Corrosion under insulation (CUI) is a major problem for petroleum and chemical process industries. CUI can result in sudden and hazardous leaks (safety concern), and plant shutdowns with high losses of production-volumes (economical concern). A few examples are described in this article to illustrate the problems with CUI. This article discusses the root causes of CUI and recommendations to prevent it. One of the major recommendations is the use of risk-based inspections (RBI) and the details of this RBI method are described. CUI can be especially avoided through a good cooperation between operations, inspection, and maintenance departments. (C) 2008 American Institute of Chemical Engineers Process Saf Prog 28: 30-35 2009