Large size flange face seal structure and method

Abstract

The application relates to a large-size flange end face sealing structure and a sealing method. Macroscopic unevenness of a flange surface is difficult to compensate under high test pressure, the rebounding amount is extremely small, the flange surface is not tightly attached, and leakage is prone to occur during water pressure test. Practice proves that flat gaskets cannot meet the requirements of large-size flange end face plane sealing. The application comprises an upper flange (2), a lower flange (1) and an O-shaped ring (4), the upper surface of the lower flange and the lower surface of the upper flange are respectively welded and connected with a lip ring (3) through an angle weld; the O-shaped ring is placed in a [shaped groove formed by the lip ring and the surfaces of the upper flange and the lower flange; after the upper flange and the lower flange are fastened, the O-shaped ring is attached to the surfaces of the upper flange and the lower flange. The application is used for large-size flange end face sealing.

Description

TECHNICAL FIELD

[0001] The present application relates to a large size flange end face sealing structure and sealing method. BACKGROUND

[0002] For large size flange end face sealing, asbestos gasket and graphite winding gasket in the form of flat gasket are used for sealing, and leakage occurs during water pressure test. The reason is that the compression deformation of such gasket is extremely small, and it is difficult to compensate for the macro unevenness of the flange surface under high test pressure, and the rebound amount is extremely small, and the flange surface is not tightly fitted, and leakage easily occurs during water pressure test. It has been proved that flat gasket cannot meet the requirement of large size flange end face sealing. SUMMARY

[0003] The purpose of the present application is to provide a large size flange end face sealing structure and sealing method.

[0004] The above purpose is achieved by the following technical scheme:

[0005] A large size flange end face sealing structure, which comprises an upper flange, a lower flange and an O-ring,

[0006] The upper surface of the lower flange and the lower surface of the upper flange are respectively welded and connected with the lip ring by fillet welding;

[0007] The O-ring is placed in the groove formed by the lip ring, the upper flange and the lower flange surface, and after the upper flange and the lower flange are fastened, the O-ring is tightly fitted with the upper flange and the lower flange surface.

[0008] The large size flange end face sealing structure, the inner circle of the lower flange is welded with multiple groups of pre-welding parts, and the pressing piece / rod is welded with the pre-welding parts. After the O-ring is installed, the pressing piece / rod is bent on the O-ring to press the O-ring.

[0009] The large size flange end face sealing structure, the welding angle of the lower flange and the upper flange after welding with the lip ring is ground / machined to form a smooth and flat inclined surface.

[0010] A sealing method for a large size flange end face sealing structure, the method comprising the following steps:

[0011] Step one: design of O-ring;

[0012] D2=D1-2mm

[0013] O-ring diameter:

[0014] d2=h / (1-w)

[0015] D2 = D1 - 2mm

[0016] D1 = D2 + 2mm

[0017] d2 = D2 - 2mm

[0018] h = d2 / 2

[0019] W = 15% - 30%

[0020] W = 15% - 30%

[0021] Step 2: The diameter d2 of the O-ring is calculated by the compression rate, and the compression rate is controlled to be about 15-20%. The compression rate calculation formula is 100 x (d2-2δ) / d2.

[0022] The diameter D2 of the O-ring is determined by the size of D1, and D2 = D1-2mm. The diameter D1 is determined by the tangent of the two side fillet weld lines of the upper flange and the lower flange, and the size of d2.

[0023] Step 3: The size of d2 / 2 < h < 2δ after the assembly of the compression sheet / rod.

[0024] Step 4: Before heat treatment, evenly distribute the pre-welding piece in the inner circle of the flange. When the O-ring is installed, the pre-welding piece is welded with the flange before heat treatment, and the compression sheet / rod is welded with the pre-welding piece after heat treatment. After the O-ring is installed in place, the compression sheet / rod is bent onto the O-ring, and the O-ring is compressed.

[0025] Step 5: The O-ring is pre-sealed by the clamping of the upper flange and the lower flange. When the water pressure rises, the O-ring will be pushed to the inside of the [cavity, so that the O-ring is in close contact with the [cavity formed by the two flanges. When the water pressure gradually rises, the gap between the flanges is filled and sealed by the deformation of the O-ring, and the pressure is transmitted to a larger contact surface, ensuring the integrity of the O-ring under pressure, thereby completing the water pressure test sealing of the large diameter flange.

[0026] Advantages:

[0027] 1. The O-ring is pre-sealed by the clamping of the upper flange and the lower flange. When the water pressure rises, the O-ring will be pushed to the inside of the [cavity, so that the O-ring is in close contact with the [cavity formed by the two flanges. When the water pressure gradually rises, the gap between the flanges is filled and sealed by the deformation of the O-ring, and the pressure is transmitted to a larger contact surface, ensuring the integrity of the O-ring under pressure, thereby completing the water pressure test sealing of the large diameter flange.

[0028] 2. The lip ring is welded to the upper and lower flange surfaces by fillet welding, and the fillet welding surface is polished and machined to form a smooth and flat slope after welding, so as to avoid the uneven surface of the welding seam from causing the O-ring surface to be bitten;

[0029] The O-ring is placed in the [shaped groove formed by the lip ring and the upper and lower flange surfaces, and after the flange fastener is tightened, the O-ring is in close contact with the upper and lower flange surfaces, and during the water pressure test, the O-ring is tightly attached to the upper and lower flange surfaces and the fillet weld under the internal pressure, thereby achieving sealing. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings are provided to illustrate the structure of the present application; Figure 1 The accompanying drawings are provided to illustrate the structure of the present application;

[0031] The accompanying drawings are provided to illustrate the structure of the present application; Figure 2 The accompanying drawings are provided to illustrate the structure of the present application;

[0032] The accompanying drawings are provided to illustrate the structure of the present application; Figure 3 The accompanying drawings are provided to illustrate the structure of the present application;

[0033] The accompanying drawings are provided to illustrate the structure of the present application; Figure 4 The accompanying drawings are provided to illustrate the structure of the present application;

[0034] The accompanying drawings are provided to illustrate the structure of the present application; Figure 5 The accompanying drawings are provided to illustrate the structure of the present application;

[0035] The accompanying drawings are provided to illustrate the structure of the present application; Figure 6 The accompanying drawings are provided to illustrate the structure of the present application;

[0036] In the drawings: 1, upper flange; 2, lower flange; 3, lip ring; 4, O-ring; 5, pre-welding piece; 6, compression piece / rod. DETAILED DESCRIPTION

[0037] Example 1:

[0038] A large-size flange end face sealing structure, which comprises an upper flange 2, a lower flange 1 and an O-ring 4,

[0039] The upper surface of the lower flange and the lower surface of the upper flange are respectively welded to the lip ring 3 by fillet welding;

[0040] The O-ring is placed in the [shaped groove formed by the lip ring and the upper and lower flange surfaces, and after the flange fastener is tightened, the O-ring is in close contact with the upper and lower flange surfaces, and during the water pressure test, the O-ring is tightly attached to the upper and lower flange surfaces and the fillet weld under the internal pressure, thereby achieving sealing.

[0041] Example 2:

[0042] According to the large size flange end face sealing structure of embodiment 1, the lower flange inner circle welding uniformly distributes a plurality of pre-welding pieces 5, the pressing piece / rod 6 is welded with the pre-welding piece, the pressing piece / rod is bent to the O-shaped ring after the O-shaped ring is installed, and the O-shaped ring is pressed.

[0043] Embodiment 3:

[0044] According to the large size flange end face sealing structure of embodiment 1 or 2, the welding angle of the lower flange and the upper flange after being welded with the lip ring is polished / machined to be a smooth and flat slope, so as to avoid the uneven welding surface to bite the surface of the O-shaped ring.

[0045] Embodiment 4:

[0046] A sealing method for a large size flange end face sealing structure, the method comprising the following steps:

[0047] Step one: design of the O-shaped ring;

[0048] D2=D1-2mm

[0049] O-shaped ring diameter:

[0050] d2=h / (1-w)

[0051] Wherein: D2 is the O-shaped ring diameter

[0052] D1 is the diameter corresponding to the tangent of the two side fillet weld lines of the cavity

[0053] d2 is the O-shaped ring diameter

[0054] h is the height after being pressed in the sealed cavity

[0055] W is the design compression rate of the O-shaped ring

[0056] Compression rate w: 15%-30% under static pressure;

[0057] Step two: the O-shaped ring cross-sectional diameter d2 size is calculated by the compression rate, and the compression rate is controlled to be about 15-20%, and the compression rate calculation formula is 100x(d2-2δ) / d2;

[0058] The O-shaped ring diameter D2 size is determined by the D1 size, D2=D1-2mm, and the diameter D1 is determined by the tangent of the two side fillet weld lines of the upper flange and the lower flange, and d2 size;

[0059] The O-shaped ring 4 can adopt a slanting cut and a glued form.

[0060] Step three: the pressing piece / rod assembly size d2 / 2

[0061] Step four: before heat treatment, the uniform pre-welding is welded in the inner circle of the flange, and the O-ring is installed. Before heat treatment, the pre-welding is welded with the flange, and after heat treatment, the pre-welding is welded with the pre-welding. After the O-ring is installed in place, the pressing piece / rod is bent to the O-ring, and the O-ring is pressed tightly;

[0062] Step five: the O-ring is pre-sealed by clamping the upper flange and the lower flange, and when the water pressure rises, the O-ring will be pushed to the inside of the cavity, so that the O-ring is in close contact with the cavity formed by the two flanges. When the water pressure gradually rises, the gap between the flanges is filled and sealed by the deformation of the O-ring, and the pressure is transmitted to a larger contact surface, ensuring the integrity of the O-ring under pressure, thereby completing the water pressure test sealing of the large diameter flange.

[0063] Directly locking the two large diameter flanges with bolts can effectively reduce the extrusion gap g value of the sealing filler, thereby improving the safety and reliability of the water pressure. This locking method forms a cavity body on the end face of the two flanges. Since there are welded structures on flange 1 and flange 2, there are two inclined angles in the cavity body. The sealing filler (O-ring) is placed in the groove to form a water pressure sealing structure similar to an excircle.

Claims

1. A sealing method for a large-size flange end face sealing structure, characterized in that: The method includes the following steps: Step 1: O-ring design; D2 = D1 - 2mm, O-ring diameter: d2 = h / (1-w); where: D2 is the mid-diameter of the O-ring; D1 is the diameter corresponding to the tangent to the fillet weld edge of the cavity; d2 is the O-ring diameter; h is the height after being compressed by the sealed cavity; W is the design compression rate of the O-ring; compression rate w: 15%-30% under static pressure; Step 2: The O-ring cross-sectional diameter d2 is calculated using the compression ratio, which is controlled at 15-20%. The compression ratio calculation formula is 100×(d2-2δ) / d2. The O-ring diameter D2 is determined by the D1 dimension, where D2=D1-2mm. The diameter D1 is determined by the tangency of the fillet weld edges on both sides of the upper and lower flanges and the d2 dimension. Where: δ is the lip ring thickness. Step 3: After the clamping plate / rod is assembled, the dimensions d2 / 2 < h < 2δ; Step 4: Before heat treatment, weld pre-welded parts evenly on the inner circle of the flange. When installing the O-ring, use the pre-welded parts and the clamping plate / rod. The pre-welded parts are welded to the flange before heat treatment. After heat treatment, weld the clamping plate / rod to the pre-welded parts. After installing the O-ring in place, bend the clamping plate / rod onto the O-ring to press the O-ring tight. Step 5: The O-ring is pre-sealed by clamping the upper and lower flanges. When the water pressure increases, the O-ring will be pushed to the inside of the cavity, so that the O-ring is in close contact with the cavity formed by the two flanges. As the water pressure gradually increases, the O-ring will fill and seal the gap between the flanges by deforming, and at the same time, the pressure will be transmitted to a larger contact surface to ensure the integrity of the O-ring when bearing pressure, thus completing the water pressure test sealing of the large diameter flange. The upper surface of the lower flange and the lower surface of the upper flange are respectively welded to the lip ring with fillet welds; the O-ring is placed in the [-shaped groove formed by the lip ring, the upper flange, and the lower flange; after the upper flange and the lower flange are fastened, the O-ring is in contact with the surfaces of the upper flange and the lower flange. The lower flange has multiple pre-welded parts evenly distributed on its inner circle. The clamping plate / rod is welded to the pre-welded parts. After the O-ring is installed, the clamping plate / rod is bent onto the O-ring to press the O-ring tight. The weld bead surfaces of the lower flange and upper flange after welding to the lip ring are ground / machined to form a smooth, flat bevel.

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