Red Seal Sheet Metal Worker Practice Exam

Why is an expansion joint important in ductwork?

1. To prevent noise from air movement

2. To allow maintenance access

3. To accommodate thermal movement

4. To enhance aesthetic appearance of ducts

The correct answer is: To accommodate thermal movement

An expansion joint is crucial in ductwork because it is specifically designed to accommodate thermal movement. As materials heat up or cool down, they expand and contract. In the case of ductwork, when air moves through, it can cause the metal to heat up, leading to expansion. Conversely, when the airflow decreases or when the temperature of the ductwork drops, the metal will contract. If there is no allowance for this movement, the duct may warp, crack, or even pull apart at the seams due to stress, leading to potential leaks and inefficient airflow. Incorporating expansion joints into duct systems prevents these issues, ensuring that the ductwork maintains its integrity over time while also contributing to the overall efficiency of the heating, ventilation, and air conditioning (HVAC) system. It ensures that the system operates smoothly without causing damage that could require costly repairs or lead to reduced performance.