A bottom protection structure for high-pressure valve stem packing

Abstract

A bottom protection structure for the stem packing of a high-pressure valve comprises a lower concave ring, a middle ring and an upper convex ring, which are assembled from bottom to top to form a combined body with a connected cavity, and then installed at the bottom of the packing box with a gap between the stem and the valve. The invention has a simple structure and is easy to manufacture. It effectively protects the bottom packing of the stem under high-pressure working conditions, ensures the sealing of the stem under high-pressure working conditions (1500LB, 2500LB), and prolongs the service life of the valve.

Description

Technical Field

[0001] The invention relates to the technical field of valve manufacturing, and in particular to a structure capable of protecting a valve stem bottom packing from being damaged by being washed away by a high-pressure medium. Background Art

[0002] In the existing technology of valve manufacturing, the valve stem is generally sealed with packing. The common sealing structure is as follows: Figure 1 As shown. A packing pad 13 is placed at the bottom of the stuffing box 2, and several circles of flexible graphite packing rings are placed on the packing pad 13. The nut is tightened to form a downward pressure, and the packing 6 is compressed by the pressure plate and the compression sleeve to form a valve stem seal.

[0003] This structure is applicable to general medium and low pressure valves, but for high pressure valves, especially valves with pressures of 1500LB (25MPa) and 2500LB (42MPa), the medium directly impacts the packing 6 through the gap between the stuffing box 2 and the valve stem 1, and the gap between the stuffing pad 13 and the valve stem 1, causing the packing to be damaged and the valve stem seal to leak, thus making the valve unusable. However, this gap must exist in the transmission of valve parts. Summary of the invention

[0004] The invention provides a valve stem packing bottom protection structure, which solves the problem that the valve stem packing bottom is easily impacted by high-pressure medium, resulting in valve stem packing seal failure.

[0005] The technical solution adopted by the present invention is:

[0006] A bottom protection structure for a stem packing of a high-pressure valve comprises a lower concave ring, a middle ring and an upper convex ring. The three are assembled in sequence from bottom to top to form a combined body with a connected cavity, and then installed at the bottom of the packing box with a gap between the valve stem and the ring.

[0007] The lower concave ring has a groove on the inner ring surface and a U-shaped ring groove on the upper end surface; the upper end surface of the middle ring has a notch in the center line direction; the upper convex ring is a ring with a T-shaped cross-section; during assembly, the inner ring surfaces of the lower concave ring, the middle ring and the upper convex ring all maintain the same gap with the valve stem, and the T-shaped leg gap of the upper convex ring extends into the U-shaped ring groove of the lower concave ring and a gap is left between the bottom of the T-shaped leg and the bottom of the U-shaped ring groove, and the T-shaped shoulder of the upper convex ring presses the middle ring and the lower concave ring.

[0008] The present invention has a simple structure and is easy to manufacture. It can effectively protect the filler at the bottom of the valve stem under high-pressure conditions, ensure the sealing of the valve stem under high-pressure conditions (1500LB, 2500LB), and extend the service life of the valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the universal packing seal structure;

[0010] Figure 2 for Figure 1 The enlarged schematic diagram of the middle part I;

[0011] Figure 3 It is a schematic diagram of the structure of the present invention;

[0012] Figure 4 Figure 3 The enlarged schematic diagram of the middle part II;

[0013] Figure 5 This is a schematic diagram of the concave ring structure of the present invention;

[0014] Figure 6 It is a schematic diagram of the upper convex ring structure of the present invention;

[0015] Figure 7 Schematic diagram of the ring structure in the present invention. DETAILED DESCRIPTION

[0016] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] Reference Figures 2 to 5 A bottom protection structure of a high-pressure valve stem packing includes a lower concave ring 3, a middle ring 4, and an upper convex ring 5. The three are assembled from bottom to top to form a combination with a connected cavity, and then installed at the bottom of the stuffing box 2 with a gap between the valve stem 1. The connected cavity reduces the pressure of the medium and avoids the impact of the medium on the packing 6 at the bottom.

[0018] The above-mentioned connected cavity structure is formed as follows: the lower concave ring 3 is provided with a groove 14 on the inner ring surface and a U-shaped ring groove 15 on the upper end surface; a notch 16 is provided in the center line direction of the upper end surface of the middle ring 4; the upper convex ring 5 is a ring with a T-shaped cross-section; during assembly, the inner ring surfaces of the lower concave ring 3, the middle ring 4, and the upper convex ring 5 all maintain the same gap with the valve stem 1, and the T-shaped leg gap of the upper convex ring 5 extends into the U-shaped ring groove 15 of the lower concave ring 3 and a gap is left between the bottom of the T-shaped leg and the bottom of the U-shaped ring groove 15, the T-shaped shoulder of the upper convex ring 5 presses the middle ring 4 and the lower concave ring 3 to form a combination and put it into the bottom of the stuffing box 2, and several circles of flexible graphite rings are placed on the upper convex ring 5, and the nut 12 and the disc spring 11 are tightened to form a downward pressure, and the packing 4 is pressed by the pressure plate 10 and the pressing sleeve 9 to form a seal of the valve stem 1. Figure 3 The number 7 is the pin and the number 8 is the swing bolt.

[0019] Working process of the present invention:

[0020] like Figure 2 , Figure 3 , Figure 5As shown, the high-pressure medium enters the gap between the inner ring surface of the lower concave ring 3, the middle ring 4, the upper convex ring 5 and the valve stem 1, and first encounters the groove 14 on the inner ring surface of the lower concave ring 3. The medium forms a vortex in the groove cavity which is much larger than the gap volume, and the movement speed and pressure are reduced. The medium spiraled out of the groove 14 continues to move forward, and enters the labyrinth-like cavity formed by the assembly of the lower concave ring 3, the middle ring 4, and the upper convex ring 5 through the notch 16 on the middle ring 4, so that the pressure of the medium is further reduced, and the impact damage of the medium on the packing 6 is avoided.

Claims

1. A bottom protection structure for a high-pressure valve stem packing, characterized in that: The invention comprises a lower concave ring (3), a middle ring (4) and an upper convex ring (5), which are assembled from bottom to top in sequence to form a combined body with a connected cavity, and then installed at the bottom of a stuffing box (2) with a gap with the valve stem; the lower concave ring (3) has a groove (14) on the inner ring surface and a U-shaped ring groove (15) on the upper end surface; the middle ring (4) has a notch (16) in the center line direction of the upper end surface; the upper convex ring (5) is a ring with a T-shaped cross-section; during assembly, the inner ring surfaces of the lower concave ring (3), the middle ring (4) and the upper convex ring (5) all maintain the same gap with the valve stem (1), while the T-shaped leg gap of the upper convex ring (5) extends into the U-shaped ring groove (15) of the lower concave ring (3) and a gap is left between the bottom of the T-shaped leg and the bottom of the U-shaped ring groove (15), and the T-shaped shoulder of the upper convex ring (5) presses the middle ring (4) and the lower concave ring (3).

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