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 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 is corrosion under fireproofing?

Recognition of Corrosion Under Fireproofing (CUF) What is CUF? CUF refers to corrosion of piping, pressure vessels, and structural components resulting from water trapped under fireproofing.

What is the CUI range?

Although CUI can occur over a broad temperature range of -10 – 250 ˚F, the greatest potential and most severe environment is between 120 – 200 ˚F. Seven controllable factors affecting CUI have been identified.

How can you prevent insulation from failing?

Again, the best way to reduce the threat of insulation failure due to moisture is to use an impermeable insulation product. If the insulation material is impermeable, a jacketing is needed to provide mechanical protection on above-ground and below-ground installations.

How do you identify corrosion?

Next, nondestructive testing (NDT) and inspection techniques are performed to locate and identify the type of corrosion damage. Common NDT methods used to detect corrosion include ultrasonic testing, radiographic testing, and magnetic flux leakage.

What can cause insulation to become damaged?

Common Causes of Insulation Failure

• Electrical Stresses. Overvoltage and impulses lead to electrical stress, which leads to insulation failure.
• Aging of Insulation. This specific failure of insulation is a slow process.
• Contaminants Enter Insulation.

What are the 4 conditions necessary for corrosion to occur?

All four elements (anode, cathode, electryolyte, and return current path) are necessary for corrosion to occur. Removing any one of these elements will stop the current flow and galvanic corrosion will not occur.