Why should threaded fittings be avoided in wet environments?

Threaded fittings are less suitable for wet environments primarily because they can lead to leaks and corrosion over time. In these conditions, water can infiltrate the threaded joints, compromising the seal. Moisture and potential stagnant water can corrode the threads, weakening the connection and increasing the risk of leaks.

Moreover, the threads create a space where water can accumulate, exacerbating the rusting or corrosion processes. Over time, even slight movement or vibrations can cause the threaded joints to loosen, further increasing the chance of leaks. This is critical in industries where leaks can result in significant damage, safety hazards, or costly downtime.

While the durability of welded fittings, the cost of fittings, and installation difficulties might play roles in fittings selection, the primary concern in wet environments is the susceptibility of threaded fittings to leak and corrode, making option B the most relevant choice in this context.