The globe valve, also known as the cut-off valve, belongs to the forced sealing valve which is a kind of cut-off valve. According to the connection method, it is divided into three kinds: flange connection, clamp connection, weld connection. The valve has stipulated the flow direction of the globe valve from top to bottom , so the installation has directional.
The globe valve is designed to be low inlet and high outlet , the purpose is to make the flow resistance small and save effort when opening the valve. At the same time, when the valve is closed, the packing material between the valve shell and the valve cover and the packing around the valve stem are not stressed, and the medium pressure and temperature will not be affected for a long time which can extend the service life and reduce the probability of leakage. In addition, it can replace the seals when valves in closed statation , it is very easy for maintenance.
Under normal circumstances, the globe valve is low inlet high outlet , however, there are some special cases in which the globe valve is high inlet low outlet :
● High pressure globe valve with diameter larger than 100mm
Due to the poor sealing performance of the large diameter valve, the medium pressure acts on the top of the valve disc to increase the sealing of the valve.
● When there are two globe valve in one pipeline, the second globe valve requires "high inlet and low outlet"
In order to ensure the sealing , it required two globe valve for the working condition which open/closed constantly
● Boiler exhaust, vent stop valve
Boiler exhaust, blow-off valve is only used in the boiler starting water process, the opening and closing frequency is small, incase the sealing is not good and caused the loss of working medium, in order to imporve the sealing function , some power plants make globe valve installation direction high inlet & low outlet
