Parts of a typical globe valve

The globe valve body is the main pressure containing structure of the valve and the most easily identified as it forms the mass of the valve. It contains all of the valve's internal parts that will come in contact with the substance being controlled by the valve. The bonnet is connected to the physique and provides the ascendancy of the fluid, gas, or slurry that is getting controlled.
Globe valves are typically two-port valves, although three port valves are also produced mostly in straight-flow configuration. Ports are openings in the body for fluid flowing in or out. The two ports may be oriented straight across from each other or anywhere on the body. Globe valves with ports at such an angle are called angle globe valves. Globe valves are mainly used for corrosive or high viscous fluids which solidify at room temperature. This is because straight valves are designed so that the outlet pipe is in line with the inlet pipe and the fluid has a good chance of staying there in the case of horizontal piping. In the case of angle valves, the outlet pipe is directed towards the bottom. This allows the fluid to drain off. In turn, this prevents clogging and corrosion of the valve components over a period of time.
The closure member of the valve, plugs are connected to the stem which is slid or screwed up or down to throttle the flow. Plugs are about of the antithesis or asymmetric type. Asymmetric plugs are solid and are acclimated with abate valves or with low burden drops beyond the valve. The advantages are simpler design, with one accessible aperture aisle at the bench and usually lower cost. The disadvantages are the bound size; with a ample asymmetric bung the armament bare to bench and authority the breeze about becomes impractical. Balanced plugs accept holes through the plug. Advantages cover easier shut off as the bung does not accept to affected changeless forces. However, a additional aperture aisle is created amid the bung and the cage, and amount is about higher.
The cage is allotment of the valve that surrounds the bung and is amid central the physique of the valve. Typically, the cage is one of the greatest determiners of breeze aural the valve. As the bung is confused added of the openings in the cage are apparent and breeze is added and carnality versa. The architecture and blueprint of the openings can accept a ample aftereffect on breeze of actual. Cages are aswell acclimated to adviser the bung to the bench of the valve for a acceptable shutoff, substituting the allegorical from the bonnet.
The seat ring provides a stable, uniform and replaceable shut off surface. Seat rings are usually held in place by pressure from the fastening of the bonnet to the top of the body. This pushes the cage down on the lip of the seat ring and holds it firmly to the body of the valve. Seat rings may also be threaded and screwed into a thread cut in the same area of the body.
Economical globe valves or stop valves with a similar mechanism used in plumbing often have a rubber washer at the bottom of the disc for the seating surface, so that rubber can be compressed against the seat to form a leak-tight seal when shut.
 http://www.datianvalve.com/ProList/132.html