VALVES

Introduction to Valves – Pressure Seal Valves

PRESSURE SEAL VALVES Pressure seal construction is adopted for Valves for high pressure service, typically in excess of above 170 bar. The unique feature about the pressure seal Bonnet is that the body-Bonnet joints seals improves as the internal pressure in the Valve increases, compared to other constructions where the increase in internal pressure tends to create leaks in the body-Bonnet joint. PRESSURE SEAL DESIGN A/B – BONNET TENDENCY TO MOVE UP OR DOWN AS PRESSURE CHANGES C – SYSTEM PRESSURE D – SEALING FORCES DUE TO PRESSURE The higher the internal pressure, the greater the sealing force. Easy dismantling is made possible by dropping the Bonnet assembly into the body cavity and driving out the four-segmental thrust rings by means of a push pin. Relying on fairly sim...

Types of Valves Used on Ships: Gate Valve – Part 1

A variety of valves are used in the piping and machinery systems of the ship as per the need of the flow pattern of the liquid. All valves used on ships have the basic functionality of regulating the flow of the liquid in the pipes. Valves are used for almost all machinery systems on ships for controlling and regulating fluid through pipes. Although valves are known as efficiency decreasing device as they reduce the energy in the liquid flow, their use is imperative in applications where limited flow is required. Therefore, for any aspiring or serving marine engineer, it is extremely necessary to know about construction and working of various types of valves used on ships. In this first article of the series “Types of valves used on ships”, learn about one of the most important valves used...

Globe Valve Used on Ships : Design and Maintenance

Glove valve, a type of valve, is commonly used on board ships in places such as bilge suction lines. A linear motion valve, which regulates the flow of the fluid, the valve has a globe (bulbous) shaped body that houses the valve seat and the disc. The general arrangement of a globe valve consists of the valve seat and the disc arranged at right angle to the axis of the valve. The perpendicular movement of the disc, away from the valve seat, causes a space between the disc and the disc ring, which opens the valve. This characteristic provides good throttling ability to the globe valve which is extremely helpful in regulating the flow of the fluid. The globe valve is used not only in starting and stopping the fluid flow but also for regulating the same. Construction of Globe Valve Though the...

THE 4 TYPES OF BALL VALVES – SINGLE BODY, SPLIT BODY, TOP ENTRY AND WELDED

There are four general body styles of ball valves: single body, split body, top entry, and welded. There are four general types of ball valves: full port, standard port, reduced port, and v port A full port ball valve has an oversized ball so that the hole in the ball is the same size as the pipeline resulting in lower friction loss. Flow is unrestricted, but the valve is larger. A standard port ball valve is usually less expensive, but has a smaller ball and a correspondingly smaller port. Flow through this valve is one pipe size smaller than the valve’s pipe size resulting in slightly restricted flow.  In reduced port ball valves, flow through the valve is one pipe sizes smaller than the valve’s pipe size resulting in restricted flow. A v port ball valve has either a ‘v...

How does it work : Gate Valves

All valves are designed to stop, allow or throttle the flow of a process fluid. Gate valves, one of the original valve designs, are ideally suited for on/off, primarily liquid, service. A gate valve functions by lifting a rectangular or circular gate out of the path of the fluid. When the valve is fully open, gate valves are full bore, meaning there is nothing to obstruct the flow because the gate and pipeline diameter have the same opening. This bore diameter also determines the valve size. An advantage of this full-bore design is very low friction loss, which saves energy and reduces total cost of ownership. Gate & Segment There are four primary designs for gate valves – a slab gate, an expanding gate, a wedge valve and a knife gate valve. Slab gate valves are comprised of a single g...

Main Difference between floating ball valve and trunnion ball valve

Ball valve could be divided into two types according to the ball working principles, floating ball valve and trunnion mounted ball valve. So what’s the difference between floating ball valve and trunnion mounted ball valve ? You would be able to choose which to use for your real condition after knowing below details. Let’s go. Appearance 1. If you see a ball valve with a down trunnion, it must be trunnion mounted ball valve, because floating ball valve don’t have. 2. When a ball valve have seat injection fitting, there’s no doubt it’s a trunnion ball valve. But you can’t say it must be a floating ball valve, because very small size turnnion ball valve also don’t have seat injection fitting, such as 2″ 150LB. Working Priciples 1. The ball of a floating ball ball is movable, it moves s...

Types of Valves – Multi-turn valve & Quarter-turn valve

The operative of the valve closure member The kind of closure member movement defines both the geometry and operative of the valve. Multi-turn valve (linear motion valve):  The closure member has a linear displacement generally by turning its threaded stem several times. This operation is slow, but it gives accuracy and stability to position the closure member, which is necessary in some control valves. Types of valves: Gate valve, Globe valve, Fixed cone valve, Needle valve and Pinch valve. Quarter-turn valve (rotary valve):  The closure member as well its shaft turn 0º-90º; from the fully-open position to the fully-closed position. They are quick opening/closure valves. Types of valves: Ball valve, Butterfly valve, Plug valve, Spherical valve. The functionality of the valve Control: pres...

Is a Metal-seated Ball Valve for You?

Metal-seated ball valves were first introduced to the market to address many of the shortcomings of their soft-seat counterparts. The ability to withstand severe service conditions such as high temperatures, cryogenic conditions, abrasive mediums, slurries, and flow control make them ideal candidates for the use in 0il refinery, petrochemical, mining, pulp and paper, iron and steel mill, electric power generation and water treatment industries. Ball valves are a low-torque, quarter-turn valve with low resistance to flow that are suitable for on-off utility and process services. They have a straight-through configuration and good control characteristics but are not generally used for throttling applications. The majorities of ball valves have soft-seat inserts and use a thermoplastic materi...

Introduction to Valve – Bellow Seal Valve

BELLOW(S) SEAL(ED)S Leakage at various points in pipelines found in chemical plants creates emissions. All such leakage points can be detected using various methods and instruments and should be noted by the plant engineer. Critical leakage points include flanged gasket joints and the f / pump gland packing, etc. Today the chemical process industry is gearing itself towards safer technology for better environmental protection and it has become every process engineer’s responsibility to design plants that limit damage to the environment through the prevention of leakage of any toxic chemicals.      LEAKAGE FROM THE VALVE GLAND OR STUFFING BOX is normally a concern for the maintenance or plant engineer. This leakage means: a) Loss of material b) Pollution to the atmosphere c) Dangerous...

Differences between Forging and Casting Valves

Forging is a kind of process that using metal forming machinery presses to metal billet, making it deform plastically to acquire mechanical properties, shape and size. Forging is a common forming process widely utilized in machinery. Forging can eliminate cast loose and welding holes inside metal. The mechanical properties of forging are more excellent than castings. Based on temperature, forging can be classified into cold forging and hot forging. Generally, cold forging is in progress under room temperature. Hot forging is conducted under temperature which is higher than recrystallization temperature of metal. The forging whose temperature is lower than recrystallization is called as warm forging. Casting is a kind of injection molding, injecting molten liquid metal into prepared mould. ...

Introduction to Valves – Check valves

CHECK VALVES Check valves are “automatic” valves that open with forward flow and close with reverse flow. The pressure of the fluid passing through a system opens the valve, while any reversal of flow will close the valve. Exact operation will vary depending on the type of Check valve mechanism. Most common types of Check valves are swing, lift (piston and ball), butterfly, stop and tilting-disk. TYPES OF CHECK VALVES SWING CHECK VALVE A basic Swing Check valve consists of a valve body, a bonnet, and a disk that is connected to a hinge. The disk swings away from the valve-seat to allow flow in the forward direction, and returns to valve-seat when upstream flow is stopped, to prevent backflow. The disc in a swing type Check valve is unguided as it fully opens or closes. There ar...

How Do Check Valves Function, And Why Would They Be Selected Over Other Valve Types?

Also known as non-return, one-way, and clack valves, check valves are different from other types of valves in their ability to pass fluid in solely one direction. This sort of function is essential for a variety of safety applications, as well as for preventing overflow. How Check Valves Function Operating on a two-port system, check valves have an opening where fluid or gas is drawn in to the first port. It is then regulated by a mechanism separating the two ports that allows water to be drawn from the first to the second port and out an opening without allowing fluids to reenter the first port. Types of Check Valves Ball Check Valve – This check valve uses a ball covering a round opening to separate the first and second port. When fluid is drawn in, the ball is pushed forward. When the f...

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