When it comes to the inspection of flanged joints, many Non-Destructive Testing (NDT) methods have been considered for detecting corrosion on the sealing face; however, it was really the development of Phased Array Ultrasonic Testing (PAUT) that allowed operators to manage this risk non-intrusively. Traditional management included the ‘splitting’ of flange joints during outages, and inspectors would perform visual inspection to determine the condition. This mechanical splitting process is clearly very costly and can only be performed when the system is offline. And that’s why the implementation of PAUT was accepted by the industry as a clear improvement in terms of both safety and performance.
The raised face flange is the most commonly used type. Like the name suggests, it has a raised area machined on the flange face equal to the contact area of a gasket. This is the most critical area for the prevention of leaks. Crevice corrosion may occur in the crevices or gaps between the flange and the mating surface of the pipe or where it connects with equipment. This type of corrosion is often caused by the accumulation of aggressive chemicals or the depletion of oxygen within the crevice. Corrosion in the sealing area can lead to loss of containment, posing a significant risk of releasing the product and causing a catastrophic effect.
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