Clarifying the Applicability of PREN Equations: A Short Focused Review

The application of pitting resistance equivalent number (PREN) equations for stainless steels has become ubiquitous across many industries, none more so than the petroleum industry. These useful equations are often used to develop new alloys based on generating the highest possible PREN, however, they are frequently applied incorrectly to environments that are not consistent with the original basis of their development. This focused review presents some of the origins of the PREN equations and their limitations especially for use in oil and gas applications.