All-welded ball valve rod sealing structure with excellent sealing performance

Abstract

The utility model discloses an all-welded ball valve rod sealing structure with excellent sealing performance, relates to the technical field of ball valves, and solves the problems of poor sealing performance of a valve rod position and complicated assembly. Comprising an upper sealing seat and a lower sealing seat, fillers are arranged among the upper sealing seat, the valve rod and the flange plate; lubricating grease is filled between the inner wall of the upper sealing seat and the valve rod; a four-piece ring is mounted at the bottom of the upper sealing seat, and the upper sealing seat abuts against the four-piece ring; the middle body is provided with a positioning step matched with the outer step ring groove, a matching step is arranged at the position, opposite to the inner step ring groove, of the valve rod, and a shaft sleeve is assembled between the matching step and the inner step groove. Multiple sealing barriers are formed, the sealing performance at the position of the valve rod is remarkably improved, and medium leakage is effectively prevented; the packing enhances the axial sealing effect; the four open rings play a role in stably supporting and positioning the upper sealing seat, so that the reliability of the sealing structure is improved, the assembly process is simplified, and the assembly difficulty and cost are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of ball valves, and particularly to a stem seal structure of a fully welded ball valve with excellent sealing performance. Background Technique

[0002] Nowadays, in industrial fields such as petroleum, natural gas, and chemical industry, fully welded ball valves are widely used due to their good sealing performance, corrosion resistance, and long service life. The stem of a fully welded ball valve is a key component for realizing the opening and closing operation of the valve, and the reliability of its seal structure directly affects the overall sealing performance and operation safety of the valve.

[0003] The existing stem seal structures of fully welded ball valves usually adopt a single sealing method or a simple combination of sealing components, such as relying only on O-ring seals or packing seals. In the process of long-term use, this single seal structure is easily affected by factors such as medium pressure fluctuations, temperature changes, and wear, resulting in the aging, deformation, or damage of the seals, thus causing seal failure and medium leakage. Especially in harsh working conditions such as high pressure, high corrosion, or flammable and explosive environments, once leakage occurs, it will not only cause medium waste, but also may trigger serious safety accidents such as fires and explosions, threatening the lives of personnel and causing huge economic losses. There are also some seal structures that use multiple sealing components, but the cooperation between the components is not reasonable enough. Not only is the sealing effect not good, but also in the assembly process, due to the defects in the structural design, the assembly process is cumbersome, the operation difficulty is large, the production and maintenance costs are increased, and it is difficult to meet the requirements of modern industry for efficient, reliable sealing, and convenient installation. Content of the Utility Model

[0004] The purpose of the utility model: In order to overcome the defects of the prior art, the utility model provides a stem seal structure of a fully welded ball valve with excellent sealing performance, and solves the problems of poor sealing at the stem position and cumbersome assembly.

[0005] The technical solution of the utility model: The fully welded ball valve includes a stem, a middle body, and a flange. The stem passes through the flange and the middle body. The stem seal structure includes an upper seal seat close to the flange and a lower seal seat located below the upper seal seat. The upper seal seat and the lower seal seat are respectively sealed and connected to the middle body and the stem through seals; there is packing between the upper seal seat, the stem, and the flange, and grease is filled between the inner wall of the upper seal seat and the stem; a four-opening ring is installed at the bottom of the upper seal seat, and the four-opening ring is embedded in the inner wall of the middle body to form a mechanical fit, and the upper seal seat is in contact with the four-opening ring; inner and outer stepped annular grooves are respectively opened on the inner and outer sides of the bottom of the lower seal seat, the middle body is provided with a positioning step adapted to the outer stepped annular groove, the stem is provided with a mating step at a position corresponding to the inner stepped annular groove, and a shaft sleeve is assembled between the mating step and the inner stepped groove.

[0006] With the above technical solution, by setting the upper sealing seat close to the flange and the lower sealing seat below it, and sealingly connecting with the middle body and the valve stem through sealing rings respectively, multiple sealing barriers are formed, significantly improving the sealing performance at the valve stem and effectively preventing medium leakage; the packing enhances the axial sealing effect, and the grease can not only reduce the frictional resistance when the valve stem rotates, but also assist in sealing to prevent impurities from entering the sealing gap; the four-opening ring installed at the bottom of the upper sealing seat forms a mechanical fit with the inner wall of the middle body, providing stable support and positioning for the upper sealing seat to prevent it from displacing under the action of medium pressure or external force; the inner stepped ring groove and the outer stepped ring groove on the inner and outer sides of the bottom of the lower sealing seat cooperate with the positioning step of the middle body, the mating step of the valve stem and the shaft sleeve, realizing the precise positioning and stable installation of the lower sealing seat, not only improving the reliability of the sealing structure, but also simplifying the assembly process and reducing the assembly difficulty and cost.

[0007] In a possible design, the upper sealing seat is provided with a packing cavity for accommodating the packing. The packing cavity is axially arranged along the upper sealing seat, opens upward and is located at the inner wall of the upper sealing seat.

[0008] With the above design, it is more convenient to fill and replace the packing. At the same time, the axially arranged packing cavity can better guide the force of the packing, making the packing deform uniformly when compressed, further enhancing the sealing effect and effectively preventing the medium from leaking axially along the valve stem.

[0009] In a possible design, a pressing platform is convexly provided on the bottom surface of the flange. The pressing platform is pressed into the packing cavity and tightly presses on the packing.

[0010] With the above design, a stable and continuous pressure can be applied to the packing, ensuring that the packing is always in a good sealing state, avoiding sealing failure caused by packing loosening, and at the same time simplifying the packing pressing operation and improving the assembly efficiency.

[0011] In a possible design, a grease storage cavity for storing grease is provided between the upper sealing seat and the valve stem. The grease storage cavity is circumferentially distributed around the valve stem.

[0012] With the above design, the grease storage cavity can store a sufficient amount of grease to ensure that a good lubrication state is always maintained between the valve stem and the upper sealing seat during the long-term operation of the valve, reducing wear and extending the service life of the sealing structure. At the same time, continuous lubrication also helps to maintain good sealing performance.

[0013] In a possible design, a plurality of grease through holes are provided on the upper sealing seat in a circumferential manner. The grease through holes communicate with the grease storage cavity, and a joint is provided on the middle body. The joint communicates with the grease through holes.

[0014] With the above design, grease can be conveniently replenished into the grease storage cavity through the joint, ensuring continuous supply of grease. Maintenance operations can be carried out without disassembling the sealing structure, reducing the maintenance difficulty and cost, and improving the maintainability of the equipment.

[0015] In a possible design, a plurality of annular grooves are provided on the inner and outer wall parts of the upper sealing seat and the lower sealing seat, and the sealing rings are adaptively installed in the corresponding annular grooves.

[0016] With the above design, the annular grooves make the installation of the sealing rings more stable, not prone to displacement or falling off. At the same time, the setting of multiple sealing rings further enhances the sealing effect, can adapt to the medium pressure in different directions, effectively prevents the medium from leaking from the gaps between the sealing seat and the middle body and the valve stem, and further improves the sealing reliability and stability of the entire valve stem sealing structure. Description of the Drawings

[0017] Figure 1 It is a three-dimensional sectional view of the fully welded ball valve of the present utility model;

[0018] Figure 2 For the present utility model Figure 1 The partial enlarged view at A;

[0019] Figure 3 For the present utility model Figure 1 The partial sectional view of the B-B plane;

[0020] Figure 4 It is an exploded view of the valve stem sealing structure of the present utility model;

[0021] Among them, 1. Valve stem; 11. Matching step; 2. Middle body; 21. Positioning step; 3. Flange; 31. Pressing platform; 4. Upper sealing seat; 41. Sealing ring; 5. Lower sealing seat; 51. Inner stepped ring groove; 52. Outer stepped ring groove; 6. Packing; 7. Four-opening ring; 8. Bush; 9. Grease storage cavity; 91. Grease passage hole; 92. Joint. Detailed Embodiments

[0022] Such as Figures 1-4A stem seal structure of a fully welded ball valve with excellent sealing performance is shown. The fully welded ball valve mainly consists of a stem 1, a middle body 2 and a flange 3. The stem 1 passes through the flange 3 and the middle body 2 and forms an assembled connection. Its stem 1 seal structure includes an upper seal seat 4 on the side of the flange 3 and a lower seal seat 5 arranged below the upper seal seat 4. The upper seal seat 4 and the lower seal seat 5 respectively achieve interference sealing with the inner wall of the middle body 2 and the outer surface of the stem 1 through the adapted sealing rings 41, forming a double sealing barrier. A packing 6 is filled between the upper seal seat 4, the stem 1 and the flange 3 to strengthen the axial sealing effect. At the same time, special lubricating grease is injected into the space between the inner wall of the upper seal seat 4 and the surface of the stem 1, which reduces the rotational friction of the stem 1 and further improves the sealing performance. The four-opening ring 7 or the three-opening ring installed at the bottom of the upper seal seat 4 is fitted with the inner wall of the middle body 2 through the inner wall groove machined in the middle body 2, forming a stable mechanical positioning structure, providing reliable support and limit for the upper seal seat 4, and ensuring its stability under high-pressure conditions. Inner step ring grooves 51 and outer step ring grooves 52 are respectively provided on the inner and outer sides of the bottom of the lower seal seat 5. A positioning step 21 that is precisely matched with the outer step ring groove 52 is machined at the corresponding position on the inner wall of the middle body 2, and the stem 1 is provided with a mating step 11 opposite to the inner step ring groove 51. During the assembly process, the coaxial positioning of the lower seal seat 5, the stem 1 and the middle body 2 is realized by installing a bushing 8 between the mating step 11 and the inner step ring groove 51, effectively improving the overall stability and sealing reliability of the seal structure.

[0023] During the installation process of the fully welded ball valve, first, the stem 1 is installed through the through holes reserved in the flange 3 and the middle body 2. Then install the stem 1 seal structure. First, install the bushing 8 on the mating step 11 of the stem 1, and then put the lower seal seat 5 on the stem 1, so that the outer step ring groove 52 on the outer side of the bottom of the lower seal seat 5 is precisely aligned and engaged with the positioning step 21 on the inner wall of the middle body 2 to realize the preliminary positioning of the lower seal seat 5 and the stem 1. Then install and embed the four-opening ring 7 on the inner wall of the middle body 2, and the four-opening ring 7 forms a mechanical fit with the middle body 2. Next, install the upper seal seat 4 above the four-opening ring 7 so that it abuts against the four-opening ring 7. In this way, the upper seal seat 4 and the lower seal seat 5 are respectively in close contact with the middle body 2 and the stem 1 through the sealing rings 41 pre-installed in the annular grooves. Finally, fill the appropriate packing 6 in the gap between the upper seal seat 4, the stem 1 and the flange 3, and at the same time inject lubricating grease between the inner wall of the upper seal seat 4 and the stem 1. Thus, the installation of the entire stem 1 seal structure is completed, realizing multiple seals and stable mechanical fits. The assembly process is simple and the assembly position is deterministic.

[0024] During the machining process of the upper sealing seat 4, a packing cavity is axially formed on the inner wall by machining, and the opening of the packing cavity faces upward. During installation, the packing 6 is filled into the packing cavity through the opening. Since the packing cavity is axially arranged, during subsequent pressing operations, the packing 6 can be uniformly deformed under axial pressure, closely fitting the valve stem 1 and the inner wall of the upper sealing seat 4, effectively preventing the medium from leaking axially along the valve stem 1. At the same time, the opening design of the packing cavity also facilitates the filling and later replacement operations of the packing 6.

[0025] Machine the flange 3, and project a pressing platform 31 on its bottom surface by processes such as milling or stamping. During assembly, install the flange 3 in the corresponding position, so that the pressing platform 31 is accurately pressed into the packing cavity of the upper sealing seat 4 and tightly presses on the packing 6, applying a stable and continuous pressure to the packing 6 to ensure that the packing 6 is always in a good sealing state. The structure of the pressing platform 31 simplifies the pressing operation of the packing 6, eliminating the need for additional complex pressing devices and improving the assembly efficiency.

[0026] Through machining, a grease storage cavity 9 is formed on the inner wall of the upper sealing seat 4 at the position corresponding to the valve stem 1, circumferentially distributed around the valve stem 1. The position above the grease storage cavity 9 is sealed by the upper sealing seat 4, and the lower part is sealed by the lower sealing seat 5, thus preventing the leakage of lubricating grease and ensuring the reliability of the seal. During assembly, first put the upper sealing seat 4 on the valve stem 1, and then inject a sufficient amount of lubricating grease into the grease storage cavity 9.

[0027] A plurality of grease through holes 91 are evenly formed in the circumferential direction on the upper sealing seat 4, and the grease through holes 91 are connected to the grease storage cavity 9 through machining processes such as drilling; at the same time, a connector 92 is arranged at the corresponding position on the middle body 2, and the connector 92 is connected to the grease through holes 91 through a pipeline or other connecting structures. The grease through holes 91 need to avoid the ring body of the four-opening ring 7 to prevent the blockage of the grease through holes 91 and make the pumping of grease into the grease through holes 91 smoother. During the use of the valve, when it is necessary to replenish the lubricating grease, the lubricating grease can be conveniently injected into the grease storage cavity 9 through the connector 92 without disassembling the sealing structure.

[0028] During the machining of the upper sealing seat 4 and the lower sealing seat 5, a plurality of annular grooves are respectively arranged on their inner and outer wall parts by processes such as milling. Before installation, fit the appropriate sealing rings 41 into the corresponding annular grooves to ensure that the sealing rings 41 closely fit the annular grooves. During assembly, the upper sealing seat 4 and the lower sealing seat 5 with the sealing rings 41 are respectively assembled with the middle body 2 and the valve stem 1. The setting of a plurality of sealing rings 41 can adapt to the medium pressure in different directions and effectively prevent the medium from leaking from the gaps between the sealing seat and the middle body 2 and the valve stem 1.

[0029] During the operation of a fully welded ball valve, the medium mainly escapes and leaks upward along the gap between the valve stem 1 and the middle body 2 from the position of the lower seal seat 5. When the medium moves upward inside the ball valve, it first encounters the inner step ring groove 51 and the outer step ring groove 52 on the inner and outer sides of the bottom of the lower seal seat 5. The outer step ring groove 52 cooperates with the positioning step 21 of the middle body 2 to compress the outer sealing ring 41 to form the first radial seal; the combination of the inner step ring groove 51, the mating step 11 of the valve stem 1 and the bushing 8 deforms the inner sealing ring 41 to form the second radial seal. The double sealing rings 41 effectively block the upward movement of the medium along the gaps between the lower seal seat 5, the middle body 2 and the valve stem 1. If the medium breaks through the lower seal seat 5, it will enter the area between the upper seal seat 4, the valve stem 1 and the flange 3. At this time, the packing 6 filled in the packing cavity axially arranged on the inner wall of the upper seal seat 4 expands axially under the pressing of the pressing table 31 of the flange 3 to fill the gap, forming a tight axial sealing structure to prevent the medium from leaking upward continuously. During the process, the sealing ring 41 embedded in the annular groove will also produce radial deformation to further fill the fine gaps between the seal seat and the valve stem 1 and the middle body 2, forming a radial sealing structure. In addition, the pre-injected grease adheres tightly to the surface of the valve stem 1 under the medium pressure to form a dynamic sealing layer. The grease can be replenished through the grease hole 91 and the joint 92 of the middle body 2, and continuously maintain the pressure higher than the medium pressure to achieve the active interception of leakage. During the process, the four-opening ring 7 is clamped on the inner wall of the middle body 2 to form a stable support for the upper seal seat 4. Even if the medium pressure fluctuates, the four-opening ring 7 can prevent the upper seal seat 4 from shifting, ensuring that all sealing components are always in effective cooperation and maintaining the integrity of the sealing structure. In summary, through the synergistic effect of the components of the lower seal seat 5 and the upper seal seat 4, a stepped plugging path is constructed from multiple dimensions of radial and axial directions, and finally the efficient interception of the upward escaping medium is achieved, ensuring the reliability and stability of the sealing performance of the fully welded ball valve.

Claims

1. A stem seal structure of a fully welded ball valve with excellent sealing performance. The fully welded ball valve includes a valve stem (1), a middle body (2), and a flange (3). The valve stem (1) passes through the flange (3) and the middle body (2). It is characterized in that: The sealing structure of the valve stem (1) includes an upper sealing seat (4) close to the flange (3) and a lower sealing seat (5) located below the upper sealing seat (4). The upper sealing seat (4) and the lower sealing seat (5) are respectively sealed and connected to the middle body (2) and the valve stem (1) through sealing rings (41); a packing (6) is arranged between the upper sealing seat (4), the valve stem (1) and the flange (3), and grease is filled between the inner wall of the upper sealing seat (4) and the valve stem (1); a four-opening ring (7) is installed at the bottom of the upper sealing seat (4), and the four-opening ring (7) is embedded on the inner wall of the middle body (2) to form a mechanical fit, and the upper sealing seat (4) is in contact with the four-opening ring (7); inner stepped annular grooves (51) and outer stepped annular grooves (52) are respectively formed on the inner side and the outer side of the bottom of the lower sealing seat (5), a positioning step (21) adapted to the outer stepped annular groove (52) is arranged on the middle body (2), a mating step (11) is arranged on the valve stem (1) at a position corresponding to the inner stepped annular groove (51), and a shaft sleeve (8) is assembled between the mating step (11) and the inner stepped groove.

2. The stem seal structure of the all-welded ball valve with excellent sealing performance according to claim 1, characterized in that: The upper sealing seat (4) is provided with a packing cavity for accommodating the packing (6), and the packing cavity is arranged along the axial direction of the upper sealing seat (4), opens upward and is located at the inner wall of the upper sealing seat (4).

3. The stem seal structure of the all-welded ball valve with excellent sealing performance according to claim 2, characterized in that: A pressing platform (31) protrudes from the bottom surface of the flange (3), and the pressing platform (31) is pressed into the packing cavity and tightly presses on the packing (6).

4. The stem seal structure of the fully welded ball valve with excellent sealing performance according to claim 1, wherein: A grease storage cavity (9) for storing grease is arranged between the upper sealing seat (4) and the valve stem (1), and the grease storage cavity (9) is distributed circumferentially around the valve stem (1).

5. The stem seal structure of the all-welded ball valve with excellent sealing performance according to claim 4, characterized in that: A plurality of grease through holes (91) are arranged in a ring on the upper sealing seat (4), the grease through holes (91) communicate with the grease storage cavity (9), a joint (92) is arranged on the middle body (2), and the joint (92) communicates with the grease through holes (91).

6. The fully welded ball valve stem sealing structure with excellent sealing performance according to any one of claims 1-5, characterized in that: A plurality of annular grooves are arranged on the inner and outer wall parts of the upper sealing seat (4) and the lower sealing seat (5), and the sealing ring (41) is adaptively embedded in the corresponding annular groove.

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