Valve body, sometimes called the shell, is the primary pressure boundary of a valve. It serves as the principal element of a valve assembly because it is the framework that holds everything of valve together.
Body of valve has to withstand many forces inside the valve. It is the first pressure boundary of a valve, resists fluid pressure loads from connecting piping. Body of valve also experiences many forces due to end connections of a valve. It receives inlet and outlet piping through threaded, bolted, or welded joints.
The basic form of a valve body ranges from simple block shapes to highly complex shapes in which the bonnet, a removable piece to make assembly possible, form part of the pressure resisting body.