What type of fitting allows for expansion and contraction in piping systems?

• A. Union
• B. Elbow
• C. Coupling
• D. Expansion joint

Answer: (D)

The expansion joint is specifically designed to accommodate expansion and contraction in piping systems. As fluids are transported through pipes, temperature fluctuations can cause the materials to expand or contract, which may lead to stress and damage if not properly managed. Expansion joints provide a flexible section in the piping that can absorb these movements, thus preventing potential leaks or breaks caused by thermal cycling.

Unlike the other options, which serve different functions—such as unions for easy disconnection, elbows for changing the direction of the pipe, and couplings for joining two lengths of pipe—expansion joints are uniquely crafted to handle the dynamic changes in length caused by temperature variations. This capability to prevent stress and accommodate movement makes expansion joints critical components in many piping systems.