Sight Windows are an effective and economical way of viewing tank, pressure vessel, piping system interiors. They are also referred to as Sight Glasses and are often replaceable or removable. Fluid clarity, color, level and flow can be monitored through the window. Sight Windows can be mounted by bolting, welding or direct insertion into the end of the tank or pipe. Welding may require a radius pad that conforms to the pipe or curved vessels or a flat pad that mounts to a flat tank wall.