updated to NACE SP0472 )