What is a characteristic of both the screwed joint and the union joint?

The characteristic that defines both the screwed joint and the union joint is that both involve threaded pipes. This threading is a crucial method of connection, allowing for easy assembly and disassembly without the need for welding or other more permanent forms of joining. Screwed joints are commonly found in various piping systems, and they are particularly valuable for applications where components may need to be replaced or serviced over time.

Both joints can be utilized with thick wall tubes, which provide the mechanical strength necessary to withstand operational pressures, especially in applications such as water supply and chemical processing. The threaded construction facilitates a secure fit, minimizing the risk of leaks while still allowing for maintenance when required.

Other choices do not accurately reflect a shared characteristic of both joint types: welding is not a requirement for either joint, as they are designed to be assembled without it. While they can be utilized in gas pipelines, this is not a defining feature, as they are also found in many other applications beyond just gas transfer. Lastly, while some types of joints can be made from plastic, both the screwed and union joints are often made from metals or other durable materials suitable for high-pressure environments.