Globe Valve



Globe valves, so-called because of their outside shape, are widely used in plant piping. They are suitable for manual and automatic operation. Unlike the gate valve, globe valve can be used for regulating flow or pressures as well as complete shutoff of flow. It may also be used sometime as a pressure relief valve or as a check valve. Compared with a gate valve or ball valve, the globe valve has considerably higher pressure loss in the fully open position. This is because the flow of fluid changes direction as it goes through the valve. The L/D ratio for this type of valve is approximately 340. Globe valves are manufactured in sizes up to NPS 16. They are generally hand wheel–operated. A typical globe valve is shown in Figure 12.13.Get more news about globe valve,you can vist our website!

Globe valves are valves in which the seating element (disk) is moved on and off perpendicular to the plane of the seat (Figure 4.60). Globe valves are built up to 6 in. (DN 150) to 8 in. (DN 200). The seat opening varies in direct proportion to the travel of the disk. Globe valves are well suited for applications requiring flow regulation. The seating load can be effectively controlled by the stem, thus giving the globe valve good sealing characteristics. Globe valves are generally used for

Globe valves are used primarily in situations where throttling of the commodity is required. By simply rotating the handwheel, the rate at which the commodity flows through the valve can be adjusted to any desired level. Having the valve seat parallel to the line of flow is an important feature of the globe valve. This feature makes the globe valve efficient when throttling commodities as well as yielding minimal disc and seat erosion. This s-shaped configuration, however, creates a large amount of resistance within the valve. The design of the globe valve body forces the flow of the commodity to change direction within the valve itself. This change in direction creates substantial pressure drop and turbulence. The globe valve is therefore not recommended when flow resistance and pressure drop are to be avoided. In most installations the commodity is routed into the valve’s body from below the valve seat and disc. This flow direction uses the pressure of the commodity to aid in the opening operation of the valve. It also reduces wear on the valve seats and disc. One exception however is when high temperature steam is routed through the valve. The extreme temperature of the steam contacting the valve seat from below creates a significant temperature difference from the top of the seat and disc. This temperature difference across the valve’s seats and disc causes the metal of the disc to contract which results in leakage. Therefore when high temperature steam is routed through a globe valve, it is routed into the valve from the top of the disc, opposite of normal commodity flow direction. Figure 5.6 depicts the internal view of a globe valve.

Globe valves are used in the oil and gas industry for fluid regulation or throttling. Cavitation as the main operation problem associated with globe valves as well as some of the mitigation approaches have been discussed in this chapter. Different types of globe valves such as needle, straight pattern, and Y-pattern have been explained briefly. Some aspects of the valve design such as wall thickness, bore, face-to-face dimensions based on international standards such as API and ASME have been included in this chapter. Readers can get practical information about the design of different components of this type of valve such as body, bonnet, yoke, steam, seat, backseat, etc., that has been explained in this chapter. This chapter contains many pictures of globe valves during manufacturing, assembly, and testing such as pressure, fugitive emission, or flow capacity measurement testing.