Production of large-diameter national standard flange corrugated pipe globe valve globe valve

1WJ41HLarge caliber national standard flange corrugated pipe globe valveOverview

In petroleum and chemical facilities, corrugated pipe globe valves are often used in pipelines to prevent the leakage of harmful, toxic, or flammable liquid media. However, due to the long stroke of the bellows, the large-diameter bellows globe valve is prone to instability during use, resulting in friction between the inner wall of the bellows and the valve stem, which affects the service life of the bellows. In addition, the flat key that guides the axial movement of the valve stem and prevents the valve stem from rotating often increases the vertical axial shear stress due to excessive valve opening, which is prone to damage. A new type of large-diameter corrugated pipe globe valve was designed based on the working conditions. After analyzing the problems with the valve, improvements have been made to its structure, operation, and environment. Firstly, increase the limit welfare fee for flat key I by adding a 3mm thick stainless steel packing pad to the PTFE material's lower packing to prevent the packing from becoming dirty and limiting the valve stem.

When the valve is closed, if it cannot be closed, it should not be forcefully closed with force. Instead, the valve should be opened, flushed with fluid for a period of time, and then closed again. If it still cannot be closed, the grinding sealing surface should be checked. When the valve is opened, when the valve reaches a certain height and the valve stem encounters small resistance, try not to continue forcibly opening to extend the life of the valve stem and its sealing components. When installing a globe valve with a thrust ball bearing on the upper part of the valve stem, it is important to avoid direct condensation water dripping onto the valve stem, which can cause rusting of the valve stem.

2. Structural characteristics

The large-diameter bellows globe valve is mainly composed of valve body, valve disc, valve stem, bellows, and valve cover with packing box. An extension pipe is connected between the valve body and the valve cover with bolts to form an elongated valve chamber. The lower part of the valve stem is located inside the valve chamber, and its end is fixed to the valve disc with a split nut. The upper part of the valve stem passes through the packing box on the valve cover, and the external threaded part of the upper end of the valve stem engages with the valve stem nut. The valve stem nut is fixed in the seat hole on the upper part of the valve cover with bearings and bearing covers. The handwheel is fitted with a square hole and the square head of the valve stem nut. The lift of the valve stem is limited by the cap. The cap is connected to the top of the valve stem nut with internal threads, and the cap, valve stem nut, and handwheel are locked and fixed together with a round nut that meshes with the external threads on the cap. The packing is placed inside the packing box and pressurized by the packing cover to maintain the original packing seal of the shut-off valve and prevent leakage of the liquid flow medium.

The corrugated pipe is composed of two ordinary stroke corrugated pipe components welded in series and installed in the valve chamber. The end face ring of the upper corrugated pipe is welded to the connecting flange, which is clamped between the valve cover and the connecting surface of the extension pipe with a sealing gasket. The end face rings of the two corrugated pipes are welded together. The other end of the lower corrugated pipe is welded to the lower part of the valve stem to prevent leakage of liquid medium from the corrugated pipe. This not only increases the stroke of the valve stem, but also prevents individual bellows from twisting and becoming unstable due to excessive stroke, avoiding damage to the bellows wall. A flat key is installed between the valve stem and the valve cover to guide the valve stem to only move up and down axially when rotating the handwheel, and cannot rotate.

The WJ41H bellows globe valve adopts a bellows structure inside, and the lower end of the stainless steel bellows is welded to the valve stem to prevent process fluid from corroding the valve stem. The other end is placed between the valve body and the valve cover to form a static seal. Adopting a dual sealing design, if the bellows fails, the valve stem packing will also prevent leakage. The bellows is welded to the valve stem to maintain stable operating performance and avoid valve stem vibration caused by valve plug vibration. Suitable for pipelines containing steam, flammable, explosive, thermal oil, high-purity, toxic and other media.

WJ41HLarge caliber national standard flange corrugated pipe globe valvePerformance characteristics:

① The key component of the bellows globe valve is the metal bellows. The lower end is automatically roll welded to the valve stem assembly, and the upper end is automatically roll welded to the connecting plate, forming a metal barrier between the fluid medium and the atmosphere to ensure zero leakage of the valve stem;

② The valve disc adopts a conical design, and the sealing surface forms a flow line with the medium, resulting in better sealing performance and longer service life;

③ Double sealing design (bellows+packing): If the bellows fails, the valve stem packing will also prevent leakage and comply with international sealing standards;

④ The valve cover comes with a grease fitting, which can directly lubricate the valve stem, nut, and shaft sleeve, unlike traditional methods that only lubricate the threads;

⑤ Ergonomic design of the handwheel ensures longer service life, easy and convenient operation, and greater safety and reliability.

3、WJ41HLarge caliber national standard flange corrugated pipe globe valveperformance

The large-diameter bellows globe valve (DN150, PN64) is a valve that adds a bellows component to the valve stem of a regular globe valve chamber to prevent valve stem sealing failure. The bellows seal and packing seal work together to form a dual seal, ensuring the reliability of the axial dynamic seal. The packing is prone to leakage during long-term use. In the design, a loading packing compression mechanism is used to make the sealing of the packing more durable and reliable. The large-diameter corrugated pipe globe valve adopts a series connection of two corrugated pipes, which not only ensures the travel requirements but also prevents the instability of the corrugated pipes. In order to prevent the bellows from twisting during valve opening and closing, an anti rotation flat key is installed on the valve stem. The flat key has both anti rotation and guiding functions. During the valve opening process, the flat key is subjected to both horizontal shear stress in the anti rotation direction and vertical shear stress in the limited position direction, making it highly susceptible to damage. Therefore, a cap nut is added to the top of the valve stem to limit the valve opening position and reduce the stress on the flat key.

Adopting a dual sealing design, if the bellows fails, the valve stem packing will also prevent leakage. The bellows is welded to the valve stem to maintain stable operating performance and avoid valve stem vibration caused by valve plug vibration. Suitable for pipelines containing steam, flammable, explosive, thermal oil, high-purity, toxic and other media. Suitable for flammable, explosive, highly toxic, toxic fluids, high-temperature heat transfer oils, liquid ammonia and other media with a nominal pressure of PN1.6~16MPa and a working temperature of -29~350 ℃. Widely used in other gas systems such as petrochemicals, chemical fiber textiles, plastic papermaking, power steel, printing and dyeing rubber, natural gas, etc., with safe and reliable performance, it is widely used in industrial fluids such as ethylene glycol. The driving methods include manual, gear transmission, electric, pneumatic, etc. The product structure is reasonable, the sealing is reliable, and the double sturdy and durable corrugated pipe sealing design (corrugated pipe+packing) ensures zero leakage of the valve stem. No fluid loss, improving factory equipment safety. And comply with international sealing standards. The sealing surface is welded with Co based hard alloy, which has good wear resistance, corrosion resistance, friction resistance, and long service life. The valve stem undergoes quenching and surface nitriding treatment, exhibiting excellent corrosion resistance and friction resistance; Valve stem lifting position indication, more intuitive.

WJ41HLarge caliber national standard flange corrugated pipe globe valveManufacturing standards:

Product performance specifications:

Note: The series valve connection flange can be designed and manufactured according to user requirements

1.6MPa main external connection dimensions and weight:

Main external connection dimensions and weight of 2.5 MPa:

Main external connection dimensions and weight of 4.0 MPa:

4、WJ41HLarge caliber national standard flange corrugated pipe globe valveConclusion

The large-diameter corrugated pipe globe valve solves the problem of pipe wall wear caused by the instability of corrugated pipes with long stroke by using a combination of corrugated pipes, and also solves the problem of eliminating vertical shear stress in the flat key axis. After the improvement of the bellows globe valve, there were no further malfunctions such as bellows cracking, valve stem rusting, or leakage, and the usage was good. The bellows globe valve adopts a bellows structure inside, and the lower end of the stainless steel bellows is welded to the valve stem to prevent the process fluid from corroding the valve stem. The other end is placed between the valve body and the valve cover to form a static seal. Adopting a dual sealing design, if the bellows fails, the valve stem packing will also prevent leakage. The bellows is welded to the valve stem to maintain stable operating performance and avoid valve stem vibration caused by valve plug vibration. Suitable for pipelines containing steam, flammable, explosive, thermal oil, high-purity, toxic and other media. Before installation, please check the installation and maintenance guide, nameplate, and technical information to determine if this product is suitable.

3.1 Check the materials, pressure, temperature, and their values to ensure that the operating limits are below the system's conditions. The system should also include safety devices to prevent overpressure.

3.2 Remove the cover plate from the connection port.

3.3 Install the globe valve in the direction of the arrow shown on the valve body. Place the valve stem in a vertical direction, and the valve can be installed in a horizontal or vertical plane.

3.4 Important Reminder: After installing the balance valve core, the valve should be installed so that the upstream fluid enters the valve chamber on the valve body first, and the fluid pressure acts on the upper part of the balance valve core, which is opposite to the usual installation direction. If the standard valve is replaced or the balance valve core is installed, the flow direction of the valve needs to be turned 180 degrees, and a new flow arrow should be marked on the valve body to indicate the new flow direction.

The valve cannot be installed upside down.

What is a balance valve core and how does it work?

A balanced valve core is a two pole switch system (as shown in Figure 6). The small valve (A) acts as a pilot valve and opens first during operation, allowing fluid to enter downstream at a certain speed. The pressure difference between the upstream and downstream of the valve gradually decreases, making it easy for the main valve to lift off the valve seat. To assist in valve closure, the fluid medium should first flow towards the upper valve chamber, which is opposite to the usual flow direction. This device is mainly used to assist in closing large-diameter valves. For shut-off valves with large diameters or large pressure differentials, the normal flow direction will make it difficult for the valve to close. By changing the flow direction and installing a small valve (A), this problem can be easily solved. For valves of different diameters, when the pressure difference between the upstream and downstream of the system exceeds the values listed in the table below, a balancing valve core must be used, otherwise the valve cannot be closed.

In the steam system pipeline, a steam drain valve should be installed nearby upstream of the valve to ensure that the condensed water in the pipeline can be discharged normally when the valve is closed, and to prevent water hammer damage to the valve. You can choose float or thermal power drain valves, which are also crucial for the drain valves of the entire steam system pipeline. DN125

When opening the shut-off valve, it must be operated slowly to avoid system vibration.

3.7 Note: When performing maintenance operations downstream of the globe valve, two globe valves should be installed (with a relief valve installed between the two valves) to ensure safety. If the valve is the last valve on the pipeline, for safety reasons, a blind flange should be installed at the valve outlet.

5.1 The bellows sealed globe valve eliminates the frequent leakage of valve stem packing seal and plays an important role in energy conservation.

5.2 The valve is manually operated through a handwheel, and attention must be paid to the correct direction of movement of the valve stem during operation.

To fully open the valve, simply turn the handwheel to lift the valve stem to position (the valve position indicator on the stem is level with the "+" on the valve cap), then turn it clockwise 1/8 to 1/4 turn to eliminate recoil and prevent damage to the valve stem, bellows, and other components caused by attempting to open the valve again when it is already in the fully open position.

There are two positions on the stem of the Speisak bellows sealed globe valve ("+" indicates fully open valve; "1" indicates fully closed valve).

5.3 If using a handle for operation, be careful not to apply too much force, otherwise it may cause valve damage.

The 5.4 model with a throttle valve core can be used for throttle control. The number of turns the handwheel rotates will affect the flow. When the required flow rate is obtained, tighten the locking screw and travel limiter. This can reduce the vibration of the valve and the relationship between the number of turns of the handwheel of each caliber valve and the flow rate.

All internal components of the bellows sealed globe valve can be replaced (see Part 7, Spare Parts)

Attention: Please carefully read the safety information in Chapter 1 before maintenance.

Warning: The valve body gasket contains a thin stainless steel support ring, which may cause personal injury if not handled carefully.

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