Bonnet
In pumps, a bonnet is a metal covering for the openings in the valve chambers. A bonnet may be any of various hoods, covers, or protective devices. Valve bonnets are available in many designs and models (the most typical are: bolted, round bolted, welded, pressure seal) and are often manufactured using the same material grade of the valve body. The bonnet is connected with the body by a threaded, bolted, or welded joint connection – and different types of gaskets are used to ensure leak-free connections between the body and the bonnet.