1500Lb & 2500Lb Globe valves
Negotiable /Unit
Min.Order:1 Unit
Zhongrui International Limited
1500Lb & 2500Lb Globe valves
Body
The body is the main pressure containing structure of the valve and the most but 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 body and provides the containment of the fluid, gas, or slurry that is being 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 on the body, or oriented at an angle such as a 90° angle. Globe valves with ports at such an angle are called angle globe valves. Angle type globe valves are mainly used for corrosive or high viscous fluid which shall solidify at room temperature. This is because straight valve shall have outlet pipe inline to the inlet pipe and the fluid has chance of staying there in case of horizontal piping whereas in the case of angle valve the outlet pipe shall be directed towards bottom which will allow the fluid to drain of instead of staying there which will in turn clog or corrode the valve components when allowed to settle down. A globe valve can also have a body in the shape of a "Y". This will allow the construction of valve to be straight at the bottom instead of conventional pot type construction (to arrange bottom seat) in case of other valves. This will again allow the fluid to pass through without low cavities which shall let the fluid clog or corrode in long run of settling down.
Bonnet
The bonnet provides a leakproof closure for the valve body. The threaded section of the stem goes through a hole with matching threads in the bonnet. Globe valves may have a screw-in, union, or bolted bonnet. Screw-in bonnet is the simplest bonnet, offering a durable, pressure-tight seal. Union bonnet is suitable for applications requiring frequent inspection or cleaning. It also gives the body added strength. A bonnet attached with bolts is used for larger or higher pressure applications. Bonnets also contain the packing, which is a wearable material that maintains the seal between the bonnet and the stem during valve cycling
Plug or disc (disk)
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 typically of the balance or unbalanced type. Unbalanced plugs are solid and are used with smaller valves or with low pressure drops across the valve. The advantages are simpler design, with one possible leak path at the seat and usually lower cost. The disadvantages are the limited size; with a large unbalanced plug the forces needed to seat and hold the flow often becomes impractical. Balanced plugs have holes through the plug. Advantages include easier shut off as the plug does not have to overcome static forces. However, a second leak path is created between the plug and the cage, cost is generally higher.
Stem
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.
Cage
The cage is part of the valve that surrounds the plug and is located inside the body of the valve. Typically, the cage is one of the greatest determiners of flow within the valve. As the plug is moved more of the openings in the cage are exposed and flow is increased and vice versa. The design and layout of the openings can have a large effect on flow of material (the flow characteristics of different materials at temperatures, pressures that are in a range). Cages are also used to guide the plug to the seat of the valve for a good shutoff, substituting the guiding from the bonnet.
Seat ring
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. However this method makes removal of the seat ring during maintenance difficult if not impossible. Seat rings are also typically beveled at the seating surface to allow for some guiding during the final stages of closing the valve.
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.
Materials
Typically globe valves are made of metallic alloys, although some synthetic materials are available. These materials are chosen based on pressure, temperature, controlled media properties. Corrosive and/or erosive process streams may require a compromise in material selection or exotic alloys or body coatings to minimize these material interactions and extend the life of the valve or valve trim components. Typically, carbon steel alloys are specified for noncorrosive applications. Other alloys such as Hastelloy, Monel, Inconel and others are available.
Packing material must also be considered during valve selection. Typically the requirement for a low friction packing conflict with a durable material that will provide low maintenance requirements during service life. Corrosive applications can further complicate packing material selection as the typical packing materials may or may not be compatible with the processed materials. Typically graphite or PTFE is used due to its low friction coefficient. Enviro-seal applications also have the availability of constant applied force (live-load) packing. While more complex, it allows for constant packing force load throughout the life of the packing material. This packing helps meet contemporary environmental laws.
Applicable standards:
Steel glboe valves, BS 1873 / API 600
Steel valves, ASME B16.34
Face to face, ASME B16.10
Flanges end, ASME B16.5
Buttwelding ends, ASME B16.25
Inspection and test, API 598
Design description:
Straight patteren body design
OS & Y,outside screw and yoke
BB,Bolted bonnet
Yoke intergral with bonnet
Rising stem and handwheel
Loose disc,choice of plug or ball
Renewable seat ring
Impact handwheel for 10" & above
Horizontal servece
Flanged or buttwelding ends
Available with bg operator