Which statement is true regarding joints that are at least partially threaded?

In the context of joints that are at least partially threaded, the correct statement acknowledges that these types of joints can indeed leak if not properly sealed. Threaded joints rely on the tight engagement of the threads to create a seal, but this does not guarantee that a leak-free connection will occur without the use of appropriate sealing methods.

When threaded joints are made, it's essential to use sealing compounds, thread tape, or other sealing technologies to ensure that any gaps in the threading do not allow for fluid or gas to escape. Without these precautions, there is a significant chance that leaks can develop, especially under pressure when the fluid could force its way out through any undetected openings in the joint. Therefore, sealing is a crucial step to maintain the integrity and functionality of such connections, making the understanding of this principle vital for effective installation and maintenance of sprinkler systems.

The other statements do not accurately reflect the nature of threaded joints. They imply absolute certainty about leakage scenarios, which is not realistic given the variations in installation quality, the materials used, and the environmental conditions.