What type of piping requires expansion joints due to thermal expansion?

The correct choice indicates that both metal and plastic piping require expansion joints due to thermal expansion. When either type of piping heats up, it expands, and as it cools, it contracts. This expansion and contraction can lead to stress in the piping system, potentially causing damage, misalignment, or even failure if not properly managed.

Metal piping, such as copper or steel, expands more predictably but can develop significant forces if expansion joints are not included in long runs or at transitions. Plastic piping, while generally having a lower expansion rate than metals, still undergoes thermal changes that necessitate the installation of expansion joints, especially in larger installations where temperature fluctuations are common.

By using expansion joints, systems are able to accommodate these changes without inducing stress that could compromise the integrity of the piping, making it essential for effective long-term performance in both metal and plastic piping applications. This understanding highlights the importance of considering thermal expansion in piping system design, regardless of the material used.