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Understanding of welded globe valves

2020-12-05 15:25:18
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The Welded stop valve The opening and closing part of the valve disc is plug-shaped, the sealing surface is flat or conical, and the valve disc moves in a straight line along the fluid center line. There are lifting rod type (the valve rod rises and falls, and the hand wheel does not rise and fall), and there are also lifting and rotating rod type (the hand wheel and the valve rod rotate and lift together, and the nut is located on the valve body).

Globe valve It mainly belongs to the national compulsory sealing design valve, so when the valve is automatically closed, a certain pressure must be applied to the valve disc to force the sealing surface not to leak. When the medium begins to enter valve 6 from the bottom of the valve disc, the resistance we need to overcome is the friction force between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the diameter of the valve stem should be larger, otherwise the valve stem will be bent. In recent years, since the emergence of self sealing valve enterprises, the medium flow direction of the stop valve changes from the top of the valve disc into the valve chamber. Under the influence of the medium working pressure, the force to close the valve is small, but the force to open the valve is large. The diameter of the valve stem can be reduced correspondingly. At the same time, under the interaction of media, the valve of this teaching form is also more strict. In China, the "top-down" valve was used.

The type of globe valve is divided into external thread type and internal thread type according to the position of stem thread. According to the flow direction of the medium, there are straight through, direct current and angle. The stop valve is divided into sealing form, packing sealing stop valve and bellows sealing stop valve.

 Welded stop valve

Installation and maintenance of stop valve

The bellows globe valve operated by hand wheel and handle can be installed in any other position of a pipeline.

Handwheel, handle and mechanism shall not be used for lifting.

The flow direction of the medium should be consistent with the arrow direction shown on the valve body.

When the stop valve is opened, the opening height of the disc is 25% ~ 30% of the nominal diameter, and the flow rate has reached a large level, indicating that the valve has reached the full open position. Therefore, the full open position of the globe valve shall be determined by the stroke of the disc.

The globe valve has the following advantages:

1. The structure is simple, and the manufacture and maintenance are convenient.

2. Small working stroke, short opening and closing time.

3. Good sealing performance, small friction force between sealing surfaces and long life cycle.

The disadvantages of the stop valve are as follows:

1. The flow resistance of the fluid is large, and the force required for opening and closing is large.

2. It can be used in the medium with particles, high viscosity influence and easy coking.

3. Poor regulation performance.

The type of globe valve is divided into external thread type and internal thread type according to the position of stem thread. According to the flow direction of the medium, there are straight through, direct current and angle. The stop valve is divided into sealing form, packing sealing stop valve and bellows sealing stop valve.

Installation of stop valve and safety precautions:

The handwheel and stop valve can be installed in any position.

2. Do not use handwheel, handle and mechanical device for lifting.

Medium 3. The flow direction should be consistent with the arrow direction shown in the valve body.

Structural features of stop valve:

1. Different pressure self tightening sealing system structure is adopted in the valve middle chamber, and the sealing performance is getting better and better

2. The sealing surface design of valve disc and valve seat is made of Stellite cobalt base cemented carbide by spray welding, which has good wear resistance, high temperature resistance, corrosion resistance, scratch resistance and good performance

3. High temperature creep resistance design

4. The valve rod adopts an integrated forging enterprise structure. After quenching and tempering and surface nitriding treatment, it has good corrosion resistance and scratch resistance

5. The depth of the filling function of the cover is reasonable, the packing is added with anti-corrosion agent, and the sealing is reliable.

It is suitable for cutting off or connecting the working medium on the pipes of high pressure water, steam, oil products and overheated steam produced by high temperature water and metallurgy in thermal power plants, universities of petroleum, chemical engineering, metallurgy, etc.

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Jiangsu Zhonghe Valve Co., Ltd

Service hotline: 0515-87282699

Fax: 0515-87939900

E-MAIL :zhonghe_ valve@163.com

Address: a2202, No. 99, Shehe East Road, Funing County, Jiangsu Province

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