Steam generator manhole self-tightening sealing structure and method for changing forced sealing into self-tightening sealing

Abstract

The invention belongs to the technical field of nuclear power mechanical equipment pressure boundary flange sealing, and discloses a steam generator manhole self-tightening sealing structure and a method for changing forced sealing into self-tightening sealing. The sealing structure comprises an end pressing ring, a floating top cover, a quadruple ring, a restraining ring and a wedge-shaped pad, the restraining ring serves as a supporting structure of a restraining bolt and a restraining nut, the end pressing ring, the quadruple ring and the restraining ring interact to provide restraining loads, the floating top cover is tensioned to extrude the wedge-shaped pad, and the wedge-shaped pad deforms to generate elastic potential energy so as to obtain sealing specific pressure. According to the method, a pressing ring assembly, a wedge-shaped pad, a floating top cover, a restraining ring and a tensioning assembly are installed on a manhole flange body, and the wedge-shaped pad is extruded by tensioning the floating top cover so that the wedge-shaped pad can deform to generate elastic potential energy. The steam generator manhole sealing structure is suitable for a current steam generator manhole sealing structure, the safety and reliability of steam generator manhole sealing and the use and maintenance convenience are improved, and the production economy of full-period use and maintenance of a steam generator is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of pressure boundary flange sealing of nuclear power machinery and equipment, and in particular relates to a self-tightening sealing structure of a steam generator manhole and a method for converting a forced seal into a self-tightening seal. Background Art

[0002] The pressure boundary flange seals of nuclear power machinery and equipment mainly include O-ring seals, metal flat gasket seals, double cone seals, Wood seals, wedge gasket seals, etc.

[0003] O-ring seals and spiral wound gasket seals are forced seals. Their principle relies on the preload of the connecting parts (such as main bolts) to ensure that there is a certain sealing pressure ratio between the flange cover, the sealing element, and the end of the flange body to achieve sealing. As the internal pressure increases, the flange cover floats, the bolts are stretched, and the sealing pressure ratio decreases accordingly. Therefore, forced sealing requires a large bolt preload so that the gasket still has a large residual compression stress under working conditions to ensure reliable sealing between the gasket, the flange cover, and the end of the flange body. Usually, the total load on the initial bolts should reach 3 to 5 times the minimum sealing pressure ratio of the gasket.

[0004] Double cone seal is a semi-self-tightening seal. This sealing method mainly relies on the bolt pre-tightening force to make the sealing element produce elastic deformation and provide a specific pressure to establish the initial seal. When the pressure increases, the contact pressure of the sealing surface also increases, thereby ensuring the sealing performance during operation. This seal still requires technically very high main bolts and a large initial load.

[0005] Wood seals are self-tightening seals. This sealing technology uses the characteristics of the structure to increase the sealing pressure ratio between the gasket, flange cover, and flange body ends as the working pressure increases. Self-tightening seals do not require a large bolt pre-tightening force. The higher the pressure, the greater the compression force of the sealing element on the contact surface, the better the sealing performance, and the seal remains reliable when the operating conditions fluctuate. Self-tightening seals can be divided into radial self-tightening seals and axial self-tightening seals. Self-tightening seals such as Wood seals do not require large-sized main bolts, and use smaller restraining bolts to provide the initial gasket sealing pressure ratio. The greater the internal pressure of the subsequent device, the greater the gasket sealing pressure ratio and the more reliable the seal.

[0006] At present, the manhole sealing structure of the in-service nuclear power steam generator adopts metal flat gasket sealing, which is a kind of forced sealing.

[0007] The disadvantages of existing steam generator manhole seals in service are:

[0008] 1. Main bolts must be used, and the initial load applied to the main bolts is very large, which causes the main bolt threads to be severely squeezed or even bitten by the bolt holes and nuts, making disassembly and assembly difficult;

[0009] 2. Metal flat gaskets have very high requirements for the uniformity and accuracy of bolt pre-tightening. Insufficient or excessive pre-tightening force of local bolts often causes tightness leakage or gasket damage. In order to control the uniformity of bolt pre-tightening, cumbersome methods such as measuring the elongation of the bolts are often used to pre-tighten the bolts, resulting in complex bolt manufacturing process and operation;

[0010] 3. Since the bolts are arranged outside the manhole flange cover, the calculated diameter of the flange cover is large, resulting in a large calculated thickness of the manhole cover, a large weight of the manhole flange cover, and complex disassembly and positioning of the manhole;

[0011] 4. The flat gasket forced seal structure has poor adaptability when facing equipment working condition transformation, especially when the pressure fluctuates frequently, which can easily cause fatigue of the main bolts, etc.;

[0012] 5. When the flat gasket forced seal structure operates at high temperature for a long time, the stress relaxation of the main bolts and gaskets often leads to a decrease in the seal pressure ratio and causes leakage. Summary of the invention

[0013] The purpose of this application is to overcome the defects of the prior art and provide a self-tightening sealing structure for a steam generator manhole and a method for converting a forced seal to a self-tightening seal, which is suitable for the current steam generator manhole sealing structure, is beneficial to improving the safety and reliability of the steam generator manhole sealing, the convenience of use and maintenance, and improving the production economy of the full cycle use and maintenance of the steam generator.

[0014] In order to achieve the above objectives, this application provides the following technical solutions:

[0015] In a first aspect, the present application provides a steam generator manhole self-tightening sealing structure, comprising:

[0016] The end pressure ring is arranged on the top of the manhole flange body, and the tension bolts are installed on the side;

[0017] A floating top cover is arranged inside the manhole flange body, the floating top cover has an outer cone angle of the floating top cover, the outer cone angle β of the floating top cover forms a triangular area with the inner circle of the manhole flange, and an elastic wedge-shaped gasket is arranged in the triangular area;

[0018] A four-in-one ring is arranged on the inner side of the end pressure ring and is fixed in the groove formed by the end pressure ring and the manhole flange body through the tension bolts;

[0019] A check ring is arranged on the top of the end pressure ring. The check ring is connected through a check assembly and pulls the floating top cover so that the floating top cover squeezes the wedge-shaped gasket. The wedge-shaped gasket deforms to generate elastic potential energy to obtain a sealing specific pressure.

[0020] In some embodiments, the wedge-shaped gasket has an inner taper angle α of the wedge-shaped gasket, and the inner taper angle α of the wedge-shaped gasket is equal to the outer taper angle β of the floating top cover.

[0021] In some embodiments, the wedge-shaped gasket outer diameter D4 is smaller than the inner diameter of the manhole flange body, the wedge-shaped gasket width W is greater than the inner straight section height L of the wedge-shaped gasket, and the wedge-shaped gasket height H is greater than the wedge-shaped gasket width W.

[0022] In some embodiments, the outer diameter D4 of the wedge-shaped gasket is 0.2 to 0.5 mm smaller than the inner diameter, the width W of the wedge-shaped gasket is nearly 3 times the height L of the inner straight section of the wedge-shaped gasket, and the height H of the wedge-shaped gasket is 1 to 2.2 times the width W of the wedge-shaped gasket.

[0023] In some embodiments, a metal edging is provided in a region with a height range of A≥5 mm on the upper surface of the wedge-shaped gasket and B≥5 mm on the lower surface of the wedge-shaped gasket.

[0024] In some embodiments, the four-ring includes two X blocks and two Y blocks that are cut in parallel and symmetrically, the two X blocks are arranged at 3 o'clock and 9 o'clock respectively, and the two Y blocks are arranged at 6 o'clock and 12 o'clock respectively.

[0025] In some embodiments, radially arranged tension bolt holes are provided on the X-block, and the tension bolt holes are aligned with the third through holes provided on the side of the end pressure ring.

[0026] In some embodiments, the outer diameter D2 of the four-in-one ring is 0.5-1 mm smaller than the step sinking circle diameter of the manhole flange body, and the inner diameter D1 of the four-in-one ring is the same as the inner diameter D3 of the wedge-shaped gasket.

[0027] In some embodiments, a positioning step is provided on the outer side of the top of the containment ring, the surface of the positioning step is matched with the inner circle of the end pressure ring, and the containment ring is arranged against the end pressure ring.

[0028] In some embodiments, the outer diameter D6 of the positioning step of the containment ring is 1-2 mm smaller than the inner diameter of the end pressure ring, and the height of the positioning step is 4-8 mm.

[0029] In some embodiments, the containment assembly includes a containment bolt and a containment nut, a second through hole is formed on the containment ring, and a second bolt hole is formed on the floating top cover.

[0030] In some embodiments, a spring washer is provided between the containment ring and the containment nut.

[0031] In some embodiments, the diameter D7 of the through hole of the containment ring bolt is 1-2 mm larger than the outer diameter of the thread of the containment bolt.

[0032] In some embodiments, the end pressure ring is provided with a first through hole, the manhole flange body is provided with a second bolt hole, the end pressure ring bolt passes through the first through hole, is screwed into the second bolt hole and is fixedly connected by the end pressure ring nut.

[0033] In some embodiments, the floating top cover, the four-ring, and the containment ring are made of alloy steel, high alloy steel, or nickel-based alloy.

[0034] In some embodiments, the wedge-shaped gasket is made of aluminum, mild steel or graphite.

[0035] In a second aspect, the present application provides a method for converting a steam generator manhole forced seal into a self-tightening seal, comprising the following steps:

[0036] Step 1: Align the end pressure ring with the end of the manhole flange body, arrange the two third through holes of the end pressure ring toward the 3 o'clock and 9 o'clock positions respectively, and install the pressure ring bolts and pressure ring nuts;

[0037] Step 2: Assemble the floating top cover, arrange the side with the outer cone angle β of the floating top cover outward, install the wedge-shaped gasket, and then install the four blocks of the four-ring, arrange the two blocks with the tension bolt holes at the 3 o'clock and 9 o'clock positions respectively and align with the third through hole, and install the tension bolt from the side of the end pressure ring;

[0038] Step 3: Install a check ring on the end pressure ring, align the second through hole of the check ring with the second bolt hole of the floating top cover, screw in the check bolt, install a spring washer and a check nut on the outside, and tighten the check nut after pre-fixing.

[0039] Furthermore, step 1 specifically includes:

[0040] Assemble the end pressure ring so that the end pressure ring is aligned with the end of the manhole flange body, the first through hole corresponds to the first bolt hole one by one, and the two tension bolt through holes should be at the 3 o'clock and 9 o'clock positions respectively when facing the manhole;

[0041] The compression ring bolt is installed by screwing into the bolt hole of the manhole flange body, and the compression ring nut is installed by sleeve screwing, so that the compression ring nut abuts against the end surface of the end compression ring;

[0042] Four groups of the compression ring bolts and compression ring nuts are evenly installed, and after all the compression ring bolts and compression ring nuts are pre-assembled, the compression ring nuts are tightened.

[0043] Furthermore, step 2 specifically includes:

[0044] Assemble the floating top cover, with the side with the outer cone angle β of the floating top cover facing outwards;

[0045] The side of the wedge-shaped gasket with the inner cone angle α of the wedge-shaped gasket is embedded inwardly into the triangle formed by the outer cone angle β of the floating top cover and the inner circle of the manhole flange, and the initial installation position of the wedge-shaped gasket and the floating top cover is at a certain distance from the four-ring limiting step on the manhole flange body;

[0046] Install the two Y blocks of the four-way ring, and then install the two X blocks, the two Y blocks are respectively at 6 o'clock and 12 o'clock, the two X blocks are respectively at 3 o'clock and 9 o'clock, the two tensioning bolt holes are coaxially arranged with the third through hole, and the tensioning bolts are installed from the side of the end pressure ring.

[0047] Furthermore, step 3 specifically includes:

[0048] The containment ring is mounted on the end pressure ring, one side of the positioning step of the containment ring matches the inner circle of the end pressure ring, and the bolt through holes on the containment ring correspond one to one with the bolt holes of the containment ring on the floating top cover;

[0049] The containment bolt is screwed into the second bolt hole of the floating top cover through the second through hole of the containment ring, and a spring washer 8 and a containment nut 7 are screwed onto the outer end of the containment bolt;

[0050] Four groups of the check bolts, spring washers and check nuts are evenly installed to pre-fix the check ring. After all the check bolts, spring washers and check nuts are pre-assembled, the check nuts are finally tightened.

[0051] Compared with the prior art, the steam generator manhole self-tightening sealing structure and the forced sealing to self-tightening sealing method provided in the present application have the following beneficial effects:

[0052] The steam generator manhole self-tightening sealing structure provided by the present application has the advantages of light structure, economy, reliability and strong adaptability to working conditions. By placing the internal pressure flat cover inside, the calculated diameter of the floating top cover is reduced, thereby achieving the purpose of reducing the calculated thickness of the floating top cover and reducing the weight. The weight of the floating top cover is ≤80kg, which is much smaller than the deadweight of the forced sealing manhole flange cover of nearly 300kg, reducing the risk of assembly operation.

[0053] Furthermore, the initial sealing pressure ratio of the wedge-shaped gasket is provided by the restraining bolt, and the sealing pressure ratio of the gasket of the subsequent sealing structure is provided by the internal pressure of the equipment, thereby ensuring that the sealing structure still has a good sealing effect when the working conditions of the equipment chamber change. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for the technical description.

[0055] Figure 1 A schematic diagram of the structure of the steam generator manhole self-tightening sealing structure provided in this application;

[0056] Figure 2 A schematic diagram of the structure of the floating roof provided for this application;

[0057] Figure 3 A schematic diagram of the structure of the wedge-shaped gasket provided for this application;

[0058] Figure 4 A front view of the four-ring provided for this application;

[0059] Figure 5 A cross-sectional view of a four-ring provided for this application;

[0060] Figure 6 A schematic diagram of the structure of the containment ring provided in this application;

[0061] Figure 7 A flow chart of a method for converting a forced seal of a steam generator manhole into a self-tightening seal provided in the present application.

[0062] Description of reference numerals:

[0063] 1. Wedge-shaped gasket; 2. Four-way ring; 3. Pressure ring bolt; 4. Pressure ring nut; 5. Restraining ring; 6. Floating top cover; 7. Restraining nut; 8. Spring washer; 9. Restraining bolt; 10. End pressure ring; 11. Tension bolt; 12. Manhole flange body; 13. Metal edging;

[0064] D1, inner diameter of the check ring; D2, outer diameter of the check ring; D3, inner diameter of the wedge-shaped gasket; D4, outer diameter of the wedge-shaped gasket; D5, outer diameter of the floating top cover; D6, inner diameter of the check ring positioning step; D7, diameter of the check ring bolt through hole;

[0065] MA, the major diameter of the four-way ring tension bolt hole; MB, the major diameter of the four-way ring restraining bolt hole;

[0066] H, height of wedge-shaped gasket; L, height of the inner straight section of the wedge-shaped gasket; W, width of the wedge-shaped gasket;

[0067] A. Upper surface of wedge-shaped gasket; B. Lower surface of wedge-shaped gasket;

[0068] α, inner cone angle of wedge-shaped gasket; β, outer cone angle of floating top cover. DETAILED DESCRIPTION

[0069] The following is further explained in detail through specific implementation methods.

[0070] like Figures 1 to 6As shown, the present application provides a steam generator manhole self-tightening sealing structure, including a wedge-shaped gasket 1, a four-in-one ring 2, a pressure ring assembly, a check ring 5, a floating top cover 6, a check assembly, an end pressure ring 10, and a tension bolt 11. The pressure ring assembly includes a pressure ring bolt 3 and a pressure ring nut 4, and the check assembly includes a check bolt 9 and a check nut 7.

[0071] The end pressing ring 10 is arranged against the manhole flange body 12, and the end pressing ring 10 is fixed to the manhole flange body 12 through the pressing ring assembly. The flange body 12 is provided with a first bolt hole, and the end pressing ring 10 is provided with a first through hole adapted to the first bolt hole. During installation, the first bolt hole is aligned with the first through hole (coaxial arrangement), and the pressing ring assembly connects the end pressing ring 10 and the manhole flange body 12 through the first bolt hole and the first through hole.

[0072] Specifically, the end pressing ring bolt 3 and the end pressing ring nut 4 work together to fix the end pressing ring 10 on the manhole flange body 12. The end pressing ring 10 replaces the original forced-sealed manhole flange cover and provides a limiting groove for the four-ring 2, and the limiting groove faces the inner side of the manhole flange body 12.

[0073] The end pressure ring 10 is annular in structure with a hollow middle portion, which is convenient for installing the wedge-shaped gasket 1, the four-ring 2 and the floating top cover 6. Two third through holes are also provided on the side of the end pressure ring 10, and the third through holes are used to install the tension bolts 11.

[0074] In some embodiments, for the purpose of structural material deformation coordination, the material used for the end compression ring 10 has the same or similar physical properties as the material used for the manhole flange body 12 , for example, SA-508 or 18MND5 alloy steel.

[0075] In some embodiments, the end pressure ring 10 is provided with 16 first through holes, and the flange body 12 is provided with 16 matching first bolt holes, each first through hole corresponds to the center circle of the corresponding first bolt hole, and the size of the first through hole is 2 to 3 mm larger than the size of the first bolt hole.

[0076] In some embodiments, the thread specifications of the end clamping ring bolt 3 and the end clamping ring nut 4 are adapted to the manhole flange body 12, and the actual specifications are M45×3 or M48×4, and the number is 16 pieces each. The mechanical properties of the end clamping ring bolt 3 are not lower than the requirements of grade 8.8 in GB / T3098.1; the mechanical properties of the end clamping ring nut 4 are not lower than the requirements of grade 8 in GB / T 3098.1. The diameter of the third through hole on the end clamping ring 10 is 1 to 2 mm larger than the outer diameter of the thread of the tension bolt 11.

[0077] like Figure 1 and Figure 2As shown, the floating roof 6 is installed inside the manhole flange body 12. The floating roof 6 is provided with a second bolt hole, the check ring 5 is provided with a second through hole, and the check assembly connects the check ring 5 and the floating roof 6 through the second bolt hole and the second through hole. The check assembly is used to tighten the floating roof 6 so that the floating roof 6 squeezes the wedge-shaped gasket 1.

[0078] The floating top cover 6 has an outer cone angle β of the floating top cover. The wedge-shaped gasket 1 is installed in a triangular area formed by the outer cone angle β of the floating top cover and the inner circle of the manhole flange.

[0079] In some embodiments, for assembly and positioning purposes, the outer diameter D5 of the floating top cover is 0.2-0.5 mm smaller than the inner diameter of the manhole flange body 12 .

[0080] In some embodiments, the size and number of the restraining bolt holes on the floating roof 6 are adapted to the specifications and number of the restraining bolts 9. Optionally, the number of the restraining bolts 9 is an integer multiple of 2.

[0081] In some embodiments, for safety, as the first contact material of the medium, the floating top cover 6 is made of alloy steel, high alloy steel or nickel-based alloy with high strength, good toughness and corrosion resistance.

[0082] like Figure 3 As shown, the wedge-shaped gasket 1 is an annular structure as a whole, the outer diameter D4 of the wedge-shaped gasket is smaller than the inner diameter of the manhole flange body 12, the width W of the wedge-shaped gasket is larger than the height L of the inner straight section of the wedge-shaped gasket, and the height H of the wedge-shaped gasket is larger than the width W of the wedge-shaped gasket. The outer cone angle β of the floating top cover is equal to the inner cone angle α of the wedge-shaped gasket, and the inner cone angle α of the wedge-shaped gasket is generally between 30 and 45°. This angle can ensure that when the gasket is squeezed and deformed, the vertical surface and the inclined surface direction of the gasket have compression-rebound potential energy that meets the sealing requirements at the same time.

[0083] In some embodiments, the outer diameter D4 of the wedge-shaped gasket is 0.2 to 0.5 mm smaller than the inner circle of the manhole flange body 12; the width W of the wedge-shaped gasket is nearly 3 times the height L of the inner straight section of the wedge-shaped gasket; the height H of the wedge-shaped gasket is 1 to 2.2 times the width W of the wedge-shaped gasket, preferably between 1.5 and 1.8 times. This size ratio can ensure that when the gasket is squeezed and deformed, both the vertical and inclined directions of the gasket have compression-rebound potential energy that meets the sealing requirements.

[0084] In some embodiments, for the stability of the wedge-shaped gasket 1 and its integrity before and after compression, metal edging treatment (metal edging 13 is provided), such as metal foil edging, is adopted in the area within the height range of the upper surface A≥5mm and the lower surface B≥5mm of the wedge-shaped gasket.

[0085] In some embodiments, in order to obtain good sealing pressure ratio under high temperature and high pressure, the wedge-shaped gasket 1 is made of aluminum-based, mild steel or graphite materials with good compression performance.

[0086] like Figure 1 , Figure 4 and Figure 5 As shown, the four-way ring 2 and the wedge-shaped gasket 1 and the floating top cover 6 for axially limiting the manhole, the four-way ring 2 is fixed in the groove formed by the end pressure ring 10 and the manhole flange body 12 by the tension bolts 11.

[0087] The four-in-one ring 2 is cut into four symmetrical parts: X-block, X-block, Y-block, and Y-block. The cutting lines are as follows: Figure 4 As shown. The X block is arranged relative to another X block, and the Y block is arranged relative to another Y block. When installing, install two Y blocks first, and then install two X blocks. The two Y blocks are at 6 o'clock and 12 o'clock respectively, and the two X blocks are at 3 o'clock and 9 o'clock respectively.

[0088] The tension bolt holes are set at the center of the two X-blocks and arranged in the radial direction. The tension bolt holes are through holes, the bolt through holes (third through holes) of the end pressure ring 10 are aligned with the tension bolt holes, and the tension bolts 11 are installed from the side of the end pressure ring 10. The tension bolts 11 penetrate the bolt through holes and the tension bolt holes to tighten the four-in-one ring 2 in the radial direction.

[0089] In some embodiments, for the convenience of assembly and fixing, the outer diameter D2 of the four-in-one ring is 0.5-1 mm smaller than the diameter of the step sinking circle on the manhole flange body 12. The inner diameter D1 of the four-in-one ring is the same as or similar to the inner diameter D3 of the wedge-shaped gasket.

[0090] In some embodiments, the outer diameter MA of the threads of the two tension bolts on the four-way ring 2 is not less than 8 mm, and the mechanical properties of the tension bolts 11 are not less than the requirements of grade 8.8 materials in GB / T 3098.1.

[0091] In some embodiments, for safety reasons, the four-ring 2 is made of alloy steel, high alloy steel or nickel-based alloy material with high shear strength.

[0092] like Figure 6 As shown, the check ring 5 is an annular structure as a whole, and a positioning step is provided on the outer side of the top of the check ring 5. The positioning step surface is adapted to the inner circle of the end pressure ring 10. When installed, the check ring 5 abuts against the end pressure ring 10. A group of second through holes on the check ring 5 correspond to the second bolt holes of the floating top cover 6 one by one. The check bolts 9 are screwed into the second bolt holes of the floating top cover 6 through the second through holes of the check ring 5, and the check nuts 7 are installed.

[0093] The restraining ring 5 serves as a supporting structure for the restraining bolts 9 and the restraining nuts 7. The three interact with each other to provide a restraining load, tighten the floating top cover 6, and squeeze the wedge-shaped gasket 1. The deformation of the wedge-shaped gasket 1 generates elastic potential energy, thereby obtaining a sealing specific pressure.

[0094] In some embodiments, the thread specification MB of the restraining bolt 9 should not be lower than M16, and the mechanical properties of the restraining bolt 9 should not be lower than the requirements of grade 8.8 materials in GB / T 3098.1. The mechanical properties of the restraining nut 7 should not be lower than the requirements of grade 8 materials in GB / T 3098.1.

[0095] In some embodiments, the outer diameter D6 of the restraining ring positioning step is 1-2 mm smaller than the inner diameter of the end pressure ring 10, and the height of the positioning step is 4-8 mm.

[0096] In some embodiments, the diameter of the second through hole of the containment ring 5 (diameter D7 of the through hole of the containment ring bolt) is 1-2 mm larger than the outer diameter of the thread of the containment bolt 9 .

[0097] In some embodiments, for safety reasons, the containment ring 5 is made of alloy steel, high alloy steel, nickel-based alloy or other materials with high strength and good toughness.

[0098] In some embodiments, in order to ensure the effectiveness of the sealing pressure ratio on the wedge gasket 1 during the axial movement of the floating top cover 6 due to changes in internal pressure, a spring washer 8 is added between the restraining nut 7 and the restraining ring 5. The specifications of the spring washer 8 match the restraining bolt 9, and its material should be spring steel or high-temperature precipitation hardening alloy.

[0099] When the steam generator manhole self-tightening sealing structure is in use, the total load of the end pressure ring 10 bolts should not be less than the total load of the floating top cover 6 pushed by the internal pressure at any time. The total internal pressure load F is usually calculated according to the maximum working pressure of the chamber and the cross-sectional area of ​​the manhole, and the minimum pre-tightening load F / 16 of a single pressure ring bolt is further calculated. The specific pre-tightening of the pressure ring bolt can be achieved by tightening the nut with a hydraulic tool or stretching the bolt.

[0100] When the manhole self-tightening sealing structure is used, the initial total load on the check bolt 9 meets the minimum sealing pressure ratio requirement of the wedge-shaped gasket 1. Usually, the minimum total load of all check bolts is calculated according to the minimum sealing pressure ratio of the wedge-shaped gasket and the gasket action area, and the minimum preload of a single check bolt is further calculated. The check bolt can be pre-tightened by tightening the check nut with a torque tool.

[0101] like Figure 7 As shown, based on the above-mentioned steam generator manhole self-tightening sealing structure, the present application provides a method for converting a steam generator manhole forced seal into a self-tightening seal, comprising the following steps:

[0102] Step 1: Align the end pressure ring 10 with the end of the manhole flange body 12, arrange the two through holes (third through holes) on the side of the end pressure ring 10 toward the 3 o'clock and 9 o'clock positions respectively, and install the pressure ring bolt 3 and the pressure ring nut 4.

[0103] Specifically, the end pressure ring 10 is assembled by the positioning auxiliary tooling, so that the end pressure ring 10 is aligned with the end of the manhole flange body 12, and the 16 first through holes correspond to the 16 first bolt holes on the end of the manhole flange body one by one, wherein the two tensioning bolt 11 through holes should be at the 3 o'clock and 9 o'clock positions respectively when facing the manhole; the pressure ring bolt 3 is installed by screwing into the bolt hole of the manhole flange body, and the pressure ring nut 4 is installed by sleeve screwing. For the initial installation, the pressure ring nut 4 is made to be close to the end face of the end pressure ring 10 by hand or an ordinary wrench, and four groups of pressure ring bolts 3 and pressure ring nuts 4 are evenly installed first. At this time, the positioning auxiliary tooling can be removed. After all the pressure ring bolts 3 and nuts 4 are pre-assembled, the pressure ring nut 4 is tightened in 3 gears with the help of a hydraulic or electric torque wrench according to a torque of 1500-2500N·m.

[0104] Step 2: Assemble the floating top cover 6, with the side with the outer cone angle β of the floating top cover facing outward, install the wedge gasket 1, and then install the four blocks of the four-piece ring 2. The two blocks with the tensioning bolt holes are arranged at the 3 o'clock and 9 o'clock positions respectively and aligned with the third through hole, and the tensioning bolts 11 are installed from the side of the end pressure ring 10.

[0105] Specifically, the floating top cover 6 is assembled with the help of the lifting tool, and the side of the floating top cover 6 with the outer cone angle (the outer cone angle β of the floating top cover) faces outward; then the side of the wedge-shaped gasket 1 with the inner cone angle (the inner cone angle α of the wedge-shaped gasket) faces inward and is embedded in the triangular area formed by the outer cone angle β of the floating top cover and the inner circle of the manhole flange. The initial installation position of the wedge-shaped gasket 1 and the floating top cover 6 is at a certain distance from the limiting step of the four-in-one ring 2 on the manhole flange body 12 to avoid affecting the installation of the four-in-one ring 2. First install the two Y blocks of the four-in-one ring 2, and then install the two X blocks. The two Y blocks are at the 6 o'clock and 12 o'clock positions respectively, and the two X blocks are at the 3 o'clock and 9 o'clock positions respectively. The tension bolt holes on the two X blocks are coaxial with the bolt through holes on the end pressure ring 10. Finally, the tension bolt 11 is installed from the side of the end pressure ring 10, and the installation torque is controlled at 12 to 24 N·m.

[0106] Step 3: Install the check ring 5 on the end pressure ring 10, align the second through hole of the check ring 5 with the second bolt hole of the floating top cover 6, screw in the check bolt 9, install the spring washer 8 and the check nut 7 on the outside, and tighten the check nut 7 after pre-fixing.

[0107] Specifically, the check ring 5 is assembled on the end pressure ring 10, one side of the positioning step of the check ring 5 matches the inner circle of the end pressure ring 10, the bolt through holes on the check ring 5 correspond one to one with the bolt holes of the check ring 5 on the floating top cover 6, the check bolt 9 is screwed into the second bolt hole of the floating top cover 6 through the second through hole of the check ring 5, the spring washer 8 and the check nut 7 are screwed on the outer end of the check bolt 9, four groups of check bolts 9, spring washers 8 and check nuts 7 are evenly installed first to pre-fix the check ring 5, and after all the check bolts 9, spring washers 8 and check nuts 7 are pre-assembled, the check nuts 7 are tightened in 3 gears with the help of a hydraulic or electric torque wrench.

[0108] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims

1. A steam generator manhole self-tightening sealing structure, characterized in that: include: The end pressure ring (10) is arranged on the top of the manhole flange body (12), and the side thereof is provided with a tensioning bolt (11); A floating top cover (6) is arranged inside the manhole flange body (12), the floating top cover (6) having a floating top cover outer cone angle, the floating top cover outer cone angle β and the inner circle of the manhole flange forming a triangular area, and an elastic wedge-shaped gasket (1) is arranged in the triangular area; A four-in-one ring (2) is arranged on the inner side of the end pressure ring (10) and is fixed in a groove formed by the end pressure ring (10) and the manhole flange body (12) through the tension bolts (11); A check ring (5) is arranged on the top of the end pressure ring (10). The check ring (5) is connected to and pulls the floating top cover (6) through a check assembly, so that the floating top cover (6) squeezes the wedge-shaped gasket (1). The wedge-shaped gasket (1) deforms to generate elastic potential energy, thereby obtaining a sealing specific pressure.

2. The steam generator manhole self-tightening sealing structure according to claim 1, characterized in that: The wedge-shaped gasket (1) has an inner cone angle α of the wedge-shaped gasket, and the inner cone angle α of the wedge-shaped gasket is equal to the outer cone angle β of the floating top cover.

3. The steam generator manhole self-tightening sealing structure according to claim 1 or 2, characterized in that: The wedge-shaped gasket (1) has an outer diameter D4 that is smaller than the inner diameter of the manhole flange body (12), a width W of the wedge-shaped gasket that is larger than a height L of the inner straight section of the wedge-shaped gasket, and a height H of the wedge-shaped gasket that is larger than the width W of the wedge-shaped gasket.

4. The steam generator manhole self-tightening sealing structure according to claim 3, characterized in that: The outer diameter D4 of the wedge-shaped gasket is 0.2-0.5 mm smaller than the inner diameter. The width W of the wedge-shaped gasket is nearly 3 times the height L of the inner straight section of the wedge-shaped gasket. The height H of the wedge-shaped gasket is 1-2.2 times the width W of the wedge-shaped gasket.

5. The steam generator manhole self-tightening sealing structure according to claim 1 or 2, characterized in that: A metal edging (13) is arranged in an area with a height range of A≥5mm on the upper surface of the wedge-shaped gasket and B≥5mm on the lower surface of the wedge-shaped gasket.

6. The steam generator manhole self-tightening sealing structure according to claim 1, characterized in that: The four-in-one ring (2) comprises two X blocks and two Y blocks which are cut in parallel and symmetrically, the two X blocks are arranged at 3 o'clock and 9 o'clock respectively, and the two Y blocks are arranged at 6 o'clock and 12 o'clock respectively.

7. The steam generator manhole self-tightening sealing structure according to claim 6, characterized in that: The X-block is provided with radially arranged tension bolt holes, and the tension bolt holes are aligned with the third through holes formed on the side of the end pressure ring (10).

8. The steam generator manhole self-tightening sealing structure according to claim 6 or 7, characterized in that: The outer diameter D2 of the four-way ring (2) is 0.5 to 1 mm smaller than the diameter of the step sinking circle of the manhole flange body (12), and the inner diameter D1 of the four-way ring is the same as the inner diameter D3 of the wedge-shaped gasket.

9. The steam generator manhole self-tightening sealing structure according to claim 1, characterized in that: A positioning step is provided on the outer side of the top of the restraining ring (5), and the surface of the positioning step is adapted to the inner circle of the end pressure ring (10), and the restraining ring (5) is arranged against the end pressure ring (10).

10. The steam generator manhole self-tightening sealing structure according to claim 9, characterized in that: The outer diameter D6 of the positioning step of the restraining ring is 1 to 2 mm smaller than the inner diameter of the end pressure ring (10), and the height of the positioning step is 4 to 8 mm.

11. The steam generator manhole self-tightening sealing structure according to claim 1, characterized in that: The containment assembly comprises a containment bolt (9) and a containment nut (7), a second through hole is provided on the containment ring (5), and a second bolt hole is provided on the floating top cover (6).

12. The steam generator manhole self-tightening sealing structure according to claim 11, characterized in that: A spring washer (8) is provided between the containment ring (5) and the containment nut (7).

13. The steam generator manhole self-tightening sealing structure according to claim 11, characterized in that: The diameter D7 of the through hole of the restraining ring bolt is 1 to 2 mm larger than the outer diameter of the thread of the restraining bolt (9).

14. The steam generator manhole self-tightening sealing structure according to claim 1, characterized in that: The end pressure ring (10) is provided with a first through hole, the manhole flange body (12) is provided with a second bolt hole, and the end pressure ring bolt (3) passes through the first through hole and is screwed into the second bolt hole and is fixedly connected by the end pressure ring nut (4).

15. The steam generator manhole self-tightening sealing structure according to claim 1, characterized in that: The floating top cover (6), the four-ring (2) and the containment ring (5) are made of alloy steel, high alloy steel or nickel-based alloy.

16. The steam generator manhole self-tightening sealing structure according to claim 1, characterized in that: The wedge-shaped gasket (1) is made of aluminum, mild steel or graphite.

17. A method for converting a forced seal of a steam generator manhole into a self-tight seal, characterized in that: The following steps are involved: Step 1: Align the end pressure ring (10) with the end of the manhole flange body (12), arrange the two third through holes of the end pressure ring (10) toward the 3 o'clock and 9 o'clock positions respectively, and install the pressure ring bolt (3) and the pressure ring nut (4); Step 2: Assemble the floating top cover (6), arrange the side with the outer cone angle β of the floating top cover outward, install the wedge-shaped gasket (1), and then install the four blocks of the four-piece ring (2), the two blocks with the tension bolt holes are arranged at the 3 o'clock and 9 o'clock positions respectively and aligned with the third through hole, and install the tension bolt (11) from the side of the end pressure ring (10); Step 3: Install the check ring (5) on the end pressure ring (10), align the second through hole of the check ring (5) with the second bolt hole of the floating top cover (6), screw in the check bolt (9), install the spring washer (8) and the check nut (7) on the outside, and tighten the check nut (7) after pre-fixing.

18. The steam generator manhole self-tightening sealing structure according to claim 17, characterized in that: Step 1 specifically includes: Assemble the end pressure ring (10) so that the end pressure ring (10) is aligned with the end of the manhole flange body (12), the first through hole corresponds to the first bolt hole one by one, and the two through holes of the tension bolts (11) are respectively located at the 3 o'clock and 9 o'clock positions when facing the manhole; The compression ring bolt (3) is installed by screwing into the bolt hole of the manhole flange body, and the compression ring nut (4) is installed by screwing, so that the compression ring nut (4) abuts against the end surface of the end compression ring (10); Four groups of the pressing ring bolts (3) and pressing ring nuts (4) are evenly installed, and after all the pressing ring bolts (3) and pressing ring nuts (4) are pre-assembled, the pressing ring nuts (4) are tightened.

19. The steam generator manhole self-tightening sealing structure according to claim 17, characterized in that: Step 2 specifically includes: Assembling the floating top cover (6) with the side with the outer cone angle β of the floating top cover facing outwards; The wedge-shaped gasket (1) is embedded inwardly with the side with the inner cone angle α of the wedge-shaped gasket facing inward into the triangular area formed by the outer cone angle β of the floating top cover and the inner circle of the manhole flange, and the initial installation position of the wedge-shaped gasket (1) and the floating top cover (6) is at a certain distance from the limiting step of the four-ring (2) on the manhole flange body (12); The two Y blocks of the four-way ring (2) are installed, and then the two X blocks are installed, the two Y blocks are respectively located at 6 o'clock and 12 o'clock, and the two X blocks are respectively located at 3 o'clock and 9 o'clock. The two tensioning bolt holes are coaxially arranged with the third through hole, and the tensioning bolt (11) is installed from the side of the end pressure ring (10).

20. The steam generator manhole self-tightening sealing structure according to claim 17, characterized in that: Step 3 specifically includes: The containment ring (5) is mounted on the end pressure ring (10), one side of the positioning step of the containment ring (5) matches the inner circle of the end pressure ring (10), and the bolt through holes on the containment ring (5) correspond one to one with the bolt holes of the containment ring (5) on the floating top cover (6); The containment bolt (9) is screwed into the second bolt hole of the floating top cover (6) through the second through hole of the containment ring (5), and a spring washer (8) and a containment nut (7) are screwed onto the outer end of the containment bolt (9); Four groups of the restraining bolts (9), the spring washers (8) and the restraining nuts (7) are evenly installed to pre-fix the restraining ring (5); after all the restraining bolts (9), the spring washers (8) and the restraining nuts (7) are pre-assembled, the restraining nuts (7) are finally tightened.

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