Floating ball valve is a ball valve with an unsupported control device ,other than the 2 seats it rests on, so that the ball goes in the valve space to help seal off the line pressure.
The key to floating ball valve performance is the design of seal, regardless of whether the seats are produced of plastic, metal and other stuff. Another vital feature of ball valve performance is the stem seal design. A typical floating ball control device seals off the line force using soft such as PTEE (a plastic matertial known as polytetrafluoroethylene and otherwise called as Teflon) or TFM. TFM has a slight temperature/pressure benefit over PTFE. Both known for the quite high temperature and pressure capabilities, PTFE and TFM are perfect options for seat material.