What are the 5 wet lay-up methods?

The method of wet lay-up aims to protect the internal surfaces of a vessel, typically a boiler or heat exchanger, during periods of inactivity. The correct answer includes a steam blanket, nitrogen, hot deaerated fill, sodium nitrite, and hydrazine/morpholine, each playing a vital role in preventing corrosion and maintaining system integrity.

The steam blanket creates a protective layer that reduces the amount of oxygen and moisture in the system, which helps in preventing corrosion. Nitrogen is an inert gas that displaces oxygen, further reducing the chances of oxidation. The hot deaerated fill refers to water that has been treated to remove dissolved gases—primarily oxygen and carbon dioxide—which are detrimental to metal structures. Sodium nitrite serves as a corrosion inhibitor, offering a protective film on the metal surfaces. Lastly, hydrazine/morpholine assists in maintaining pH levels and offers additional corrosion protection.

In this context, the other options may include incorrect combinations of methods or substances that do not align with the established procedures for effective wet lay-ups. For example, using steam or deionized fill improperly might not provide the necessary protective qualities that the selected correct method boasts.