Purpose of embedding puddle flange inside the walls of closed valve chambers

When valves are closed to stop water flow in a pipeline, a thrust is produced along the direction of the pipeline. Henceforth, it is essential to restrain the valves at the time of closure to prevent it from moving in the thrust direction. If the closed valve is situated inside valve chambers, it is connected to a puddle flange embedded inside a wall of chamber. So the closed valves can be effectively restrained from the thrust action at the time of the closure of valves.