VALVES

valve A Valve may be defined as a mechanical device by A Valve may be defined as a mechanical device by

which the which the

flow of liquid or gas may be started, stopped or regulated flow of liquid or gas may be started, stopped or regulated by a movable by a movable

part that opens, shuts or partially obstructs one or more part that opens, shuts or partially obstructs one or more ports or ports or

passageways.passageways.

What does a valve do ?A Valve may be designed to direct, start, stop,

mix or

regulate the flow, pressure, or temperature of a process fluid.

A Valve by nature of their design and materials can :

1)Open and Close2)Turn on and off3)Regulate4)Isolate

Extremely large array of liquids and gases

range size of valves

A Valve may range in size from a fraction of an inch to 9mtr in diameter.

range of pressure and temperature handled

A Valve can handle pressures ranging from vacuum to more than 140 MPA/m2 and temperatures from the cryogenic region to 815 Deg Celcius

materials used for valves

In most cases the required body material is the same as

the pipe material which may be Carbon Steel, Stainless Steel or

Chrome- Molybdenum Steel ( Commonly called Chrome Molly )

Chrome - Molybdenum steel

It is a good material that falls between the

characteristics of carbon steel and stainless steel. It can handle higher

pressure and temperatures than carbon steel making it ideal for high

pressure steam or flashing condensate applications.

Special alloys are specified for special service or severe service valves

e.g. Hastealloy B & C may be selected for a highly acidic fluid service or

Monel or bronze body may be selected for a pure Oxygen Service.

Castings, forgings or barstock:

Valve bodies are made from Castings, forgings or barstock.

Castings are the least expensive choice because of the process and

higher volumes run by the Manufacturer.

Forgings are required for special materials and / or higher pressure

ratings , such as ANSI classes 1500, 2500 or 4500.

TYPES OF VALVES

1.GATE VALVE

2.GLOBE VALVE

3.BALL VALVE

4.CHECK VALVE

5.BUTTERFLY VALVE

6.PLUG VALVE

7. DIAPHRAGM VALVE

8.SAFTY & RELIF VALVE

GATE VALVE

A Gate valve is a multi turn valve in which the port is

loosed by a flat-faced vertical disk that slides at right angles

over the seat. It is primarily designed for on-off service,

where it is operated infrequently.

It can be applied to general service, oil, gas, air

slurries, heavy liquids, steam, non-condensing gases and

liquids, corrosive liquids.

GATE VALVE INSTALLATION GUIDELINES

Because of their linear motion gate valves have a greater height than other manual valves and this must be taken into consideration during installation.

Large sized Gate Valves are normally installed in horizontal lines.

Gravity tends to pull gate out of alignment with the seats in larger gate valve sizes requiring some additional mechanical support.

User to ensure that the matching end piping flanges are aligned if the valve has flanged end connection.

TYPES OF GATE VALVE

1.FLANGED GATE VALVE

2.BUTTWELDED GATE VALVE

3.THREADED GATE VALVE

4.SOCKETWELD GATE VALVE

1.FLANGED GATE VALVE

2.BUTTWELDED GATE VALVE

3.THREADED GATE VALVE

4.SOCKETWELD GATE VALVE

GLOBE VALVE

A Globe valve is a linear motion valve and is generally

used for both on-off throttling applications.

Although the globe design can handle high-pressure

classes, due to the thrust limitations of the hand operator

globe valves are usually applied to lower pressure

applications.

TYPES OF GLOBE VALVE

1.FLANGED GLOBE VALVE

2.BUTTWELDED GLOBE VALVE

3.THREADED GLOBE VALVE

1.FLANGED GLOBE VALVE

2.BUTTWELDED GLOBE VALVE

3.THREADED GLOBE VALVE

BALL VALVE

The valves, which are best, used for on-off service, as well as moderate throttling situations that require minimal accuracy.

TYPES OF BALL VALVES1.FLANGED BALL VALVE2.BUTTWELDED BALL VALVE

1.FLANGED BALL VALVE

2.BUTTWELDED

BUTTERFLY VALVE

Unlike gate or globe valve designs, where the closure element

moves out of the flow stream, the butterfly disk is located in the middle

of the flow stream.

In a Butterfly valve the fluid moves from the inlet to the outlet,

with the disk being the only obstruction to the flow.

It creates some turbulence to the flow, even in the open position.

Types of Butterfly Valves:

1.Wafer body type.

2.Flanged body type.

3.Lug-body style.

4.Slit-body style.

5.Eccentric and Cammed Butterfly valve.

1.Wafer body type.

2.Flanged body type.

3.Lug-body style.

CHECK VALVE

Check valves (also known as non-return valves)

are automatic valves that prevent a return or reverse

flow of the process.

The check valve operation is dependent upon

the flow direction of the process, which may be

created by a pump or pressure drop.

Types of CHECK Valves:

1.SWING CHECK VALVE.

2.WAFER CHECK VALVE.

Plug Valve

It is a quarter-turn manual valve that uses a

cylindrical or tapered plug to permit or prevent straight-

through flow through the body.

Plug valves are either lubricated or non-lubricated.

For non-lubricated valves, the plug may be inserted from

the top or bottom of the valve body.

Types of plug Valves:

1.Cylindrical Plug

2.Conical Plug

DIAPHRAGM Valve

Diaphragm Valves consist of a rigid body formed with a weir

placed in the flow path, a flexible diaphragm which forms the upper

pressure boundary of the valve, a compressor which is used to force

diaphragm against the weir, and the bonnet and hand wheel which

secure the diaphragm to the body and actuate the compressor.

They are manufactured in Variety of end connections:

Welding end socket or butt welding, flanged, screwed or

threaded, clamp ends, solvent cement joint ends for thermoplastic

valves and male sanitary threaded ends.

Types of Diaphragm Valves:

1.Weir type

2. Straight through type

Safety & Relief Valves

Safety valves

They are also known as pop safety valves.

They are spring loaded, quick opening, full flow valves for

systems containing pressurized, compressible fluids such as

steam, air, or other vapors or gases.

The set pressure is adjusted by increasing or decreasing

the spring compression.

The difference between the opening pressure and

the closing pressure is called blow down.

Relief Valves

They are similar to safety valve but open only slightly at set

pressure.

Instead of full opening, they open wider if the pressure

increase above the set pressure.

Relief valves are normally used for liquids, such as water or

oil, where release of a small volume will rapidly lower the pressure.

more Valves

1.needle valve

2.foot valve

3.balanced valve

4.gauge valve

5.slide valve

6.Blow down valve