Valve Archives

Ball Valve

20th November 2018/0 Comments/in Valve/by Mari-saba

Ball Valve

A Ball Valve is a device with a spherical closure unit that provides on/off control of flow. The sphere has a port, also known as a bore, through the center.

When the valve is positioned such that the bore is aligned in the same direction as the pipeline, it is in open position and fluid can flow through it. When rotated 90 degrees, the bore becomes perpendicular to the flow path, meaning the valve is closed and the fluid cannot pass through.

Valve ultilize for control/flow/stop the fluid (water/air/gas) in piping, and there are many kind of valves. These valves generally classified kind of valves depend on application and purpose of using.

There are 4 kind of concepts “Pushing” “Rotating” “Sliding” “Squeezing” for valve’s action. And Ball Valve is classified concept “Rotating” by sealing style.

For strong(merit) points are resistance of fluid is quite little because the port size is same with piping line, and operation is easy and able to do for short time operation by quarter turn operation style.

As the name suggests, ball valves are valves that use a ball to control the flow of substances from one opening to the next. These valves work by allowing the hole to be open, blocked, or open partially to regulate the flow of gas/liquid.

Ball valves are the ideal choice for using with gases as they are able to offer better sealing. They are very versatile as they support pressures up to 700 bars and temperatures up to 200°C and sizes typically range from 0.5 cm to 30 cm. They are easy to operate and repair as they contain a simple structure.

They are designed with special measures that permit only a 90-degree rotation which is required for the opening and closing of ball valves. These valves are a notable industrial choice because of their reliable and air-tight sealing when in the closed position.

Advantages

They contain a compact and low-maintenance design that requires no lubrication
They are cost-effective among all of the valves
The biggest advantage of ball valves is that they have poor throttling characteristics that can cause the seat of a ball valve to easily erode.
They provide leak-proof service.
They open and close quickly.
Ball valves have multi-way design flexibility.

Disadvantages

Ball valves are not suitable for permanent throttling.
In residual fluids, the particles in the fluid collide with the surfaces and stick to them. This may cause leakage, abrasion, and other problems.

Applications

Ball Valves are used for flow and pressure control and shut off for corrosive fluids, slurries, normal liquid and gases.
They are used in the oil and natural gas industry, but also find a place in many manufacturing sectors, chemical storage, and even residential uses.

Types of Ball Valves

There are five general body styles of ball valves: single body, three-piece body, split body, top entry, and welded.

The difference is based on how the pieces of the valve—especially the casing that contains the ball itself—are manufactured and assembled. The valve operation is the same in each case. In addition, there are different styles related to the bore of the ball mechanism itself.

What is a full port or full bore ball valve?

Has a straight flow path
Offers little or no resistance to flow
The flow path through the valve does not become narrower on the inside

The inner diameter of the pipe coming into a full bore valve is the same diameter as the flow path through the valve body and out through the other side of the valve. Most full bore valves are two-way, quarter-turn ball valves.

What is a standard port or standard bore ball valve?

Has a straight flow path
Flow restriction produces a pressure drop
The flow path through the valve becomes narrower on the inside

A standard bore valve body is about the same diameter as the pipe or tube coming into and exiting it. The working part of the valve is the ball inside the valve body. Since the working part of the valve fits inside the valve body, the bore through the valve ball is smaller than the diameter of the valve’s connecting pipe or tube.

Gate Valve Type, Advantage and Disadvantage, Applications

17th November 2018/0 Comments/in Valve/by Mari-saba

Gate Valve, Type, Advantage and Disadvantage, Applications

Gate valves are widely used for all types of applications and are suitable for both above-ground and underground installation. Not least for underground installations, it is paramount to choose the right type of valve to avoid high replacement costs.

Gate valves are designed for fully open or fully closed service. They are installed in pipelines as isolating valves, and should not be used as a control or regulating valves.

Operation of a gate valve is performed doing an either clockwise to close (CTC) or clockwise to open (CTO) rotating motion of the stem. When operating the valve stem, the gate moves up- or downwards on the threaded part of the stem.

History of a gate valve

The term Gate Valve originated from the words gatan, gap, gasse and gat, and implies a passage with a barrier, which can be hinged on one side, allowing it to be OPENED and CLOSED.

Some of the first known gate valves were used by the Egyptians, Greeks, and Romans when irrigating fields with water. These were simple wooden barriers, but they were well-suited for the requirements of the task.

In the 19th century, intensive development of gate valves moved quickly forward due to their increasing use in industrial operations. Over time the materials involved in their manufacture were improved and modified to suit different applications.

In addition, there were significant improvements in the efficiency of both internal and external sealing methods.

Type of Gate Valve

There is a different type of gate valve, such as:

Standard
Wedge Types
Solid Tapered Wedge
Solid Pliable Wedge
Double Disc type
Bellow Design
Cryogenic Design
Knife Plate
Hulk Plate

Advantages of Gate Valves

The closing feature is very good.
These valves can be used both ways in the circuit
They provide laminar flow, the pressure loss is minimum

Disadvantages of Gate Valves

They cannot be opened and closed quickly. To fully open or closed wheel or gearbox actuators, the shaft should be rotated as many as the full open revolution number. The full open revolution number is equal to the pitch
Assembly, start-up, and maintenance require large space.
In the fully closed position, the slow movement of the slide causes high flow speed. Due to vibration and collision, abrasion and deformation occur in the seating surfaces and the surface gets damaged from friction.
In systems where high-temperature changes irregularly, due to the load in the pipe at the valve end, leakages in gate valves occur.
At the place of operation, repair and maintenance of seating surfaces are difficult.

Application of Gate valve

Socket or butt-welding end-gate valves in air, fuel gas, feedwater, steam, lube oil, and other systems are typical applications. Threaded-end gate valves may be used in air, gaseous, or liquid systems.
Concern for leakage from threaded connection can be addressed by seal welding the threaded connection or by using thread sealants, as appropriate. In low-pressure and low-temperature systems such as fire protection systems’ water piping or water distribution pipelines, flanged gate valves are commonly used.

Refrences:

https://www.avkvalves.eu

http://www.schuf.de

http://www.pipingguide.net

https://www.ksb.com

What is a Globe Valve?

11th November 2018/0 Comments/in Valve/by Mari-saba

What is a Globe Valve?

A globe valve is a linear motion valve used to stop, start, and regulate the fluid flow. The globe valve disk can be removed entirely from the flow path, or it can completely close the flow path. During opening and closing of globe valve, disc moves perpendicularly to the seat.

The globe valve is used for throttling flow control. Shut off is accomplished by moving the disc against the flow stream rather than across it as in the case with a gate valve. The flow pattern through a globe valve involves changes in direction, resulting in greater resistance to flow, causing a high-pressure drop.

Advantages and disadvantages of Globe valves

ADVANTAGES:

Good shutoff capability
Moderate to good throttling capability
Shorter stroke (compared to a gate valve)
Available in tee, wye, and angle patterns, each offering unique capabilities
Easy to machine or resurface the seats
With disc not attached to the stem, the valve can be used as a stop-check valve

DISADVANTAGES:

Higher pressure drop (compared to a gate valve)
Requires greater force or a larger actuator to seat the valve (with pressure under the seat)
Throttling flow under the seat and shutoff flow over the seat

GLOBE VALVE APPLICATIONS

The following are some of the typical applications of globe valves:

Cooling water systems.
Fuel oil systems.
Feedwater or chemical feed systems.
Boiler and main steam vents and drains.
Turbine lube oil system and others.

Types of Globe Valve

There is three common type of valve.

Z-body type valve

This is the simplest and most commonly used design of globe valves, favorable for applications involving water flow. The name Z-shaped is derived from the Z shaped diaphragm or partition in the bulbous shaped body. The stem and the disc move at right angle to the valve body, aligning with the horizontally arranged seat. The stem passes through the bonnet attached to a wide opening at the top.

Y-body type valve

The Y-body type valve design is a solution to the problem of pressure drop which is commonly found in globe valves. In this design, the valve seat and stem are angled at approximately 45° to the valve axis. This results in a much straighter path for the fluid flow, providing a more pressure resistant environment inside the valve.

The Y-body valves are mainly suited for high-pressure applications wherein problems related to pressure drop are common. However, in the case of throttling purpose, the pressure resistance might not work effectively, especially if the valve is smaller in size. This is also because, in smaller valves, the flow passage is not as carefully streamlined as that in larger vessels.

Angle Valve design

The angle globe valve is a modification of the design of the basic Z-shaped glove valve. The inlet and outlet ends are placed at right angles and the diaphragm is generally a simple flat plate. The fluid flows through the valve body in a right-angled flow path and gets discharged downwards in a more symmetrical manner. These characteristics are extremely important in applications involving high pressure. However, in moderate conditions, the valve functions more or less similar to the Z Shaped Valve.

Refrences:

https://medium.com

https://www.bmengineering.co.uk

http://www.ladishvalves.com

https://www.emerson.com

Types of Valves

6th November 2018/0 Comments/in Valve/by Mari-saba

Types of Valves

In the industry, we have different Types of Valves , each with a specific application. In this article, we introduce the most widely used valves.

BALL VALVES

A ball valve is a shut-off valve that controls the flow of a liquid or gas by means of a rotary ball having a bore. By rotating the ball a quarter turn (90 degrees) around its axis, the medium can flow through or is blocked.

Floating Ball Valve

In floating ball valve, the ball is held in the position by the compression of the two elastomeric seats against the ball. The ball is free to float inside the valve body. See the highlighted portion in the image and remember as you will see the difference when I will explain you about trunnion mounted ball valve.

Trunnion Mounted Ball Valve

Trunnion mounted ball valve is a solution to the problem of excessive torque required by floating ball valve in high-pressure service. A short shaft like an extension that called trunnion set in the body. You can see this in the image. In this design steam and ball work as a single unit. The ball is supported by two floating or spring-loaded seats that remain in constant contact with the ball.

Gate Valve

Gate valves are widely used for all types of applications and are suitable for both above ground and underground installation. Not least for underground installations it is paramount to choose the right type of valve to avoid high replacement costs.

Gate valves are often used when minimum pressure loss and a free bore is needed. When fully open, a typical gate valve has no obstruction in the flow path resulting in a very low pressure loss, and this design makes it possible to use a pipe-cleaning pig. A gate valve is a multiturn valve meaning that the operation of the valve is done by means of a threaded stem. As the valve has to turn multiple times to go from open to closed position, the slow operation also prevents water hammer effects.

Globe Valve

A globe valve is a linear motion valve used to stop, start, and regulate the fluid flow. The globe valve disk can be removed entirely from the flow path, or it can completely close the flow path. During opening and closing of globe valve, disc moves perpendicularly to the seat.

This movement creates the annular space between the disk and seat ring that gradually close as the valve closed. This characteristic provides the globe valve good throttling ability required for regulating the flow.

Leakage from globe valve seat is less as compared to the gate valve, mainly due to right angle contact between the disk and seat ring, which allows tighter seal between seat the disk.

CHECK VALVES

Leak-free, tight sealing, protection against reverse flow and minimal flow direction changes are at the core of Flowserve check valve designs. A broad range of configurations that includes piston, tilting disc, spring-loaded disc and dual-plate models meets the critical, high-temperature/pressure demands of the world’s major industries. Customers can carefully match application requirements through myriad valve body, seat and disc options.

https://hardhatengineer.com/ball-valve-floating-trunnion-mounted-ball-valves/

https://hardhatengineer.com/globe-valve-types-angle-parts/

https://www.flowserve.com/en/products/valves/check-valves

Ball Valve