RU2165046C1 - Method of protection of ball cocks against wear - Google Patents

Abstract

FIELD: gas, chemical and other industries; repair and reconditioning of ball cocks. SUBSTANCE: method consists in introducing sealing polymer paste into ball cock sealing unit followed by delay for completion of polymerization process. This paste is introduced into cavity of cock under pressure through drain pipe union when cock is placed in OPEN position forming the sealing ring-envelope in clearance between surface of sphere, cock body and seats in the course of polymerization of sealing paste. EFFECT: reduced wear of parts in "seat- sphere" contact area; increased service life of ball cocks. 2 cl, 4 dwg

Description

 The invention relates to valves, in particular to the technology of repair and recovery of ball valves, and can be used in gas, chemical and other industries, including technological communications of gas production and gas transmission systems.

A known method of protection against wear of ball valves, based on the introduction of a sealing paste in the seal nodes of the ball valve (see A. Bolshakov and other pilot industrial repair of ball valves. - Gas industry, 1998, N 12.)
The specified method does not provide for the elimination of leaks in shutoff valves for a long time, since restoring the tightness of the shielded part of the saddle-sphere interface requires the development of a specialized stand that allows obtaining the necessary turn of the ball valve that allows the probe with paste to enter this part of the valve. This method does not allow to obtain high-quality restoration of the sealing element of the saddle. The process of abrasive wear of the interface, deformation of the contact zone are not eliminated and can progress, which leads to the need to replace the crane itself. In addition, the work on replacing the crane associated with the re-cutting is time-consuming, unsafe and expensive. Replacing worn-out valve seals with a welded body is not economically viable and requires large transportation and technological costs.

 Of the known methods, the closest to the proposed one is a method of protection against wear of ball valves, based on the elimination of leaks in the saddle-sphere conjugation by injection through the lubricating channels using the injection device of the polymer sealing paste in the closed position of the valve (see G.S. Krutenko, EV Trofimov. “Fluid for hydraulic systems and sealing material for shut-off valves of main gas pipelines” - a review by VNII GAZPROM, series “Transport and storage of oil and gas”, 1988, issue 8).

 A disadvantage of the known solution is the low degree of sealing, due to the fact that the lubricant channels of the cranes with a diameter of 1 mm are clogged with polymerization products from grease and process dirt, which does not always allow the polymerizable material with different degrees of viscosity to be brought into the contact zone. Due to vibration of the gas pipeline, precipitating mechanical impurities inside the valve body and valve flange are compacted, carefully separated, and fill all gaps (voids) inside the valve, including falling into the nodes of the thrust bearing and valve spindle, as well as into the contact zone of the seat sealing element with the sphere surface. At the same time, during the rotation of the sphere and the passage of the high-speed gas flow, intensive wear of the contact zone occurs and, as a result, the valve is leaky.

 Foreign bodies, such as scale, cinder electrodes and others, fall into the gap between the surfaces of the sphere, body and flange, become jammed and, when the sphere rotates, form transverse scratches and grooves on the sealing elements of the seats. This leads to a complete loss of operability of the ball valve.

 In addition, this method is intended for emergencies in the position of the valve "Closed", and the number of operations of the valve does not exceed 2-3 times, after which, as a rule, the paste breaks into the pipeline or its "biting" sphere. The paste breaks into the gas pipeline due to the fact that paste is supplied from the lubricating channels under the pressure of the grease nipple to the outside of the seat sealing element, located in the tap passage section area, where there are no conditions for its resistance to the gas pressure head.

 The basis of the present invention is the creation of a method of protection against wear of ball valves, which reduces the wear rate of the parts of the sealing contact in the interface "saddle-sphere" by creating an intermediate sealing ring-shell of polymerizable material in the gap between the surfaces of the sphere, the body of the valve and the saddles which is to increase the service life of ball valves.

 The problem is achieved in that in a method of protecting against wear of ball valves, including the introduction of a polymer sealing paste into the seal assembly of a ball valve and subsequent exposure to the completion of the polymerization process, according to the invention, said paste is introduced into a previously prepared valve cavity under pressure achieved by a commercially-used press oiler at ΔР = 0.4 MPa through the drain fitting in the open position of the valve with the formation of a sealing ring-o-ring during the polymerization of the sealing paste Points in the gap between the surface of the sphere, the body of the crane, and saddles.

 It is advisable to introduce the polymer paste under pressure until it appears in the tap decompression fitting hole.

 The essence of the method is illustrated by drawings, where figure 1 shows a General view of a ball valve; in FIG. 2 shows a lubrication assembly; in FIG. 3 shows a general view of the tap after pumping the sealing paste into it; in FIG. 4 shows the lubrication unit after injection of the sealing paste into it.

 The ball valve includes a housing 1, a bearing 2 of a thrust bearing 3, an o-ring 4, a sphere 5, a flange of a valve 6, a lubrication unit 7, consisting essentially of a grease fitting 8, lubricant channels 9 passing in the housing of the seat 10 to supply lubricant to the sealing contact zone element 11 with a sphere 5. In the crane body there is a spindle unit 12 with sliding bearings 13, and there are also decompression 14 and drain 15 choke holes with a diameter of 14 mm, through which, using drain valves 16, with a diameter of 0.5 mm, pressure is correspondingly relieved gas and drain accumulated liquid (water condensate) to the atmosphere, wherein the mechanical impurities, corrosion products, almost no foreign bodies are removed.

 The method is as follows.

 After thoroughly washing the cavity of the crane in a closed or slightly ajar position and dissolving the adhesion products formed on the surface of the sphere 5 (see FIG. 2), the crane cavity is blown and dried. Then, in the "Open" position of the valve, a polymer sealing paste is pressed through the drain fitting 15 under pressure so that all the gaps between the surface of the sphere 5 and the inner surface of the body 1 and the valve flange 2 are selected. The control of filling the entire gap volume with the paste is carried out by fixing the moment it appears in the opening of the decompression fitting 14. After some time has passed, when the polymerization process is completed, a third, locking and regulating ring-shell 17 is formed, located between the two main 11, and the resulting ring-shell completely located in the internal cavity of the crane, filling all the gaps and accumulation of mechanical impurities, as well as between the inner surfaces of the sealing elements 11 of the saddle 10 (Fig. 4) and, therefore, it is practically not exposed to high-speed gas pressure when the valve is triggered, which increases the durability of the shell ring.

 In addition, due to a change in the trajectory of the high-speed gas flow with mechanical impurities, intensive wear of the surface of the sealing element 11 of the seat 10 in contact with the surface of the sphere 5 is eliminated, which also contributes to an increase in the service life of the saddle-sphere conjugation.

 When the valve is slightly opened, a high-speed gas flow rushes only into the opening of the transition section of the valve and does not fall into the gap between the surfaces of the sphere 5 and the valve body 1, because there is a shell ring 17, which prevents the flow of gas through the gap, separation of mechanical impurities, as well as hydrate formation and external glaciation of the valve.

 In the process of pressing the polymerizable sealing material and minor twists of the sphere 5, the material penetrates into the bearing 2, thrust bearing 3 and all the gaps in this part of the crane are filled. As a result of this, the so-called “ascent” effect of the crane sphere 5 occurs, namely that the sphere occupies a strictly fixed working position, while all technical distortions and jamming in the bearing 2 and the thrust bearing 3 are eliminated and the force required to rotate the sphere 5 is sharply reduced. Such a stable position is maintained after the polymerization of the sealing material.

When choosing a sealing sealing material used in the proposed method, you must be guided by the following:
- in the process of pumping material into the gap between the body and the sphere of the crane, it must fill in all the gaps in the interface "saddle-sphere";
- the material should have the smallest possible adhesion to the surface of the sphere;
- to have high strength characteristics, providing resistance to the differential pressure of gas up to 8-10 MPa;
- the viscosity characteristics of the material should practically not change over a wide temperature range (-45 - 120 ^o C);
- the material should be affordable, providing a cost-effective recovery process for cranes;
- the material should provide the least complexity when pressing (feeding) it into the internal cavity of the crane.

 As such a sealing sealing material, polymer compositions can be used, for example, based on polysulfide rubbers (thiocols), polyester resins (PN-1), or polyurethane rubbers (K-31, SKPS) containing or not containing a hardener (the latter determines the polymerization time composition).

 Such sealing materials are produced both by domestic industry and abroad, for example by the company "Diamond" Germany.

 Conducted bench tests showed that when implementing the described scheme, a shell ring is obtained that does not collapse when the crane is triggered by 23 or more cycles at ΔP = 0.4 MPa.

 In addition, the proposed method for restoring performance and increasing the service life of ball valves can be used both in the operation of the valves and in the process of their manufacture in the factory.

Claims (2)

 1. The method of protection against wear of ball valves, including the introduction of a polymer sealing paste into the seal assembly of the ball valve and subsequent exposure to the completion of the polymerization process, characterized in that the paste is introduced into the pre-prepared cavity of the valve under pressure through the drain fitting in the open position of the valve with the formation with the polymerization process of the sealing paste of the sealing ring - the shell in the gap between the surfaces of the sphere, the body of the valve and the seats.  2. The method according to claim 1, characterized in that the introduction of the polymer sealing paste is carried out before it appears in the opening of the decompression fitting of the tap.

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