NACE RP0472 is a recommended practice (RP) that outlines procedures for protecting pipelines from external corrosion. The standard covers various aspects, including:
: This standard has effectively replaced API RP 942 , serving as the primary industry consensus for preventing environmental cracking in petroleum refinery weldments.
The standard emphasizes that welding procedures (SMAW, GMAW, FCAW, GTAW, and SAW) must be validated to produce welds within hardness limits. Proper heat input and post-weld heat treatment (PWHT) are crucial. 3. Prevention of Specific Damage Mechanisms
Enhanced guidance for performing local post-weld heat treatment (Appendix D). Cooling Time Concept ( t8/5t sub 8 / 5 end-sub
The standard dictates specific locations for hardness tests on cross-sections of the weld, including base metal, HAZ, and weld metal.
The central tenet of NACE SP0472 is controlling the hardness of the weld and Heat Affected Zone (HAZ). High hardness in steel correlates with increased susceptibility to SSC.