Rubber expansion joints

Rubber expansion joints are not generally considered to be valves. The primary purpose of an expansion joint is to absorb movement due to thermal expansion, vibration, or misalignment in a piping system. This flexibility helps to minimize stress on the piping and its components, reducing the risk of damage and extending the system's lifespan.
On the other hand, valves are primarily designed for flow control or isolation within a piping system. They regulate the flow of fluid or gas, allowing the system to be shut off, turned on, or adjusted as needed. Valves come in various types and serve specific functions, such as controlling pressure, regulating flow rate, or directing the flow of the medium.
The reason rubber expansion joints are distinct from valves lies in their intended functions and design. Expansion joints are composed of flexible materials, such as rubber or fabric, with the primary purpose of absorbing movement and vibration. They are not typically used to control or regulate fluid flow within a piping system.
Rather, they are installed to address issues related to movement, including thermal expansion or contraction of the pipework, as well as to reduce the transmission of vibration and noise. Due to their flexibility, expansion joints can accommodate axial, lateral, and angular movements, offering a degree of flexibility that valves, which are generally rigid components, do not provide.
In contrast, valves are typically made from rigid materials and are designed to control the flow of fluids or gases by opening, closing, or adjusting the pathway through the system, thereby influencing the flow rate, pressure, or direction of the medium within the piping.
In summary, while rubber expansion joints and valves both play crucial roles in piping systems, they serve distinct purposes. Expansion joints are designed to absorb movements while minimizing stress on the system, whereas valves are used for flow control and fluid regulation. Their differing functions and designs mean that expansion joints are classified as separate components from valves within the context of piping and fluid control systems.