Types of Valves

 

What is a Valve ?

A valve is a device that regulates, controls, or directs the flow of a fluid by opening, closing, or partially obstructing fluid flow. A valve is a mechanical device that controls the flow and pressure of fluid within a system or process.  So basically, it controls flow & pressure. A valve is device that regulates, controls, or directs the flow of fluid by opening, closing, or partially obstructing flow. In simple words, a valve is a mechanical device that controls the flow of pressure of fluid within a system or process. Valves serves a variety of purposes in industrial, engineering, manufacturing and scientific communities. Selecting right type of valve can determine success or failure of system or process. Valves have a wide application in pipelines, Oil and gas industry, food and beverage industry. Valves are for starting or stopping flow, regulating or throttling flow, preventing back flow or relieving and regulating pressure in fluid or gaseous handling applications.

Valves provide several functions, including:

• Starting or stopping flow based on the valve state

• Regulating flow and pressure within a piping system

• Controlling the direction of flow within a piping system

• Throttling flow rates within a piping system

• Improving safety through relieving pressure or vacuum in a piping system

Most valves fit into one of three categories:

• Multi-Turn valves: Think of these valves like a screw or piston. You crank the handle and the plug, plate, membrane, or other controlling obstruction moves into the path of the pipe blocking access. Depending on the valve, these can have higher or lower differentials allowing you to open or close them at various speeds.

• Quarter turn valves: Quarter-turn valves offer a full range of motion in a 90-degree turn of the handle. This makes them ideal for situations where precision isn’t as important as rapid action and easy opening or closing.

On top of the mechanical motion involved with a valve, also consider the method of actuation. In most cases, valves fall into one of three categories:

• Manual Valves: Typically adjusted by hand, these valves use handwheels, hand levels, gear wheels, or chains to actuate.

• Actuated Valves: Often connected to electric motors, air or pneumatic systems, hydraulic systems, or solenoids, these valves allow remote control and automation for high-precision or large-scale applications.

• Automatic Valves: Some valves activate when a specific flow condition is met. Examples include check valves closing during backflow or pressure release valves activating when an over-pressure condition is detected.

How are valves classified?                                                                    

 The valves are classified on the basis of type of mechanical motion:

Linear motion valve: Valves in which closure member moves in a straight line to allow, stop or throttle the flow are called linear motion valve.

Rotary motion valve: When valve closure member travels along an angular or circular path are called rotary motion.

Quarter turn valves: Some rotatory valves require approximately a quarter turn, 0 to 90 degrees, motion of stem to go to fully open or fully closed position or vice versa.

Valve types	Linear motion	Rotary motion	Quarter turn
Gate Valve	Yes
Globe Valve	Yes
Plug Valve		Yes	Yes
Ball Valve		Yes	Yes
Butterfly Valve		Yes	Yes
Diaphragm Valve	Yes
Pinch Valve	Yes

What is the importance of valves?

During the design of a piping system regardless of operating pressure, temperature and the type of fluid being processed inside the system (these factors are confined with their own rules and specifications), valves are generally bought from a certified supplier and installed accordingly. Different types of valves are employed in different industries so as to get a steady flow. Industrials like oil and gas, chemical industry cannot survive without valves as smooth, steady flow of raw material and particulate matter. Just like we have ON/Off switch and regulators installed at our homes, valves serve similar purpose in different industries.

Life of Valves

Life of valves is dependent on 3 factors:

1. Seal integrity -

Valve is useful as long as the seals function perfectly. If seal selection is wrong, the valve coming to service is too frequent, or worse, could fail the valve itself. The right seal will ensure optimal period between maintenance.

Metal seals last long(0.5-3 years). Next comes PTFE(0.5-2 years). Least are rubber seals(~1 year)

2. Environment -

Media being handled. Type of climate. Temperature. Pressure of media. These factors are taken into account while selecting the right material for valve body, disc/ball, and hardware.

Right material can ensure a really long life of the valve.

3. Duty factor -

Or simply, how often do you operate the valve? Frequent operation like in control duty can have maintenance period of less than 3 months. On-off duty with operation less than 30/month could give u a seal life of 12 months or more.

 Types of Valves used in Industries

1) BALL VALVES

A Ball valve is a quarter-turn rotary motion valve that uses a ball-shaped disk to stop or start the flow. Most ball valves are of the quick-acting type, which requires a 90° turn of the valve handle to operate the valve. The ball valve is Smaller and lighter than a gate valve of the same size and rating.

Ball valve is a quarter-turn rotary motion valve that uses a ball-shaped disk to stop or start the flow. It resembles a plug valve in many ways. When a port in the ball is in line, it allows flow whereas when you rotate the valve 90 degrees, solid part of the ball stop the flow.

Important Factors

Efficiency: The ball valves are used for controlling the flow of different states of substances like gas, liquid, semi-liquid. One of the biggest advantages of ball valves is that they can be operated at both very high and low temperatures. Ball valves also have an excellent sealing making them an ideal choice for controlling gaseous flow.

Typical operating temperatures: -55°C to 300°C

Factors affecting lifespan: 

• Media with suspended particulates that are abrasive in nature can cause the valve seals to fail prematurely.

• With an actuated ball valve, the valve seals are almost always the first component to fail, usually in the form of a leak either from the stem seal or seats noted by downstream leakage when the valve is in the off position. For this reason, it is common to attempt to repair the valve by replacing the soft seals. 

• There is more than one way to power a ball valve. Manual ball valves are controlled by turning a lever or handle on top of the valve. Since these valves must be powered by an operator, they are not the right choice for high-cycle applications or for valves located in hard-to-reach places. 

Market Overview

The Ball Valve Market was valued at USD 11.68 billion in 2020 and is expected to reach USD 13.93 billion by 2026, registering a CAGR of 3% during the forecast period (2021 - 2026). A global increase in the demand for oil and gas is expected to be one of the major factors contributing to the ball valve market growth.

Applications

•          Ball valves are excellent in chemical applications, including the most challenging services (e.g. dry chlorine, hydrofluoric acid, oxygen).

•   General sizes available are 1/2" to 12".

•     Compliant with ASME is the flange rating, either 150, 300, 600, 900# or occasionally higher classes, enabling high performance ball valves to withstand up to 2250 psi.

•       The operating temperature which is primarily dependent on seats and seals may be rated as high as 550°F.

2) CHECK VALVE 

A check valve is basically a one-way valve, in which the flow can run freely one way, but if the flow turns the valve will close to protect the piping, other valves, pumps etc. If the flow turns and no check valve is installed, water hammer can occur. These valves are activated by the flowing material in the pipeline. The pressure of the fluid passing through the system opens the valve, while any reversal of flow will close the valve. A check valve relies on a pressure differential to work. They require a higher pressure on the input side of the valve than the output side to open the valve. When the pressure is higher on the outlet side (or the input side pressure is not high enough), the valve will close.

Important Factors

 MAINTENANCE COSTS: It is usually safe to say that the more moving parts in a valve, the greater the need for maintenance. A simple Lift Check Valve can provide service for decades without maintenance because the disc stem slides through permanently lubricated bearings. Lift Check Valve springs are typically proof of design tested to at least 50,000 cycles and can last far longer.

Operating Temperature: -18°C to 540°C

Market Overview

Industry check valves market value to grow by USD 2.5 billion at over 4% CAGR during 2021-2025 .34% of market growth to originate from APAC during the forecast period

Based on the end-user, the oil and gas segment will offer maximum opportunities for vendors during the forecast period. The industry check valves market is expected to have a neutral impact due to the spread of COVID-19

Applications

•       Check valves are used in a variety of markets and applications as they contain simple design and versatile material options.

•    They help to prevent backflow and maintain pressure.

•   Check valves can be seen in industries such as refining, petrochemical, chemical, oilfield production, water, steam, refining petrol, and viscous fluids.

3)GATE VALVES

Gate Valves are designed to serve as isolation valves.  These valves help to control the flow of liquid through the pipes. To start or stop the water flow or any other kind of liquid, these valves are affixed to the pipelines. Gate valves are used to either halt or start the flow of water. Functioning of gate valves includes the lifting of a circular of the rectangular gate out of the fluid path. When gate valves are open, there will be nothing to obstruct the flow as the pipeline diameter and gate have the same opening. The valve size can be determined with this bore diameter.

Important Factors

Minimal erosion: In comparison to other valve options, gate valves typically experience less erosion on their sealing surface when they are fully open. This minimal erosion is largely attributed to the valve’s tight seal functioning.

Energy-efficiency: Gate valves are an energy-efficient valve option, as the movement direction or ram is perpendicular to the media flow direction. As a result, less power is consumed when opening or closing the gate valves in comparison to globe valves.

Operating Temperature:  -272°C to 675°C

Lifespan:  The average valves would last about 25-years.

Market Overview

Rapid Industrialization is Augmenting the Demand for Industrial Valves gate valves find foremost application in oil & gas, mining, pulp & paper and chemical industries. As the industrialization is rising across all regions, especially in emerging economies such as India, Brazil, China and others, the demand for knife gate valve is expected to rise in upcoming years. Rapid growth in industries such as water & wastewater treatment, oil & gas, chemical and petrochemical, where liquid handling is essential, the demand for valves is intensely high and this is a major driving factor behind rising consumption of knife gate valves across the globe. 

Applications

•    Gate valves are suitable to use in high temperature and pressure conditions.
•    They are used for on-off applications

4)GLOBE VALVES

Globe Valves are among the most popular type of valves used in various applications. These valves are similar to gate valves and use linear motion to throttle flow. They are used to control the flow in a pipeline and they regulate by the position of a movable disk in relation to the stationary ring seat. Globe valves are composed of a baffle that splits the inside of the pipe, which is typically parallel to the pipe's length. They are named for their spherical body shape with the two halves of the body being separated by an internal baffle. It consists of a movable disk-type element and a stationary ring seat in a generally spherical body.

Important Factors

Efficiency: The friction between the parts in globe valves is lesser compared to other types making them ideal for frequent usage. Also, the globe valves are made up of durable material contributing to their sturdiness. Good shutoff capability, Less friction between sealing surfaces and longer life span.

Operating Temperature: -272°C to 540°C

Market Overview

The Global Industrial Valves Market stood at around $66 billion in 2019, and is forecast to surpass $84 billion by 2025, on account of extensive use of industrial valves in oil & gas and power industries.

Applications

Global valves are used primarily for throttling purposes. They may be considered as general-purpose flow control valves that are used for high-temperature applications. 

5) BUTTERFLY VALVES

Butterfly Valves are designed to regulate flow, but with limited control capability. Butterfly valves are easily operated by rotating a handle 90 degrees. It consists of a metal disc in the body of the valve which is positioned perpendicular to the flow in the closed position. Regulation of liquid flow can be allowed through intermediate rotations. Butterfly valves are configured to operate electronically, manually or pneumatically.

Important Factors 

Efficiency: One big benefit of using a butterfly valve is that it can be operated both mechanically and electronically. Butterfly valves are efficient compared to the traditional types of valves. In addition to that, butterfly valves are easier to install and maintain. They are frequently used in water management and food processing industry.

Operating Temperature: -30°C to 538°C

Market Overview

The global butterfly valve market is envisioned to receive impetus due to increasing focus on the development of smart cities, high demand for energy, and advancement of oil and gas production facilities. The global butterfly valve market could be classified as per product and end user. 

Applications

• Butterfly valves can be used in pharmaceutical, chemical, and food processing services.
• They are used for corrosive liquids at low temp and pressure.

TO SEE THE WORKING OF DIFFERENT VALVES YOU CAN VISIT THE FOLLOWING LINKS:

Working of globe Valve: https://youtu.be/qLSl9ZGIl0A

Working of gate valve: https://youtu.be/zoOB_NDr0io

Working of ball valve: https://youtu.be/RvD1R8Tlr9M 

Working of Butterfly valve: https://youtu.be/zhi7_YQZhOs

  

REFERENCES 

Refer following sites for more information:

• Processing magazine, George Packard, 5 factors that impact the lifespan of ball valves, Apr 22nd, 2021, Available at: https://www.processingmagazine.com/valves-actuators/article/21216968/5-factors-that-impact-the-lifespan-of-your-ball-valves 

• Engineering ToolBox, (2003). Valves - Typical Operating Temperatures. [online] Available at: https://www.engineeringtoolbox.com/valves-operating-temperatures-d_222.html [Accessed Day Mo. Year].

• Chakradhara Raju A, studied at University Visvesvaraya College of Engineering,      https://www.quora.com/Does-the-life-span-of-industrially-used-valves-ball-valve-globe-valve-etc-depend-on-the-number-of-times-theyre-open-closed

• Efficiencies of Industrial Valves, August 6, 2019, https://industrytoday.com/efficiencies-of-industrial-valves/

•   https://www.thomasnet.com/articles/pumps-valves-accessories/types-of-valves/

• https://hardhatengineer.com/different-types-valves-used-piping/

• https://www.valmatic.com/Portals/0/pdfs/DesignSelectionCheckValves.pdf

• https://www.tigervalve.com/advantages-of-using-an-industrial-gate-valve#:~:text=Gate%20valves%20are%20an%20energy,help%20reduce%20total%20ownership%20cost.

•       https://chemicalengineeringworld.com/different-types-of-valves/

           

PUBLISHED BY   

ROHAN BEDKE, VAISHNAVI BIRADAR, MD MUZZAMMIL HUSSAIN, IMRAN AHMAD, MANOJ JADHAV.

STUDENTS, DEPARTMENT OF CHEMICAL ENGINEERING AND TECHNOLOGY, VIT, PUNE