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What’s a Globe Valve?
A globe valve refers to a valve in which the closing element (disc) moves along the centerline of the valve seat. According to the movement of the valve disc, the change in the valve seat opening is directly proportional to the valve disc stroke. Due to the relatively short opening or closing stroke of the valve stem and the highly reliable cut-off function, as well as the proportional relationship between the change of the valve seat opening and the stroke of the valve disc, this type of valve is very suitable for regulating flow. Therefore, this type of valve is very suitable for use as a cut-off or regulating and throttling device.
Once the valve disc of the globe valve is moved away from the closed position, there is no longer contact between its seat and the sealing surface of the valve disc. Therefore, the mechanical wear of its sealing surface is minimal, and its sealing performance is excellent. The disadvantage is that particles in the flowing medium may be trapped between the sealing surfaces. However, if the valve disc is made into a steel ball or ceramic ball, this problem can also be solved. Due to the fact that the seat and disc of most globe valves are relatively easy to repair or replace, and there is no need to disassemble the entire valve from the pipeline when repairing or replacing sealing components, this is very suitable for situations where the valve and pipeline are welded together.
Due to the change in the flow direction of the medium through this type of valve, the minimum flow resistance of the globe valve is also higher than that of most other types of valves. However, based on the structure of the valve body and the layout of the valve stem relative to the inlet and outlet channels, this situation can be improved. At the same time, due to the small stroke between the opening and closing of the shut-off valve disc, and the ability of the sealing surface to withstand multiple opening and closing, it is very suitable for situations that require frequent opening and closing.
Globe valves can be used in most medium flow systems. Various forms of globe valves have been developed to meet various purposes in departments such as petrochemicals, power, metallurgy, urban construction, and chemical engineering.
The use of globe valves is extremely common, but due to the large opening and closing torque and long structural length, the nominal size is usually limited to DN250 or below, and there are also DN400. However, special attention should be paid to the inlet and outlet direction when selecting. Generally, the medium of globe valves below DN150 mostly flows from below the valve disc, while the medium of globe valves above DN200 mostly flows from above the valve disc. This is due to the closing torque of the valve. In order to reduce the opening or closing torque, globe valves above DN200 are generally equipped with internal or external bypass valves. However, the American Petroleum Institute standard API 623 specifies a maximum nominal pressure of CL2500 and a maximum nominal size of NPS12, with nominal pressures ranging from CL150 to CL1500 and a nominal size of NPS24.
The most obvious advantage of a shut-off valve:
1) During the opening and closing process, the friction between the valve disc and the valve body sealing surface is smaller than that of the gate valve, so it is wear-resistant.
2) The opening height is generally only 1/4 of the diameter of the valve seat channel, so it is much smaller than a gate valve.
3) Usually, there is only one sealing surface on the valve body and disc, so the manufacturing process is relatively good and easy to maintain.
However, the disadvantages of globe valves cannot be ignored. The main disadvantage is that the flow resistance coefficient is relatively large, which causes pressure loss, especially in hydraulic devices, where this pressure loss is particularly significant.
Globe Valves Main features:
(1)The structure of globe valve is simpler than gate valve, and it is more convenient to manufacture and maintain.
(2) The sealing surface is not easy to wear and abrasion, good sealing, opening and closing of the valve flap and the valve body sealing surface of the valve body without relative sliding, so the wear and abrasion are not serious, good sealing performance, long service life.
(3)When opening and closing, the flap stroke is small, so the height of the globe valve is smaller than the gate valve, but the length of the structure is longer than the gate valve.
(4) opening and closing torque, opening and closing more laborious, opening and closing time is longer.
(5) Fluid resistance, because the valve body media channel is more zigzag, fluid resistance, power consumption.
(6) media flow direction nominal pressure PN ≤ 16MPa, generally used downstream, the media from the valve under the direction of upward flow; nominal pressure PN ≥ 20MPa, generally used countercurrent, the media from the valve on the direction of downstream flow. To increase the sealing energy. When used, the cut-off valve medium can only flow in one direction, can not change the flow direction.
(7) full open valve flap is often subject to erosion.
Applicable occasions for shut-off valves:
(1) Needle shaped globe valves are used for precise flow control. The valve disc is usually integrated with the valve stem, and it has a needle shaped head that fits well with the valve seat and has very high accuracy. Moreover, the thread pitch of the needle shaped globe valve stem is finer than that of the valve stem thread of a general globe valve. Under normal circumstances, the size of the valve seat hole for needle shaped globe valves is smaller than the size of the pipeline. Therefore, it is usually limited to use in pipelines with smaller nominal diameters and is more commonly used for sampling valves.
(2) The valve stem and channel of the DC stop valve form a certain angle, and the sealing surface of the valve seat also has a certain angle with the inlet and outlet channels. The valve body can be made into a whole or separate type. The split valve body globe valve uses two valve bodies to clamp the valve seat in the middle for easy maintenance. This type of shut-off valve ensures that the flow direction of the fluid remains almost unchanged, and the flow resistance is minimized in the shut-off valve. The sealing surfaces of the valve seat and disc can be welded with hard alloy, making the entire valve more resistant to erosion and corrosion. It is very suitable for pipeline control in alumina production processes, as well as in pipelines with coking and solid particles.
(3) The most important advantage of the angle globe valve is that it can be installed in a pipeline system corner, saving not only elbows but also easy to use. Hence, this type of valve is most suitable for application at the synthetic ammonia production system and refrigeration system of the fertilizer plant. J44H-160, J44H-320, L44H-160, I44H-320 are fully designed for synthetic ammonia production systems.
(4) Structural characteristics of this valve are: the valve body is split and integral types, the valve disc is of STL hard alloy steel balls or amorphous material ceramic balls which are made by powder preparation, high temperature sintering, and precision grinding. The lower end of the valve stem is swaged to enclose the ball inside the valve stem ball hole. Spherical sealing in three-dimensional motion between the ball and the valve stem ball hole generates infinite sealing lines; this is how it increases its service life on the sealing surface to infinity while also keeping steady. Due to spherical sealing designs, this type of valve finds general utility with smaller nominal diameters: approximately DN6~DN25. The valve is suitable for the following: high-temperature and high-pressure steam pipelines in nuclear power plants and thermal power plants, instrument pipelines in sampling and sewage systems, temperature resistant-pressure resistant-wear-resistant-corrosion-resistant pipelines in petrochemical systems.
(5) Cut-off valve structurally for the high-temperature and high-pressure power plants are that the connection between the valve body and the valve cover is pressure self-tight sealing or clamp type and a connection between the valve body and the pipeline is butt welding. The valve body material is mostly chromium molybdenum steel or chromium-molybdenum vanadium steel, and the sealing surface is mostly hard alloy welding. Therefore, this type of valve is suitable for high temperatures with good heat resistance and pressure; Sealing surfaces are resistant to wear, scratches, No suitable wiki engines were found for corrosion medium water sealing performance being considerably longer life most suitable for pipelines of high-temperature and high-pressure water, steam oil products in thermal power industrial globe valve systems, petrochemical systems, metallurgy industry having been widely used.
(6) API globe valves are designed strictly in accordance with API 623-2015 and ASME B16.34; valve body and valve cover connection, packing box installation, stem nut of the valve, and upper seal all strictly according to the design of API 623. Valve material selection fully meets the requirements of API 623. Structural length complies with ASME B16.10; flange connection size shall be per ASME B16.5. Valves shall be strictly inspected and tested according to API598, which is why this type of valve finds extensive application in petrochemical pipelines, as well as power, metallurgy, textile systems, etc.
(7) The oxygen pipeline cutoff valve is strictly designed for oxygen pipelines. The packing box shall be strictly sealed, and external dirt should not be allowed in the packing box. There are grounding devices on the flanges at both ends of the valve body. After being mounted on the pipeline, it should be grounded to prevent static electricity and fire. The shell material of this valve is austenitic stainless steel or copper; both materials have good conductivity and do not easily generate static electricity that will cause ignition. Polytetrachloroethylene is the sealing material for the valve body material, which is a soft seal with good sealing performance: zero gas leakage during airtight test with gas. The valve is degreased strictly with carbon tetrachloride before assembly- no grease or dirt, absolutely not; will not cause static electricity and fire. This valve is appropriate for oxygen pipelines in the metallurgical system and also suitable for oxygen pipelines in other industries.
(8) Petroleum liquefied gas shut-off valves are applicable to pipelines or equipment of petroleum liquefied gas, with attention brought to its structure in terms of fire protection requirements. The filler is polytetrafluoroethylene, having no external leakage with sealing reliable. PTFE or nylon and valve body material for the soft seal is also effective. The shut-off valve is suitable as an opening and closing piece for a lLiquefied Petroleum Gas pipeline system that has other media ≤ 80 ℃ working temperature pipelines.
(9) The stem of this type of globe valve does not come into direct contact with the working medium. Suitable for different working conditions depending on the material of the shell, sealing pair, packing, and valve stem. If the valve body and cover material is carbon steel, the sealing material is alloy steel, the packing is flexible graphite, and the valve stem material is Cr13 series stainless steel, it is suitable for water, steam, and oil pipelines; If the material of the valve body and cover is 12Cr18Ni9 or 06Cr19Ni10, the sealing material is the valve body itself or hard alloy, the packing is polytetrafluoroethylene, and the valve stem material is 14Cr17Ni2, it is suitable for corrosive media pipelines or devices based on nitric acid; If the material of the valve body and valve cover is 06Cr17Ni12Mo2Ti, the sealing material is the valve body itself or hard alloy, the packing is polytetrafluoroethylene, and the valve stem material is 14Cr18Ni11Si4AlTi, it is suitable for corrosive media pipelines or devices based on acetic acid. However, the maximum nominal size of this type of globe valve is DN200. Globe valves above DN200 should be equipped with a bypass valve or an internal bypass structure should be designed. Generally, the inlet end of globe valves with a diameter of ≥ DN200 is above the valve disc, that is, high inlet and low outlet. This is to prevent excessive force during closing and the valve stem from being too thick.
(10) The stem thread of this type of globe valve is directly in contact with the working medium, and is directly corroded by the medium, making the stem thread prone to corrosion and causing difficulty in opening and closing. This type of shut-off valve has a relatively small nominal size, generally between DN6 and DN50, and is mostly used in instrument valves and sampling valves.
(11) API 602 Forged Steel Globe Valve This type of globe valve is designed according to the American Petroleum Institute standard API 602. The valve body and valve cover are forged from carbon steel or stainless steel, and the valve body and valve cover are connected by bolts, threads, and welding. There are upper threaded valve stem and lower threaded valve stem. The sealing material is Cr13 steel, stainless acid resistant steel, and STL hard alloy. The packing is flexible graphite or polytetrafluoroethylene. The connection methods include flange, thread, socket welding, and butt welding. The pressure rating is CL800~CL1500, and the nominal size is NPS%~NPS2 ½。 Widely used in equipment and pipelines in petrochemical, power, chemical and other sectors, the working medium is steam, oil, and corrosive medium. The structural length shall comply with ASME B16.10, the flange connection size shall comply with ASME B16.5, the welding end size shall comply with ASME B16.25, the socket welding hole size shall comply with ASME B16.11, and the threaded connection end size shall comply with ASME B1.20.1.
(12) Plunger stop valve: This type of plunger valve belongs to radial sealing, which is achieved by two elastic sealing rings nested on the polished plunger. Two elastic sealing rings are separated by a sleeve ring, and the load applied to the valve cover through the connecting bolts of the valve body and valve cover presses the elastic sealing ring around the plunger firmly to ensure sealing. The material combination of this valve is carbon steel for the shell, Crl3 stainless steel for the plunger, and flexible graphite for the sealing ring, which can be used in pipelines for water, steam, and oil; If the shell is made of stainless acid resistant steel, the plunger is made of stainless acid resistant steel, and the sealing ring is made of polytetrafluoroethylene, it is suitable for acidic and alkaline corrosive media. The advantages of this valve are reliable sealing, long service life, and easy maintenance; The disadvantage is slow opening and closing speed. This type of valve is widely used in urban construction systems and water and steam pipelines in urban heating.
Principles for selecting globe valves:
Globe valves are one of the most widely used valve types. With the development of ball valves and butterfly valves, some of the applications of globe valves have been replaced. However, from the characteristics of globe valves themselves, they cannot be replaced. The selection principles are:
1) Globe valves should be selected on pipelines or devices with high temperature and high pressure media. It is advisable to use globe valves on high-temperature and high-pressure pipelines in petrochemical systems such as thermal power plants, nuclear power plants, and petrochemical systems.
2) On pipelines with less strict requirements for flow resistance. That is, places where pressure loss is not considered much.
3) Small valves can choose globe valves, such as needle valves, instrument valves, sampling valves, pressure gauge valves, etc.
4) There is flow regulation or pressure regulation, but the precision requirement for regulation is not high, and the diameter of the pipeline is relatively small. For example, on pipelines with a nominal size ≤ 50mm, it is advisable to use a globe valve or a throttle valve.
5) Small and large fertilizers in the production of synthetic ammonia industry should use high-pressure angle globe valves or high-pressure angle throttle valves with nominal pressures of PN160 or PN320.
6) In the desilication workshop and pipelines prone to coking during the production of alumina by Bayer process, it is advisable to use a separate valve body with removable valve seats
DC stop valve or DC throttle valve with hard alloy sealing pair.
7) In the water supply and heating engineering of urban construction, for pipelines with smaller nominal sizes, globe valves, balance valves, or plunger valves can be used, such as on pipelines with nominal sizes less than DN150.
Globe Valve Usage:
Suitable for flammable and explosive, permeable and radioactive media, as well as industrial pipelines with strict requirements for sealing.
What’s a Globe Valve?
A globe valve refers to a valve in which the closing element (disc) moves along the centerline of the valve seat. According to the movement of the valve disc, the change in the valve seat opening is directly proportional to the valve disc stroke. Due to the relatively short opening or closing stroke of the valve stem and the highly reliable cut-off function, as well as the proportional relationship between the change of the valve seat opening and the stroke of the valve disc, this type of valve is very suitable for regulating flow. Therefore, this type of valve is very suitable for use as a cut-off or regulating and throttling device.
Once the valve disc of the globe valve is moved away from the closed position, there is no longer contact between its seat and the sealing surface of the valve disc. Therefore, the mechanical wear of its sealing surface is minimal, and its sealing performance is excellent. The disadvantage is that particles in the flowing medium may be trapped between the sealing surfaces. However, if the valve disc is made into a steel ball or ceramic ball, this problem can also be solved. Due to the fact that the seat and disc of most globe valves are relatively easy to repair or replace, and there is no need to disassemble the entire valve from the pipeline when repairing or replacing sealing components, this is very suitable for situations where the valve and pipeline are welded together.
Due to the change in the flow direction of the medium through this type of valve, the minimum flow resistance of the globe valve is also higher than that of most other types of valves. However, based on the structure of the valve body and the layout of the valve stem relative to the inlet and outlet channels, this situation can be improved. At the same time, due to the small stroke between the opening and closing of the shut-off valve disc, and the ability of the sealing surface to withstand multiple opening and closing, it is very suitable for situations that require frequent opening and closing.
Globe valves can be used in most medium flow systems. Various forms of globe valves have been developed to meet various purposes in departments such as petrochemicals, power, metallurgy, urban construction, and chemical engineering.
The use of globe valves is extremely common, but due to the large opening and closing torque and long structural length, the nominal size is usually limited to DN250 or below, and there are also DN400. However, special attention should be paid to the inlet and outlet direction when selecting. Generally, the medium of globe valves below DN150 mostly flows from below the valve disc, while the medium of globe valves above DN200 mostly flows from above the valve disc. This is due to the closing torque of the valve. In order to reduce the opening or closing torque, globe valves above DN200 are generally equipped with internal or external bypass valves. However, the American Petroleum Institute standard API 623 specifies a maximum nominal pressure of CL2500 and a maximum nominal size of NPS12, with nominal pressures ranging from CL150 to CL1500 and a nominal size of NPS24.
The most obvious advantage of a shut-off valve:
1) During the opening and closing process, the friction between the valve disc and the valve body sealing surface is smaller than that of the gate valve, so it is wear-resistant.
2) The opening height is generally only 1/4 of the diameter of the valve seat channel, so it is much smaller than a gate valve.
3) Usually, there is only one sealing surface on the valve body and disc, so the manufacturing process is relatively good and easy to maintain.
However, the disadvantages of globe valves cannot be ignored. The main disadvantage is that the flow resistance coefficient is relatively large, which causes pressure loss, especially in hydraulic devices, where this pressure loss is particularly significant.
Globe Valves Main features:
(1)The structure of globe valve is simpler than gate valve, and it is more convenient to manufacture and maintain.
(2) The sealing surface is not easy to wear and abrasion, good sealing, opening and closing of the valve flap and the valve body sealing surface of the valve body without relative sliding, so the wear and abrasion are not serious, good sealing performance, long service life.
(3)When opening and closing, the flap stroke is small, so the height of the globe valve is smaller than the gate valve, but the length of the structure is longer than the gate valve.
(4) opening and closing torque, opening and closing more laborious, opening and closing time is longer.
(5) Fluid resistance, because the valve body media channel is more zigzag, fluid resistance, power consumption.
(6) media flow direction nominal pressure PN ≤ 16MPa, generally used downstream, the media from the valve under the direction of upward flow; nominal pressure PN ≥ 20MPa, generally used countercurrent, the media from the valve on the direction of downstream flow. To increase the sealing energy. When used, the cut-off valve medium can only flow in one direction, can not change the flow direction.
(7) full open valve flap is often subject to erosion.
Applicable occasions for shut-off valves:
(1) Needle shaped globe valves are used for precise flow control. The valve disc is usually integrated with the valve stem, and it has a needle shaped head that fits well with the valve seat and has very high accuracy. Moreover, the thread pitch of the needle shaped globe valve stem is finer than that of the valve stem thread of a general globe valve. Under normal circumstances, the size of the valve seat hole for needle shaped globe valves is smaller than the size of the pipeline. Therefore, it is usually limited to use in pipelines with smaller nominal diameters and is more commonly used for sampling valves.
(2) The valve stem and channel of the DC stop valve form a certain angle, and the sealing surface of the valve seat also has a certain angle with the inlet and outlet channels. The valve body can be made into a whole or separate type. The split valve body globe valve uses two valve bodies to clamp the valve seat in the middle for easy maintenance. This type of shut-off valve ensures that the flow direction of the fluid remains almost unchanged, and the flow resistance is minimized in the shut-off valve. The sealing surfaces of the valve seat and disc can be welded with hard alloy, making the entire valve more resistant to erosion and corrosion. It is very suitable for pipeline control in alumina production processes, as well as in pipelines with coking and solid particles.
(3) The most important advantage of the angle globe valve is that it can be installed in a pipeline system corner, saving not only elbows but also easy to use. Hence, this type of valve is most suitable for application at the synthetic ammonia production system and refrigeration system of the fertilizer plant. J44H-160, J44H-320, L44H-160, I44H-320 are fully designed for synthetic ammonia production systems.
(4) Structural characteristics of this valve are: the valve body is split and integral types, the valve disc is of STL hard alloy steel balls or amorphous material ceramic balls which are made by powder preparation, high temperature sintering, and precision grinding. The lower end of the valve stem is swaged to enclose the ball inside the valve stem ball hole. Spherical sealing in three-dimensional motion between the ball and the valve stem ball hole generates infinite sealing lines; this is how it increases its service life on the sealing surface to infinity while also keeping steady. Due to spherical sealing designs, this type of valve finds general utility with smaller nominal diameters: approximately DN6~DN25. The valve is suitable for the following: high-temperature and high-pressure steam pipelines in nuclear power plants and thermal power plants, instrument pipelines in sampling and sewage systems, temperature resistant-pressure resistant-wear-resistant-corrosion-resistant pipelines in petrochemical systems.
(5) Cut-off valve structurally for the high-temperature and high-pressure power plants are that the connection between the valve body and the valve cover is pressure self-tight sealing or clamp type and a connection between the valve body and the pipeline is butt welding. The valve body material is mostly chromium molybdenum steel or chromium-molybdenum vanadium steel, and the sealing surface is mostly hard alloy welding. Therefore, this type of valve is suitable for high temperatures with good heat resistance and pressure; Sealing surfaces are resistant to wear, scratches, No suitable wiki engines were found for corrosion medium water sealing performance being considerably longer life most suitable for pipelines of high-temperature and high-pressure water, steam oil products in thermal power industrial globe valve systems, petrochemical systems, metallurgy industry having been widely used.
(6) API globe valves are designed strictly in accordance with API 623-2015 and ASME B16.34; valve body and valve cover connection, packing box installation, stem nut of the valve, and upper seal all strictly according to the design of API 623. Valve material selection fully meets the requirements of API 623. Structural length complies with ASME B16.10; flange connection size shall be per ASME B16.5. Valves shall be strictly inspected and tested according to API598, which is why this type of valve finds extensive application in petrochemical pipelines, as well as power, metallurgy, textile systems, etc.
(7) The oxygen pipeline cutoff valve is strictly designed for oxygen pipelines. The packing box shall be strictly sealed, and external dirt should not be allowed in the packing box. There are grounding devices on the flanges at both ends of the valve body. After being mounted on the pipeline, it should be grounded to prevent static electricity and fire. The shell material of this valve is austenitic stainless steel or copper; both materials have good conductivity and do not easily generate static electricity that will cause ignition. Polytetrachloroethylene is the sealing material for the valve body material, which is a soft seal with good sealing performance: zero gas leakage during airtight test with gas. The valve is degreased strictly with carbon tetrachloride before assembly- no grease or dirt, absolutely not; will not cause static electricity and fire. This valve is appropriate for oxygen pipelines in the metallurgical system and also suitable for oxygen pipelines in other industries.
(8) Petroleum liquefied gas shut-off valves are applicable to pipelines or equipment of petroleum liquefied gas, with attention brought to its structure in terms of fire protection requirements. The filler is polytetrafluoroethylene, having no external leakage with sealing reliable. PTFE or nylon and valve body material for the soft seal is also effective. The shut-off valve is suitable as an opening and closing piece for a lLiquefied Petroleum Gas pipeline system that has other media ≤ 80 ℃ working temperature pipelines.
(9) The stem of this type of globe valve does not come into direct contact with the working medium. Suitable for different working conditions depending on the material of the shell, sealing pair, packing, and valve stem. If the valve body and cover material is carbon steel, the sealing material is alloy steel, the packing is flexible graphite, and the valve stem material is Cr13 series stainless steel, it is suitable for water, steam, and oil pipelines; If the material of the valve body and cover is 12Cr18Ni9 or 06Cr19Ni10, the sealing material is the valve body itself or hard alloy, the packing is polytetrafluoroethylene, and the valve stem material is 14Cr17Ni2, it is suitable for corrosive media pipelines or devices based on nitric acid; If the material of the valve body and valve cover is 06Cr17Ni12Mo2Ti, the sealing material is the valve body itself or hard alloy, the packing is polytetrafluoroethylene, and the valve stem material is 14Cr18Ni11Si4AlTi, it is suitable for corrosive media pipelines or devices based on acetic acid. However, the maximum nominal size of this type of globe valve is DN200. Globe valves above DN200 should be equipped with a bypass valve or an internal bypass structure should be designed. Generally, the inlet end of globe valves with a diameter of ≥ DN200 is above the valve disc, that is, high inlet and low outlet. This is to prevent excessive force during closing and the valve stem from being too thick.
(10) The stem thread of this type of globe valve is directly in contact with the working medium, and is directly corroded by the medium, making the stem thread prone to corrosion and causing difficulty in opening and closing. This type of shut-off valve has a relatively small nominal size, generally between DN6 and DN50, and is mostly used in instrument valves and sampling valves.
(11) API 602 Forged Steel Globe Valve This type of globe valve is designed according to the American Petroleum Institute standard API 602. The valve body and valve cover are forged from carbon steel or stainless steel, and the valve body and valve cover are connected by bolts, threads, and welding. There are upper threaded valve stem and lower threaded valve stem. The sealing material is Cr13 steel, stainless acid resistant steel, and STL hard alloy. The packing is flexible graphite or polytetrafluoroethylene. The connection methods include flange, thread, socket welding, and butt welding. The pressure rating is CL800~CL1500, and the nominal size is NPS%~NPS2 ½。 Widely used in equipment and pipelines in petrochemical, power, chemical and other sectors, the working medium is steam, oil, and corrosive medium. The structural length shall comply with ASME B16.10, the flange connection size shall comply with ASME B16.5, the welding end size shall comply with ASME B16.25, the socket welding hole size shall comply with ASME B16.11, and the threaded connection end size shall comply with ASME B1.20.1.
(12) Plunger stop valve: This type of plunger valve belongs to radial sealing, which is achieved by two elastic sealing rings nested on the polished plunger. Two elastic sealing rings are separated by a sleeve ring, and the load applied to the valve cover through the connecting bolts of the valve body and valve cover presses the elastic sealing ring around the plunger firmly to ensure sealing. The material combination of this valve is carbon steel for the shell, Crl3 stainless steel for the plunger, and flexible graphite for the sealing ring, which can be used in pipelines for water, steam, and oil; If the shell is made of stainless acid resistant steel, the plunger is made of stainless acid resistant steel, and the sealing ring is made of polytetrafluoroethylene, it is suitable for acidic and alkaline corrosive media. The advantages of this valve are reliable sealing, long service life, and easy maintenance; The disadvantage is slow opening and closing speed. This type of valve is widely used in urban construction systems and water and steam pipelines in urban heating.
Principles for selecting globe valves:
Globe valves are one of the most widely used valve types. With the development of ball valves and butterfly valves, some of the applications of globe valves have been replaced. However, from the characteristics of globe valves themselves, they cannot be replaced. The selection principles are:
1) Globe valves should be selected on pipelines or devices with high temperature and high pressure media. It is advisable to use globe valves on high-temperature and high-pressure pipelines in petrochemical systems such as thermal power plants, nuclear power plants, and petrochemical systems.
2) On pipelines with less strict requirements for flow resistance. That is, places where pressure loss is not considered much.
3) Small valves can choose globe valves, such as needle valves, instrument valves, sampling valves, pressure gauge valves, etc.
4) There is flow regulation or pressure regulation, but the precision requirement for regulation is not high, and the diameter of the pipeline is relatively small. For example, on pipelines with a nominal size ≤ 50mm, it is advisable to use a globe valve or a throttle valve.
5) Small and large fertilizers in the production of synthetic ammonia industry should use high-pressure angle globe valves or high-pressure angle throttle valves with nominal pressures of PN160 or PN320.
6) In the desilication workshop and pipelines prone to coking during the production of alumina by Bayer process, it is advisable to use a separate valve body with removable valve seats
DC stop valve or DC throttle valve with hard alloy sealing pair.
7) In the water supply and heating engineering of urban construction, for pipelines with smaller nominal sizes, globe valves, balance valves, or plunger valves can be used, such as on pipelines with nominal sizes less than DN150.
Globe Valve Usage:
Suitable for flammable and explosive, permeable and radioactive media, as well as industrial pipelines with strict requirements for sealing.
