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valves

Valves are used for main three purposes listed below.
For Isolation of flow.
For Regulation of flow.
For avoiding the reversal of the flow.
The valves used for isolation cannot be used for regulation but other way round is possible.
Various types of valves.
1) Gate valve
2) Ball valve
3) Plug valve
4) Butterfly valve
5) Globe valve
6) Needle valve
7) Check valve
8) Control valve (Handled by Instrumentation Department)
9) Pressure relief valve or Safety valve (Handled by Instrumentation Department)
First five valves are used for isolating the flow, 5th & 6th valves are used for regulating the flow and 7th valve is used for avoiding the reversal of the flow.
1)GATE VALVE
It is the most commonly & very widely used valve in industrial piping for isolation of the flow. It is manually operated and it is not recommended for regulation of the flow. Installation of this valve is possible from both the ends. Hence it is bi-directional valve.
A) End preparation:
a) Cast Steel valves have Flanged or Butt weld end preparation.
b) Forged Steel valves have Socket weld or Threaded end preparation.
B) Design & dimension standard:
The dimension Standard for gate valve is as follows.
API 600 For Cast Steel valves (Flanged / BW valves) companion document to ISO 10434
API 602 Forged Steel valves (SW / Threaded valves)
* API 603 “Corrosion Resistant Bolted Bonnet Gate Valves
ANSI B 16.34 For Pressure & Temperature limitation & Rating
ANSI B 16.10 For face to face dimension of Flanged & BW end
API 598 For Testing of valve
*API 6D “Specification for Pipeline Valves”,  it is a companion document to ISO 14314.
Manufacturers Standardization Society
*SP-70 “Cast Iron Gate Valves”
*SP-80 “Bronze Gate, Globe, Angle and Check Valves”
*SP-81 “Stainless Steel Bonnetless, Flanged, Knife Gate Valves”
American Waterworks Association
*AWWA C500 “Metal – Seated Gate Valves for Water Supply Service”
*AWWA C509 “Resilient – Seated Gate Valves for Water Supply Service”
*AWWA C515 “Resilient – Seated Gate Valves for Water Supply Service”
C) Main parts:
Gate valve has following main parts.
Body
Bonnet
Internals / Trim / Wetted parts: Parts that come in direct contact with the fluid. Gate valve has following Internals / Trim / Wetted parts. Wedge / Seat Ring / Stem / Gland Bush
D) Pressure class:
There are 150, 300, 600, 900, 1500, 2500 ratings for Flanged & BW valve.
There is 800 rating for SW or Threaded valve.
E) Material:
Forged Steel Cast Steel
CS ASTM A 105 ASTM A 216 Gr WCB
LTCS ASTM A 350 Gr LF2 ASTM A 352 Gr LCB
LAS ASTM A 182 Gr F11 ASTM A 217 Gr WC6
ASTM A 182 Gr F22 ASTM A 217 Gr WC9
ASTM A 182 Gr F9
SS ASTM A 182 Gr F304 ASTM A 351 Gr CF8
ASTM A 182 Gr F304L ASTM A 351 Gr CF8M
ASTM A 182 Gr F316 ASTM A 351 Gr CF3M
ASTM A 182 Gr F316L ASTM A 351 Gr CF3C
ASTM A 182 Gr F321
2)GLOBE VALVE
The fluid while passing through this valve changes its flow direction and hence this valve causes increased resistance to flow which result into considerable pressure drop. So this valve is not suitable where pressure drop is critical. This valve is mainly used for regulation of the flow. Inlet and outlet of this valve are fixed. Hence installation of this valve is unidirectional. Flow direction is marked on the valve body.
A) End preparation:
Same as Gate valve.
B) Design & dimension standard:
BS 5352 For SW / Threaded valves
BS 1873 For Flanged / BW valves
ANSI / ASTM B 16.34 For Pressure & Temperature Limitation and Rating
ANSI / ASTM B 16.10 For face to face dimension of Flanged / BW end valves
API 598 For Testing of valve
C) Main parts:
Globe valve has following main parts.
Body
Bonnet
Internals / Trim / Wetted parts: Globe valve has following Wetted parts.
Disc
Seat Ring
Stem
Gland Bush
D) Pressure class:
Same as Gate valve.
E) Material:
Same as Gate valve.

3 ) CHECK VALVE
It is sometimes referred to as Non Return Valve.It is self-operated valve and allows the flow to pass in one direction and will not allow reverse flow.Installation of this valve is unidirectional.Flow direction is marked on the body.
A) Type and end connection:
1) Lift Check Valve (up to 1 ½’’) : Socket Weld / Threaded / Butt Weld
2) Swing Check Valve ( >= 2’’) : Flanged / Butt Weld
3) Wafer type Check Valve: Wafer type / Wafer lug type. It is to be kept between two flanges.
B) Design & dimension standard:
BS 5352 For Lift Check Valve
BS 1868 For Swing Check Valve
API 594 For Wafer Check Valve
ANSI / ASTM B 16.34 For Pressure & Temperature Limitation and Rating
ANSI / ASME B 16.10 For Face to Face dimension
API 598 For Testing of valve
C) Main parts:
Lift Check Valve: Swing Check Valve: Wafer Check Valve:
Body Body Body
Cover Cover Plates
Spring Disc Spring
Disc Seat Hinge pin
Seat Hinge Pin
Disc Carrier
D) Pressure class:
Same as Gate Valve
E) Material:
Lift Check Valve (up to 1.5” & SW / Threaded / BW): Same as forged Gate Valve.
Swing Check Valve (>= 2’’& Flanged / BW): Same as cast steel Gate Valve.
Wafer type Check Valve (Wafer type / Wafer lug type): Same as cast steel Gate Valve.
Internals Internals
4 )BALL VALVE
This valve is used for isolation & for quick on / off. It is mainly used in utility line i.e. cooling water, instrument air etc, and in hazardous and combustible fluid. Rotating the lever by 900 opens or closes this valves fully. Hence this valve is called quarter turn valve. Fire safe design as per API 607 is available for this valve. Installation of this valve is possible from both the ends. Hence it is bi-directional valve. 3-way and 4-way construction is possible in ball valve by providing “T” or “L” port in the ball.
A) End connection:
Socket Weld & Threaded End – up to 1.5’’, 3-piece design
Flanged / Butt Weld- 2 piece design
B) Design & dimension standard:
BS 5351 For Ball Valves
ANSI/ASME B 16.10 For Face to Face dimension
ANSI/ASTM B 16.34 For Pressure & Temperature Limitation and Rating
API 598 For Testing of Valves
C) Main parts:
Ball valve has following main parts.
Body
Ball valve has following internals.
Ball
Seat
Stem
D) Pressure class:
Same as Gate Valve
E) Material:
Same as Gate Valve
Here Seat material is PTFE (Poly Tetra Fluoro Ethylene)
Fire safe valves are available as per API 607 & has following seats
Primary Soft Seat of PTFE
Secondary Metal to Metal Seat

5) BUTTERFLY VALVE
It is mostly used for isolation and in specific case used for regulation.Regulation is not as precise as Globe Valve
A) End connection:
Same as Wafer check valve
Wafer type / Wafer lug type / Flange end / Butt end
B) Design & dimension standard:
API 609 For Butterfly valve
ANSI / ASME B 16.10 For Face to Face dimension
ANSI / ASTM B 16.34 For Pressure & Temperature Limitation and Rating
API 598 For Testing of valve
C) Main parts:
Butterfly valve has following main parts.
Body
Butterfly valve has following internals.
Disc / Shaft / Seat
D) Pressure class:
Same as Gate Valve of cast steel type
E) Material:
Same as cast steel Gate Valve
Seat Material: EPDM, Nitrile – These are one kind of Rubber,  soft material
EPDM – Ethylene Propylene Di Monomer
6) PLUG VALVE
This valve is used for regulation, isolation and quick on / off in combustible or Hazardous fluid. 3-way and 4-way construction is possible in plug valve by providing “T” or “L” port in the plug.
A) End connection:
Socket Weld / Threaded
Flanged / Butt Weld
B) Design & dimension standard:
BS 5353 For Plug valve
ANSI / ASME B 16.10 For Face to Face dimension
ANSI / ASTM B 16.34 For Pressure & Temperature Limitation and Rating
API 598 For Testing of valves
C) Main parts:
Plug valve has following main parts.
Body
Cover
Plug valve has following internals.
Stem
Plug
Sealant
D) Pressure class:
Same as Gate Valve
E) Material:
Same as Gate Valve
7) CONTROL VALVE ( Handled by Instrumentation Department )
These valves are self operated type. They have actuators. Actuators operate on the signal received from an instrument. They are used for very fine throttling and to have desired process parameters(pressure, temperature, flow) of fluid. Control Valves can be of the following types based on parameters to be controlled:
1)Pressure control valve – Receives signal from Pressure Indicator / Pressure Transmitter.
2)Temperature control valve – Receives signal from Temperature Indicator / Temperature Transmitter
3)Flow control valve – Receives signal from Flow Indicator / Flow Transmitter
There are two types of signal:
1)Pneumatic – Valve has pneumatic actuator. (tubing is used)
2)Electric – Valve has electrical (solenoid) actuator. (cables are used)
3)Based on construction, control valve has following types:
i)Butterfly Valve
ii)Globe Valve
iii)Ball Valve
A) End connection:
Flanged End or BW. Flange end is always preferred because of regular servicing & maintenance.
B) Material :
Same as other cast steel valves.
C) Design & dimension standard:
Same as other valves.
D) Pressure class:
Same as other valves.
8 ) SAFETY VALVE
This valve is also known as Pressure relief valve. It is used for safe operation of plant. This valve releases excess pressure when it exceeds set pressure. Pressure is set by spring.Inlet of this valve is one size lower or equal to the inlet pipe size. Outlet is at least one or more size higher to outlet pipe size.
A) Material & pressure class:
Same as Gate Valve
B) Main parts:
Pressure safety valve has following main parts.
Body / Bonnet
Safety valve internals: Spring / Disc / Stem
C) Design & dimension standard: API 526:
For Pressure & Temperature Limitation and Rating and for Center to Face Dimension. Outlet pressure class <= Inlet pressure class

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