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Valve Review: Functions of manual valves

Manual valves serve three major functions in fluid-handling systems: stopping and starting flow, controlling flow rate, and diverting flow. Valves for stopping and starting flow are frequently employed also for controlling flow rate, and vice versa, while valves for diverting flow are designed for that single purpose.

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Valve Review: Valve Packing

Compression packings are the sealing elements in stuffing boxes. They consist of a soft material that is stuffed into the stuffing box and compressed by a gland to form a seal around the valve stem. The packings may have to withstand extremes of temperature, be resistant to aggressive media, display a low friction factor and adequate structural strength, and be impervious to the fluid to be sealed. To meet this wide range of requirements, and at the same time offer economy of use, innumerable types of packing constructions have evolved.

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Valve Review: Valve Gasket

Flat metallic gaskets adapt to the irregularities of the flange face by elastic and plastic deformation. To inhibit plastic deformation of the flange face, the yield shear strength of the gasket material must be considerably lower than that of the flange material.

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Valve Review: Valve Sealing

One of the duties of most valves is to provide a fluid seal between the seat and the closure member. If the closure member is moved by a stem that penetrates into the pressure system from the outside, another fluid seal must be provided around the stem.

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Control Valve Basics: Sizing and Selection

In this article, we try to demonstrate control valve design and sizing calculation.

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Emergency Shutdown Valve

The function of the shutdown valve is to shut-off the fluid flow inside the fluid flow line or pipe when an emergency that leads to a hazardous situation comes. It is an actuator operated valve mainly used for safety purpose that is why it is called Emergency shutdown valve. It is also known as the shutdown valve or SDV, ESDV, ESV, ESD.

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An introduction to control valve

A control valve is used in the oil and gas industry to regulate the flow rate of the fluid in a pipeline or process (and the related process parameters as pressure, temperature, and level) according to signals managed by a controller. The role of a flow control valve in the complex petrochemical process is key, as the multiple loops involved in the process should be kept under strict and dynamic control to make sure that the process, as a whole, works as intended and produces the desired output in terms of quantity, quality and time.

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Globe Valves

What is a globe valve? When shall it be used instead of gate and ball valves? In this article, we illustrate the scope of this type of valve (which is, in a word, to regulate the flow), the differences with other types of valve, the alternative designs, and specifications (BS 1873 for the cast steel and API 602/BS 5352 for the forged steel type).

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Gate Valve for Piping (API 600, 602, 603)

What is a gate valve? It is a shut-off device to open and close the flow of the fluid conveyed by a piping system (or a pipeline). A gate valve is a bi-directional valve, as the fluid may flow in either direction. The installation of this type of valve creates a modest pressure drop in the pipeline, lower than globe valves. Gate valves have forged bodies for bore sizes below 2 inches (API 602/BS 5352), and cast bodies for larger sizes (API 600, API 603, API 6D).

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Types of Pneumatic Valve Actuators

Rotary Actuators: Different Mechanical Styles There are 2 main styles of rotary pneumatic actuators for use on ball, butterfly and plug valves: Rack-n-pinion, and Scotch Yoke. While at first they may appear drastically different, they are actually quite similar. Both operate by converting the linear motion of a piston in a cylinder into rotational motion of the stem drive.

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What is a Valve Actuator?

A valve actuator is a mechanical device that uses a power source to operate a valve. This power source can be electric, pneumatic (compressed air), or hydraulic (the flow of oil). There are two main types of actuators, one for each of the two main types of valves that require them. They are rotary and linear.

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Control Valve Sizing

When control valve professionals talk about "control valve sizing," they really mean the entire process of selecting the valve that will do the best job of controlling the process. Selecting the right size valve is an important part of the process, but there are other equally important considerations as well.

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