7.4.4 CUI
External inspection of insulated piping systems should include a review of the insulation system integrity for
conditions that could lead to CUI and signs of ongoing CUI. API 570 documents the requirements of a CUI inspection
program. Sources of moisture can include rain, water leaks, condensation, deluge systems, and cooling towers. The
two forms of CUI are localized corrosion of carbon steel and chloride SCC of austenitic stainless steels. See API 571
for additional details on CUI mechanisms.