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Donít Crack Under Pressure: How Eddy Current Array Helps Spot Chloride Stress Corrosion Cracking in Stainless Steel Pipes
By: Eddyfi Technologies
Source: Eddyfi Technologies
There are many non-destructive testing (NDT) techniques, but not all of them are suited to every type of application. For example, X-rays, or radiography, and computed tomography cannot be deployed without access to both sides of the asset and require extensive operator training. Similarly, ultrasonic testing is very versatile but requires direct contact and appropriate coupling with the surface under test, which is not always possible.

When it comes to chloride stress corrosion cracking (ClSCC or CSCC), a type of corrosion that can lead to the catastrophic failure of stainless steel pipes, penetrant testing (PT) is the most commonly used inspection technique. However, eddy current array (ECA) offers several advantages over PT, including the ability to detect far-side defects. In this article we will look at the advantages of ECA over PT for detecting CISCC.

Chloride stress corrosion cracking is a type of corrosion that occurs when stainless steel is exposed to chloride-containing environments such as seawater, de-icing salts, or industrial chemicals. CSCC can lead to the catastrophic failure of stainless steel pipes, making it a significant concern for asset owners and operators in the oil and gas, chemical processing, and nuclear power industries.

Letís consider a component that is in an environment containing high levels of chloride, which can deposit on the stainless steel. In the beginning, the amount is small enough that it wonít cause any damage, but over time there will be an accumulation of chloride ions on the surface, enabling the formation of pitting or crevices.

These pits and crevices may continue to evolve as corrosion, but in high-temperature environments [≥ 60 degrees Celsius (140 degrees Fahrenheit)] where residual stress or other mechanical constraints exist in the material, cracks can start to form and will tend to evolve faster than corrosion.

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