What causes corrosion under insulation?
Corrosion under insulation (CUI) is the corrosion of piping and vessels that occurs beneath insulation as a result of water penetration. The water can come from rain water, leakage, deluge system water, wash water, or sweating from temperature cycling or low temperature operation such as refrigeration units.
How to prevent corrosion under insulation?
Wrapping equipment with aluminum foil before applying insulation will reduce the risk of corrosion, since the foil provides a physical barrier that prevents the saturated chloride solution from reaching the metal surface.
How can you tell if there is corrosion under insulation?
The most common and straightforward way to inspect for corrosion under insulation is to cut plugs in the insulation that can be removed to allow for ultrasonic testing. The other commonly used methods are radiography, and complete insulation removal. More advanced methods include pulsed eddy current.
What causes Cui?
CUI occurs through penetration of water or moisture and contamination via condensation or external sources (e.g., rain, sprinkler system). CUI can be very localized, with most of the equipment remaining in good condition.
Where does galvanic corrosion occur?
Galvanic corrosion (also called ‘ dissimilar metal corrosion’ or wrongly ‘electrolysis’) refers to corrosion damage induced when two dissimilar materials are coupled in a corrosive electrolyte. It occurs when two (or more) dissimilar metals are brought into electrical contact under water.
How do you stop Cui?
Both conventional aluminum jacketing and steel jacketing can be effective at keeping out the intrusion of water and preventing CUI. Hence, protective jacketing is the most important tool in the CUI prevention toolbox.
How do you identify corrosion?
Common NDT methods used to detect corrosion include ultrasonic testing, radiographic testing, and magnetic flux leakage. Risk-based inspection and fitness-for-service assessments are additional methodologies and processes that can complement a monitoring program.
How do you know if pipes are corroded?
The Ultrasonic Technology tool (UT) is another inspection tool used for corrosion detection in pipelines. It provides similar data as the MFL PIG tool. It can directly quantify the thickness of the pipe wall by transmitting an ultrasonic pulse into the wall and processing the reflected signal .
What is Cui range?
Sources of moisture range from rainwater, spillage from process operations or even condensation on a metal surface in a humid environment. When considering your own system’s vulnerability to CUI, strictly speaking, the API 583 standard lists a temperature range of 32 F to 212 F when looking for moisture in a system.
What is CUI inspection?
ATS experts conduct corrosion under insulation (CUI) testing and inspections. Corrosion under insulation is a type of metal corrosion that occurs due to moisture and oxygen exposure. Breaks in jacketing or insulation can allow water to seep into an insulation system via rain, condensation, or spillage.