Types of Valves and Applications

Question 1

What is a globe valve and its application?

Answer 1

A globe valve is a linear motion valve and are primarily designed to stop, start and regulate flow. Globe valves can be used to control cooling water systems, fuel oil systems, high-point vents and low-point drains when leak tightness and safety are major considerations, feed water, chemical feed, condenser air extraction, extraction drain systems, boiler vents, drains, main steam vents drains, heater drains, turbine seals and drains, and turbine lube oil systems.

Question 2

What are the three basic globe valve body designs?

Answer 2

Tee, angle, and wye.

Question 3

What is a globe-tee valve and its application?

Answer 3

This is the most common body type for a globe valve. The horizontal setting of the seat allows the stem and disk to travel perpendicular to the horizontal line. This design has the lowest coefficient of flow and highest pressure drop. They’re used in severe throttling services, such as in bypass lines around a control valve. When pressure drop is not a concern and throttling is required, this globe valve design is a good solution.

Question 4

What is a globe-angle valve and its application?

Answer 4

The ends of this globe valve are at a 90° angle allowing fluid to flow in a single 90° turn. This valve is used for applications that have periods of pulsating flow because of their ability to handle “the slugging effect” which naturally occurs with a pulsating flow.

Question 5

What is a globe-wye valve and its application?

Answer 5

This type is an alternative for the high pressure drop commonly found in globe valves. The seat and stem are at a 45° angle which provides a straighter flow path when fully open and offers the least resistance of flow. This design is commonly used for throttling during seasonal or start-up operations.

Question 6

What is a plug valve and its application?

Answer 6

A plug valve is a quarter-turn manual valve that uses a cylindrical or tapered plug to permit or prevent straight through flow through the body. The plug has a straight through full port opening. Plug valve can be used in on-off, basic moderate throttling, and diverting services. They are commonly used in low-pressure-low-temperature services, although some high-pressure-high-temperature designs also exists. They can be used for steam, water, oil, gas, and chemical liquid services.

Question 7

What are the three main types of plug valves?

Answer 7

Lubricated, non-lubricated, and soft-sealed/fire safe.

Question 8

What is a lubricated plug valve and its application?

Answer 8

Uses a lubricant usually made up of a base oil and viscosity improver that is injected under pressure between the plug face and body seat to reduce friction and seal ports. They can be used in processes that use fluids that carry mildly abrasive particles such as dirty upstream applications, gas pipeline systems that need bypass valves, and as blow-down valves on valve stations.

Question 9

What is a non-lubricated plug valve and its application?

Answer 9

It is a tapered or cone-shape that acts as a wedge and presses a polymeric sleeve against the body cavity. The use of the sleeve reduces friction between the plug mechanism and body. In addition, they are limited to temperature and compatibility of the non-metallic materials they are made of. It is preferred in applications where maintenance needs to be kept to a minimum. Examples include the following: special services in sulphur, hydrogen fluoride, or where liquids could be trapped or solidify and potentially jam the valve.

Question 10

What is a soft-sealed/fire safe plug valve and its application?

Answer 10

These valves use a combination of a floating ball, graphoil seals and metal-to-metal seating to provide tight shut-off while preventing external stem leakage. In normal working conditions, the ball rests against two seats, ensuring bubble-tight closure.They are often used in corrosive, highly toxic, highly hazardous and other harsh environment, including occasions that strictly prohibit leakage, as well as occasions where sanitary valve materials won’t pollute the medium. They are also used to prevent the flow of flammable liquids and gases.

Question 11

What is a needle valve and its application?

Answer 11

This type of valve uses a needle to regulate flow and it is very precise. It is commonly used in engines, such as central heating systems and automatic carburetors, water treatment and distribution, dams, reservoirs, power plants and industry needle valves are used for: flow control, pressure regulation, pump start, turbine by-pass, discharge, reservoir inlets, and air regulation.

Question 12

What is a gate valve and its application?

Answer 12

A gate valve is where a gate raises or lowers to regulate flow. It is kept either fully closed or open. It is not suitable for partial flow control. They can be used in any process plant, potable water, wastewater, neutral liquids, and gas.

Question 13

What are the three main types of gate valves?

Answer 13

Wedge, double-disc, and conduit.

Question 14

What is a wedge-type gate valve and its application?

Answer 14

It is a gate that is allowed to flex as the valve seat compresses due to thermal expansion of steam pipeline and prevent thermal blinding. They are used to regulate high flow or turbulent applications such as steam service.

Question 15

What is a double-disc type gate valve and its application?

Answer 15

This type of gate valve is operated by an electric actuator has parallel seats against which the wedge is driven when the gate is closes. This results in a tight seal between the disc and the seat. They are not used under low pressure limitations. It is commonly used to regulate steam.

Question 16

What is a conduit type gate valve and its application?

Answer 16

This type of gate valve is designed and manufactured with the rising stem to accommodate the floating movement of the gate. They are commonly used to regulate the flow of gas and oil.

Question 17

What is a ball valve and its application?

Answer 17

A ball valve is where a ball that has a hollow core, operates in the center of the valve body. When the hole is parallel to the pipe there is flow. When the hole is perpendicular to the pipe, there is no flow. Common applications include: the control of flow of corrosive fluids, 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.

Question 18

What are the main types of ball valves?

Answer 18

Full port, standard port, reduced port, and v port.

Question 19

What is a full port ball valve and its application?

Answer 19

Full port valves, also known as full bore valves, have no restriction of flow from the original pipe diameter. That means the full port valve will maintain a consistent flow rate. They can be used to regulate flow of both solids and liquids. They are commonly used when pressure drop is a concern.

Question 20

What is a standard port ball valve and its application?

Answer 20

Standard-port ball valves are used where pressure drop, turbulence in the flow and material characteristics are not a concern. They also have the advantages of smaller size and lower cost. They produce a larger pressure drop when it is fully open; it is typically used for regulating flow to a coil.

Question 21

What is a reduced port ball valve and its application?

Answer 21

It is a valve in which the bore is reduced to one or two nominal sizes lower. This provides a more restricted flow path, generally resulting in higher energy losses. They are used where pressure drop, turbulence in the flow and material characteristics are not a concern.

Question 22

What is a v-shaped ball valve and its application?

Answer 22

A V-port ball valve has either a “V” shaped ball or a “V” shaped seat. This type of valve also is known as a control valve in which the flow velocities need to be controlled / regulated as required per the application.

Question 23

What is a control valve and its application?

Answer 23

A valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller. This enables the direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and liquid level.

Question 24

What is a pinch valve and its application?

Answer 24

This valve comprises of a flexible elastomer body that obstructs the flow of media through the pinching mechanism of the rubber sleeve, which is the main working element. The rubber sleeve is pinched closed either by the application of fluid pressure or mechanically in the body. It can be used to regulate flow of food and beverage, pharmaceuticals, cements, waste water treatment, and several others, mainly because it offers pressurized cleaning and movement of the flowing media.

Question 25

What is butterfly valve and its application?

Answer 25

This type of valve is a quarter-turn rotational motion valve, that is used to stop, regulate, and start flow. When the butterfly valve is fully closed, the disk completely blocks the line. When it is fully opened, the disc is at a right angle to the flow of gas or liquid.

Question 26

What is a high performance butterfly valve?

Answer 26

This type of butterfly valve is a reliable for handling high temperature and high-pressure situations, and when superior adjustable stem packing is needed to control stem leakage or emissions. These are for temperatures of up to 1200 degrees F and pressures of up to 1440 psig(150-600# ANSI). They are used in oil refineries, high-pressure steam and offshore applications where more extreme conditions exist, and a much higher reliable performance, and/or higher cycle life is required.

Question 27

What are the three different seat types of butterfly valves?

Answer 27

Rubber-lined, plastic-lined, and metal.