Several problems should be paid attention to in the application of valve lined with fluorine plastic anti-corrosion valve according to the on-off nature of medium

Several problems should be paid attention to in the application of valve lined with fluorine plastic anti-corrosion valve according to the on-off nature of medium

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Gate valves
Gate valve is used as a cut-off medium, the whole flow through when fully open, the pressure loss of the medium running at this time is minimized. Gate valves are usually suitable for operating conditions that do not require frequent opening and closing, and keep the gate fully open or fully closed. Not intended for use as a regulator or throttling. For THE HIGH speed flow MEDIUM, THE gate CAN cause the gate vibration in the condition of local opening, and the vibration may damage the sealing surface of the gate and seat, and the throttle will cause the gate to suffer from the erosion of the medium. From the structural form, the main difference is the form of the sealing element used. According to the form of sealing elements, gate valves are often divided into several different types, such as wedge gate valves, parallel gate valves, parallel double gate valves, wedge double gate gates, etc. The most commonly used form is wedge gate valve and parallel gate valve.
Globe valve
The stem axis of the globe valve is perpendicular to the sealing face of the seat. The RELATIVELY SHORT STEM OPENING OR CLOSING TRAVEL AND VERY RELIABLE CUT-OFF ACTION MAKE THIS VALVE IDEAL FOR MEDIUM CUTTING OR REGULATING AND THROTTLING USE.
Once the disc of the globe valve is in the open condition, it is no longer in contact between the seat and disc sealing surface, and has a very reliable cut off action, fit this valve is very suitable for cutting off or regulating and throttling the use of the medium.
Once stop valve is fully open, it will no longer have a contact between the seat and clapper sealing surfaces, and thus its sealing surface mechanical wear and tear is small, because most of the cut-off valve seat and valve disc is easy to repair or replace the whole valve sealing components without removed from the pipeline, for the valve and pipeline welding into one occasion is very applicable. The flow direction of the medium through this valve has changed, so the flow resistance of the globe valve is higher than that of other valves.
Commonly used globe valve has the following kinds: 1) Angle globe valve; In an Angle globe valve, the flow changes direction only once so that the pressure drop through the valve is smaller than in a conventional globe valve. 2) straight flow stop valve; In A STRAIGHT FLOW OR Y-SHAPED GLOBE VALVE, THE FLOW PATH OF THE BODY IS DIAGONAL TO the MAIN flow, so that the damage to the flow state is smaller than in a conventional globe valve, and the pressure loss through the valve is correspondingly smaller. 3) plunger globe valve: this form of globe valve is a variation of the conventional globe valve. In this valve, the disc and seat are usually designed based on the plunger principle. The disc is polished into a plunger connected to the stem, and the seal is achieved by two elastic sealing rings on the plunger. The TWO ELASTIC RINGS ARE SEPARATED BY A SLEEVE RING AND THE RING AROUND THE plunGER IS COMPRESSED BY a LOAD APPLIED TO THE COVER BY THE COVER NUT. The FLEXIBLE SEAL RING CAN BE REPLACED AND CAN BE MADE OF A WIDE VARIETY OF MATERIALS. The valve is mainly used for opening or closing, but is equipped with a special form of plunger or special sleeve ring and can also be used to regulate flow.
Butterfly valve
The butterfly plate of the butterfly valve is installed in the diameter direction of the pipe. In the cylindrical channel of the butterfly valve body, the disc shaped butterfly plate rotates around the axis, the rotation Angle is between 0 and 90, rotate to 90, the valve brand is fully open.
Butterfly valve simple structure, small volume, light weight, only a few parts. And only need to rotate 90 can quickly open and close, simple operation, at the same time the valve has good fluid control characteristics. When the butterfly valve is in the fully open position, the thickness of the butterfly plate is the resistance when the medium flows through the valve body, so the pressure drop generated by the valve is small, so it has better flow control characteristics. Butterfly valve has two types of seal and metal seal. Elastic seal valve, sealing ring can be mounted on the body or attached to the butterfly plate around.
The valve with metal seal is generally longer than the valve with elastic seal, but it is difficult to achieve complete seal. Metal seals can adapt to higher working temperatures, and elastic seals have defects limited by temperature.
If a butterfly valve is required to be used as a flow control, it is important to correctly select the valve size and type. Butterfly valve structure principle is especially suitable for the production of large diameter valve. Butterfly valve is not only used in petroleum, gas, chemical, water treatment and other general industries, but also used in the cooling water system of thermal power stations.
The commonly used butterfly valve has two kinds of butterfly valve and flange butterfly valve. The wafer butterfly valve is connected between the two pipe flanges with a double bolt, flange butterfly valve is a valve with a flange, with bolts on both ends of the valve flange connected to the pipe flange.
Ball valve
Ball valve is evolved from the plug valve. It has the same rotation of 90 degrees lift action, the difference is that the plug body is a sphere, with circular through holes or channels through its axis. The RATIO OF THE SPHERE TO THE CHANNEL OPENING SHOULD BE SUCH THAT WHEN THE BALL IS ROTATED BY 90 DEGREES, THE SPHERE SHOULD APPEAR AT BOTH THE INLET AND outlet, THUS CUTTING OFF THE flow.
Ball valves require only a 90 degree rotation and a small rotational moment to close tightly. Completely equal valve body cavity for the medium provides little resistance, straight through the flow channel. It is usually thought that ball valves are most suitable for direct open and close use, but recent developments have been designed to make it with throttling and flow control. The main feature of ball valve is its compact structure, easy operation and maintenance, suitable for water, solvents, acids and natural gas and other general working media, but also suitable for poor working conditions of media, such as oxygen, hydrogen peroxide, methane and ethylene. Ball valve body can be integral, can also be combined.
Abstract: The reasonable selection and application of fluorine lined plastic anti-corrosion valve is the project of everyone’s concern. We put forward the following precautions according to the majority of users’ experience in field application for many years, for your reference.
Key words: valve, fluorine lined plastic valve
Fluorine lined plastic anti-corrosion valve in petroleum, chemical industry, medicine, metallurgy, electric power and other industries contact acid and alkali and other strong corrosive media device has been the best application, but how to choose a good, good use of fluorine lined plastic valve, according to our users over the years of field application experience, The following precautions should be put forward for the use of the medium temperature, pressure, pressure difference and other conditions when the fluorine lined anti-corrosion valve is selected:
1, fluorine lined plastic valve medium temperature: Our company’s various types of fluorine lined plastic valves, the use of fluorine plastic is F46 (FEP), the use of medium temperature can not exceed 150℃ (medium temperature can be 150℃ for a short time, long time use temperature should be controlled in 120℃), otherwise, the valve components lining F46 easy to soften, deformation, resulting in the valve closed undead, large leakage.
If the temperature of the medium used is below 180℃ for a short time, and the temperature is below 150℃ for a long time, another kind of fluorine plastic – PFA can be selected, but the lining of PFA fluorine plastic is more expensive than the lining of F46 in price.
2, do not have negative pressure. Fluorine lined plastic valve should avoid the use of negative pressure in the pipeline, if there is negative pressure, easy to cause the fluorine lined plastic layer in the valve cavity is sucked out (drum out), peeling, leading to valve opening and closing failure.
3, the pressure, pressure difference should be controlled in the permissible range. Especially bellows seal lined fluorine plastic regulating valve, globe valve. Because the bellows are made of tetrafluoric materials, the pressure and pressure difference are large, which can easily lead to the rupture of the bellows.
Bellows seal lined fluorine plastic regulating valve, the use of condition pressure, pressure difference is large, can be changed to PTFE packing seal.
4. The medium condition of fluorine lined plastic valve should not have hard particles, crystals, impurities, etc., so as not to wear out the valve core and valve seat lined fluorine plastic layer or PTFE bellows in the operation of opening and closing. The medium has hard particles, crystals, impurities, selection, spool, seat can be used to Hastelloy.
5, lined with fluorine plastic regulating valve should be according to the required flow (Cv value) correct selection of valve diameter size. When choose, should according to the need of traffic (Cv) and other technical parameters are calculated the valve size should be chosen and the opening of the valve, such as valve’s size too big, certainly will makes the valve in the opening for a long time running, under the condition of rather smaller and medium pressure, so easy to make the valve core and valve rod by the impact of the media and make the valve vibrates, The valve core rod in the medium for a long time under the impact, even will make the valve stem fracture.
Users in the selection of all kinds of fluorine lined plastic valves, should be as far as possible to understand, master the use of technical conditions, in order to select, use well, improve the service life of the valve. When it is beyond the scope of technical conditions, it should be proposed to the manufacturer, and the corresponding countermeasures should be taken to solve the problem through joint consultation.


Post time: Aug-08-2022

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