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Comparison of bellows globe valve and ordinary globe valve

August 12, 2020

Comparison of bellows globe valve and ordinary globe valve:

Globe valve (3)

1. Double sealing design (bellows + packing) If the bellows fails, the stem packing will also avoid leakage and meet international sealing standards.
2. There is no fluid loss, reducing energy loss and improving plant equipment safety.
3. Long service life, reduce maintenance times and lower operating costs.
4. The sturdy and durable bellows seal design ensures zero leakage of the valve stem and provides maintenance-free conditions.
5. The gas medium valve seat adopts PTFE soft sealing material to improve the sealing performance of this valve.
6. High temperature resistance≤425℃The valve seat adopts conical hard seal. Achieve airtight performance and zero leakage.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest globe valve manufacturers in China, main products are butterfly valves, check valves, gate valves and globe valves. Key words: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

Our products use advanced manufacturing technology, and strictly conform to API, DIN, BS, EN, ISO, GB and other international standards. The main products are butterfly valves, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…), etc. Our products are widely used in various fields such as marine industry, shipbuilding, petrochemical, metallurgy, water treatment, fire fighting, water supply and drainage, etc. The company has won unanimous recognition and praise from customers with high quality and good reputation.

Classification of the globe valves-(2)

August 12, 2020

According to the classification of purposes, the globe valve can be divided into the following types:

12 Globe-valve-4

The fluorine-lined stop valve: it is suitable for various concentrations of aqua regia, sulfuric acid, hydrochloric acid, hydrofluoric acid and various organic acids, strong acids, strong oxidants, and various concentrations of strong alkali organic solvents and other Use on corrosive gas and liquid medium pipelines.

The national standard globe valve: it is the most commonly used product in the globe valve series. The API American standard globe valve and the American standard globe valve implement ANSI and API standards. The sealing surfaces of the disc and seat are made of Stellite cobalt-based hard with different hardness. It is made of alloy surfacing, with reliable sealing, high hardness, wear resistance, high temperature resistance, corrosion resistance, good scratch resistance and long life.

Needle valve: it is a small-caliber instrument valve, which plays a role of opening and closing and precise flow control in the instrument measurement pipeline system. It mainly includes power station instrument series, oil field special series, American standard series, etc.

Cryogenic globe valve: it usually refers to the valve whose working temperature is lower than -110℃, which is widely used in LNG, LPG and other low temperature industries. Since 2008, the globe valve with a suitable temperature of -196℃ can be manufactured, and all parts are pretreated with liquid nitrogen at low temperature to completely avoid seal deformation and leakage during use.

The plunger valve: it is also known as the plunger stop valve. Its sealing surface adopts a radial sealing structure. The load exerted on the valve cover by two elastic sealing rings sleeved on the polished plunger through the connecting bolts of the valve body and the valve cover The elastic sealing ring around the plug compresses the shut-off valve for sealing.

The insulation jacket cut-off valve: it adopts the insulation jacket design, using external heat source to circulate heating outside the valve, which can effectively prevent temperature loss when the medium passes through the valve and ensure the temperature of the medium.

The forged steel globe valve: it is designed and manufactured in accordance with API 602 standards, and provides three bonnet design forms: bolted bonnet, welded bonnet, pressure self-tightening bonnet, users can choose different forms according to their needs, providing RF flanges, NPT thread, SW welding type three connection methods.

The special oxygen stop valve: it is made of silicon brass or stainless steel with excellent material, which has the advantages of high mechanical strength, wear resistance, and good safety. Used in oxygen pipelines, it has the best explosion-proof and flame-retardant performance, eliminates the unsafe factors on the oxygen pipelines, and is widely used in the pipeline network of oxygen-using projects such as steel, metallurgy, petrochemical, and chemical industries. In addition to the functions of ordinary valves, it also has its own characteristics. Strict oil prohibition measures are adopted during manufacturing, and all parts are subjected to strict degreasing treatment before installation.

The bellows stop valve: it adopts a shaped stainless steel bellows design. The bellows reciprocating test is 10,000 times without failure, and the sealing performance is reliable. It is suitable for industrial and mining with inflammable, explosive, toxic and harmful media, and can effectively prevent valve leakage.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest valve manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Details: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

Classification of the globe valves-(1)

August 12, 2020

According to the channel direction, the globe valve is devided into 4 types:

Globe valve (6)

1) Straight-through globe valve.
2) Direct flow stop valve: In direct flow or Y-shaped stop valve, the flow passage of the valve body is in a diagonal line with the main flow passage, so that the damage degree of the flow state is less than that of the conventional stop valve, so the pressure loss through the valve is also corresponding Is too small.
3) Angle type stop valve: In the angle type stop valve, the fluid only needs to change its direction once, so that the pressure drop through this valve is smaller than that of the conventional structure.
4) Plunger type globe valve: This type of globe valve is a variation of the conventional globe valve. In this valve, the disc and valve seat are usually designed based on the plunger principle. The valve clack is polished so that the plunger is connected to the valve stem, and the sealing is achieved by two elastic sealing rings sleeved on the plunger. The two elastic sealing rings are separated by a collar, and the sealing ring around the plunger is pressed firmly by the load exerted on the bonnet by the bonnet nut. The elastic sealing ring can be replaced and can be made of various materials. The valve is mainly used for “open” or “close”, but it is equipped with a special form of plunger or a special collar, which can also be used to adjust the flow .

The position of the thread on the valve stem:

1) Upper threaded stem stop valve: The thread of the stem of the stop valve is on the outside of the valve body. The advantage is that the valve stem is not corroded by the medium and is convenient for lubrication. This structure is more common.

2) Bottom thread stem stop valve: The thread of the stem of the stop valve is in the valve body. The stem thread of this structure is in direct contact with the medium, which is susceptible to corrosion and cannot be lubricated. This structure is used in places with small diameters and low temperatures.

There are many domestic manufacturers of globe valves, and most of the connection sizes are not uniform. It is mainly divided into the following categories: General category based on JB/T2203-1999 “Structural Length of Stop Valves”. At present, most domestic shut-off valve manufacturers design and produce according to this standard. However, this standard is not perfect, and the specifications are not complete. The maximum nominal diameter of a single gate valve is DN1200, and the maximum nominal diameter of a double gate valve is DN1500. According to the specifications of the shut-off valve produced by the manufacturer and the information available, the smallest nominal diameter of the angle-type shut-off valve is DN15, and the nominal diameter of the Z-type straight-through shut-off valve reaches DN2000. After research, the connection size of each manufacturer is not uniform. In order to have a unified standard, users can interchange the same specifications when selecting and installing, it is recommended that China General Machinery Research Institute revise JB/T2203-1999 “Structural Length of Stop Valves”. It is recommended that the design institute and users choose according to the standard, and the stop valve manufacturer should design and manufacture according to the standard.

The working principle and characteristics of the globe valve

August 12, 2020

The globe valve is a tool that relies on the pressure of the valve stem to make the sealing surface of the disc and the sealing surface of the valve seat tightly fit to prevent the flow of the medium. It is a forced sealing valve and is one of the most widely used valves.

According to the direction of the passage, the globe valve is divided into four types: straight-through globe valve, direct-flow globe valve, angle globe valve and plunger globe valve.
1. Working principle of globe valve:

Globe valve (9)

The stop valve, also called the cut-off valve, is one of the most widely used valves. The reason why it is popular is that the friction between the sealing surfaces is small during the opening and closing process, which is relatively durable, has a small opening height, and is easy to manufacture. , Easy maintenance, not only suitable for medium and low pressure, but also suitable for high pressure. The closing principle of the shut-off valve is to rely on the pressure of the valve stem to make the sealing surface of the disc and the sealing surface of the valve seat closely fit, preventing the flow of the medium. Our country’s valve “Sanhua” once stipulated that the flow direction of the stop valve should be from top to bottom, so there is directionality when installing. The structural length of the shut-off valve is longer than that of the gate valve, and the fluid resistance is large, and the sealing reliability is not strong during long-term operation.

As one of the most important cut-off valves, the globe valve plays an important role in the aerospace field. As an important component of aerospace equipment, the shut-off valve realizes the functions of medium transportation, cut-off, and adjustment, and its sealing performance directly affects the safe and reliable operation of aerospace equipment. Studying the influencing factors and influencing rules of the sealing characteristics of typical globe valves has guiding significance for the structural design of the valve sealing pair, thereby improving the sealing performance and reliability of the valve.

2. Globe valve characteristics:

The valve plays an important role in cutting off and throttling the medium in the pipeline. As an extremely important cut-off valve, the valve is sealed by applying a torque to the valve stem, and the valve stem is in the axial direction. The valve clack applies pressure to make the sealing surface of the valve clack closely fit the sealing surface of the valve seat, and prevent the medium from leaking along the gap between the sealing surfaces.

The sealing pair of the globe valve is composed of a valve flap sealing surface and a valve seat sealing surface, and the valve stem drives the valve flap to move vertically along the center line of the valve seat. During the opening and closing process of the globe valve, the opening height is small, the flow is easy to adjust, and the manufacturing and maintenance are convenient, and the pressure application range is wide.

Compared with another commonly used shut-off valve in industrial production, an alarm valve, the shut-off valve is simpler than the former in terms of structure, and is easy to manufacture and maintain. In terms of service life, the sealing surface of the globe valve is not easy to wear and scratch. During the opening and closing process of the valve, there is no relative sliding between the valve disc and the sealing surface of the seat, so the wear and abrasion of the sealing surface are small, so the sealing is improved. During the full closing process of the auxiliary service life stop valve, the disc stroke is small, and its height is relatively small compared to the alarm valve. The shortcoming of the globe valve is that the opening and closing torque is large and it is difficult to achieve rapid opening and closing. Because the flow passage in the valve body is relatively tortuous, the fluid flow resistance is large, and the fluid power is lost in the pipeline.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Posts

Comparison of bellows globe valve and ordinary globe valve

Classification of the globe valves-(2)

Classification of the globe valves-(1)

The working principle and characteristics of the globe valve

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