CUI is a concern for insulated vessels operating at 500°F that are:

CUI is a concern for insulated vessels operating at 500°F that are:

• A. In intermittent service
• B. Made of stainless steel
• C. Made of low chromes
• D. Have poorly maintained insulation

Answer: (A)

The correct choice relates to the conditions under which Corrosion Under Insulation (CUI) is of particular concern. When insulated vessels operate at elevated temperatures, such as 500°F, the risk for CUI significantly increases, especially if the vessels are in intermittent service. This is due to the thermal cycling that occurs which can lead to condensation forming on the surface of the vessel, especially when it cools down. In intermittent service, the vessel may experience fluctuating temperatures that can lead to moisture accumulation beneath the insulation when temperatures drop. This moisture creates an environment conducive to corrosion, as it can remain trapped under the insulation and promote the degradation of the metal over time. Therefore, CUI is a notable concern in vessels that do not maintain a steady operating temperature. While other factors, such as material composition and insulation maintenance, can influence the likelihood of CUI, intermittent operation is specifically harmful as it introduces cycles of heating and cooling that exacerbate moisture issues.

The correct choice relates to the conditions under which Corrosion Under Insulation (CUI) is of particular concern. When insulated vessels operate at elevated temperatures, such as 500°F, the risk for CUI significantly increases, especially if the vessels are in intermittent service. This is due to the thermal cycling that occurs which can lead to condensation forming on the surface of the vessel, especially when it cools down.

In intermittent service, the vessel may experience fluctuating temperatures that can lead to moisture accumulation beneath the insulation when temperatures drop. This moisture creates an environment conducive to corrosion, as it can remain trapped under the insulation and promote the degradation of the metal over time. Therefore, CUI is a notable concern in vessels that do not maintain a steady operating temperature.

While other factors, such as material composition and insulation maintenance, can influence the likelihood of CUI, intermittent operation is specifically harmful as it introduces cycles of heating and cooling that exacerbate moisture issues.