Many midstream folks think that because they have a clean service with minimal internal corrosion and no cracking potential, there is no place for RBI in their plant. Refineries in arid climates, or chemical plants running batch processes think they don’t need to worry about CUI because the atmosphere is either too dry or they don’t spend enough time in the CUI operating temperature range. However with RBI’s power to predict CUI corrosion rates, it could be the saving grace they need to ensure their CUI is managed appropriately.
API RP581 provides a corrosion rate calculator for CUI that has proven to be a fairly good screening tool that takes into account operating temperature, external environment, insulation type, insulation quality and any coating you may have underneath the insulation. By including each of these variables, a specific corrosion rate can be predicted for each piece of equipment, and actually each section of your equipment if it is broken into components such as the top of a tower versus the bottom.
Once these corrosion rates are applied to their corresponding equipment items, an estimated amount of damage due to CUI can be determined (utilizing time in service and quality of previous CUI inspections, if any have been completed). Comparing these degrees of damage can be the initial screening basis you need to get your CUI program off the ground.
Have you created a CUI program? How did you start the screening process? How have you expanded your program from its grassroots?