What is a common method to detect corrosion in areas above the liquid level in vessels with acidic contents?

Hydrogen blistering examination is an effective method for detecting corrosion in areas above the liquid level, especially in vessels that contain acidic contents. In such environments, the reaction between the acid and metal can lead to the formation of hydrogen gas, which can subsequently cause blisters or internal damage to the metal’s surface. These blisters are indicative of localized corrosion, which may not be easily detectable by traditional visual inspection methods.

Using hydrogen blistering examination allows inspectors to identify areas where blisters have formed and assess the extent of the corrosion damage. This is critical, as corrosion can significantly compromise the structural integrity of pressure vessels, particularly in regions where the fluid level fluctuates, exposing certain metal areas to corrosion while others remain submerged.

Other methods listed in the options have their applications but are not as specialized for this particular type of corrosion in vessels containing acids. Sound testing may detect flaws or discontinuities, but it does not specifically target corrosion. Hydrostatic testing evaluates the vessel's ability to withstand pressure but does not effectively reveal corrosion above the liquid level. Infrared thermography can identify temperature variations that may indicate an issue, but it is not typically used for direct corrosion detection in acidic environments, particularly in the areas mentioned.