Corrosion is a phenomenon in which materials are dissolved into the environment. In normal corrosion, material dissolved generally or locally and the wall thickness decreases, but a phenomenon in which corrosion progresses in a crack-like manner in a very narrow area under constant stress is called stress corrosion cracking. . This occurs when three conditions are met: environment, material, and stress.
Countermeasures
After a certain period of use, it is necessary to perform the following inspections and evaluations to prevent fracture:
- Subcategory: Stress Corrosion Cracking
- Damage mode: Cracks
- Inspection: Visual inspection, liquid penetrant testing, ultrasonic testing, magnetic particle testing (for steels).
- Evaluation: Assessment of crack susceptibility based on material and environmental factors, detection of cracks, measurement of their presence, depth, and length in areas where crack formation is possible.
- Actions: Establish criteria for crack removal, repair, component replacement, and material change based on the assessment.
There are many detail mechanisms for stress corrosion cracking. Followings are recommended for plant maintenance countermeasures;
> To confirm the detail mechanisms by using FPAI Class 2
> To implement the countermeasures suggested