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What is a backseat of Gate Valve

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What is a backseat?A backseat is a seating arrangement inside the bonnet. It provides a seal between the stem and bonnet and prevents system pressure from building against the valve packing when the valve is fully open. Back seats are often applied in gate and globe valves (source: wermac.org).
How to use the backseat?
The backseat should only be used to isolate the gland packing from the line medium for example when gland packing leakage is evident and until the valve can be de-pressurised and repaired.
How to not use the backseat?
Under no circumstances should the  backseat be used to allow gland packing replacement or repair while the valve and system are pressurized.Having clarified these 3 questions, the issue seems quite simple.
But it is not!One of the most common errors done on site is to believe that if the Gatevalve is back-seated (fully open position – and backseat sealing made), this will help to prevent wear of the packing rings.
Unfortunately using the back seat  in this way over a longer period of time, could  result in some serious issues:a)  Since the body, bonnet, stem, and disc heat up and expand at different rates, experience shows that valve can get jammed/blocked in back-seated positon.b) The gland packing will dry out since it’s not exposed to the steam, and could immediately blow upon closing of the valve.The simple but important rule for valve users, preventing misuse of the backseat!“Once the valve is brought into fully open position (back-seated), turn the hand wheel back one full turn”(this should be clearly stated in every Installation, Maintenance and Operating Manual of Valve Manufacturers),The other issue valve users experience is the problem with actuated valves. It does not matter if electric-, pneumatic- or hydraulic actuators are used. If the valve manufacturer does not correctly adjust the actuator in the open position, we will get back to the same problems (as described earlier). Field experience on high pressure/temperature drain valves (globe valve), pneumatically actuated and usually in fail safe open position, showing clearly the premature use of the gland packing rings.
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What is the difference between floating ball valve and Trunnion Ball Valves?

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What is the difference between floating ball valve and Trunnion Ball Valves? The ball of the floating ball valve is floating. Under the action of medium pressure, the ball can produce a certain displacement and press tightly on the sealing surface of the outlet end to ensure the sealing of the outlet end.

 

The floating ball valve has the advantages of small volume, light weight and simple structure. The ball of the floating ball valve has the function of free floating, which can better ensure the sealing; The ball can rotate freely in the valve seat sealing ring with the help of the valve stem. When opening, the ball hole is aligned with the pipe diameter to ensure that the working medium resistance of the pipe is very small. When the valve rod rotates for 1 / 4 turn, the ball hole is perpendicular to the channel of the valve. The ball is tightly pressed on the valve seat sealing ring at the outlet end by the preload and medium pressure applied to the two valve seat sealing rings, so as to ensure the complete sealing of the valve. This kind of ball valve is a one-sided forced seal.

The ball of the fixed ball valve can only rotate along the shaft under the action of the upper and lower valve shafts. The valve seat clings to the valve ball under the action of the back spring. The connection mode of valve ball and valve shaft includes welding, casting, forging and split type; There are many domestic key pin connections and many imported spline connections. Fixed ball valves are equipped with floating valve seats. After being subjected to medium pressure, the valve seats move to make the sealing ring tightly press on the ball to ensure sealing. Bearings are usually installed on the upper and lower shafts of the ball, with small operating torque. It is suitable for high-pressure and large-diameter valves. The common driving modes of fixed ball valves are worm gear drive, manual, electric and pneumatic. Most fixed ball valves are flanged, but there are also fixed ball valves in the form of welding.

 

 

 

 

 

 

 

 

 

 

 

 

 

The ball of the Trunnion Ball Valves can only rotate along the shaft under the action of the upper and lower valve shafts. The valve seat clings to the valve ball under the action of the back spring. The connection mode of valve ball and valve shaft includes welding, casting, forging and split type; There are many domestic key pin connections and many imported spline connections. Trunnion Ball Valves are equipped with floating valve seats. After being subjected to medium pressure, the valve seats move to make the sealing ring tightly press on the ball to ensure sealing. Bearings are usually installed on the upper and lower shafts of the ball, with small operating torque. It is suitable for high-pressure and large-diameter valves. The common driving modes of fixed ball valves are worm gear drive, manual, electric and pneumatic. Most Trunnion Ball Valves are flanged, but there are also fixed ball valves in the form of welding.

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What is a Y strainer?

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There are styles of strainers, basket and y. The y strainer is generally used wherein there’s a small quantity of cloth to be amassed. This strainer may be established inside the horizontal or vertical function. The basket must be to the bottom of the pipe or dealing with the down flow direction to collect the particles. A y strainer can include a blow-off connection for automatic cleansing. With drinks, y strainers have a greater strain drop than basket strainers because of their length (comparing identical sizes). However, with gases a y strainer has a enormously low-strain drop.

Y type strainers are used to remove impurities from liquid and gas lines. They are fitted into piping systems to protect pumps and control valves from getting damaged by the solid debris. Y strainers are the most common type of industrial strainers and are used in systems where the amount of debris to be removed is low; they are also cost-effective as compared to other types of strainers. They are also flexible and can be applied in different ways, making them a good fit for all piping systems.

It is also important to note that the cost of the y strainer is nothing compared to the amount of money you will spend on replacing your mechanical equipment such as pumps, turbines and heat exchangers if they get damaged due to lack of the strainer. In this blog, we are going to have an indepth look at how the y strainer works to protect your apparatus.

How to Install the Y Strainer

 

 

 

 

 

 

 

The Y strainers can be used in a horizontal or vertical manner, depending on your system and preference. Before installing your strainer, ensure that you keenly analyse the direction of the blowdown chamber, which is the chamber that collects the debris. The fliter leg of the Y strainer should be in a downward position so as to ensure that the trapped impurities do not get back into the system. While installing a large y strainer, it is important to include pipe fittings to support the piping. 

Another important factor to note before installing the Y strainer is that the pressure rating of the strainer should coincide with that of the system. The Installation of the y strainer critically depends on the kind of strainer you have. Ensure that you fully understand the kind of strainer you have before installing it. Always read through the manual carefully before starting your installation process.

Y strainers work in different kinds of systems, mainly liquid and steam chambers. However, when buying a y strainer for steam service, always ensure that you notify your supplier so they can know the type of y strainer that will work for you. In most instances, you will be provided with a special housing for steam works.

As liquid flows through the y strainer, the screen of the strainer obstructs the flow and collects the debris from the liquid before allowing the process to continue. This obstruction causes the pressure of the liquid to drop, which is commonly referred to as pressure drop in the strainer. The draining plug, which is made up of two metal plates, forms a seal that prevents the liquid from flowing out of the chamber. This keeps the filtered and unfiltered liquid from mixing.

The mesh on the y strainer then traps any form of impurities from the liquid and prevents them from flowing to other parts of the system. This is how the y strainer works to protect dirt particles from getting to the main system parts. Y strainers work in high-velocity systems where the pressure is up to 6,000 psi.

How the y strainer works makes it a better choice in comparison to basket strainers which are built for pressures of up to 1500 psi. There are different ways in which you can connect the y strainer to your pipeline. You can either thread it or bolt it to the flange. This majorly depends on the kind of material used on the strainer. Y strainers are made out of different materials, mainly stainless steel, iron and cast iron. Some are made from carbon and bronze.

Maintenance of the Y Strainer

 

Compared to other types of industrial strainers, the Y strainer requires very minimal maintenance which makes it your most ideal kind of strainer. However, it is critical to keep tabs of the pressure in the system to ensure that the strainer does not get clogged. The Y strainer is cleaned manually by removing the screen completely which means that the system has to stop entirely during cleaning. Let us have a quick look at how you can ensure that your y strainer is in the best condition to perform its functions.

Install a Pressure Gauge: It is easy to forget to monitor the pressure of your system, especially if you have several systems running simultaneously. In this case, a pressure gauge will help you perform this task effectively and alert you in case of any pending pressure drops. This will help you schedule your cleaning before the strainer gets completely damaged due to extreme clogging.

Install a Blow-down Connection: Instead of having to take the Y strainer apart every time it needs cleaning, opt for a blowdown connection whereby a gate valve is connected to the end of the system, allowing you to to clean out the debris down the drain as the system stays put. This will save the time used to disconnect and reconnect the y strainer, hence limiting the system downtimes.

Have Extra Screens at Hand: This enables you to save the time used to clean and put back the screes of the strainer. A few replacement screens can be used as the dirty one gets cleaned for the future. This is also in an effort to avoid any system downtimes.

Always Depressurize before Cleaning: Before opening up your y strainer for cleaning purposes, always ensure that the pressure is low. Cleaning out pressurized strainers can cause serious injury to the handler and damage the strainer.

Do Not Overwork Your Strainer: Always ensure that you get the right kind of industrial strainer for your system so that you do not end up overworking your strainer.

Pros of the Y Strainer

The flexibility of the Y strainer allows you to apply it in different ways, either vertically or horizontally. This is not the case with basket strainers which can only be applied in a horizontal position.

How the y strainer works makes it ideal for high-pressure systems as it can withstand very high pressures as compared to other types of strainers.

Y strainers are cheaper in price compared to other industrial strainers. Their small and compact size makes them more price friendly.

Y strainers require very minimal maintenance and can be reused several times, as long as they are properly cleaned to prevent clogging of the strainer.

Cons of the Y Strainer

Cleaning of the Y strainer requires an interruption of the whole system which leads to frequent downtimes. This gives the duplex basket strainer an upper hand due to the fact that one basket can be kept running while the other one is getting cleaned.

The small screen of the Y strainer cannot accommodate high concentration of impurities, making it suitable for systems with very minimal filtration work.

Conclusion

The Y strainer is the most common type of strainer found in most piping systems. Compared to other types of industrial strainers, the y strainer is very easy to install, and you can start up your system sooner with this strainer. It also comes in different types of material, the most common one being stainless steel. Depending on your system needs, let us supply you with an ideal y strainer to perform your tasks. Visit our website for more information on the Y strainer and other types of industrial strainers.

What’s The Difference Between Carbon Steel And Cast Iron?

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What’s The Difference Between Carbon Steel And Cast Iron?

Carbon steel is an iron – carbon alloy with a carbon content of 0.0218% to 2.11%. Cast iron generally has a carbon content of 2.5% to 3.5%. Carbon steel castings has relatively good strength and toughness and is used to manufacture various mechanical parts and metal products. The properties of cast iron are lower than steel, especially the tensile strength and plasticity are low, and it cannot be forged, but its hardness and compressive strength are better.

Mild steel casting in carbon steel products

Mild steel refers to steel with 0.15 to 0.25 percent carbon and not many additional alloying components. Mild steel products are essential. More than half of the common carbon steel products are mild steel casting. Like some mild steel casting samples shown above, Dawang provides you with various mild steel products. Regarding mild steel cost, we will provide you with a satisfactory price. For more information, please consult our mild steel cost service.

What Are The Defects Of Carbon Steel Castings?

Carbon steel casting generally has the following defects:

1. Gas Porosity

The reason for the pores is that there is too much water in the molding material or a lot of gas – producing substances; the air permeability of molding sand and core sand is poor; the pouring speed is too fast.

2. Trachoma

The causes of blisters include insufficient molding sand strength; insufficient molding sand compactness; and too fast pouring speed.

3. Shrinkage

The cause of shrinkage cavity is poor feeding of the casting during solidification.

4. Sticky sand

The cause of sticky sand is the poor fire resistance of the molding sand or the high pouring temperature.

5. Cracks

The causes of the cracks are the large difference in the wall thickness of the castings; the improper setting of the gating system; the new difference between the sand mold and the core.

How To Distinguish Carbon Steel Casting Grades?

Carbon steel casting grades are divided into three subgroups according to the carbon content of the metal: Low carbon steel castings/Mild steels (up to 0.3% carbon), Medium carbon steel castings(0.3–0.6% carbon), and High carbon steel castings (more than 0.6% carbon).

What is the material of WCB / LCB / LCC / wc6 / WC9 in the valve？

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WCB / LCB / LCC / wc6 / wc9 are commonly used materials for valves, but many people don’t know what they mean. Let’s introduce these materials in detail today

W. Wrought casting;
C-carbon steel;
A. B, C indicates the strength value of steel grade from low to high
WCA, WCB and WCC represent carbon steel, ABC represents strength grade, and WCB is commonly used. The pipe material corresponding to WCB shall be A106B and the forging material shall be A105.
Wc6 is a casting of alloy steel, the corresponding pipe material is about a355 P11, and the forging is A182 F11;
wc9, high temperature resistant alloy steel, corresponding to about a355 P22, and forgings corresponding to A182 F22.
WC weldable castings
LCB / LCC (ASTM a352) low temperature carbon steel

1. Chemical Composition Requirements

Chemical Composition of ASTM A217 Castings, %
Grade UNS C Mn P S Si Cr Mo Others
WC1 J12524 ≤0.25 0.50-0.80 ≤0.04 ≤0.045 ≤0.60 – 0.45-0.65 *A
WC4 J12082 0.05-0.20 0.50-0.80 ≤0.04 ≤0.045 ≤0.60 0.50-0.80 0.45-0.65 *B
WC5 J22000 0.05-0.20 0.40-0.70 ≤0.04 ≤0.045 ≤0.60 0.50-0.90 0.90-1.20 *C
WC6 J12072 0.05-0.20 0.50-0.80 ≤0.035 ≤0.035 ≤0.60 1.00-1.50 0.45-0.65 *D
WC9 J21890 0.05-0.18 0.40-0.70 ≤0.035 ≤0.035 ≤0.60 2.00-2.75 0.90-1.20 *E
WC11 J11872 0.15-0.21 0.50-0.80 ≤0.020 ≤0.015 0.30-0.60 1.00-1.50 0.45-0.65 *F
C5 J42045 ≤0.20 0.40-0.70 ≤0.04 ≤0.045 ≤0.75 4.00-6.50 0.45-0.65 *G
C12 J82090 ≤0.20 0.35-0.65 ≤0.035 ≤0.035 ≤1.00 8.00-10.00 0.90-1.20 *H
C12A J84090 0.08-0.12 0.30-0.60 ≤0.025 ≤0.010 0.20-0.50 8.0-9.5 0.85-1.05 *H
CA15 J91150 ≤0.15 ≤1.00 ≤0.040 ≤0.025 ≤1.50 11.5-14.0 ≤0.50 *I

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*All values are maximum unless otherwise specified.

*A – Total Residual{Cu:≤0.50,Ni:≤0.50,Cr≤0.35,W≤0.10}:≤1.00. *B – Ni:0.70-1.10,Total Residual{Cu:≤0.50,W≤0.10}:≤0.60.

*C – Ni:0.60-1.00,Total Residual{Cu:≤0.50,W≤0.10}:≤0.60. *D – Total Residual{Cu:≤0.50,Ni:≤0.50,W≤0.10}:≤1.00.

*E – Total Residual{Cu:≤0.50,Ni:≤0.50,W≤0.10}:≤1.00. *F – Total Residual{Al:≤0.01,Cu:≤0.35,Ni:≤0.50,V≤0.03}:≤1.00.

*G – Total Residual{Cu:≤0.50,Ni:≤0.50,W≤0.10}:≤1.00. *H – Total Residual{Cu:≤0.50,Ni:≤0.50,W≤0.10}:≤1.00.

*I – Ni:≤0.40,Co:0.06-0.10,N:0.03-0.07,V:0.18-0.25,Total Residual{Al:≤0.02,Ti≤0.01,Zr≤0.01}. *J – Ni:≤1.00.

*Values from *A to *J shall be furnished with the unit “%”.

3. Heat Treatment
All castings shall receive a heat treatment proper to their design and chemical composition.
ASTM A217 castings shall be furnished in the normalized and tempered conditions; Grades WC1, WC4, WC5, WC6, and CA15 shall be tempered at 1100°F [595°C] min; Grades WC9, C5, C12, and WC11 shall be tempered at 1250°F [675°C] min; Grade C12A shall be thermally treated, either by normalizingand-tempering or by accelerated cooling from the austenitizing temperature by air blasting or liquid quenching, followed by tempering. C12A castings shall be austenitized at 1900-1975°F [1040-1080°C] and tempered at 1350-1470°F [730-800°C].
Heat treatment shall be performed after castings have been allowed to cool below the transformation range.

4. Quality Control
The surface of ASTM A217 castings (either valve, flange, fittings or other piping component) shall be visually examined and shall be free of sand, scale, cracks, and hot tears.
Hollow castings of Grade C12A, larger than NPS 4 [DN 100], and whose internal surfaces are not accessible to the visual examination above-mentioned, shall be examined by the ultrasonic examination prescribed in Supplementary Requirement S7.

Ball Valves

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Ball Valves
Introduction
This article contains all the information you need to know about Ball Valves.

Read further and learn more about:

What is a ball valve and how does it work?
Parts of a ball valve
Types of ball valves
Materials of construction of ball valves
Advantages and limitations of ball valves
And much more…

 

 

 

 

 

 

 

 

Chapter 1: What is a Ball Valve and How Does It Work?
A ball valve is a shut-off valve that allows, obstructs, and controls the flow of liquids, gases, and vapors in a piping system by rotating the ball having a bore inside the valve. The ball is mounted against two seats and has a shaft that connects it to the operating and control mechanism that rotates the ball. When the cross-section of the bore is perpendicular to the area of the flow, the fluid is not permitted to pass through the valve. The fluid flows through from the valve, and the fluid flow rate depends on the area of the bore exposed to the floor.

 

 

 

 

 

 

 

 

 

 

Ball valves are a type of quarter-turn valve along with plug valves and butterfly valves. They can be operated manually or by using an actuator. The simplest operation of a ball valve is through the use of a wrench or a lever manually turned by an operator. Torque is applied to rotate the lever arm by 90° by either clockwise or counterclockwise to open or close the valve. If the lever arm is parallel to the pipe, it indicates that the valve is open. If the lever arm is perpendicular to the pipe, it indicates that the valve is closed.

Ball valves come in many designs and features to satisfy various industrial needs. The standards and specifications for ball valves vary depending on the industry where it is utilized.

 

Chapter 2: Parts of a Ball Valve
The basic components of a ball valve include the following:

 

 

 

 

 

 

 

 

Valve housing
All internal components of a ball valve are contained inside the valve housing or the body. It is made of a hard and rigid metal, thermoplastic, or thermoplastic-lined metal that protects the components of the ball valve. It also allows access to the external control mechanism that rotates the ball.

Parts of a Ball Valve

Ball
The ball is a sphere that has a hole in its center. The hole in its center is called the bore. The bore serves as the flow opening of the fluid when the cross-section of the fluid flow path and the bore is coplanar. Otherwise, the flow is throttled. A ball valve may have a solid ball or a hollow ball. A solid ball has a constant opening diameter throughout its structure, which helps the fluid to smoothly flow at a constant velocity. A hollow ball, on the other hand, has a hollow internal structure, and the space inside it allows more fluid to pass through the valve. However, the larger space creates turbulence and high velocities. A hollow ball is more lightweight and cheap compared to a solid ball.

Shaft
The shaft connects the ball to the control mechanism that rotates the ball. The shaft has seals such as O-rings and packing rings to seal the shaft and the bonnet to avoid leakage of the fluid. The shaft may be manually operated by a lever or a handwheel or operated by an electric, pneumatic, or hydraulic actuation.

Bonnet
The bonnet is an extension of the valve housing that contains and protects the shaft and its packing. It may be welded or bolted to the body. It is also made of hard metal and it covers the opening made from connecting the shaft to the external control mechanism.

Seat
The valve seats provide sealing between the ball and its body. The upstream seat is adjacent to the inlet side of the valve. The downstream seat is found on the opposite side of the upstream seat which is adjacent to the discharge side of the valve.

GET YOUR COMPANY LISTED BELOW

 

Chapter 3: Types of Ball Valves

Ball valves may be classified according to their housing assembly, ball design, and bore profile.

Housing Assembly

  • One-Piece Ball Valve

Housing Assembly
One-Piece Ball Valve
A one-piece ball valve has a single-piece cast body that houses the internal components of the ball valve. This eliminates the risk of leakage of the fluid from the valve. One-piece ball valves are the cheapest ball valves and always have a reduced bore. A welded one-piece ball valve is more common but cannot be dismantled for cleaning and repaired once damaged; therefore, it is only used for applications with a low possibility of particle build-up, and where sanitation is not a major concern. On the other hand, screwed one-piece ball valves can be cleaned, serviced, and repaired, but dismantling requires special tools.

 

 

 

 

 

Split Body Ball Valves
Split Body Ball Valves are valves that are assembled on the sides of their balls. A split body ball valve may be a two-piece or a three-piece ball valve:

Two-Piece Ball Valve
A two-piece ball valve consists of housing divided into two pieces that are fitted together. The main piece contains the ball and a connection to one end, and the other piece holds the internal components together and has a connection to the other end. Two-piece housing is the most common type among ball valves. The two parts can be dismantled for cleaning, maintenance, and inspection but it requires removal of the valve from the pipe.

 

 

 

 

 

 

Three-Piece Ball Valve
A three-piece ball valve consists of the housing for the internal components of the valve which are fitted and held together by bolt connections to its two ends. The ends are threaded or welded to the main pipe.

Three-piece ball valves are used for applications that rely heavily on valves, that their maintenance activities must frequently be done. They can be cleaned and serviced easily and their seats and seals can be routinely replaced by just taking the valve body out without disturbing the two ends. Three-piece ball valves are commonly used in the food and beverage and pharmaceutical industries where sanitation is crucial to safety and product quality.

 

 

 

 

 

 

 

Top Entry Ball Valve
A top entry ball valve allows access to the internals of the valve by simply removing the bonnet on top of the valve. This allows in-line maintenance activities (i.e., dismantling, cleaning, inspection, and repairing the valve) without removing the ball valve from the main pipe.

Three-Piece Ball Valve 2

Ball Design
Floating Ball Valves
The floating ball is the most common ball design in ball valves. The ball is suspended inside the valve and free to move in a lateral direction when the valve is in a closed position. It is sandwiched between two seats that support the valve and hold it in place. The ball is connected to the shaft in a slot on one end while the other end is free. When the valve is in an open position, the shaft connection to the slot at the top of the ball prevents the ball from moving laterally.

The sealing action is only dependent on fluid pressure. During an operation of a floating ball valve, the inlet pressure of the fluid forces the ball to the outlet seat which prevents the fluid from escaping from the valve body. The fluid pressure on the ball and the seats are higher when the ball valve is in the closed position.

Floating ball valves have the simplest design. They come in smaller diameters and are suitable for liquids and gases operating under low to moderate pressures. The application of floating ball valves is limited by the amount of pressure the seats can handle. At high fluid pressure, the seats can be deformed from the pressure exerted by the ball which can affect the sealing characteristics of the valve under low pressure. Furthermore, the torque to rotate the stem depends on the force required to counteract the same fluid force acting on the ball and seals.

Floating Ball Valve

Trunnion Ball Valves
In a trunnion ball valve, the ball is supported by an additional shaft at its bottom which is called the trunnion. This holds the ball in its place and limits the movement of the ball to its axis. The ball can only move if the valve shaft rotates. Trunnion ball valves also feature spring-loaded seats. The inlet fluid pressure activates the springs towards the ball held by the trunnion, which creates a tight sealing.

Trunnion ball valves are available in small to large diameters, but it is more expensive than floating ball designs. They can operate efficiently in a wide range of pressures and they are ideal for high-pressure applications since the fluid pressure is also dissipated to the trunnion and the springs of the seats. Hence, they are easier to operate with a lower operating torque or a small actuator.

 

Vented Ball Valve
A vented ball valve is constructed and operates in the same way as a standard ball valve, except that the vented ball has small orifices drilled into its side. When the valve is closed, the orifice is directed to the outlet side of the valve. The drilled hole is used to vent trapped gases which causes a build-up of internal pressure inside the valve, to prevent leaking, valve failure, and explosion.

Vented ball valves are used in compressed air systems, cryogenic processing and conveying volatile liquids are also referred to as the “cryogenic valve” because of their usefulness in cryogenic processing.

 

Bore Profile
Full Bore Ball Valve
A full bore has a bore diameter similar to the pipe diameter. The flow area for the fluid for full bore valves remains constant, therefore the flow resistance offered by this type is very low. Minimal frictional loss is encountered during fluid flow; hence the pressure drop is low. A high pressure drop in a piping system causes pumping more difficult. However, since the bore diameter should be equal to the pipe size, it requires a larger ball size and housing which makes it more expensive than a reduced bore.

Full bore ball valves are easier to maintain and clean. In pipelines, the pipes are maintained and inspected by an operation called pigging. A spherical or cylindrical device called pigs is allowed to flow in the pipes to detect and remove any build-up without interfering with the fluid inside the pipeline. This operation is possible with an installed full-bore ball valve.

Full bore ball valves are also used in conveying liquids with mixed solids where flow restrictions cause the build-up of particles that can eventually cause separation of the mixtures that will flow through it.

 

Reduced Bore Ball Valve
A reduced bore has a bore diameter smaller by a pipe size than the (connection) pipe diameter. The actual reduction is determined by the agreement between the manufacturer and the customer. The flow area for the fluid becomes narrower at the downstream outlet, therefore there are frictional losses that are introduced which result in a pressure drop. Since the amount of flow discharge remains constant, the velocity increases with the decrease in the flow area.

Reduced bore ball valves are more common than full bore ball valves. They are used in applications where product flow rate and turbulence are not potential concerns and particle build-up is not likely to occur. The reduced bore is less expensive than the full bore since it requires a smaller ball size and housing. Compared to other types of valves, the reduced bore ball valves have relatively smaller pressure drop.

 

Segmented Ball Valve
A segmented ball valve has a V-shaped notch on its ball. A segmented ball valve has good flow rate control which depends on the ball rotation. Aside from that, it also has a good shut-off capability. The flow characteristic in a segment ball valve approaches an equal percentage flow characteristic. The flow rate in a segmented ball valve increases exponentially as the ball reaches its fully opened position.

 

Other Types of Ball Valve
Cavity-Filled Ball Valve
A cavity-filled ball valve has a seat design that fills the gap between the ball and its body. This eliminates the possibility of entrapped media or particle build-up over time around the ball which can cause contamination or blocking of the fluid flow. Cavity-filled ball valves are easier to clean and maintain.

Cavity-filled ball valves are valuable in industries where sanitation is crucial, such as in food, pharmaceutical, and bioprocessing industries. They are ideal in handling solid-liquid mixtures such as slurries.

 

Multi-Port Ball Valve
Multi-port ball valves are used in diverting, combining, splitting, or shutting off multiple fluid streams through the use of a ball with an L-shaped or T-shaped bore segmented through its middle. A flow upstream to the inlet of a multi-port valve can be split into multiple outlet streams. It can split a flow, but cannot distribute the flow to its outlet streams in pre-determined flow rates. It can also join multiple flow streams into a single stream, or simply change the direction of the fluid flow. The schematic diagram below shows possible flow configurations of an L-shaped and a T-shaped multi-port ball valve.

 

Chapter 4: Materials of Construction of Ball Valves
The ball valve‘s ball and its housing are commonly constructed from the following materials:

Brass
Brass is an alloy of copper and zinc that can be distinguished by its dull yellowish to reddish color, depending on the amount of zinc. It is the most common material for ball valves. Brass is a tough, strong, and durable metal that can withstand high temperatures and pressures. The copper in brass alloy has antimicrobial properties that inhibit the growth and reproduction of microbes on its surface. Brass has good chemical, corrosion, and biofouling resistance. It is inert to most acids, alkalis, and bases, except for solutions with high chlorine content. Chlorine can cause dezincification, a reaction where chloride ions strip away zinc from the alloy, causing a porous structure. Dezincification can drastically reduce the strength of the material.

Brass ball valves are not difficult to fabricate because of their malleability, and they are also easy to cast and weld. They are lighter and cheaper than steel ball valves. They are also easy to assemble in the piping system. Common applications of brass ball valves are in food, chemical, and oil and gas processing, and in conveying gaseous fluids. It is also safe to use in the delivery of potable drinking water.

 

Stainless Steel
Stainless steel is a type of steel that contains higher chromium content and some amounts of nickel. The chromium content of stainless steel makes it acquire a superior corrosion resistance. Stainless steel is known for its excellent strength, toughness, and durability. It also retains its strength in high temperatures and pressures.

Stainless steel ball valves are commonly constructed in 304 and 316 Stainless Steel grades. The 304 Stainless Steel has 18% chromium and 8% nickel, while 316 Stainless Steel has 18% chromium and 10% nickel and trace amounts of molybdenum. The combination of nickel and molybdenum makes the 316 Stainless Steel resistant to chlorides.

There are applications where the use of a stainless-steel ball valve is an excellent choice. They are used in swimming pools to handle chlorinated water. In harsh industrial environments such as desalination and petroleum refining plants, they offer better resistance to corrosive chemicals under high temperatures and pressures. In breweries, stainless steel pipes and valves are used to handle wort, a reactive liquid that is extracted during the mashing process.

 

Polyvinyl Chloride (PVC)
PVC is a tough, rigid and durable plastic material. Compared to brass and stainless-steel alloys, they generally have lower strength but they are cheaper. They are resistant to corrosion and most acids, bases, and salt solutions. However, they are not resistant to aromatic compounds and hydrocarbons. PVC ball valves have a lower temperature and pressure rating, for up to 150 psi and 140°F, respectively. Application of PVC ball valves includes plumbing, irrigation, and water distribution systems.

Chlorinated PVC (CPVC) is a type of PVC that has been chlorinated by a free radical reaction initiated by UV light. The chlorination of PVC results in higher temperature resistance. CPVC ball valves can handle higher temperatures of up to 200°F.

 

Polypropylene Ball Valve (PP)
PP is a tough, durable, lightweight, and flexible thermoplastic made from propylene monomer. It offers good resistance to most acids and bases, but has selective compatibility with organic substances and solvents. Its chemical resistance decreases with increasing temperatures. The maximum operating temperature of PP is 82°C. PP ball valves are suitable for regulating the flow of fluids with a wide range of viscosity. They are used as materials for ball valves in the manufacturing of sugar, fertilizers, chemicals, paper, and others.

 

Glass Fiber-Reinforced Polypropylene Ball Valve (GFPP)
In GFPPs, glass fibers are reinforced to polypropylene to increase its dimensional stability, rigidity, and chemical resistance, and to reduce the PP‘s coefficient of thermal expansion. Its heat deflection temperature is increased up to 150°C for a 40% GFPP at 264 psi. Reinforcement of glass fibers in PP increases cost-efficiency and makes it operate in more harsher and heavy-duty applications.

 

Polyvinylidene Difluoride Ball Valve (PVDF)
PVDF is a high purity, durable, thermoplastic fluoropolymer with high molecular weight. It is synthesized from gaseous vinylidene fluoride monomer by a free-radical polymerization process. It is also resistant to abrasion. This material has excellent chemical resistance that makes it suitable for handling reactive liquids and gaseous substances such as sulfuric acid, hydrochloric acid, nitric acid, hydrocarbons, fuels, and solvents that are aromatic, aliphatic, and halogenated in nature. It is used as a material for ball valves in industries such as water purification, wastewater treatment, and in food and pharmaceutical processing because of its good biofouling properties that is resistant to the growth of microbial films. It also remains unaffected by exposure to sunlight and UV. The maximum operating temperature of PVDF is around 115°C.

Polyethylene (PE)
PE is a durable, flexible, lightweight, and the most abundant thermoplastic. PE is compatible with most compounds, including strong acids and bases, and to some organic compounds including oils and alcohols. Its increasing crystallinity and density makes it more chemical resistant. PE ball valves are used in handling fluids in many manufacturing processes, as well as in water purification and wastewater treatment. The maximum operating temperature of PVDF is around 60°C.

Polyethylene Ball Valve

The seat is made from a softer material, such as an elastomeric material or plastic, for better sealing with the ball. A qualified seat material must also possess the following characteristics:

A low coefficient of friction
High compression strength
Creep resistance
High corrosion and chemical resistance
Compatibility with the flowing media

Examples of seat materials for ball valves are:

Polytetrafluoroethylene (PTFE), or also known as Teflon TM
TFM
Polyamide (Nylon)
Polyether ether ketone (PEEK)
UHMW Polyethylene
Acetal
A metal-seated ball valve has the ability to withstand higher temperatures and hydraulic pressures. They can handle more abrasive and corrosive fluids better.

Chapter 5: Advantages and Limitations of Ball Valves
The benefits of using a ball valve are the following:

Ball valves induce a low pressure drop compared to other types of valves since the flow has minimal restrictions. In liquids, a high pressure drop across a valve may result in turbulence and cavitation. Cavitation happens when the liquid pressure falls below the critical pressure, the vapor phase of the liquid is formed. As the pressure recovers, the bubbles collapse which damages the valve.
Since it only requires a one-quarter turn to fully shut off or open, the ball valves immediately restrict or allow flow. This advantage is important for controlling the liquid level of a tank or a reservoir.
A small amount of torque or a small actuator is needed to rotate the ball valve.
Lubrication is unnecessary because of the surface properties of the seats.
Ball valves offer a reduced chance of leakage because the ball seals tightly against the seats. The sealing action is done by fluid pressure.
Several ball valve designs are available to satisfy a specific application. Some ball valve designs feature pressure relief, variable flow rate control, flow splitting, and mixing, etc.
Ball valves are relatively cheaper.
There are several limitations the user must remember to preserve the functionality of the ball valve:

Throttling is possible in ball valves, but it should be sustained for a long time. When the ball valve is in a throttling position, the seats are exposed to the high-velocity fluid flow and more compressive force, which causes erosion. Therefore, it is not advisable for throttling applications. Standard ball valves may be used in throttling low pressure gases. Segmented ball valves may be used in limited throttling applications. However, advanced ball valves with modified designs or seats made from engineered materials that are suitable for throttling applications are commercially available.
Application is limited by the maximum allowable working temperature of the seats. For higher temperatures, metal or ceramic seats are an alternative.
Suspended particles may build up between the body and ball, causing leakage, erosion, and valve failure. Hence, it is advised to do frequent maintenance on ball valves handling slurries and suspensions.
Conclusion
Ball valves are shut-off valves used to allow or obstruct the flow of fluids by rotating the ball having a bore inside it by 900. They can be operated manually or by an actuator.
Ball valves consist of the ball, shaft, and seat which are contained in the valve housing. The ball is placed between two seats and has a stem that connects it to the operating mechanism.
Types of ball valves are classified according to their housing assembly, ball design, and bore profile. Ball valves come in many designs and features to satisfy the needs of a specific industry.
As the housing is divided into many pieces, the cleaning and maintenance of the ball valves get easier but more expensive to acquire.
There are different types of ball design to select from, depending on the working pressure it will be installed to.
A smaller bore diameter has a larger pressure drop across the valve, which makes pumping difficult and more expensive. The ball may have a multiport bore which can be used for splitting and combining flow rates and diverting flow directions.
The material for ball valves must be hard, tough, and rigid. The seats must have a low coefficient of friction, high compressive strength, and compatibility with the working fluid. However, the application of ball valves is limited by the working temperature of the seats.
Ball valves are easy to operate and activated and offer minimal risk to leakage.
Throttling is not advisable for ball valves.
Proper maintenance must be done to avoid particle build-up between the ball and the body.
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Which is better gate valve or ball valve

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In real life, there are many valve products, but the most common valves are ball valves and gate valves, which are also used the most. However, for people who buy ball valves and gate valves, we will know what kind of use and function they have, as well as the difference between them, and how to choose high-quality ball valves and gate valves before buying. To this end, we have summarized some knowledge about ball valves and gate valves. Let me tell you Which is better gate valve or ball valve?

Which is better ball valve or gate valve

Because both gate valve and ball valve can be used after the regulating valve, the functions they undertake are basically similar. They are only different in structure, so users often have questions about whether to choose gate valve or ball valve. This is exactly what this article will discuss today. Before starting the problem, we should first make it clear that there is no better concept of which product is better for the gate valve or ball valve installed before and after the regulating valve. Only the more suitable one can be selected according to the actual situation of the user and the working conditions. Let’s first briefly understand the characteristics of gate valve and ball valve.

Functionally, the gate valve can be installed before and after the regulating valve, which is mainly used for water supply and hot water pipeline, commonly known as water valve. Generally, it is not used on the steam pipeline. The reason is that when the steam pressure is high, the ram is difficult to open under pressure. At the same time, it is not suitable to be used on the pipeline with sediment. Because the sediment is deposited in the ram seating groove, the RAM will not be closed tightly. The opening and closing part of the gate valve is the gate, and the movement direction of the gate is perpendicular to the fluid direction. The gate valve can only be fully opened and closed, not adjusted and throttled. The ball valve can also be installed before and after the regulating valve. It is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. It has the same action of rotating 90 degrees. The difference is that the cock body is a sphere with a circular through hole or channel passing through its axis.

From the point of view of advantages, the more prominent advantages of gate valve are small resistance, short size and low price. The relative advantage of ball valve is that its fluid control characteristics are better than gate valve. It only needs to rotate 90 degrees and a small rotating torque to close tightly. Ball valve is most suitable for switch and shut-off valve.
From the above, we can see that both gate valve and ball valve can be used before and after the regulating valve. These two valves are not suitable for flow control. However, the fluid control characteristics of ball valve are better than gate valve, and the tightness is also better than gate valve. However, in the actual installation case, although the gate valve and ball valve are installed before and after the regulating valve, the gate valve is more selected by the user. Why? The details are as follows:

1. The ball valve is troublesome to open and close, and has high requirements for the sealing surface. The sealing of the ball valve has strict requirements on the production and processing process. If the right manufacturer is not selected, it is easy for the technology to fail to meet the requirements, resulting in internal leakage of the ball valve. Therefore, the cost is relatively high, especially the large-diameter ball valve. The gate valve has the advantages of low procurement cost, good sealing effect, labor-saving switching, and can provide the maximum overflow channel without resistance when the gate valve is fully open.
2. If the ball valve is in a static state for a long time, it will be stuck after being used for a period of time.
3. Ball valve has higher requirements for medium than gate valve. For example, ball valves can only be used for media containing more fiber and oxygen.

To sum up, the main differences between ball valve and gate valve lie in the differences in valve core, valve seat, stroke, actuator, medium flow direction, maintenance, etc. in general, it is better to install gate valve or ball valve before and after the control valve. Considering the economy, use gate valve, which is much cheaper. Or gate valves are selected for large-diameter and low-pressure oil, steam and water pipelines. Considering the tightness, the ball valve is used. The ball valve is suitable for working conditions, has high leakage level requirements, is suitable for rapid opening and closing, and its quality life is better than that of the gate valve.

Speak to one of STV’s knowledgeable advisers about your ball valve requirements today by calling 15157766245 or email [email protected].

FAQ

Can I use a ball valve instead of a gate valve?

Therefore, ball valves are better suited for applications like natural gas where a proper seal long-term is important. … However, for high pressure applications a gate valve is better suited. This is due to the fast opening/closing of the ball valve that may cause a water hammer.

When would you use a gate valve?

Gate valves are used when a straight-line flow of fluid and minimum flow restriction are needed. Gate valves use a sliding plate within the valve body to stop, limit, or permit full flow of fluids through the valve. The gate is usually wedge-shaped.

What is the best type of valve?

Ball valves are perhaps the most reliable type of valve and are commonly used for main water shutoffs and for branch line shutoffs. Like gate valves, a ball valve is designed as an all-or-nothing valve—they should be either fully open to allow full flow, or fully closed to stop all water flow.

How to install the Stainless steel sight glass?

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Flange sight glass and wafer  sight glass I think that is to say this kind of commodity. The standard name of the Ministry of chemical industry is high-pressure vessel flange sight glass. Due to the structure, that is, a whole piece of laminated glass is sandwiched between the two tablet flanges, which is called tablet flange sight glass by many people; Because the laminated glass is fixed by the two flanges, it is also called the clamp flange sight glass.
1、 Principle of flange sight glass and relevant professional knowledge
The installation specification is small, the driver torque is small, the actual operation is simple and fast, and it also has the characteristics of excellent total flow adjustment and closing sealing. This is the core flange sight glass mode in the application industry of large and medium specifications and low and medium working pressure.
Main application: the flange mirror can be used in the tower of chemical plant with high temperature, strong corrosion, easy poisoning, great risk factors and easy crystal formation, so as to ensure its production a complete. Structure: the flange mirror is mainly composed of flange mirror base plate, flange mirror laminated glass, gate valve components, etc.
2、 Frequently asked questions
(1) change the material of flange gasket.
The PTFE plate with corrosion resistance and heat resistance shall be applied. During installation, the raised surface and sealing gasket shall be solved to carry out appearance inspection, and there shall be no defects such as axial pipe groove and scratch. The rubber sealing gasket shall be installed and leveled, the position shall be accurate, there shall be no inclination or deviation of management center, and the touch shall be excellent, which exceeds the application regulations.
(2) improve the management method of production process index value.
Strictly control the exhaust temperature of the pre distillation tower at 120 ℃, the working pressure of 1.765mpa, the exhaust temperature of the primary absorption tower ≤ 46 ℃, and the working pressure of 1.765mpa to avoid overheating and overpressure.
Sight glass refers to a device used to observe the materials inside containers and equipment. It is a complete accessory and should be inspected regularly. According to the shape, it is divided into circular and rectangular mirrors. According to the purpose, it is divided into peeping and lighting mirrors. According to the structure, it is divided into mirrors with lining and without lining, with neck, with cover, double-layer a full, thermal insulation, with scraper, with flushing device and mirrors suitable for powdery materials.

Sight glass for the petroleum, chemical industry, chemical fiber, medicine, food and other industrial production equipment, to facilitate odservation of any meterial inside the device operating conditions.

316 flange sight glass is our common type sight glass/ flow indicator, double windows can help monitoring clearly.Suitable for a variety of environments, wide range of use.

Body Glass Material Seal Material Working Temperature Operating Pressure Connection Type
Carbon Steel Tempered Borosilicate Glass NBR

PTFE

 -10ºC~250ºC 0.6~2.5Mpa Thread End
SS304 Quartz Glass -30ºC~800ºC 0.6~1.0Mpa Flange End
SS316
FPR Soda Lime Glass 0ºC~80ºC 0.6~1.0Mpa Weld End

STV Valve Technology Group Co., Ltd is a professional Stainless steel sight glass manufacturer, specializes in producing straight through  sight glass,Flange Stainless steel sight , floating,Ball type Stainless steel sight glass and water flow indicator.

What is the different Globe and Gate valves

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Globe Valve vs gate valve

 

 

 

 

 

 

 

 

 

Globe valve, gate valve, butterfly valve, check valve and ball valve are indispensable control components in various pipeline systems. Each valve is different in appearance, structure and even functional use. However, the globe valve and gate valve have some similarities in appearance, and both have the function of cutting off in the pipeline. Therefore, many friends who have little contact with the valve will confuse the two. In fact, if you observe carefully, the difference between stop valve and gate valve is quite big. This article introduces the difference between globe valve and gate valve.

Difference in structure

When the installation space is limited, attention should be paid to the selection. The gate valve can be tightly closed with the sealing surface by medium pressure, so as to achieve the effect of no leakage. When opening and closing, the sealing surface of the valve core and the valve seat always contact and rub against each other, so the sealing surface is easy to wear. When the gate valve is close to closing, the pressure difference between the front and rear of the pipeline is large, making the wear of the sealing surface more serious.
The structure of the gate valve will be more complex than the globe valve. From the appearance, in the case of the same diameter, the gate valve is higher than the globe valve, and the globe valve is longer than the gate valve. In addition, the gate valve can be divided into exposed rod and concealed rod. The globe valve is not.

Difference Working principle

When the globe valve is opened and closed, it is a rising stem type, that is, rotate the handwheel, and the handwheel will rotate and rise and fall with the valve stem. The gate valve rotates the hand wheel to make the valve stem rise and fall, and the position of the hand wheel itself remains unchanged. The flow is different. The gate valve is required to be fully open or fully closed, while the globe valve is not required. The globe valve has specified inlet and outlet directions; The gate valve has no inlet and outlet direction requirements.
In addition, the gate valve is only fully open or fully closed. The opening and closing stroke of the gate valve is large and the opening and closing time is long. The movement stroke of the valve plate of the globe valve is much smaller, and the valve plate of the stop valve can stop at a certain place during movement for flow regulation. The gate valve can only be used for cut-off without other functions.

Different functions

The globe valve can be used for both cut-off and flow regulation. The fluid resistance of the globe valve is relatively large and the opening and closing is laborious, but the opening and closing stroke is short because the distance between the valve plate and the sealing surface is short.
Because the gate valve can only be fully opened and fully closed, when it is fully opened, the medium flow resistance in the valve body channel is almost 0, so the opening and closing of the gate valve is very labor-saving, but the gate is far from the sealing surface and the opening and closing time is long.

Difference Installation and flow direction

The effect of gate valve flow direction is the same in both directions. There is no requirement for inlet and outlet direction during installation, and the medium can flow in both directions. The stop valve needs to be installed in strict accordance with the direction marked by the arrow of the valve body. There is also a written provision on the inlet and outlet direction of the stop valve. The “three modernizations” of valves in China stipulates that the flow direction of the stop valve shall be from top to bottom.

The globe valve is low in and high out. From the appearance, it is obvious that the pipeline is not on the same phase horizontal line. The gate valve flow path is on a horizontal line. The stroke of the gate valve is larger than that of the globe valve.

When you need to purchase gate valve or globe valves, contact our team at STV Valve Technology Group Co., Ltd. We’ve been proudly manufacturing gate valves and globe valve since 2008 and offer solutions for all your custom and standard valve needs. We manufacture everything right here in the china for exceptional quality control and fast delivery. Call us today at (86) 15157766245 to request a quote for our high performance valve.

what’s the Check valve opening pressure?

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Check valve refers to the valve that automatically opens and closes the valve disc depending on the flow of the medium itself to prevent the backflow of the medium, also known as check valve, one-way valve, reverse flow valve and back pressure valve. The check valve belongs to an automatic valve, which is mainly used to prevent medium backflow, reverse rotation of pump and driving motor, and discharge of container medium,if the opening pressure is too high, the system of our swing check valve may be overpressured, so the pressure in front of the check valve must be guaranteed.

What is the opening pressure of general swing check valve?

1.The pressure of swing opening has nothing to do with the size of the valve. It depends on the place of use of the valve.

2.The pressure drop of swing check valve is related to horizontal installation and vertical installation. If it is vertical installation, the pressure drop is equivalent to two elbows. If it is horizontal installation, the pressure drop is equivalent to the pressure generated by the weight of two elbows + disc of swing check valve.

3.The starting pressure of the swing check valve without spring is related to the thickness of the check plate. The thicker it is, the heavier it is. The greater the pressure difference before and after it can be opened

4.The starting pressure of swing check valve with spring is not only related to the thickness of check plate, but also related to spring.

 

The minimum upstream pressure required to operate the valve is called the cracking pressure, generally between 1 and 5 psi. Check valves are designed specifically with this number in mind. The degree of opening on a check valve is determined by the flow rate.

There is no problem using 2.5MPa swing check valve for 0.4MPa fluid

Generally, the used high-pressure pipes of check valves are within 5kg.

 

 

 

 

 

 

 

 

 

 

 

In need of assistance in selecting a check valve with a specific opening pressure? The experts at STV VA;VE have the knowledge and experience to help. Shop stvvalves.com today!

What is the cracking pressure of a check valve

FAQ

Do check valves have different pressures?

It also helps ensure the check valve and the application perform as expected. Sizing check valves is different from sizing many other types of flow control and shutoff valves. … The good news is that spring loaded or spring assist check valves are designed with a wide range of very specific cracking pressures.

What is valve opening pressure?

The set pressure, also called the opening pressure, of a safety or relief valve is the inlet pressure at which the valve begins to open as required by code.

What is a low pressure check valve?

A specialty diaphragm check valve that opens with virtually no forward pressure. In this position the sealing disc is supported internally allowing the valve to operate under high flow conditions with relatively no force or stress on the disc.

What is valve opening pressure?

The set pressure, also called the opening pressure, of a safety or relief valve is the inlet pressure at which the valve begins to open as required by code.

Does a check valve need pressure?

A check valve requires a minimum upstream pressure (pressure differential between inlet and outlet) to open the valve and allow flow through it. This minimum upstream pressure at which the valve opening occurs is called the check valve ‘cracking pressure’

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