Safety valve main sealing structure suitable for low-pressure corrosive working condition

Abstract

A safety valve main sealing structure applicable to low-pressure corrosive working conditions relates to the field of safety valves and comprises a valve seat, a valve clack and a sealing block connected to the valve clack. An elastic sealing lip is arranged on the peripheral edge of the sealing block, the elastic sealing lip comprises an annular V-shaped groove and a metal supporting spring, the annular V-shaped groove is formed in the peripheral face of the sealing block, and the opening end of the V-shaped groove is located at the position of the peripheral face of the sealing block; the section of the annular metal supporting spring is in a V shape, and the outer ring face of the metal supporting spring is the opening end of the V shape. The metal supporting spring is located in the V-shaped groove. The safety valve can meet the requirements of low-pressure working conditions and corrosion resistance, and under the low-pressure corrosive working conditions, the safety valve has reliable sealing performance and certain medium impurity resistance.

Description

Technical Field

[0001] The present application belongs to the technical field of safety valve design, and is an elastic main sealing structure technology suitable for corrosive media such as organic solvents, inorganic acids, alkalis, ketones, aromatic hydrocarbons, hydrogen chloride, etc., and can be used for safety valves under low-pressure working conditions. Background Art

[0002] When the safety valve is used in the working conditions of low system pressure and corrosive medium, the main sealing structure will use a plastic sealing block soft sealing structure with excellent corrosion resistance. The traditional plastic block sealing structure such as Figure 1 , 2 The sealing pair of the conventional plastic block sealing structure is composed of a valve seat 1 and a sealing block 4. The sealing block 4 is fixed between the valve disc 2 and the pressing block 3 by means of a hexagon socket cylindrical head screw 5. The valve disc 2 presses the sealing block 4 against the boss of the valve seat 1 under the action of the sealing force to form a seal.

[0003] The sealing performance of the traditional plastic block sealing structure safety valve has the following problems:

[0004] ① Large-sized safety valves working under low pressure conditions have poor sealing effects during sealing tests.

[0005] The reason for this problem is that, on the one hand, under low-pressure conditions, according to the working principle of the safety valve, the sealing force of the spring-loaded safety valve is provided by the spring. A low set pressure corresponds to a low-rigidity spring, and the provided sealing force is low; for the pilot safety valve, the sealing force is provided by the medium force, and the sealing force is low under the condition of low medium force. In summary, under low-pressure conditions, the lower sealing force of any valve type of safety valve will cause insufficient sealing pressure ratio between the sealing block 4 and the valve seat 1. On the other hand, according to the sealing mechanism, the sealing pressure ratio formed on the sealing surface must be greater than the required pressure ratio to ensure sealing. The size of the required pressure ratio is inversely proportional to the width of the sealing surface. Due to the high hardness of the sealing block 4, the indentation depth formed by the boss of the valve seat 1 on the sealing block 4 is not enough, resulting in a too narrow width of the sealing surface, making the required pressure ratio too large, and the sealing pressure ratio is less than the required pressure ratio, resulting in the safety valve failing to pass the factory sealing test. Since the sealing area of ​​a large-sized safety valve is large, it is more difficult to press out an indentation of effective depth, so the difficulty in passing the sealing test is more prominent on large-sized pilot safety valves.

[0006] ② The sealing performance of online use is not ideal and is easily affected by impurities, which may lead to leakage of the safety valve.

[0007] The reason for this problem is that due to the high hardness and insufficient elasticity of the sealing block 4, the fine impurities in the medium will form a leakage channel on the sealing surface. The overly hard sealing block cannot compensate for the influence of the impurities, causing the pilot safety valve to leak online. Summary of the invention

[0008] The technical problem solved by the present application is: to overcome the deficiencies of the prior art and provide a main sealing structure of a safety valve suitable for low-pressure corrosive working conditions, which can meet the requirements of low-pressure working conditions and corrosion resistance. Under low-pressure corrosive working conditions, the safety valve has reliable sealing performance and a certain ability to resist medium impurities.

[0009] This application designs a new low-pressure sealing block structure, uses corrosion-resistant modified PTFE material, designs an elastic sealing lip structure, improves the elasticity of the sealing block, and designs the valve seat to be flat, which serves the purpose of widening the width of the sealing surface. The above design effectively solves the problem of poor sealing effect during the sealing test of the safety valve under low-pressure conditions due to the required high specific pressure and insufficient sealing specific pressure, improves the sealing performance, and at the same time, the more elastic sealing block improves the ability to resist medium impurities during online work.

[0010] The technical solutions provided by this application are as follows:

[0011] A main sealing structure of a safety valve suitable for low-pressure corrosive working conditions, comprising a valve seat, a valve disc and a sealing block, wherein the sealing block is connected to the valve disc;

[0012] An elastic sealing lip is arranged on the outer circumferential edge of the sealing block, and the elastic sealing lip includes an annular V-shaped groove and a metal support spring. The annular V-shaped groove is arranged on the outer circumferential surface of the sealing block, and the opening end of the V-shaped groove is located at the outer circumferential surface of the sealing block; the cross-section of the annular metal support spring is V-shaped, and the outer annular surface of the metal support spring is the opening end of the V-shape; the metal support spring is located in the V-shaped groove.

[0013] The inner sides of the opening ends of the V-shaped grooves are each provided with a convex ring, and the side of the convex ring facing the axis of the sealing block is a limiting surface, and the two opening ends of the metal support spring are in contact with the two limiting surfaces respectively.

[0014] In the natural state, the opening width of the metal support spring is H1; in the natural state, the opening width of the V-shaped groove is H2, and H2 is approximately equal to 89%-91% of the value of H1.

[0015] The angle of the V-shaped groove is 29°-32°.

[0016] The distance between the surface of the sealing block facing the valve seat and the inner surface of the V-shaped groove is the lower lip of the elastic sealing lip, and the thickness of the lower lip is consistent at all locations.

[0017] The valve flap is provided with a mounting groove for mounting a sealing block, and the outer diameter of the lower lip is smaller than the outer diameter of the mounting groove.

[0018] The end of the V-shaped groove close to the axial direction of the sealing block is the groove bottom, and the diameter of the groove bottom surface should be larger than the diameter of the inner wall surface of the valve seat.

[0019] The width of the convex ring at the lower lip position along the groove depth direction ranges from 0.3 to 0.4 mm, and the thickness of the convex ring at the lower lip position is 50% of the thickness of the lower lip.

[0020] In summary, this application at least includes the following beneficial technical effects:

[0021] By designing an elastic sealing lip structure, embedding a metal support spring in the sealing lip and selecting corrosion-resistant modified PTFE material, an elastic sealing block suitable for low-pressure and corrosion-resistant working conditions is designed, making the main sealing structure of the safety valve more resistant to medium impurities and improving the sealing performance and service life under low-pressure conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the traditional sealing block structure;

[0023] Figure 2 Schematic diagram of the sealing surface of the traditional sealing block structure under the action of sealing force;

[0024] Figure 3 Schematic diagram of the low-pressure sealing block structure;

[0025] Figure 4 Schematic diagram of the sealing surface of the low-pressure sealing block structure before the sealing force acts;

[0026] Figure 5 Schematic diagram of the sealing surface of the low-pressure sealing block structure under the action of sealing force.

[0027] Description of reference numerals: 1. valve seat; 2. valve flap; 3. pressure block; 4. sealing block; 5. hexagon socket head screw;

[0028] 41. V-shaped groove; 42. Metal support spring; 43. Convex ring. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of this application clearer, the following Figure 3 , 4 , 5 further describes the low-pressure sealing block structure described in this application.

[0030] The present application embodiment discloses a safety valve main sealing structure suitable for low-pressure corrosive working conditions, such as Figure 3-Figure 5 As shown, the low pressure sealing block structure is as follows Figure 3 As shown, the material is modified PTFE material with excellent corrosion resistance and high and low temperature resistance. Its parts composition is consistent with the traditional sealing block structure. The sealing block 4 is fixed on the valve disc 2 by the pressing block 3. The pressing block 3 and the valve disc 2 are fixed by the hexagon socket head screw 5. The sealing block 4 contacts the valve seat 1, and the contact position is the sealing surface. The outer diameter of the sealing block 4 is smaller than the outer diameter of the valve seat 1 and larger than the inner diameter of the valve seat 1.

[0031] The outer peripheral edge of the sealing block 4 is provided with an elastic sealing lip, which includes an annular V-shaped groove 41 and a metal support spring 42. The annular V-shaped groove is provided on the outer peripheral surface of the sealing block 4, and the opening end of the V-shaped groove is located at the outer peripheral surface of the sealing block 4. The groove depth direction of the V-shaped groove is along the radial direction of the sealing block 4 and points to the axial direction of the sealing block 4. A convex ring 43 is provided inside the opening end of the V-shaped groove, and the side of the convex ring facing the axial direction of the sealing block 4 is the limiting surface; the cross section of the annular metal support spring is V-shaped, and the outer ring surface of the metal support spring is the opening end of the V-shape; the metal support spring is located in the V-shaped groove, and the opening end of the metal support spring contacts the limiting surface.

[0032] In the natural state, the opening width of the metal support spring is H1; in the natural state, the opening width of the V-shaped groove is H2. In order to ensure that the elasticity of the elastic sealing lip is moderate, it is necessary to control the thickness of the metal support spring and the angle of the V-shaped groove. In the natural state, H1 is approximately equal to 90% of H2, and the angle of the V-shaped groove (41) is approximately equal to 30°.

[0033] The distance between the surface of the sealing block 4 facing the valve seat 1 and the inner surface of the V-shaped groove is the lower lip of the elastic sealing lip, and the thickness of the lower lip is consistent. The valve flap 2 is provided with an installation groove for installing the sealing block 4, and the outer diameter of the lower lip is smaller than the outer diameter of the installation groove.

[0034] The end of the V-shaped groove close to the axial direction of the sealing block 4 is the groove bottom. In order to improve the durability of the sealing block 4 and avoid the deformation transition of the lower lip of the elastic sealing lip, the diameter of the groove bottom surface should be larger than the inner wall diameter of the valve seat 1.

[0035] To ensure that the metal support spring (42) can be stably placed in the V-shaped groove, the width of the convex ring (43) at the lower lip position along the groove depth direction ranges from 0.3 to 0.4 mm, and the thickness of the convex ring (43) at the lower lip position is approximately 50% of the thickness of the lower lip.

[0036] The safety valve sealing block structure for low-pressure corrosive working conditions described in this patent has the following main features:

[0037] ① Design of elastic sealing lip structure: The non-metallic sealing block has high hardness, the sealing surface width is narrow, the specific pressure must be high, the sealing force is low under low pressure conditions, and the sealing specific pressure is insufficient. Figure 3 As shown in FIG. 1 , a low-pressure sealing block structure with an elastic sealing lip is designed. The sealing lip of the sealing block in the structure is processed at the outer circle where it contacts the valve seat to increase the elasticity of the sealing block. Figure 5As shown in the figure, under the action of relatively low sealing force, the sealing block can produce a large deformation, and the valve seat boss is eliminated, the contact surface between the valve seat and the sealing block becomes a plane, the sealing surface is widened, the sealing area is effectively increased, the required specific pressure is reduced, and the sealing specific pressure is made greater than the required specific pressure. The safety valve can also maintain a good seal under low pressure conditions, and the improvement of the elasticity of the sealing block and the widening of the sealing block can resist the influence of fine impurities on the sealing performance.

[0038] ②: Design of metal support spring structure: In order to solve the problem of poor durability of the sealing block caused by the sealing lip being too soft and insufficient in elasticity, a metal support spring is embedded in the sealing lip to improve the elasticity of the sealing lip and the durability of the sealing block, thereby extending its service life.

[0039] like Figure 4 As shown in the figure, it is a schematic diagram of the sealing surface of the low-pressure sealing block structure before the sealing force acts. Since there is no sealing force at this time, the sealing block and the valve seat are only in a state of contact but not pressed tightly, and the sealing lip does not undergo obvious deformation, such as Figure 5 As shown in the figure, when low pressure is passed into the valve, the valve disc moves downward under the action of the sealing force, and the sealing lip is deformed. The sealing block is pressed against the valve seat to form a seal. Figure 2 It can be seen that when the pressure is low, the sealing surface formed by the low-pressure sealing block structure is significantly wider, which can effectively reduce the required specific pressure and achieve reliable sealing under low-pressure conditions.

[0040] In order to further improve the service life of the sealing block and solve the problem of its sealing lip being too soft and insufficient in elasticity, a metal support spring is embedded in the sealing lip to improve its elasticity, extend the service life of the low-pressure sealing block, withstand the influence of fine impurities on the sealing performance, and further improve the sealing performance under low-pressure conditions.

[0041] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0042] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A main sealing structure of a safety valve suitable for low-pressure corrosive working conditions, characterized by: It comprises a valve seat (1), a valve flap (2) and a sealing block (4), wherein the sealing block (4) is connected to the valve flap (2); The outer peripheral edge of the sealing block (4) is provided with an elastic sealing lip, the elastic sealing lip comprising an annular V-shaped groove (41) and a metal support spring (42), the annular V-shaped groove (41) is provided on the outer peripheral surface of the sealing block (4), and the opening end of the V-shaped groove (41) is located at the outer peripheral surface of the sealing block (4); the cross section of the annular metal support spring (42) is V-shaped, and the outer ring surface of the metal support spring (42) is located at the V-shaped opening end; the metal support spring (42) is located in the V-shaped groove (41).

2. A safety valve main sealing structure suitable for low-pressure corrosive working conditions according to claim 1, characterized in that: A convex ring (43) is provided inside the open end of the V-shaped groove (41), and the side of the convex ring (43) facing the axis of the sealing block (4) is a limiting surface, and the two open ends of the metal support spring (42) are in contact with the two limiting surfaces respectively.

3. A safety valve main sealing structure suitable for low-pressure corrosive working conditions according to claim 1, characterized in that: In the natural state, the opening width of the metal support spring (42) is H1; in the natural state, the opening width of the V-shaped groove (41) is H2, and H2 is approximately equal to 89%-91% of the value of H1.

4. The main sealing structure of a safety valve suitable for low-pressure corrosive working conditions according to claim 1 is characterized in that: The angle of the V-shaped groove (41) is 29°-32°.

5. The main sealing structure of a safety valve suitable for low-pressure corrosive working conditions according to claim 1 is characterized in that: The distance between the surface of the sealing block (4) facing the valve seat (1) and the inner surface of the V-shaped groove (41) is the lower lip of the elastic sealing lip, and the thickness of the lower lip is consistent at all locations.

6. The main sealing structure of a safety valve suitable for low-pressure corrosive working conditions according to claim 1, characterized in that: The valve flap (2) is provided with a mounting groove for mounting a sealing block (4), and the outer diameter of the lower lip is smaller than the outer diameter of the mounting groove.

7. The main sealing structure of a safety valve suitable for low-pressure corrosive working conditions according to claim 1, characterized in that: The end of the V-shaped groove (41) close to the axial direction of the sealing block (4) is the groove bottom, and the diameter of the groove bottom surface should be larger than the diameter of the inner wall surface of the valve seat (1).

8. The main sealing structure of a safety valve suitable for low-pressure corrosive working conditions according to claim 1 is characterized in that: The width of the convex ring (43) at the lower lip position along the groove depth direction ranges from 0.3 to 0.4 mm, and the thickness of the convex ring (43) at the lower lip position is 50% of the thickness of the lower lip.

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