What is the difference between a globe valve and a gate valve? This problem is not clear to many people. Actually, the globe valve refers to the valve that the closing part moves along the center line of the seat. The gate valve is a valve plate for opening and closing parts. The movement direction of the plate is perpendicular to the direction of the fluid. There are a lot of people are not familiar with the life of the common valve, we will introduce the pipeline system to introduce the most common globe valve and gate valve and the use of the difference.

The difference between globe valve and gate valve

1. Different structures

Gate valves are more complex than globe valves in structure and larger in height. In terms of shape, gate valves are shorter and higher than globe valves. In particular, rising stem gate valves require higher height space, which should be noted in the case of limited installation space.

2. Different sealing surfaces

When the gate valve is opened and closed, the valve core and the seat sealing surface always contact and rub with each other, so the sealing surface is easy to wear, especially when the valve is in the close state, the pressure difference between the valve core before and after is very big, the sealing surface wear is more serious;

And the globe valve disc once in the open state, its valve seat and disc sealing surface, no longer contact, so its sealing surface mechanical wear is small, but if the medium contains solid particles, easy to damage the sealing surface.

Gate valve sealing surface has a certain self-sealing ability, its valve core by the medium pressure tightly contact with the valve seat sealing surface, to achieve tight leakage. Wedge gate valve spool inclination is generally 3~6 degrees, when forced to close excessive or large temperature changes of the spool is easy to jam. Therefore, high temperature, high pressure wedge gate valve, in the structure have taken some measures to prevent the plug stuck.

The sealing surface of the globe valve can only be sealed if the valve is forcibly closed. Under the same diameter, working pressure and the same driving device, the driving torque of the globe valve is 2.5~3.5 times of the gate valve. This should be noted when adjusting the torque control mechanism of electric valves.

The sealing surface of the globe valve only contacts each other when it is completely closed. The relative slip between the valve core and the sealing surface is very small, so the sealing surface wear is also very small. And the globe valve sealing surface wear, most is due to the valve core and sealing surface before there are sundries, or due to the closed state is not tight, caused by high-speed medium erosion.

3. Different flow resistance

When the gate valve is fully open, the whole flow path is through, and the pressure loss of medium operation is the smallest. Compared with the globe valve, its main advantage is that the flow resistance is small. The flow resistance coefficient of the common gate valve is about 0.08~0.12, while the resistance coefficient of the common globe valve is about 3.5~4.5. Small opening and closing force. Gate valves are generally designed to operate without frequent opening and closing and are not suitable for regulating or throttling under conditions where the gate is either fully open or fully closed. And the globe valve in the whole journey of the flow resistance is large, the imbalance force is large, the required driving force or torque is also much larger. But it is very suitable for fluid regulation, throttling.

For high-speed flow medium, the gate in the local open condition, can cause the vibration of the valve, and vibration, and may damage the gate and seat sealing surface, and throttling, will make the gate suffer erosion of the medium.

4. Different flow directions

When the globe valve is installed, the medium can be entered from below the spool and from above two ways. The advantages of the media from the lower part of the spool is that when the valve is closed, the coil is not under pressure, which can extend the service life of the coil, and can be in front of the valve under the pressure of the pipeline, to replace the work of the coil. The disadvantage of medium from the bottom of the spool into the valve drive torque is large, about 1.05~1.08 times into the top, the stem by the axial force, the stem is easy to bend. For this reason, the medium from the bottom into the way, generally only applicable to small diameter globe valve (DN50 below), DN200 above the globe valve are selected from the above medium into the way. Electric globe valves generally use medium from the top into the way. The disadvantage of the medium from the top to the bottom is just the opposite. And the flow of gate valve, from both sides into the effect is the same.

Compared with gate valve, globe valve has the advantages of simple structure, good sealing performance and convenient manufacturing and maintenance. The disadvantage is that the liquid resistance, open and close force.

5. Different routes

Gate valves have a greater travel than globe valves.

6. Different maintenance procedures

Gate valve maintenance, not suitable for on-site pipeline, and most of the globe valve seat and disc, can be replaced online, without the entire valve, from the pipeline removed, this valve and pipeline welding into one of the occasions, is very suitable.

Use of globe and gate valves

1, the use of the globe valve

Globe valves can be used in most media flow systems. A variety of globe valves have been developed for various USES in petrochemical, electric power, metallurgy, urban construction and chemical industries.

The use of globe valves is very common, but due to the large opening and closing torque, the length of the structure is long, usually the nominal size is limited to less than 250mm, but also to 400mm, but the choice of the need to pay special attention to the direction of import and export. Generally, the globe valve media below 15Omm mostly flows in from the bottom of the disc, while the globe valve media above 2O0mm mostly flows in from the top of the disc. This is taking into account the closing torque of the valve. In order to reduce the opening or closing torque, generally more than 2O0mm of the cut-off valve are equipped with internal bypass or external bypass valve.

2. Purpose of gate valve

The gate valve is only used for fully opening or fully closing the medium on all kinds of pipelines or equipment. It is not allowed to be used for throttling.

Gate valves with handwheel or handle shall not be operated with additional auxiliary bars (if the seal is not tight, check and repair the sealing surface and other parts). The handwheel and handle rotate clockwise to close and vice versa. The gate valve with driving mechanism should be used according to the instruction.

In a word, there are many differences and USES between gate valve and globe valve. In our selection and use, we must make a good distinction between their similarities and differences, so as to avoid mistakes. The application range of gate and globe valves is determined by their characteristics. In general, globe valves are used in smaller passages where good shut-off tightness is required. Gate valves are commonly used in steam and large diameter feed water pipelines where fluid resistance is generally required to be small.