CN113847491A

CN113847491A - Flange sealing structure, application thereof and sealing performance detection method

Info

Publication number: CN113847491A
Application number: CN202111153631.3A
Authority: CN
Inventors: 孙法国
Original assignee: Changzhou Sanzhong Elastic Technology Co ltd
Current assignee: Jiangsu Sanzhong Elastic Technology Co ltd
Priority date: 2021-09-29
Filing date: 2021-09-29
Publication date: 2021-12-28
Anticipated expiration: 2041-09-29
Also published as: CN113847491B

Abstract

The invention provides a flange sealing structure, an application thereof and a sealing performance detection method, wherein the flange sealing structure comprises the following components: a first flange; the opposite end faces of the second flange and the first flange are fixedly connected, and the first flange and the second flange are identical in structure and size; the first clamping groove is formed in the connecting end face of the first flange; the second clamping groove is formed in the connecting end face of the second flange; the top ring is positioned in an accommodating cavity defined by the first clamping groove and the second clamping groove; the first sealing ring is positioned in an accommodating cavity defined by the first clamping groove and the second clamping groove and positioned on the periphery of the top ring; the second sealing ring is positioned in an accommodating cavity defined by the first clamping groove and the second clamping groove and is positioned on the periphery of the first sealing ring; the flange sealing structure has good sealing performance at high and low temperatures, and can achieve the leakage rate of high pressure and low pressure not more than 1 multiplied by 10^‑5Pa·m³/s。

Description

Flange sealing structure, application thereof and sealing performance detection method

Technical Field

The invention relates to the technical field of flange sealing, in particular to a flange sealing structure, application thereof and a sealing performance detection method.

Background

The large flange sealing is a key technology in the fields of petrochemical industry, power plants and the like, the existing large flange sealing technology is basically monopolized abroad and has higher price, the existing large flange sealing technology usually adopts rubber as a sealing ring, and the sealing performance of the rubber is influenced due to the inherent performance of the rubber under the conditions of extremely high temperature and low temperature. Therefore, a large flange sealing structure which is low in cost and can adapt to high-temperature and low-temperature severe environments is urgently needed in the market.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a flange sealing structure, an application thereof and a sealing performance detection method, and can realize the sealing stability and the economical efficiency of a large flange in high-low temperature severe environments.

In order to achieve the above objects and other objects, the present invention includes the following technical solutions: the present invention first provides a flange seal structure, which includes: a first flange; the opposite end faces of the second flange and the first flange are fixedly connected, and the first flange and the second flange are identical in structure and size; the first clamping groove is formed in the connecting end face of the first flange; the second clamping groove is formed in the connecting end face of the second flange, and the first clamping groove and the second clamping groove are symmetrically arranged and have the same structure and size; the top ring is positioned in an accommodating cavity defined by the first clamping groove and the second clamping groove; the first sealing ring is positioned in an accommodating cavity defined by the first clamping groove and the second clamping groove and positioned on the periphery of the top ring; the second sealing ring is positioned in an accommodating cavity defined by the first clamping groove and the second clamping groove and is positioned on the periphery of the first sealing ring; the top ring supports the first sealing ring and the second sealing ring to abut against the first flange and the second flange, the cross section of the clamping groove is of a right-angled trapezoid structure, two ends of the first sealing ring and the second sealing ring extend to the upper bottom edge of the right-angled trapezoid, and the elastic modulus of the first sealing ring is 1.5 x 105-2.0 x 105N/mm 2.

In one embodiment, the length of the lower bottom edge a of the first slot and the second slot is 5-20 mm, and the length of the upper bottom edge b is 3-18 mm.

In an embodiment, an included angle α between an oblique side of the right trapezoid and an end surface of the first flange or the second flange is 45 to 60 °.

In one embodiment, the cross section of the top ring is an arch structure, and the length l of the top ring is greater than or equal to the length b of the upper bottom edge of the right trapezoid and less than the length a of the lower bottom edge.

In one embodiment, the distance d between the top ring and the upper bottom edges of the first clamping groove and the second clamping groove is 0.3-2 mm.

In one embodiment, the thickness of the first sealing ring is 0.5-2 mm, the thickness of the second sealing ring is smaller than 1mm, and the thickness of the second sealing ring is smaller than that of the first sealing ring.

In one embodiment, the average linear expansion coefficient of the top ring is less than or equal to 2.5 x 10 in the working temperature range of-253 ℃ to 200 DEG C^-6And the average linear expansion coefficient of the flange is higher than that of the top ring.

In one embodiment, the top ring has an average linear expansion coefficient of not greater than 15 x 10-6 ℃ and the top ring has an average linear expansion coefficient of not greater than the flange over an operating temperature range of 200 ℃ to 500 ℃.

The invention further provides the application of the flange sealing structure in high and low temperature flange sealing.

In another aspect, the present invention provides a method for detecting the sealing performance of a flange, including the following steps: s1: providing a flange sealing structure as described above, the flange being closed at both ends in the fluid flow direction; s2: forming a through hole in the flange sealing structure, introducing a detection medium through the through hole, recording the initial pressure of the detection medium in the sealing structure and sealing the through hole; s3: placing the flange sealing structure with the detection medium in a low-temperature or high-temperature environment for 1-2 hours, and then taking out the sealing structure from the low-temperature or high-temperature environment and stabilizing the sealing structure to room temperature; s4: and recording the pressure of the detection medium in the sealing structure cooled to the room temperature, and calculating to obtain the leakage rate of the detection medium in the sealing structure.

Compared with the prior art, the flange sealing structure has the following advantages: the flange sealing structure is suitable for sealing under high and low temperature complex working conditions by selecting the top rings made of different materials, and can be particularly suitable for sealing under high and low temperature complex working conditions by arranging the sealing ring with strong elasticityThe sealing ring has certain flexibility, can reduce the processing difficulty of a large flange and reduce the production cost of the flange, can be directly connected by a flange bolt without using a top ring under low pressure, and has flexible structure. The structure has good sealing performance at high and low temperature, and can achieve the leakage rate of high pressure and low pressure not more than 1 multiplied by 10^-5Pa·m³/s。

Drawings

Fig. 1 shows a schematic cross-sectional view of a flange seal structure of the present invention.

Fig. 2 is a schematic cross-sectional view of one side of the flange seal configuration of the present invention.

Fig. 3 is a schematic cross-sectional view of a card slot of the present invention.

Figure 4 shows a schematic cross-sectional view of the other side of the seal of the present invention.

Fig. 5 is a cross-sectional top view of a card slot of the present invention.

Fig. 6 shows a schematic diagram of low-temperature detection of the sealing performance detection method of the present invention.

Fig. 7 shows a high-temperature detection schematic diagram of the sealing performance detection method of the present invention.

Detailed Description

Referring to fig. 1 and 7, embodiments of the present invention are described below with specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

As shown in fig. 1, the present invention firstly provides a flange sealing structure 100, where the flanges (1,2) may be sealing discs, also called flanges or flange discs, used for sealing joints between pipelines and pipelines, the flanges (1,2) may be connectors for connecting pipelines in the petrochemical field, the flanges (1,2) may be generally two flanges respectively installed on end faces of two segments of pipelines, and then the two flanges (1,2) are fastened together by bolts (not shown) through holes on the flanges to realize a sealed connection between pipelines and transport of fluid, and in an embodiment, the transport direction of the fluid may be as shown by an arrow 101 in fig. 1.

As shown in fig. 1, the nominal diameter of the flange (1,2) of the present invention may be 200 to 4000mm, such as 400mm, 600mm, 1000mm, etc., further, the flange (1,2) may be a large flange (1,2), and the nominal diameter of the large flange (1,2) may be 2000 to 4000mm, such as 2500mm, 3000mm, 3500 mm. The flanges (1,2) can be applied to transportation of working media with extremely strict leakage requirements, the working media can be toxic gas, organic pollutants, petroleum and the like, the working pressure of the flange sealing structure 100 can be 0-30 MPa, further 10-30 MPa, such as 15MPa and 20MPa, and the working temperature of the flange sealing structure 100 can be-253-500 ℃.

As shown in fig. 2, the sealing structure 100 according to the present invention may be a sealing structure 100 symmetrically disposed along a transverse axis of the cross-section of the first flange 1 and the second flange 2. The flange sealing structure 100 of the present invention may include a first flange 1 and a second flange 2, the first flange 1 and the second flange 2 may have opposite structures, as shown in fig. 3, a first engaging groove 11 and a second engaging groove 21 may be disposed on a connecting end surface of the first flange 1 and the second flange 2, the first engaging groove 11 and the second engaging groove 21 may be symmetrically disposed along a transverse axis of the flange, the first engaging groove 11 and the second engaging groove 21 may have the same structure and size, a cross section of the engaging groove (11,21) may be a trapezoid, and further may be a right trapezoid, as shown in fig. 4, an included angle a between an oblique side of the right trapezoid and the connecting end surface of the flange may be an acute angle, and further, the acute angle may be 45 to 60 °, for example, 50 °, 55 °, and the like.

As shown in fig. 4, the length a of the lower base of the right trapezoid may be 5-20 mm, such as 6mm, 10mm, 15mm, etc., and the height h of the right trapezoid may be 0.4-0.6 times, such as 0.5 times, the length a of the lower base of the right trapezoid may be set according to the nominal diameter of the flange, and in some embodiments, the length a of the lower base of the right trapezoid may be proportional to the nominal diameter of the flange. The length b of the upper bottom edge of the right trapezoid can be 3-18 mm, such as 4mm, 8mm, 13mm and the like.

As shown in fig. 3 and 4, the sealing structure 100 may further include a top ring 3, the top ring 3 may be located in a receiving cavity formed by the first card slot 11 and the second card slot 21, a distance d between the top ring 3 and upper bottom edges of the first card slot 11 and the second card slot 21 may be 0.3 to 2mm, and further may be 0.5 to 1.5mm, the top ring 3 may be an arched door structure, a length of the top ring 3 may be greater than or equal to a length b of an upper bottom edge of the right trapezoid, and in an embodiment, a length l of the top ring may be equal to a length b of an upper bottom edge of the right trapezoid, as shown in fig. 5, the top ring 3 may also be divided into multiple segments according to a nominal diameter of the flange, and the top ring 3 may be filled into the receiving cavity, for example, the top ring 3 may be divided into multiple segments and placed into the receiving cavity.

As shown in fig. 2, the top ring 3 may be a low expansion alloy material, in an embodiment, an average linear expansion coefficient of the top ring 3 may be equal to or less than an average linear expansion coefficient of the first flange 1 and the second flange 2, and further may be equal to or less than an average linear expansion coefficient of the first flange 1 and the second flange 2, and in some embodiments, an average linear expansion coefficient of the top ring 3 material in a range of-253 ℃ to 200 ℃ may be equal to or less than 2.5 × 10^-6Further, the temperature may be 1.5X 10 ℃ or lower^-6The elongation of the top ring 3 material may be 30 to 45%, further 30 to 35%, and the shrinkage of the top ring 3 may be 50 to 70%, further 50 to 60%, and in some embodiments, the top ring 3 may be a permanent elastic alloy 4J 36.

As shown in FIG. 2, in some examples, for example, when the flange is operated at a temperature of 200 to 500 ℃, the top ring 3 may have an average linear expansion coefficient of not more than 15X 10^-6DEG C, furtherThe step size can be 8 × 10^-6℃～12×10^-6The first flange 1 and the second flange 2 may have an average linear expansion coefficient equal to or greater than an average linear expansion coefficient of the top ring 3, and the top ring 3 may be made of a stainless steel material, such as 304 stainless steel.

As shown in fig. 2, the sealing structure 100 may further include sealing rings (4,5), the sealing rings (4,5) may include a first sealing ring 4 and a second sealing ring 5, the sealing rings (4,5) may be located between the flanges (1,2) and the top ring 3, a thickness of the first sealing ring 4 may be greater than a thickness of the second sealing ring 5, the top ring 3 may support the first sealing ring 4 and the second sealing ring 5 against the first flange 1 and the second flange 2, a cross section of the sealing rings (4,5) may be in a circular arc shape, further, a cross section of the sealing rings (4,5) may be in a semicircular structure, at least a portion of upper and lower end surfaces of the top ring 3 is covered by the sealing rings (4,5), two ends of the sealing rings (4,5) may extend to an upper bottom edge of the top ring 3, in some embodiments, the coverage of the sealing rings (4,5) between the gap enclosed by the flanges (1,2) and the top ring (3) needs to be more than 70%.

As shown in fig. 2, the first seal ring 4 may be a metal seal ring closely attached to one side of the top ring 3, the thickness of the first seal ring 4 may be 0.5 to 2mm, for example, 0.8mm, 1mm, 1.2mm, 1.5mm, the surface roughness Ra of the first seal ring 4 may be 0.2 to 1 μm, further, 0.4 to 0.6 μm, for example, 0.45 μm, 0.5 μm, the first seal ring 4 may have a certain elasticity, and the elastic modulus of the first seal ring 4 may be 1.5 × 10⁵～2.0×10⁵N/mm²And further may be 1.5X 10⁵～1.8×10⁵N/mm²The tensile strength of the first seal ring 4 may be 200MPa or more, for example, 220MPa or 250MPa, the elongation of the first seal ring 4 may be 40% or more, for example, 50% or 55%, and the density of the first seal ring 4 may be 7 to 8 g-cm^-3E.g. 7.5g cm^-3、7.8g·cm^-3、7.9g·cm^-3And the like. In one embodimentThe first sealing ring 4 may be a metal material, such as an expanded 316 steel band. The expanded 316 steel strip may be obtained by stamping a purchased 316 steel strip.

As shown in fig. 2, the second sealing ring 5 may be located on a side away from the top ring 3, the second sealing ring 5 may be a thin layer of polymer material, in some embodiments, the second sealing ring 5 may be vulcanized rubber, such as silicone rubber, the thickness of the second sealing ring 5 may be less than 1mm, such as 0.5mm, 0.4mm, 0.3mm, and the like, and the first sealing ring 4 and the second sealing ring 5 may be bonded together by hot pressing.

As shown in fig. 2, the present invention also provides a use of the sealing structure 100 as described above in flange sealing at high and low temperatures, where the high temperature may be as high as 500 ℃, and the low temperature may be as low as-253 ℃, and the present invention uses an alloy top ring 3 having a smaller expansion coefficient at high and low temperatures to cooperate with a first sealing ring 4 having a certain rigidity, and when at different high and low temperatures, the first sealing ring 4 in the middle has a larger elasticity on the basis that the top ring 3 does not contract or slightly expands in cooperation with the flanges (1,2) by virtue of contraction or expansion of the first flange 1 and the second flange 2, so as to form a larger resistance to the flanges (1,2) and the top ring 3, thereby achieving a good compression sealing effect, and the present invention has a better sealing effect particularly in an environment with a lower temperature.

As shown in fig. 6 and 7, another aspect of the present invention provides a method for detecting sealing performance of a flange sealing structure 100, where the detection of sealing performance may be detection of high and low temperature sealing performance, the detection method may be detection under normal pressure, and the method may include steps S1 to S4:

-S1: providing a flange sealing structure as described above, the flange being closed at both ends in the fluid flow direction;

-S2: forming a through hole on the flange sealing structure, introducing a detection medium into the flange sealing structure through the through hole, recording the initial pressure of the detection medium in the sealing structure and sealing the through hole;

-S3: placing the flange sealing structure with the detection medium in a low-temperature or high-temperature container for 1-2 hours, taking out the sealing structure from the low-temperature or high-temperature container, and stabilizing the sealing structure to room temperature;

-S4: and recording the pressure of the detection medium in the sealing structure cooled to the room temperature, and calculating to obtain the leakage rate of the detection medium in the sealing structure.

In step S1, when the flange sealing structure performs high and low temperature sealing performance detection, two ends of the first flange and the second flange through which fluid passes may be set in a closed state, so as to ensure that the leakage of the flange can only pass through the sealing structure.

In step S2, the detection medium may be an inert gas, such as helium, nitrogen, etc., and further may be helium, the diameter of the through hole 12 on the flange may be 1-2 mm, the initial pressure of the detection medium may be detected and recorded by a pressure sensor or a high-precision pressure gauge, and the initial pressure may be denoted as P₁E.g. helium gas introduced into P at ambient temperature₁After the pressure of (c), the through-hole 12 can be blocked for the subsequent steps.

In step S3, the low temperature container 200 may contain inorganic liquid such as liquid hydrogen, liquid nitrogen, etc., and the high temperature container 300 may be a sealed high temperature drying oven, the temperature of the high temperature drying oven may be 500 ℃, the time in the low temperature or high temperature container (200,300) may be 1 hour, and the stabilization to room temperature may be rapid stabilization to room temperature.

In step S4, in one embodiment, the calculation may be performed using the ideal gas state equation PV — nRT. The pressure of the detection medium in the sealing structure cooled to room temperature can be recorded as P₂At this time n₂＝P₂V/RT_{Often times}，n₂Represents the molecular weight of the detection medium at room temperature, wherein V represents the internal volume of the first flange and the second flange after fastening together, T_{Often times}Represents normal temperature, and is passed through P again₃V＝n₂RT_{Is low in}Or P₃V＝n₂RT_{Height of}Wherein T is_{Is low in}Or T_{Height of}Calculating actual gas pressure P at low temperature or high temperature for actual test temperature in high and low temperature environment₃The leakage rate may be given by P₃And P₂The differential pressure of (a) is divided by V and then divided by the detection time.

The detection method disclosed by the invention is simple and convenient to operate and high in accuracy, and the pressure of the flange sealing structure in the high and low temperature actual detection medium can be accurately estimated by calculating the pressure in the high and low temperature environment again after the pressure is restored to the room temperature, so that large-scale calculation software and detection equipment are omitted, and the method has the characteristics of economy and easiness in implementation.

Evaluation of

The sealing structure of the invention is tested for high and low temperature leakage rate by adopting the detection method.

Example 1

The nominal diameter of the flange is 400mm, the top ring is made of constant-elasticity alloy 4J36, the first sealing ring is made of an expanded 316 steel belt, the second sealing ring is made of silicon rubber, liquid hydrogen is used as a low-temperature medium, and helium is used as a detection medium (P)₁2MPa), the low temperature leak rate was tested.

Example 2

Example 2 was tested for low temperature leak rate similar to example 1 without using a second seal ring.

Example 3

Example 3 similar to example 1, the top ring was made of 304 stainless steel and placed in a 500 ℃ dry box with helium as the detection medium and tested for high temperature leak rate.

Example 4

Example 4 was tested for high temperature leak rate similar to example 3 without using a second seal ring.

Comparative example 1

Comparative example 1 was similar to example 1 in that the first seal ring was not used, the second seal ring was replaced with silicone rubber having the same total thickness as the first seal ring and the second seal ring, and the silicone rubber was hot-pressed on the top ring to test the low-temperature leakage rate.

Comparative example 2

Comparative example 1 and example 3 similarly, the first seal ring was not used, the second seal ring was replaced with silicone rubber having the same total thickness as the first seal ring and the second seal ring, and the silicone rubber was hot-pressed on the top ring to test the high-temperature leakage rate.

The evaluation results of the gas leakage rates of examples 1 to 4 and comparative examples 1 to 2 are shown in table 1.

TABLE 1 evaluation result table of leakage amount of examples and comparative examples

Examples	Leakage Rate (Pa · m)³/s)
		Example 1	7×10^-6
Example 2	8×10^-6
		Example 3	7.4×10^-6
Example 4	8.6×10^-6
		Comparative example 1	1.0×10^-2
Comparative example 2	8×10^-3

Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value. The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A flange seal arrangement, the seal arrangement comprising:

a first flange;

the opposite end faces of the second flange and the first flange are fixedly connected, and the first flange and the second flange are identical in structure and size;

the first clamping groove is formed in the connecting end face of the first flange;

the second clamping groove is formed in the connecting end face of the second flange, and the first clamping groove and the second clamping groove are symmetrically arranged and have the same structure and size;

the top ring is positioned in an accommodating cavity defined by the first clamping groove and the second clamping groove;

the first sealing ring is positioned in an accommodating cavity defined by the first clamping groove and the second clamping groove and positioned on the periphery of the top ring;

the second sealing ring is positioned in an accommodating cavity defined by the first clamping groove and the second clamping groove and is positioned on the periphery of the first sealing ring;

wherein the top ring supports the first seal ring and the second seal ring against the first flange and the second flangeThe cross section of the clamping groove is of a right trapezoid structure, two ends of the first sealing ring and the second sealing ring extend to the upper bottom edge of the right trapezoid, and the elastic modulus of the first sealing ring is 1.5 multiplied by 10⁵～2.0×10⁵N/mm²。

2. The flange seal structure of claim 1, wherein: the length a of the lower bottom edge of the first clamping groove and the second clamping groove is 5-20 mm, and the length b of the upper bottom edge of the second clamping groove is 3-18 mm.

3. The flange seal structure of claim 1, wherein: an included angle alpha between the hypotenuse of the right trapezoid and the end face of the first flange or the second flange is 45-60 degrees.

4. The flange seal structure of claim 1, wherein: the cross section of the top ring is of an arch structure, and the length l of the top ring is greater than or equal to the length b of the upper bottom edge of the right trapezoid and smaller than the length a of the lower bottom edge.

5. The flange seal structure of claim 1, wherein: the distance d between the top ring and the upper bottom edges of the first clamping groove and the second clamping groove is 0.3-2 mm.

6. The flange seal structure of claim 1, wherein: the thickness of first sealing washer is 0.5 ~ 2mm, the thickness of second sealing washer is less than 1mm, the thickness of second sealing washer is less than the thickness of first sealing washer.

7. The flange seal structure of claim 1, wherein: the average linear expansion coefficient of the top ring is less than or equal to 2.5 multiplied by 10 in the working temperature range of-253 ℃ to 200 DEG C^-6And the average linear expansion coefficient of the flange is higher than that of the top ring.

8. The flange seal structure of claim 1, wherein: the average linear expansion coefficient of the top ring is not more than 15 x 10 in the working temperature range of 200 ℃ to 500 DEG C^-6And the average linear expansion coefficient of the top ring is not more than the average linear expansion coefficient of the flange.

9. Use of a flange seal according to any of claims 1 to 8 for high and low temperature flange sealing.

10. A method for detecting the sealing performance of a flange is characterized by comprising the following steps: the detection method comprises the following steps:

s1: providing a flange sealing structure according to any one of claims 1 to 8, wherein both ends of the flange in the fluid flowing direction are sealed;

s2: forming a through hole in the flange sealing structure, introducing a detection medium through the through hole, recording the initial pressure of the detection medium in the sealing structure and sealing the through hole;

s3: placing the flange sealing structure with the detection medium in a low-temperature or high-temperature environment for 1-2 hours, and then taking out the sealing structure from the low-temperature or high-temperature environment and stabilizing the sealing structure to room temperature;

s4: and recording the pressure of the detection medium in the sealing structure cooled to the room temperature, and calculating to obtain the leakage rate of the detection medium in the sealing structure.