July 12, 2016
Stress Corrosion Cracking

Posted by: Casey Whalen 3:00 minute read

Hydrogen embrittlement results in Hydrogen-Assisted Stress Corrosion Cracking (HSCC), more commonly known as Stress Corrosion Cracking (SCC), which results from corrosion issues and high tensile stress, is typically associated with improper corrosion protection or internal chemical attack. If the local stresses are high enough, the areas weakened by corrosion can structurally fail via small cracking, but without causing a total pipe failure. As the pipe succumbs to this cracking and slowly yields, more surface area is exposed and more corrosion attacks, repeating the cycle. Eventually – and sometimes relatively quickly – SCC can lead to pipe failure.

The preferred method of composite repair entails grinding out or removing any pipe wall that has cracks. A composite repair can also increase the expected life of the system. If SCC occurs internally, the composite can reduce the stress at the crack tips the same way as FCG. Likewise, it will reduce stress and strain, and inhibit future corrosion if the SCC is external. Composite repairs that are properly installed with an adhesive can also act as a structurally reinforced coating.

If a corrosive attack can be stopped, SCC should no longer grow rapidly, and FCG becomes the main concern. A proper composite thickness also can be determined by assuming that the depth of any crack implies substrate strength loss equivalent to complete wall loss up to that depth.

To read our previous blog post about using a composite repair to stop fatigue crack growth (FCG), click here.

Category: Feature Articles, Pipe Wrap


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