page_title: Globe valve
section_title: Stem
hierarchical_section_title: Globe valve / Parts of a typical globe valve / Stem
caption_attribution_description: Cryogenic carbon steel socket weld globe valve. Valves and are generally made of plastic or steel, the latter being the most widely used in chemical and petrochemical applications. Steel grades range from the most common type, namely carbon steel, with standard stainless steel being the second most common. Stainless steel alloys, which include nickel or copper are used in applications that require higher corrosion or heat resistance. In such cases, the most commonly used valve configurations -- ball valves, gate valves, check valves, globe valves and butterfly valves -- are often forged or cast as duplex valves, super duplex valves, alloy 20 valves, monel valves, inconel valves, incoloy valves and 254 SMO valves (6Mo valves). Titanium valves are also used in some highly corrosive applications. Titanium is not a stainless steel alloy.
context_page_description: A globe valve, different from ball valve, is a type of valve used for regulating flow in a pipeline, consisting of a movable plug or disc element and a stationary ring seat in a generally spherical body.
  Globe valves are named for their spherical body shape with the two halves of the body being separated by an internal baffle. This has an opening that forms a seat onto which a movable plug can be screwed in to close the valve. The plug is also called a disc or disk. In globe valves, the plug is connected to a stem which is operated by screw action using a handwheel in manual valves. Typically, automated globe valves use smooth stems rather than threaded and are opened and closed by an actuator assembly.
context_section_description: The stem serves as a connector from the actuator to the inside of the valve and transmits this actuation force. Stems are either smooth for actuator controlled valves or threaded for manual valves. The smooth stems are surrounded by packing material to prevent leaking material from the valve. This packing is a wearable material and will have to be replaced during maintenance. With a smooth stem the ends are threaded to allow connection to the plug and the actuator. The stem must not only withstand a large amount of compression force during valve closure, but also have high tensile strength during valve opening. In addition, the stem must be very straight, or have low run out, in order to ensure good valve closure. This minimum run out also minimizes wear of the packing contained in the bonnet, which provides the seal against leakage. The stem may be provided with a shroud over the packing nut to prevent foreign bodies entering the packing material, which would accelerate wear.
caption: Long-stemmed  globe valve
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