Globe valves have been a mainstay in fluid control for 200 years and are now found everywhere. However, in some applications, globe valve designs can also be utilized to manage total shutdown of fluid. Globe valves are typically used to control fluid flow. Globe valve on/off and modulating usage can be seen on the exterior of houses and business structures, where valves are frequently placed.

Steam and water were essential to the Industrial Revolution, but these potentially dangerous substances needed to be restrained. The globe valve is the first valve needed to complete this task effectively. The globe valve design was so successful and well-liked that it led to the majority of the major traditional valve producers (Crane, Powell, Lunkenheimer, Chapman, and Jenkins) receiving their initial patents.

Gate valves are intended to be used in either the fully open or fully closed positions, whereas globe valves can be used as block or isolation valves but are designed to be partially open to control flow when regulating. Care should be used in design decisions when using globe valves for isolation-operated and on-off valves, as it is challenging to maintain a tight seal with considerable push on the disc. The force of the fluid will help achieve a positive seal and make it simpler to seal when the fluid flows from top to bottom.

Globe valves are perfect for control valve applications because of its regulating function, which allows for extremely fine regulation with positioners and actuators linked to the globe valve bonnet and stem. They excel in a number of fluid control applications and are referred to in these applications as “Final Control Elements.”

indirect flow path

The Globe is also known as a globe valve because of its original round shape, which still conceals the flow path’s unusual and convoluted nature. With its upper and lower channels serrated, a fully open globe valve still exhibits significant friction or barrier to fluid flow in contrast to a fully open gate or ball valve. Fluid friction caused by the tilted flow slows passage through the valve.

The flow coefficient, or “Cv,” of a valve is used to calculate the flow through it. Gate valves have extremely minimal flow resistance when they are in the open position, hence Cv will be substantially different for a gate valve and a globe valve of the same size.

The disc or plug, which serves as the globe valve closing mechanism, can be manufactured into a variety of shapes. The flow rate through the valve can change significantly based on the stem’s number of spins when the valve is open by altering the disc’s shape. The more typical or “traditional” curved disc design is utilized in the majority of applications because it is better suited than other designs to a specific movement (rotation) of the valve stem. V-port discs are appropriate for all sizes of globe valves and are designed for fine flow restriction across varying opening percentages. Absolute flow regulation is the goal of the needle kinds, however they are often only offered in smaller diameters. A soft, resilient insert can be inserted in the disc or seat when complete shutdown is required.

Globe valve trim

The real component-to-component closure in a globe valve is provided by the spool. The seat, disc, stem, backseat, and occasionally the hardware that attaches the stem to the disc make up a globe valve’s trim. Any valve’s good performance and lifespan depend on the trim design and material choice, but globe valves are more vulnerable because of their high fluid friction and complicated flow routes. Their velocity and turbulence rise as the seat and disc approach one another. Due to the corrosive nature of the fluid and the increased velocity, it is possible to damage the valve trim, which will dramatically increase the valve’s leakage when it is closed. Stringing is the term for a fault that occasionally appears as small flakes on the seat or disc. What began as a little leak path might grow and turn into a significant leak if it is not fixed in a timely manner.

The valve plug on smaller bronze globe valves is often made of the same material as the body, or occasionally a more robust bronze-like alloy. The most typical spool material for cast iron globe valves is bronze. IBBM, or “Iron Body, Bronze Mounting,” is the name of this iron trim. There are many different trim materials available for steel valves, but often one or more trim elements are made of 400 series martensitic stainless steel. Additionally, hard materials like stellite, 300 series stainless steels, and copper-nickel alloys like Monel are employed.

There are three fundamental modes for globe valves. The “T” shape, with the stem perpendicular to the pipe flow, is the most typical.
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Similar to a T-valve, an angle valve rotates the flow inside the valve 90 degrees, acting as both a flow control device and a 90 degree pipe elbow. On oil and gas “Christmas trees,” angle globe valves are the type of final output regulating valve that is still frequently employed on top of boilers.
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The “Y” design, which is the third design, is intended to tighten the design for on/off applications while reducing turbulent flow that occurs in the globe valve body. The bonnet, stem, and disc of this type of globe valve are angled at an angle of 30-45 degrees to make the flow route more straight and reduce fluid friction. Because of the decreased friction, the valve is less likely to sustain erosive damage and the piping system’s overall flow characteristics are improved.