What type of ductile-iron pipe joint is primarily used for river crossings and underwater intakes?

The ball-and-socket joint is an ideal choice for applications such as river crossings and underwater intakes due to its ability to accommodate movement and flexibility in alignment. This type of joint allows for angular deflection, which is essential when dealing with the potential shifting of pipes caused by environmental factors such as water flow, sediment movement, and temperature changes.

Unlike flanged joints, which are rigid and require precise alignment, or welded joints that are permanent and do not allow for movement, the ball-and-socket joint provides the necessary adaptability. This is crucial in underwater situations where pipes may be subjected to varying pressures and physical stressors from the surrounding environment.

Additionally, the unique design of the ball-and-socket mechanism prevents disconnection due to the forces exerted on the pipes, enhancing the durability and reliability of the system in challenging installations such as river crossings.