Check valves, also known as non - return valves, are generally used between several or dozens of drill pipes. Their function is to ensure that the flushing fluid can smoothly pass through the inner hole of the drill pipe and reach the bottom of the hole during the drilling process, but cannot flow back to the hole mouth through the inner hole of the drill pipe, that is, to ensure the one - way flow of the flushing medium and prevent reverse flow.

Ordinary check valves are used in ordinary rotary drilling and can ensure the one - way flow of the flushing medium to the bottom of the hole.

Wired check valves are used in directional drilling construction. They are equipped with a wired device inside. Not only can they ensure the one - way flow of the flushing medium, but they can also transmit the bottom - hole signals through the wired mechanism inside the check valve.