What type of corrosion might occur in areas directly below the liquid level of a vessel containing an acidic corrosion product?

Hydrogen blistering occurs when metal is subjected to a corrosive media, and in the presence of an acidic environment, hydrogen is generated as a byproduct of the corrosion reaction. In pressure vessels, especially those that contain acidic substances, this reaction becomes significant below the liquid level where the corrosive agents are more concentrated.

In this scenario, the areas just below the liquid level may experience localized hydrogen generation, which can lead to gas pockets forming in the metal. These pockets, or blisters, create pressure against the vessel wall and can ultimately lead to material failure. Hydrogen blistering is particularly prevalent in steels subjected to acidic environments due to the absorption of hydrogen into the material.

Understanding the conditions that lead to hydrogen blistering is crucial for effective inspection and maintenance of pressure vessels, as it can significantly impact the structural integrity and safety of the equipment.