Parts of a typical globe valve Globe valve

1 parts of typical globe valve

1.1 body
1.2 bonnet
1.3 plug or disc (disk)
1.4 stem
1.5 cage
1.6 seat

parts of typical globe valve


globe valve


body

the body main pressure containing structure of valve , identified forms mass of valve. contains of valve s internal parts come in contact substance being controlled valve. bonnet connected body , provides containment of fluid, gas, or slurry being controlled.

globe valves typically two-port valves, although 3 port valves produced in straight-flow configuration. ports openings in body fluid flowing in or out. 2 ports may oriented straight across each other or anywhere on body, or oriented @ angle (such 90°). globe valves ports @ such angle called angle globe valves. globe valves used corrosive or high viscous fluids solidify @ room temperature. because straight valves designed outlet pipe in line inlet pipe , fluid has chance of staying there in case of horizontal piping. in case of angle valves, outlet pipe directed towards bottom. allows fluid drain off. in turn, prevents clogging and/or corrosion of valve components on period of time. globe valve can have body in shape of y . allow construction of valve straight @ bottom opposed conventional pot type construction (to arrange bottom seat) in case of other valves. again allow fluid pass through without difficulty , minimizes fluid clogging/corrosion in long term.

bonnet

the bonnet provides leakproof closure valve body. threaded section of stem goes through hole matching threads in bonnet. globe valves may have screw-in, union, or bolted bonnet. screw-in bonnet simplest bonnet, offering durable, pressure-tight seal. union bonnet suitable applications requiring frequent inspection or cleaning. gives body added strength. bonnet attached bolts used larger or higher pressure applications. bonnet contains packing, wearable material maintains seal between bonnet , stem during valve cycling.

plug or disc (disk)

the closure member of valve, plugs connected stem slid or screwed or down throttle flow. plugs typically of balance or unbalanced type. unbalanced plugs solid , used smaller valves or low pressure drops across valve. advantages simpler design, 1 possible leak path @ seat , lower cost. disadvantages limited size; large unbalanced plug forces needed seat , hold flow becomes impractical. balanced plugs have holes through plug. advantages include easier shut off plug not have overcome static forces. however, second leak path created between plug , cage, , cost higher.

stem

the stem serves connector actuator inside of valve , transmits actuation force. stems either smooth actuator controlled valves or threaded manual valves. smooth stems surrounded packing material prevent leaking material valve. packing wearable material , have replaced during maintenance. smooth stem ends threaded allow connection plug , actuator. stem must not withstand large amount of compression force during valve closure, have high tensile strength during valve opening. in addition, stem must straight, or have low run out, in order ensure valve closure. minimum run out minimizes wear of packing contained in bonnet, provides seal against leakage. stem may provided shroud on packing nut prevent foreign bodies entering packing material, accelerate wear.

cage

the cage part of valve surrounds plug , located inside body of valve. typically, cage 1 of greatest determiners of flow within valve. plug moved more of openings in cage exposed , flow increased , vice versa. design , layout of openings can have large effect on flow of material (the flow characteristics of different materials @ temperatures, pressures in range). cages used guide plug seat of valve shutoff, substituting guiding bonnet.

seat

the seat ring provides stable, uniform , replaceable shut off surface. seat screwed in or torqued . pushes cage down on lip of seat , holds firmly body of valve. seat may threaded , screwed thread cut in same area of body. method makes removal of seat ring during maintenance difficult if not impossible. seat rings typically beveled @ seating surface allow guiding during final stages of closing valve.

economical globe valves or stop valves similar mechanism used in plumbing have rubber washer @ bottom of disc seating surface, rubber can compressed against seat form leak-tight seal when shut.