KR900005736B1 - Plug valve and method of its lining using four inert ethylene-resin - Google Patents

Abstract

The direct lining method of inner side of a plug valve using a 4- fluoroethylene resin consists of: that a rubber bag and core are inseted into the plug valve body and a cover flange and pressing plate are inserted; that 4-fluoroethylene resin powder fills up between the rubber bag and the valve body and top cover is inserted; that the resin powder is oppressed in the waterpressure vessel at 180-350 kg/cm2 for 20-40 min; after putting out from the water- pressure vessel, removing the top cover, assistant ring, pressing plate, cover flange, core and rubber bag; heating in an electric furnance upto 380≰C of heating ratio 40≰C/hr. for 4 hrs.; and the valve body is cooled at room temp..

Description

Lining method of plug valve and ethylene tetrafluoride inside the valve

1 is a cross-sectional view of a tetrafluoroethylene resin tube inserted into a valve body according to a conventional blow molding method using compressed air.

FIG. 2 is a cross-sectional view of the tube in FIG. 1 in which both ends of the tube are flared to a flange which is attached to the valve body, and then the tube is expanded by blowing compressed air.

3 is a cross-sectional view of the tube being expanded according to the blow molding method and then flared at the upper portion of the middle of the valve body.

4 is a cross-sectional view of a valve body for direct lining in accordance with the present invention.

5 is a cross-sectional view of a state in which a rubber bag and a core are mounted on a casting body for direct lining and then ethylene tetrafluoride is filled between the rubber bag and the housing.

6 is a sectional view of a state in which preparations are completed.

7 is a cross-sectional view of a tetrafluoroethylene resin formed directly on the valve body by applying water pressure in a hydraulic container.

8 is a valve body completed by lining directly with ethylene resin according to the present invention.

9 is a final assembly cross-sectional view of a valve made according to the direct lining method.

* Explanation of symbols for main parts of the drawings

20: rubber bag 21,22: core

25,25 ': Auxiliary ring 26: Cover flange

27: press plate 28: top cover

The present invention relates to a method of directly lining the inner surface of a plug valve with tetrafluoroethylene resin. Valves used to control the transfer of liquids and gases in pipes and containers, particularly those used in the chemical industry, require excellent chemical resistance and stability, and various methods have been developed in the past to improve corrosion resistance and improve stability.

That is, a conventional blow molding method has been used in which the tetrafluoroethylene ethylene resin lining method is formed by sintering the resin into a separate tube and then inserting the resin into an inner surface of the valve body to blow compressed air to expand the tube. Due to the excessive expansion of the diameter of the tetrafluoroethylene ethylene resin tube, the inherent physical properties of the tetrafluoroethylene resin may be changed. In particular, since the lining thickness after the expansion is thinned to about 1 mm, the airtightness, which is the main role of the valve, is inferior. Since gaps cannot be prevented between and the tetrafluoroethylene resins, there are disadvantages such as separation or rupture of the lined tetrafluoroethylene resins at the negative pressure.

An object of the present invention is to solve the problems of the blow molding method using the compressed air to improve the productivity by closely contacting the resin on the inner surface of the valve to improve the productivity and the quality and life span of the tetrafluoroethylene fluorinated resin direct lining method Is to provide.

Various features and advantages of the present invention will be apparent from the detailed description of the direct lining method according to the present invention with reference to the accompanying drawings. A blow molding method according to the related art will be described with reference to FIGS. 1, 2, and 3.

FIG. 1 shows a separately molded and sintered tetrafluoroethylene fluorocarbon resin tube 102 for lining inside the valve body 101.

In FIG. 2, a flaring process is performed in which the end of the resin tube is extended from the flange portion of the valve to closely contact the flange surface. Then, the cover flange 103 and the housing upper side are formed on both sides. In the state that the top cover (104) is filled in the valve body 101 and the tube 102 is heated to blow compressed air to show the tube is expanded in the housing. After blown up as shown above, the cover flange and the top cover are disassembled and the end of the blow molding operation is completed by flaring the end of the resin in the housing part. The conventional blow molding operation exposes various disadvantages. The drawbacks of this drawback are firstly, it takes a lot of processes and takes a lot of time. Second, the tetrafluoroethylene ethylene resin tube must be molded separately, but the size of the inner surface of each valve body is different, so the tube must be shaped (processed) in proportion to it. Third, in order to make tubes of each size, there must be a mold for each size. Fourth, the tube should be accurate in size and diameter, have no flaws on the surface, and if there is a flaw, cracks will occur during expansion, which will greatly reduce the yield of the product. Fifth, in order to blow molding, cover flange and top cover should be filled to prevent air leakage and heat should be applied to valve body and tube. Sixth, there were many disadvantages such as deterioration of product quality due to the change of physical properties when the tube was expanded in the housing.

4 shows a valve body for direct lining of tetrafluoroethylene resins in accordance with the present invention. It should be noted here that the groove 4 having a diameter slightly larger than the diameter of the housing inner surface at any position along the housing circumferential direction is formed on the housing inner surface of the valve body. The shape of the groove is not limited, and the number of grooves may be one or two places or more above and below the housing, and the position may be selected to be easy to process when manufacturing the valve body.

The groove 4 is formed in the valve body to improve the adhesion between the resin and the valve body in the state where the resin is lined. As a result, the temperature change, By repeating various bad conditions such as pressure change and chemical change, it is possible to prevent the lining resin from being separated or ruptured from the valve body.

5 to 7 illustrate a method and process for the direct lining of tetrafluoro ethylene resins in accordance with the present invention. The direct lining method of the present invention will be described in the order shown. The valve body should not be pre-drilled with bolt holes 9 in both flanges (2, 2) and should not leak from the housing or flange when hydraulic pressure is applied.

The rubber bag 20 is inserted into the valve body, and then a center core 21 and a side core 22 are put thereinto be fixed and assembled with screws 23. At this time, ethylene tetrafluoride resin is not formed even if the water is slightly swelled, so it is stretched when water pressure is applied and elastic rubber is restored to its original shape when water pressure is removed, and a rubber bag 20 can be used to prevent leakage. , 22 should be formed a plurality of passages (24) so that the hydraulic pressure acts on the rubber bag (20).

After the cores 21 and 22 are assembled, attach the auxiliary rings 25 to both flanges 2 and 2 so that the wide ends of the rubber bags cover the auxiliary rings 25, and then cover flanges 26 and 26 and the pressing plate ( 27) and attach the auxiliary ring (25 ') to the upper part of the valve body to retract the wide side of the rubber bag (20), and then place ethylene tetrafluoroethylene powder (P) in the space between the rubber bag (20) and the valve body. To charge (figure 5). After the resin powder is completely filled, the wide end of the rubber bag 20 is connected to the auxiliary ring 25 'and the top cover 28 using the bolt 30 and the bottom cover 29 having a tap. Once assembled, preparations for lining the valves directly in accordance with the invention are shown, which is shown in FIG. Reference numeral 50 denotes a packing ring, 51 a plug, and 52 a handle.

When the valve body thus prepared is placed in the hydraulic container 40 as shown in FIG. 7, and the pressure is applied, the pressure of each of the rubber bags 20 is increased through several passages 24 formed in the cores 21 and 22. The rubber bag 20 evenly applied to the part and stretched by this water pressure compresses the resin powder P, so that the resin is pressed firmly or uniformly onto the valve body. At this time, the water pressure during compression is compressed at a constant water pressure for 20 minutes to 40 minutes at 180kg / cm2 to 350kg / cm2, of which the most suitable condition is to maintain 30 minutes under the pressure of 300kg / cm2. It is revealed by the result. Hold for about 30 minutes and then gradually reduce the pressure and take it out of the hydraulic container.The top cover (28), bottom cover (29), auxiliary ring (25 '), pressing plate (27), cover flange (26, 26), auxiliary ring (25), the screw 23 of the center core 21 and the side core 22 is unscrewed and removed, and finally, the rubber bag 20 is removed to complete the crimping operation of the ethylene resin on the valve body. The valve body, which has been pressed for resin, is heated in an electric furnace at a rate of 40 ° C per hour, heated until it reaches 380 ° C, held at this temperature for 4 hours, and taken out of the electric furnace.

After the above process, the temperature is cooled to room temperature and molding sintering is completed.

Then, the bolt holes 9 are drilled in the flanges 2 and 2 to finish the flared surface of the resin, and the valve body is processed according to the direct lining method as shown in FIG. 8. In FIG. 8 shows a plug valve completed by assembling a plug to the valve body in which the processing in FIG. 8 is completed.

As described above, the direct lining method of the present invention not only simplifies the manufacturing process but also stably completely adheres the resin to the valve, compared to the blow molding method in which the conventional resin is separately molded and sintered into the valve body and expanded. It can be seen that it is a lining method that can improve the quality, greatly reduce the loss of product, and make the product with superior quality and life.

Claims (5)

Inserting the rubber bag and the forming core into the plug valve body, attaching the auxiliary ring to both flanges so that the wide end of the rubber bag covers the auxiliary ring, and then fitting the cover flange and the pressing plate; Attaching the auxiliary ring to the upper part of the valve body, filling the space between the rubber bag and the valve body with ethylene tetrafluoride powder and allowing the wide end of the rubber bag to cover the auxiliary ring after the filling time; Putting the prepared valve body in a hydraulic container to press the resin powder at a constant water pressure for 20 to 40 minutes at 180 kg / cm 2 to 350 kg / cm 2; Removing the top cover, auxiliary ring, pressing plate, cover flange, auxiliary ring, core, and rubber bag from the hydraulic container; Putting in an electric furnace to raise the temperature at a rate of 40 ° C. per hour, heating to 380 ° C. and maintaining at this temperature for about 4 hours; Direct removal of the ethylene tetrafluoride ethylene resin on the inner surface of the plug valve comprising the step of taking out of the electric furnace to return the temperature of the valve body to room temperature in the atmosphere. The method as claimed in claim 1, further comprising a step of drilling a bolt hole in the flange face of the valve body in which the molding and sintering is completed, and finishing the resin flare face. The tetrafluorinated ethylene resin direct lining method according to any one of claims 1 and 2, wherein the hydraulic pressure of the hydraulic container is raised to 300 kg / cm 2 and maintained for 30 minutes. The plug according to any one of claims 1 to 2, wherein the valve body to be directly lined forms a groove having a diameter slightly larger than the diameter of the inner surface of the housing at a position along the circumferential direction of the housing. Method for direct lining of tetrafluoroethylene resin inside the valve. And a groove having a diameter slightly larger than the diameter of the inner surface of the housing at any position along the circumferential direction of the housing of the valve body.

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