Intoduction to valve technology

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Introduction to

Valve Technology

Presented by


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What is an Ideal Valve?

Shuts off or controls the rate of flow into, inside of, or out of piping

or other closed conduits.

When open, offers the least resistance possible to the flowingproduct

When closed, seals tightly permitting no fluid to pass. Resistant to bending loads and vibration on the associated piping.

Impervious to corrosion.

Uneffected by erosive particulate matter.

Withstands damage from large objects in the fluid stream.

Tolerates temperature extremes or cycling.

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Actual valves rarely approach the ideal performance of the perfect

valve.The engineer and user must compromise, weighing the value of eachperformance quality against the cost to provide it.

What is Reality?

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Types of Valves

Valve types range from simple shut off devices to complex servo-systems.

Sizes vary from tiny metering valves used in aerospace applicationsto pipeline and industrial valves weighing tons.

Operating pressures may be as high as 100,000 psi or as low as avacuum.

Temperatures may be as low as the cryogenic region or as high asthose of molten metals.

Leakage requirements may be very strict where even the tiniest leakmay be disastrous, or they may have lenient where loss is of minorimportance.

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Valves may be classified in different ways such as :

1. the function

2. the closure member

Valves Classifications

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Shut-off Valves

Non-return Valves

Control Valves

Safety Valves

Valve classification

1- By Function

scope of this presentation are Shut-offand Non-return valves only

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Valves Classification 2 .By Closure Member

2.1- Gate Valves

Gate valves are characterizedby a sliding gate which ismoved perpendicular to thedirection of flow.

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1/2 800 GATE VALVE

BOLTED BONNET - OS&Y

Gate Valve Examples


2.1- Gate Valves

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48 150 GATE VALVE

BOLTED BONNET - OS&Y

Gate Valve Examples


2.1- Gate Valves

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GATE VALVEINSIDE SCREW

WATER SERVICE


Gate Valve Examples2.1- Gate Valves

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GATE VALVESPARALLEL SLIDE GATE

FOR POWER PLANT



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GATE VALVESBellows Sealed

and 16



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GATE VALVE FOR WELLHEAD

PARALLEL SLIDE SLAB GATE



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KNIFE GATE VALVE



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Globe valves have a closure

member, usually in the form ofdisc or plug, which is moved bya stem perpendicular to a ringshaped seat.

Globe valves are used primarilyfor throttling purpose.

2.2- Globe Valves

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Straight (std) Pattern

GLOBE VALVE


Straight pattern globe valve have

a limited flow coefficient due tothe 90 angle of the flow passage

The seat can be renewable

(screwed-in) or integral ( a welddeposit of Stellite Gr 6)

Globe Valve Examples2.2- Globe Valves

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Y Pattern

GLOBE VALVE


The stem and closure member is

assembled at an angle tomaximize the flow coefficient (CV)of the valves (limiting the loss ofspeed)

Usually welded bonnet, and inhigh pressure for Steam service


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BELLOWS SEAL

GLOBE VALVE


Globe Valve Examples

The entire stem, stem packing

and back seating arrangement isisolated from the flow bore by aflexible metallic bellows.

The bellows is attached to thebottom end of the stem and to thebonnet by welding.

2.2- Globe Valves

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Compact BellowsSealed Globe Valve for

Steam and DowTherm


ECO-L-VALVE

The entire stem, stem packing and back

seating arrangement is isolated from theflow bore by a flexible metallic bellows.

The bellows is replaceable (screwed on

the stem).


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In this small globe valve, theclosure member is a taperedneedle point plug which actsagainst a small orifice.



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Similar in appearance to a ball

valve, it employs a mechanicalwedge closure in which the seal issqueezed tight by the downwardmotion of the stem.

2.4- Rising Stem Ball Valves

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2.3- Pinch Valves

Uses a rigid bar to press against

a flexible element such as adiaphragm or rubber tube topinch off the flow.

Is used in systems carryingslurries, as they are low in cost,and insensitive tocontamination.

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2.5- Ball Valves

The ball valve is basically a

ported sphere in a housing.

Rotation of the sphere by 90changes the position from open

to closed and from closed toopen.

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Ball Valves ExampleSide Entry

Ball assembledfrom the side of

the body


2.5- Ball Valves

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Ball assembledfrom the top ofthe body


2.5- Ball Valves

Ball Valves ExampleTop Entry

l Cl ifi i 2 Cl b

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Ball Valves ExampleSide Entry, Trunnion Mounted Ball

Side Entry Ball Valvesmay be:

- three piece

- two piece

Generally, three-piecevalve is forged body,while two-piece valve iscast body.

2 1500 ClassTwo-piece Cast Body

Duplex Stainless Steel


2.5- Ball Valves

V l Cl ifi ti 2 B Cl M b

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2.5- Ball ValvesBall Valve Example

TOP ENTRY30,900 Class

Cast Body


V l Cl ifi ti 2 B Cl M b

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2.5- Ball ValvesBall Valve Example

Top Entry30 900 ClassForged Body


Valves Classification 2 By Closure Member

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Three-Way Ball Valves


2.5- Ball Valves


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2.6- Butterfly Valves

Consists of a disc which rotates about

a shaft in a housing.

Disc closes against a ring seal to stopflow.

Used mainly in low pressure systemswhere some leakage may betolerated.


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2.7- Plug Valves

Plug valves have the closure

member as a tapered plughaving a rectangular port.

The plug is rotated through 90

to open and close the valve.


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Check valves (also known as

non-return valves) areautomatic valves thatprevent a return or reverseflow of the fluid.

They require no externalforce to operate.


2.8- Check Valves


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Dual Plate Wafer TypeCheck Valve

Main advantages :

- low weight

- small dimensions

- horizontal and vertical

installation


Check Valve Examples2.8- Check Valves


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Check Valves

42 600 Check Valve, featuring

buttweld ends and weldedpupjoints complete withdamping device (Shell OmanPipeline)


Check Valve Examples2.8- Check Valves

Intoduction to valve technology

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