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Gate Valve vs Globe Valve
Gate Valve vs Globe Valve
Globe valves and gate valves are two of the most common valves in industrial plants. Both are designed to keep systems running as efficiently and safely as possible. However, contrary to popular belief, these valves aren&#;t the same.
These valves have similar bodies, but they feature their own unique designs and have their own applications. To help you understand the differences between globe valve vs gate valve, read the guide below.
Contact The Valve Experts
Globe Valves
Globe valves vs gate valves are designed for many applications in several fields, including the oil and gas industry. However, each valve doesn&#;t serve the same function.
Globe valves are generally used to stop, start, and regulate flow within a pipe. They&#;re made with a spherical body and a disc. The disc within the globe valve is designed to move up and down from the seat. These vertical movements allow the space between the disc and the seat to change slowly when the valve starts to close. This gives the valve good throttling ability and allows it to regulate flow within a pipeline.
The flow rate of a globe valve depends on the space between the disc and the seat. The further apart they are, the more liquid that will flow through the valve.
Globe valves are also designed with a stem connected to the bonnet right above the disc to maintain a tight seal when the valve is fully closed. Because of that, globe valves are less likely to experience seat leakage compared to other valves.
These valves can double as control valves and are commonly used for corrosive, highly viscous media as well as high-pressure and high-temperature systems.
Gate Valves
Gate valves are used in plants in the oil and gas industry as well. However, they&#;re designed only to start and stop flow within a piping system. They, unfortunately, won&#;t regulate flow.
Gate valves are also designed differently than globe valves. Instead of a disc, these valves have gate faces that are parallel or wedge shaped, and they&#;re designed with a rising or a non-rising stem. This helps workers understand when the valve is fully open or fully closed.
These valves are also known to have lower pressure drops and offer little resistance to fluid flow, especially in the fully open position. Most importantly, gate valves can be set in any directional flow. Globe valves, on the other hand, can&#;t.
Learn more about Globe Valve vs Gate Valve
For more information about globe valve vs gate valve for your business, contact CPV Manufacturing.
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Globe versus Gate Valves
Globe versus Gate Valves
ADNPD(Mechanical)
(OP)
29 Jul 03 13:44
Can anyone tell me why Globe valves seal more efficiently than Wedge Gate valves?
RE: Globe versus Gate Valves
2
davefitz(Mechanical)
30 Jul 03 09:51
no, but the globe valve can be repaired in place while nearly all gate valves need to be removed from the piping system to have leakage problems repaired. Also, a globe valve can be opened against a high differential pressure, while a gate valve will bind and cannot be opened. If you try to open againast a high DP, the seat will score and leak. Also, a globe valve has a near linear characteritic of Cv vs. % open, while a gate valve has a severe parabolic characteristic and thus cannot be used for throttling.
RE: Globe versus Gate Valves
JNieuwsma(Mechanical)
30 Jul 03 10:40
*Why do globe valves seal more efficently than gate valves?
I guess that depends on your definition of "efficient". Gate valves can provide a very tight shutoff, which gets tighter with increased pressure. For globe valves, it depends on the orientation. With flow from under the disc (the "normal" configuration for globe valves), increasing pressure results decreased sealing performance (ie, possibility of leakage). With flow from over the disc, increased pressure produces a tigher seal, but the valve can be hard to open. Globe valves, at least in my training, are not generally used as shut off valves, only for throttling.
*What to do if there's a high differential pressure?
With a gate valve, higher delta P means more torque is required to open. Use a gear (or electric) operator. As an alternative, use a bypass configuration: the torque required to open a small bypass valve is minimal, open that valve first and the let the pressure across the big gate valve equalize, then open the big gate valve.
With a globe valve, again it depends on orientation. With flow under the disc, tight shutoff requires high torque: again, think gear or electric actuator, or possibly hammer-blow handwheel. Opening is easy. For flow over the disc, closing is easy but opening requires more torque (actuator), or a bypass.
*Flow Curve
I must disagree with davfitz's assertion that globe valve flow curves are essentially linear. At least in my experience, the curve is more S-shaped and tapers off once the valve is open to about 1/3 of the pipe size. It depends on the disc design, but most globe valves should not be counted on for very fine flow control (that's what a control valve is for.) But davefitz right that gate valves should not be used for throttling.
Jonathan Nieuwsma
RE: Globe versus Gate Valves
davefitz(Mechanical)
1 Aug 03 09:17
In my 30 yrs experience , nearly all process control valves have been globe or angle-globe style valves. The linear charaacteristic trim is the normal default trim. For low pressure air or gases , some applications have used butterfly valves, and for critical applications ( cavitation , very high noise) multistage trim style valves have been used. But the Globe dominates control and throttling service. A quick look at a Fisher valve catalog should suffice.
RE: Globe versus Gate Valves
Fog1(Mechanical)
12 Nov 03 11:17
Wear, that&#;s a simple answer wear. Bits of nasty hard stuff getting between the gate and the seat face, localised cavitation with liquids, areas of low pressure inducing jet streaming and then a large area of metal rubbing on a not so large area of metal which happens to be the sealing face and large loads requiring, in some cases, very high shock loads to get the valve moving.
Having said that gate valves work, just make sure the application suits the valve.
As fare as the rest of the stuff that others have pointed out about globe valves, well it all depends whose product and what application. All of what&#;s been said isn&#;t necessarily so and some of what&#;s been said is incorrect, so just be careful and don&#;t rely on a single source.
RE: Globe versus Gate Valves
JAlton(Mechanical)
12 Nov 03 17:41
It has not been my experience over the past 30 years that Globe Valves seal more efficiently than Gate Valves. I agree with much of the advice given by Davefitz and Jnieuwsma. I use Gate Valves for isolation with bypass valves to equalize upstream and downstream pressure to save the seats and the operator thus increasing the life of the valve. I use Globes Valves for throttling (control). However, I always install a gate valve upstream of the globe for positive shutoff because the globe valves do not tend to hold tight.
J. Alton Cox
www.delucatest.com
RE: Globe versus Gate Valves
jsummerfield(Electrical)
14 Nov 03 22:03
Default ANSI/FCI Class II globe style control valves leak like a sieve. Control valve leakage classifications reflect the leakage in percentage terms based upon the valve sizing coefficient. Class III are normal with Class IV still leaking, Class V still leaking and Class VI still leaking. Do not compare control valve leakage rates against gates or balls as the requirements differ quite dramatically. Shutoff valves are gates and ball valves not globes.
In my experience, (and I am getting old) throttling control valves are often globe and other patterns such as high-performance butterfly and v-ball style valves are used where the capacity is high and cavitation is not a serious issue. Typical process control valves have equal percentage trim charaacteristics as the normal default trim.Default ANSI/FCI Class II globe style control valves leak like a sieve. Control valve leakage classifications reflect the leakage in percentage terms based upon the valve sizing coefficient. Class III are normal with Class IV still leaking, Class V still leaking and Class VI still leaking. Do not compare control valve leakage rates against gates or balls as the requirements differ quite dramatically. Shutoff valves are gates and ball valves not globes.
John
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Globe vs. Gate Valves: What's the Difference?
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Gate Valve vs Globe Valve
Gate Valve vs Globe Valve
Globe valves and gate valves are two of the most common valves in industrial plants. Both are designed to keep systems running as efficiently and safely as possible. However, contrary to popular belief, these valves aren&#;t the same.
These valves have similar bodies, but they feature their own unique designs and have their own applications. To help you understand the differences between globe valve vs gate valve, read the guide below.
Contact The Valve Experts
Globe Valves
Globe valves vs gate valves are designed for many applications in several fields, including the oil and gas industry. However, each valve doesn&#;t serve the same function.
Globe valves are generally used to stop, start, and regulate flow within a pipe. They&#;re made with a spherical body and a disc. The disc within the globe valve is designed to move up and down from the seat. These vertical movements allow the space between the disc and the seat to change slowly when the valve starts to close. This gives the valve good throttling ability and allows it to regulate flow within a pipeline.
The flow rate of a globe valve depends on the space between the disc and the seat. The further apart they are, the more liquid that will flow through the valve.
Globe valves are also designed with a stem connected to the bonnet right above the disc to maintain a tight seal when the valve is fully closed. Because of that, globe valves are less likely to experience seat leakage compared to other valves.
These valves can double as control valves and are commonly used for corrosive, highly viscous media as well as high-pressure and high-temperature systems.
Gate Valves
Gate valves are used in plants in the oil and gas industry as well. However, they&#;re designed only to start and stop flow within a piping system. They, unfortunately, won&#;t regulate flow.
Gate valves are also designed differently than globe valves. Instead of a disc, these valves have gate faces that are parallel or wedge shaped, and they&#;re designed with a rising or a non-rising stem. This helps workers understand when the valve is fully open or fully closed.
These valves are also known to have lower pressure drops and offer little resistance to fluid flow, especially in the fully open position. Most importantly, gate valves can be set in any directional flow. Globe valves, on the other hand, can&#;t.
Learn more about Globe Valve vs Gate Valve
For more information about globe valve vs gate valve for your business, contact CPV Manufacturing.
Globe versus Gate Valves 3
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Globe versus Gate Valves
Globe versus Gate Valves
ADNPD(Mechanical)
(OP)
29 Jul 03 13:44
Can anyone tell me why Globe valves seal more efficiently than Wedge Gate valves?
RE: Globe versus Gate Valves
2
davefitz(Mechanical)
30 Jul 03 09:51
no, but the globe valve can be repaired in place while nearly all gate valves need to be removed from the piping system to have leakage problems repaired. Also, a globe valve can be opened against a high differential pressure, while a gate valve will bind and cannot be opened. If you try to open againast a high DP, the seat will score and leak. Also, a globe valve has a near linear characteritic of Cv vs. % open, while a gate valve has a severe parabolic characteristic and thus cannot be used for throttling.
RE: Globe versus Gate Valves
JNieuwsma(Mechanical)
30 Jul 03 10:40
*Why do globe valves seal more efficently than gate valves?
I guess that depends on your definition of "efficient". Gate valves can provide a very tight shutoff, which gets tighter with increased pressure. For globe valves, it depends on the orientation. With flow from under the disc (the "normal" configuration for globe valves), increasing pressure results decreased sealing performance (ie, possibility of leakage). With flow from over the disc, increased pressure produces a tigher seal, but the valve can be hard to open. Globe valves, at least in my training, are not generally used as shut off valves, only for throttling.
*What to do if there's a high differential pressure?
With a gate valve, higher delta P means more torque is required to open. Use a gear (or electric) operator. As an alternative, use a bypass configuration: the torque required to open a small bypass valve is minimal, open that valve first and the let the pressure across the big gate valve equalize, then open the big gate valve.
With a globe valve, again it depends on orientation. With flow under the disc, tight shutoff requires high torque: again, think gear or electric actuator, or possibly hammer-blow handwheel. Opening is easy. For flow over the disc, closing is easy but opening requires more torque (actuator), or a bypass.
*Flow Curve
I must disagree with davfitz's assertion that globe valve flow curves are essentially linear. At least in my experience, the curve is more S-shaped and tapers off once the valve is open to about 1/3 of the pipe size. It depends on the disc design, but most globe valves should not be counted on for very fine flow control (that's what a control valve is for.) But davefitz right that gate valves should not be used for throttling.
Jonathan Nieuwsma
RE: Globe versus Gate Valves
davefitz(Mechanical)
1 Aug 03 09:17
In my 30 yrs experience , nearly all process control valves have been globe or angle-globe style valves. The linear charaacteristic trim is the normal default trim. For low pressure air or gases , some applications have used butterfly valves, and for critical applications ( cavitation , very high noise) multistage trim style valves have been used. But the Globe dominates control and throttling service. A quick look at a Fisher valve catalog should suffice.
RE: Globe versus Gate Valves
Fog1(Mechanical)
12 Nov 03 11:17
Wear, that&#;s a simple answer wear. Bits of nasty hard stuff getting between the gate and the seat face, localised cavitation with liquids, areas of low pressure inducing jet streaming and then a large area of metal rubbing on a not so large area of metal which happens to be the sealing face and large loads requiring, in some cases, very high shock loads to get the valve moving.
Having said that gate valves work, just make sure the application suits the valve.
As fare as the rest of the stuff that others have pointed out about globe valves, well it all depends whose product and what application. All of what&#;s been said isn&#;t necessarily so and some of what&#;s been said is incorrect, so just be careful and don&#;t rely on a single source.
RE: Globe versus Gate Valves
JAlton(Mechanical)
12 Nov 03 17:41
It has not been my experience over the past 30 years that Globe Valves seal more efficiently than Gate Valves. I agree with much of the advice given by Davefitz and Jnieuwsma. I use Gate Valves for isolation with bypass valves to equalize upstream and downstream pressure to save the seats and the operator thus increasing the life of the valve. I use Globes Valves for throttling (control). However, I always install a gate valve upstream of the globe for positive shutoff because the globe valves do not tend to hold tight.
J. Alton Cox
www.delucatest.com
RE: Globe versus Gate Valves
jsummerfield(Electrical)
14 Nov 03 22:03
Default ANSI/FCI Class II globe style control valves leak like a sieve. Control valve leakage classifications reflect the leakage in percentage terms based upon the valve sizing coefficient. Class III are normal with Class IV still leaking, Class V still leaking and Class VI still leaking. Do not compare control valve leakage rates against gates or balls as the requirements differ quite dramatically. Shutoff valves are gates and ball valves not globes.
In my experience, (and I am getting old) throttling control valves are often globe and other patterns such as high-performance butterfly and v-ball style valves are used where the capacity is high and cavitation is not a serious issue. Typical process control valves have equal percentage trim charaacteristics as the normal default trim.Default ANSI/FCI Class II globe style control valves leak like a sieve. Control valve leakage classifications reflect the leakage in percentage terms based upon the valve sizing coefficient. Class III are normal with Class IV still leaking, Class V still leaking and Class VI still leaking. Do not compare control valve leakage rates against gates or balls as the requirements differ quite dramatically. Shutoff valves are gates and ball valves not globes.
John
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