Metal sealing ball valve suitable for working conditions of polypropylene and polyethylene powder

Abstract

The invention discloses a metal sealing ball valve suitable for polypropylene and polyethylene powder working conditions. The metal sealing ball valve comprises a valve body, a left body and a ball body fixedly arranged in a valve body inner cavity between the valve body and the left body, the lower end of the ball body is connected with a lower valve rod, the upper end of the ball body is connected with the valve rod, and the valve rod is rotated to drive a through hole to communicate or block the upstream end and the downstream end of a channel; the valve body and the left body are spliced in a butt joint mode, the valve seat is matched with the valve body and the left body to form a sealing face, a first O-shaped ring, a first check ring, a second X-shaped ring and a third check ring are arranged on the valve seat, a spring seat is arranged between the valve seat and the valve body, and a spring, a first X-shaped ring and a second check ring are arranged on the spring seat. The upper end of the valve body is connected with a lengthened neck, the upper end of the lengthened neck is connected with a packing gland, a first valve rod bearing is arranged between the valve rod and the valve body, a packing gasket and packing are arranged between the lengthened neck and the valve rod, the valve rod sequentially penetrates through the upper end of the valve body, the lengthened neck and the packing gland, and a second valve rod bearing is arranged between the lower valve rod and the ball body.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ball valves, and particularly relates to a metal sealing ball valve suitable for polypropylene and polyethylene powder working conditions. BACKGROUND

[0002] Ball valves have the advantages of minimum fluid resistance, prevention of medium impact by the ball surface and the valve seat sealing surface in the open state, reliable sealing, rapid opening and closing, and the like, and are widely used in petroleum and chemical plants. Considering the installation size requirement of the ball, a gap of more than 5 mm is usually required between the ball and the inner surface of the valve body. During the opening and closing process of the ball valve, the medium will enter the gap between the ball and the inner surface of the valve body, which has little effect on the transportation of ordinary media such as water, oil and gas, but is very unfavorable for the harsh working conditions of transporting easily self-aggregated media and requiring very high frequency switching. For example, in a polyolefin device, gas-phase polyethylene (or polypropylene) is reacted in a fluidized bed reactor under the action of a catalyst to generate powdery polyethylene (or polypropylene), and when the powdery product accumulates to a certain amount in the reactor bed layer, it is discharged through the product discharge system (Products Discharge System), i.e. PDS system. The discharge valve belongs to a very high frequency switch with a maximum switching frequency of 1.6 million times / year. The PDS system needs to use a large number of discharge valves, also known as PDS valves, which act according to the process logic sequence to discharge the product. If any valve action is not in place or fails, the PDS system will not operate normally. According to years of actual use, the service life of the current discharge valve is only 3 months, which cannot meet the requirements of long-term and stable operation of the discharge system. Through technical analysis, the main reasons for the short service life of the discharge valve are: The medium of the valve is polyethylene (or polypropylene) granular powder, which has strong self-aggregation. When the granular powder medium stays in the gap between the ball and the inner surface of the valve body, it will self-aggregate and become larger and larger, affecting the opening and closing of the valve, and in severe cases, it will cause the valve to seize. When the self-aggregated granular powder medium accumulates in the valve seat pre-tightening spring cavity, the valve seat pre-tightening spring easily loses its inherent elastic function and is in a jammed state, ultimately causing the valve to appear to be stuck.

[0003] A ball valve is disclosed in Chinese Patent No. CN117006263A, published on November 7, 2023, which comprises a ball body arranged in the inner cavity of a valve body, and a pair of combined sealing valve seats clamped on both sides of the ball body. The combined sealing valve seat comprises a valve seat ring, the inner cylindrical surface of which is in close contact with the ball body; the head and tail of the outer cylindrical surface of the valve seat ring are in sealing contact with the end surface of the valve body inner cavity through a valve seat O-ring and a dustproof ring, respectively; the middle part of the outer cylindrical surface of the valve seat ring forms a hidden cavity with the end surface of the valve body inner cavity; a cylindrical spring, a pressing ring and a valve seat sealing ring are arranged in the hidden cavity in turn from far to near the ball body; one end of the cylindrical spring abuts against the end surface of the valve body inner cavity, the other end of the cylindrical spring abuts against the pressing ring, the pressing ring abuts against the outer cylindrical surface of the valve seat sealing ring, the inner cylindrical surface of the valve seat sealing ring is in interference contact with the valve seat ring, and the upper surface of the valve seat sealing ring is in interference contact with the end surface of the inner cavity of the valve body, and the lower surface of the valve seat sealing ring is in interference contact with the outer cylindrical surface of the valve seat ring. The valve has poor sealing performance and poor cycle resistance. SUMMARY

[0004] To solve the problems in the prior art, a metal sealing ball valve suitable for polypropylene and polyethylene powder working conditions is provided. The valve body and the left body adopt a two-body structure, the first O-ring is used for sealing between the valve seat and the valve body, and the second X-ring is used for dust prevention, the valve stem is installed on the upper part of the valve body, and is connected by a lengthened neck bolt, the valve stem adopts a multiple sealing structure, two second O-rings are added to the dustproof ring, and double packing is arranged on the upper part of the valve stem, the lower valve stem is provided with a third O-ring, a fourth O-ring and a second gasket, the top flange of ISO5211 is connected to the top of the valve stem, the front of the cavity behind the valve seat is provided with a first check ring and a first O-ring, and the rear is provided with a second check ring and a first X-ring, so that dust cannot enter the cavity, the activity of the spring is ensured, and the spring failure caused by dust accumulation in the cavity is avoided, the rear of the valve seat and the valve body adopts a reverse V design, and dust cannot accumulate at this position. The application is applied to high-speed and high-frequency switching polyethylene powder dust working conditions, has good dust prevention effect and good cycle durability.

[0005] The application is achieved by the following technical solutions: A metal seal ball valve suitable for polypropylene and polyethylene powder working conditions, comprising a valve body and a left body for cutting off a flow channel, a ball body fixedly arranged in an inner cavity of the valve body between the valve body and the left body, the ball body having a through hole, a lower end of the ball body connected with a lower valve rod, an upper end of the ball body connected with a valve rod, the valve rod being rotated to drive the through hole to communicate or block the upstream end and the downstream end of the channel; the valve body and the left body being butted and assembled, a valve seat formed by cooperation of the valve body and the left body and having a first O-shaped ring, a first check ring, a second X-shaped ring and a third check ring arranged thereon, a spring seat arranged between the valve seat and the valve body, a spring, a first X-shaped ring and a second check ring arranged on the spring seat; an elongated neck connected with an upper end of the valve body, a packing gland connected with an upper end of the elongated neck, a first valve rod bearing arranged between the valve rod and the valve body, a packing washer and packing arranged between the elongated neck and the valve rod, the valve rod sequentially penetrating through the upper end of the valve body, the elongated neck and the packing gland, and a second valve rod bearing arranged between the lower valve rod and the ball body.

[0006] Preferably, the valve seat adopts a scraper structure.

[0007] Preferably, a fourth thrust bearing, a third O-shaped ring and a fourth O-shaped ring are arranged between the valve body and the lower valve rod.

[0008] Preferably, a spacer ring is arranged between the upper end of the elongated neck and the valve rod.

[0009] Preferably, a second O-shaped ring, a second thrust bearing and a third thrust bearing are arranged between the upper and lower ends of the elongated neck and the valve rod.

[0010] Preferably, the lower end of the valve body is connected with a bottom cover through a third stud and a third nut; and a second gasket is arranged between the lower end of the valve body and the bottom cover.

[0011] Preferably, the valve body is connected with the left body through a first stud and a first nut; and a first gasket is arranged between the valve body and the left body.

[0012] Preferably, the valve body is connected with the elongated neck through a second stud and a second nut; and a winding gasket is arranged between the valve body and the elongated neck.

[0013] Preferably, the upper end of the elongated neck is further provided with a second plug; the valve body is further provided with a first plug; and the packing gland is connected with the upper end of the elongated neck through a gland bolt and a gland nut.

[0014] Preferably, a first thrust bearing and a dustproof ring are further arranged between the valve body and the valve rod.

[0015] Compared with the prior art, the present application has the following advantages and beneficial effects: I. The metal sealed ball valve suitable for polypropylene and polyethylene powder working conditions provided by the present application, the valve body and the left body adopt a two-body structure, the first O-shaped ring is used for sealing between the valve seat and the valve body, and the second X-shaped ring is used for dust prevention, the valve stem is installed on the upper part of the valve body and is connected into the valve body cavity by a lengthened neck bolt, the valve stem adopts a multiple sealing structure, two second O-shaped rings are added for dust prevention, double packing is used on the upper part of the valve stem, the lower valve stem is provided with a third O-shaped ring, a fourth O-shaped ring and a second gasket, the top flange connection of ISO5211 is used on the top of the valve stem, the front of the cavity behind the valve seat adopts a first stop ring + a first O-shaped ring, and the rear adopts a second stop ring + a first X-shaped ring, so that dust cannot enter the cavity, the activity of the spring is ensured, and the spring failure caused by dust accumulation in the cavity is avoided, and the rear of the valve seat and the valve body adopts a reverse V design, so that dust cannot accumulate at this position. The present application is applied to the polyethylene powder dust working condition of high speed and high frequency switching; and has good dust prevention effect and good cycle durability.

[0016] II. The metal sealed ball valve suitable for polypropylene and polyethylene powder working conditions provided by the present application, the valve seat adopts a scraper structure, so that the accumulated powder on the ball body is removed, and the ball body is sprayed with Ni55, the valve seat is made of Sintech 6# material, the hardness of Ni55 is higher than that of Sintech 6#, and the ball body is not damaged during multiple high-speed switching.

[0017] III. The metal sealed ball valve suitable for polypropylene and polyethylene powder working conditions provided by the present application, the middle cavity of the valve body has two blowout ports (and is blocked by a first screw plug), and gas can be injected into the cavity as needed, so that the dust adhered in the valve cavity can be fully blown off to prevent the valve from being stuck; the valve stem adopts multiple sealing, the lower valve stem adopts double sealing, so that dust cannot enter the bearing, thereby avoiding the problems of scratching and torque rising, and avoiding the valve from being unable to be opened; the packing at the valve stem adopts a spacer ring design, a detection port (and is blocked by a second screw plug) is arranged at the position, and the leakage of the valve stem can be detected; the packing at the valve stem adopts a double packing design, which not only has wear resistance but also ensures the sealing of the valve stem.

[0018] IV. The metal sealed ball valve suitable for polypropylene and polyethylene powder working conditions provided by the present application, the valve realizes 2 million cycle tests, and is mainly used in typical gas phase PE and PP reactors, ethylene and propylene are pumped together with comonomers and catalysts, long-chain PE and PP polymers are generated in the reactor, and the polymers are then conveyed out, the valve is mainly used in the feeding and discharging links and plays a role of opening and closing. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present application; Figure 2 It is Figure 1 the enlarged view of position A in the middle Figure 3 is Figure 1 enlarged view of B in the middle; Figure 4 is Figure 1 enlarged view of C in the middle; Figure 5 is Figure 1 enlarged view of D in the middle; Figure 6 is a structural schematic diagram of the first screw plug in the application; Wherein: 1, valve body; 2, left body; 3, ball; 4, valve stem; 5, lower valve stem; 6, valve seat; 7, spring seat; 8, spring; 9, first O-ring; 10, first check ring; 11, first X-ring; 12, second X-ring; 13, second check ring; 14, third check ring; 15, lengthened neck; 16, bottom cover; 17, first gasket; 18, winding gasket; 19, second gasket; 20, first valve stem bearing; 21, second valve stem bearing; 23, first thrust bearing; 24, second thrust bearing; 25, third thrust bearing; 26, fourth thrust bearing; 27, dust seal; 28, second O-ring; 29, third O-ring; 30, fourth O-ring; 31, packing; 32, spacer ring; 33, packing ring; 34, packing gland; 35, gland bolt; 36, gland nut; 37, first stud; 38, first nut; 39, second stud; 40, second nut; 41, third stud; 42, third nut; 43, first screw plug; 44, second screw plug. DETAILED DESCRIPTION

[0020] The application will be further described in detail below in conjunction with examples, but the embodiments of the application are not limited thereto.

[0021] Example 1 As Figures 1-6As shown, a metal sealed ball valve suitable for polypropylene and polyethylene powder working conditions, comprising a valve body 1 and a left body 2 for cutting off the flow channel, a ball 3 fixedly arranged in the inner cavity of the valve body 1 between the valve body 1 and the left body 2, the ball 3 having a through hole, the lower end of the ball 3 being connected with a lower valve rod 5, the upper end of the ball 3 being connected with a valve rod 4, rotating the valve rod 4 to drive the through hole to communicate or block the upstream end and the downstream end of the channel; the valve body 1 and the left body 2 are butt-jointed and assembled, a valve seat 6 is formed between the valve body 1 and the left body 2, the valve seat 6 being provided with a first O-ring 9, a first retaining ring 10, a second X-ring 12 and a third retaining ring 14, a spring seat 7 being arranged between the valve seat 6 and the valve body 1, the spring seat 7 being provided with a spring 8, a first X-ring 11 and a second retaining ring 13; the upper end of the valve body 1 being connected with an extended neck 15, the upper end of the extended neck 15 being connected with a packing gland 34, a first valve rod bearing 20 being arranged between the valve rod 4 and the valve body 1, a packing washer 33 and a packing 31 being arranged between the extended neck 15 and the valve rod 4, the valve rod 4 sequentially penetrating through the upper end of the valve body 1, the extended neck 15 and the packing gland 34, a second valve rod bearing 21 being arranged between the lower valve rod 5 and the ball 3. The valve seat 6 is provided with a first accommodating groove accommodating the first O-ring 9 and the first retaining ring 10, the valve seat 6 being provided with a second accommodating groove accommodating the second X-ring 12 and the third retaining ring 14, the spring seat 7 being provided with a spring 8 groove accommodating the spring 8, the spring seat 7 being provided with a third accommodating groove accommodating the first X-ring 11 and the second retaining ring 13.

[0022] Example 2 As Figures 1-6As shown, a metal sealed ball valve suitable for polypropylene and polyethylene powder working conditions, comprising a valve body 1 and a left body 2 for cutting off the flow channel, a ball 3 fixedly arranged in the inner cavity of the valve body 1 between the valve body 1 and the left body 2, the ball 3 having a through hole, the lower end of the ball 3 being connected with a lower valve stem 5, the upper end of the ball 3 being connected with a valve stem 4, rotating the valve stem 4 to drive the through hole to communicate or block the upstream end and the downstream end of the channel; the valve body 1 and the left body 2 are butt-jointed and assembled, a valve seat 6 is formed between the valve body 1 and the left body 2 to cooperate to form a sealing surface, the valve seat 6 is provided with a first O-ring 9, a first retainer ring 10, a second X-ring 12 and a third retainer ring 14, a spring seat 7 is arranged between the valve seat 6 and the valve body 1, the spring seat 7 is provided with a spring 8, a first X-ring 11 and a second retainer ring 13; the upper end of the valve body 1 is connected with an extended neck 15, the upper end of the extended neck 15 is connected with a packing gland 34, a first valve stem bearing 20 is arranged between the valve stem 4 and the valve body 1, a packing washer 33 and a packing 31 are arranged between the extended neck 15 and the valve stem 4, the valve stem 4 passes through the upper end of the valve body 1, the extended neck 15 and the packing gland 34 in sequence, and a second valve stem bearing 21 is arranged between the lower valve stem 5 and the ball 3. The valve seat 6 is provided with a first accommodating groove accommodating the first O-ring 9 and the first retainer ring 10, the valve seat 6 is provided with a second accommodating groove accommodating the second X-ring 12 and the third retainer ring 14, the spring seat 7 is provided with a spring 8 groove accommodating the spring 8, and the spring seat 7 is provided with a third accommodating groove accommodating the first X-ring 11 and the second retainer ring 13.

[0023] Wherein, the valve seat 6 adopts a scraper structure.

[0024] Wherein, the fourth thrust bearing 26, the third O-ring 29 and the fourth O-ring 30 are arranged between the valve body 1 and the lower valve stem 5. The fourth accommodating groove accommodating the fourth thrust bearing 26, the second valve stem bearing 21, the third O-ring 29 and the fourth O-ring 30 is arranged between the valve body 1 and the lower valve stem 5.

[0025] Wherein, the spacer ring 32 is arranged between the upper end of the extended neck 15 and the valve stem 4. The fifth accommodating groove accommodating the packing 31, the packing washer 33 and the spacer ring 32 is arranged between the upper end of the extended neck 15 and the valve stem 4.

[0026] Wherein, the second O-ring 28, the second thrust bearing 24 and the third thrust bearing 25 are arranged between the upper and lower ends of the extended neck 15 and the valve stem 4. The sixth accommodating groove matching the second O-ring 28 is arranged on the upper end of the extended neck 15; the seventh accommodating groove matching the second thrust bearing 24 and the third thrust bearing 25 is arranged on the valve body 1.

[0027] The lower end of the valve body 1 is connected with the bottom cover 16 through the third stud 41 and the third nut 42, and the second gasket 19 is arranged between the lower end of the valve body 1 and the bottom cover 16.

[0028] The valve body 1 is connected with the left body 2 through the first stud 37 and the first nut 38, and the first gasket 17 is arranged between the valve body 1 and the left body 2.

[0029] The valve body 1 is connected with the lengthened neck 15 through the second stud 39 and the second nut 40, and the winding gasket 18 is arranged between the valve body 1 and the lengthened neck 15.

[0030] The upper end of the lengthened neck 15 is further provided with the second screw plug 44, and the valve body 1 is further provided with the first screw plug 43. The upper end of the lengthened neck 15 is provided with the fourth threaded hole matched with the second screw plug 44, the valve body 1 is provided with the fifth threaded hole matched with the first screw plug 43, and the lengthened neck 15 and the packing gland 34 are provided with the sixth threaded hole matched with the packing bolt 35.

[0031] The valve body 1 and the valve rod 4 are further provided with the first thrust bearing 23 and the dustproof ring 27. The valve body 1 and the valve rod 4 are provided with the eighth accommodating groove matched with the first thrust bearing 23 and the dustproof ring 27.

[0032] Compared with the prior art, the present application has the following advantages and beneficial effects: I. The metal sealed ball valve suitable for polypropylene and polyethylene powder working conditions provided by the present application, the valve body 1 and the left body 2 adopt a two-body structure, the valve seat 6 and the valve body 1 are sealed by the first O-shaped ring 9 and simultaneously dustproof by the second X-shaped ring 12, the valve stem 4 is of an upper-mounted type, is mounted into the cavity of the valve body 1 from the upper part of the valve body 1, is connected by being bolted and compressed by the lengthened neck 15, the valve stem 4 adopts a multiple sealing structure: the dustproof ring 27 is provided with two second O-shaped rings 28 for sealing, double packing 31 is arranged on the upper part of the valve stem 4; the lower valve stem 5 is provided with a third O-shaped ring 29, a fourth O-shaped ring 30 and a second gasket 19; the top flange connection of ISO5211 is adopted at the top of the valve stem 4; the cavity behind the valve seat 6 is provided with a first stop ring 10 + a first O-shaped ring 9 in front and a second stop ring 13 + a first X-shaped ring 11 in back, so that dust cannot enter the cavity, the activity of the spring 8 is ensured, and the spring 8 is prevented from being disabled due to dust accumulation in the cavity; the rear of the valve seat 6 and the valve body 1 adopts a reverse V design, so that dust cannot accumulate at this position. The present application is applied to the polyethylene powder dust working condition of high-speed and high-frequency switching; has good dustproof effect and good cyclic durability.

[0033] II. The metal sealed ball valve suitable for polypropylene and polyethylene powder working conditions provided by the present application, the valve seat 6 adopts a scraper structure, so that the accumulated powder on the ball body 3 is removed, meanwhile, the ball body 3 is sprayed with Ni55, the valve seat 6 adopts Stellite 6# material, the hardness of Ni55 is higher than that of Stellite 6#, so that the ball body 3 is not damaged when being switched at high speed for many times.

[0034] III. The metal sealed ball valve suitable for polypropylene and polyethylene powder working conditions provided by the present application, the middle cavity of the valve body 1 is respectively provided with two blowout ports (and is blocked by a first screw plug 43), if necessary, gas can be injected into the cavity, so that the dust adhered in the valve cavity can be fully blown off, and the valve is prevented from being stuck; the valve stem 4 adopts multiple sealing, the lower valve stem 5 adopts double sealing, so that dust is completely prevented from entering the bearing, thereby avoiding the problems of scratching and torque rising, and avoiding the valve from being unable to be opened; the packing 31 at the valve stem 4 adopts a spacer ring design, there is a detection port (and is blocked by a second screw plug 44) at this position, so that the leakage of the valve stem 4 of the valve can be detected; the packing 31 at the valve stem 4 adopts a double packing 31 design, so that not only wear resistance is ensured, but also the sealing of the valve stem 4 is ensured.

[0035] IV. The metal sealed ball valve suitable for polypropylene and polyethylene powder working conditions provided by the present application, the valve realizes 2 million cycle tests, is mainly used in typical gas phase PE and PP reactors, ethylene and propylene are pumped together with comonomer and catalyst, long-chain PE and PP polymers are generated in the reactor, and the polymers are conveyed out, the valve is mainly used in the links of feeding and discharging, and plays a role of opening and closing.

[0036] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change of the above embodiment according to the technical essence of the present application falls within the protection scope of the present application.

Claims

1. A metal-sealed ball valve suitable for polypropylene and polyethylene powder applications, comprising a valve body (1) and a left body (2) having a flow channel cut-off, a ball (3) fixedly disposed in the inner cavity of the valve body (1) between the valve body (1) and the left body (2), the ball (3) having a through hole, the lower end of the ball (3) being connected to a lower valve stem (5), the upper end of the ball (3) being connected to a valve stem (4), and rotating the valve stem (4) driving the through hole to connect or block the upstream and downstream ends of the channel; characterized in that: The valve body (1) and the left body (2) are assembled together, and the valve seat (6) is formed with the valve body (1) and the left body (2) to form a sealing surface. The valve seat (6) is provided with a first O-ring (9), a first retaining ring (10), a second X-ring (12) and a third retaining ring (14). A spring seat (7) is provided between the valve seat (6) and the valve body (1). The spring seat (7) is provided with a spring (8), a first X-ring (11) and a second retaining ring (13). The upper end of the valve body (1) is connected to the valve body (2). The extended neck (15) is connected to the upper end of the extended neck (15) and the packing gland (34). A first valve stem bearing (20) is provided between the valve stem (4) and the valve body (1). A packing washer (33) and packing (31) are provided between the extended neck (15) and the valve stem (4). The valve stem (4) passes through the upper end of the valve body (1), the extended neck (15) and the packing gland (34) in sequence. A second valve stem bearing (21) is provided between the lower valve stem (5) and the ball (3).

2. The metal-sealed ball valve according to claim 1, suitable for polypropylene and polyethylene powder applications, characterized in that: The valve seat (6) adopts a scraper structure.

3. A metal-sealed ball valve suitable for polypropylene and polyethylene powder applications according to claim 2, characterized in that: A fourth thrust bearing (26), a third O-ring (29), and a fourth O-ring (30) are provided between the valve body (1) and the lower valve stem (5).

4. A metal-sealed ball valve suitable for polypropylene and polyethylene powder applications according to claim 3, characterized in that: A spacer ring (32) is provided between the upper end of the extended neck (15) and the valve stem (4).

5. A metal-sealed ball valve suitable for polypropylene and polyethylene powder applications according to claim 4, characterized in that: A second O-ring (28), a second thrust bearing (24), and a third thrust bearing (25) are provided between the lower end of the extended neck (15) and the valve stem (4).

6. A metal-sealed ball valve suitable for polypropylene and polyethylene powder applications according to claim 5, characterized in that: The lower end of the valve body (1) is connected to the bottom cover (16) by a third stud (41) and a third nut (42); a second gasket (19) is provided between the lower end of the valve body (1) and the bottom cover (16).

7. A metal-sealed ball valve suitable for polypropylene and polyethylene powder applications according to claim 6, characterized in that: The valve body (1) is connected to the left body (2) by a first stud (37) and a first nut (38); a first gasket (17) is provided between the valve body (1) and the left body (2).

8. A metal-sealed ball valve suitable for polypropylene and polyethylene powder applications according to claim 7, characterized in that: The valve body (1) is connected to the extended neck (15) by the second stud (39) and the second nut (40); a spiral wound gasket (18) is provided between the valve body (1) and the extended neck (15).

9. A metal-sealed ball valve suitable for polypropylene and polyethylene powder applications according to claim 8, characterized in that: The extended neck (15) is also provided with a second screw plug (44); the valve body (1) is also provided with a first screw plug (43); the packing gland (34) is connected to the upper end of the extended neck (15) by a gland bolt (35) and a gland nut (36).

10. A metal-sealed ball valve suitable for polypropylene and polyethylene powder applications according to claim 9, characterized in that: A first thrust bearing (23) and a dust seal (27) are also provided between the valve body (1) and the valve stem (4).

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