Special stud for flange in nuclear power explosion valve

Abstract

The utility model discloses a special stud for a flange in a nuclear power explosion valve, which relates to the field of fasteners for nuclear power explosion valves and comprises a hexagonal structure section, a first threaded rod section, an unthreaded polished rod section, a second threaded rod section and a cylindrical boss section which are integrally formed, the thread structures of the first threaded rod section and the second threaded rod section are ACME trapezoidal threads with a thread angle of 29 degrees; the special stud for the flange in the nuclear power explosion valve is made of a high-temperature corrosion-resistant alloy material with the mark of ASTM A453 660B, and the surface of the special stud is plated with a silver-palladium ion plating layer; the thread height of the thread structures of the first threaded rod section and the second threaded rod section is 0.5 P, the thread top width is 0.3707 P, the thread width at the intermediate diameter position is 0.5 P, and P is the thread pitch. According to the utility model, the hexagonal structure section is arranged so as to facilitate installation and wrenching; the other end is provided with a cylindrical boss section for protecting threads; by coating the surface with the silver-palladium ion plating layer, the problem that the fatigue resistance, corrosion resistance and lubricating performance of an existing fastener need to be improved in a high-temperature environment is solved.

Description

Technical Field

[0001] The utility model relates to the field of fasteners for nuclear power bursting valves, in particular to a special stud for a flange in a nuclear power bursting valve. Background Art

[0002] Nuclear power burst valve is a part of the key and special equipment of nuclear power plants, mainly used in the fourth-level automatic pressure relief system, low-pressure injection system and shell recirculation system of nuclear power plants. Its main working principle is that under severe accident conditions, the burst unit is triggered by opening the valve signal, and the high-pressure gas generated pushes the piston in the valve to move, cutting off the blind pipe of the valve diameter, allowing cooling water to enter the core for cooling. In this way, the burst valve can effectively alleviate and prevent severe accidents, reduce the number of nuclear power unit equipment, and improve the safety and economy of the unit.

[0003] For a long time, nuclear power bursting valves and their fasteners have relied on imports. Utility Model Content

[0004] The utility model aims to provide a special stud for the flange in a nuclear power bursting valve, which is used to solve the problem that existing domestically produced fasteners are difficult to adapt to nuclear power bursting valves and have a short service life.

[0005] In order to achieve the above purpose, this utility model adopts the following technical solutions:

[0006] A special stud for flange in a nuclear power bursting valve comprises an integrally formed hexagonal structure section, a first threaded rod section, a threadless polished rod section, a second threaded rod section, and a cylindrical boss section, wherein the thread structure of the first threaded rod section and the second threaded rod section is an ACME trapezoidal thread with a tooth angle of 29 degrees.

[0007] Furthermore, the surface of the flange-specific stud in the nuclear power bursting valve is plated with a silver-palladium ion plating layer.

[0008] Furthermore, the thread structure of the first threaded rod segment and the second threaded rod segment has a thread height of 0.5P, a thread top width of 0.3707P, and a thread width at the mid-diameter of 0.5P, where P is the thread pitch.

[0009] Furthermore, the special studs for flanges in the nuclear power bursting valve are made of high-temperature corrosion-resistant alloy material with the grade ASTM A453 660B.

[0010] Compared with the prior art, the utility model has the following beneficial effects:

[0011] 1. The thread of the special stud for the flange in the nuclear power bursting valve of the utility model adopts an ACME trapezoidal thread with a tooth angle of 29°, which matches the internal thread on the bursting valve, realizing the localized independent production of fasteners for nuclear power bursting valves, replacing reliance on imports.

[0012] 2. One end of the special stud for flange in the nuclear power bursting valve of the utility model is provided with a hexagonal structure section to facilitate installation and twisting; the other end is provided with a cylindrical boss section to protect the thread.

[0013] 3. The flange-specific stud in the nuclear power bursting valve of the utility model is coated with silver palladium ion plating on the surface, which solves the problem that the fatigue resistance, corrosion resistance and lubrication performance of existing fasteners need to be improved in high temperature environments.

[0014] 4. The special stud for flange in the nuclear power bursting valve of the utility model is made of ASTM A453 660B material and has high high temperature resistance and corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the front view of the utility model;

[0016] Figure 2 for Figure 1 Schematic diagram of the thread structure at position Ⅰ;

[0017] In the figure: 1-hexagonal structure segment, 2-first threaded rod segment, 3-unthreaded smooth rod segment, 4-second threaded rod segment, 5-cylindrical boss segment, 6-silver-palladium ion plating layer. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0019] See also Figure 1-2 The utility model provides a special stud for a flange in a nuclear power bursting valve, comprising an integrally formed hexagonal structure section 1, a first threaded rod section 2, a threadless rod section 3, a second threaded rod section 4, and a cylindrical boss section 5, wherein the thread structure of the first threaded rod section 2 and the second threaded rod section 4 is an ACME trapezoidal thread with a tooth angle of 29°.

[0020] The biggest difference between the special stud for flange in the nuclear power bursting valve of the utility model and the national standard GB5796 of trapezoidal thread of my country is that the tooth angle of ACME thread is 29°, while the tooth angle of GB5796 is 30°.

[0021] Specifically, in order to match the internal thread on the bursting valve, the thread structure of the first threaded rod segment 2 and the second threaded rod segment 4 has a thread height of 0.5P, a thread top width of 0.3707P, and a thread width at the mid-diameter of 0.5P, where P is the thread pitch.

[0022] In the utility model, the hexagonal structure section 1 is used for wrench wrench, the first threaded rod section 2 is screwed and tightened with the nut, the second threaded rod section 4 is screwed into the threaded hole in the base of the bursting valve, and the unthreaded rod section 3 is located between the first threaded rod section 2 and the second threaded rod section 4, and is used to connect and tighten the flange in the bursting valve and the base of the bursting valve. The cylindrical boss section 5 is located at the end of the second threaded rod. Considering that the internal thread on the base of the bursting valve cannot be processed to the bottom of the hole, there is a section of unthreaded section at the bottom of the internal threaded hole. When the stud thread is forcibly screwed into the unthreaded section of the internal threaded hole, it is easy to damage the thread. Therefore, the cylindrical boss section 5 occupies the unthreaded section at the bottom of the internal threaded hole to protect the thread from damage. In order to ensure that the thread is not rolled during the processing, the geometric circumscribed circle diameter of the hexagonal structure section 1 is smaller than the minor diameter of the first screw rod section 2. In order to ensure the rotation and penetration of the thread, the diameter of the unthreaded rod section 3 is smaller than the minor diameter of the first threaded rod 2 and the second threaded rod 4.

[0023] Specifically, in order to improve the high temperature resistance and corrosion resistance of the special studs for flanges in nuclear power bursting valves, the special studs for flanges in nuclear power bursting valves are made of high temperature corrosion resistant alloy material with the grade ASTM A453 660B.

[0024] Specifically, in order to further improve the fatigue resistance, high temperature resistance, corrosion resistance and lubrication performance of the special studs for flanges in nuclear power bursting valves, the surface of the special studs for flanges in nuclear power bursting valves is plated with a silver-palladium ion plating layer 6.

[0025] During installation, use a wrench to tighten the hexagonal structure section 1, and the second threaded rod section 4 passes through the middle flange hole of the bursting valve and is screwed into the internal thread on the bursting valve base. The end of the cylindrical boss section 5 contacts the bottom of the internal thread hole, and the tightening is completed; insert a gasket at the left end, and screw the special nut for the middle flange into the first threaded rod section 2 until it is tightened.

[0026] The development process of the special stud for flange in the nuclear power blasting valve of the utility model is: material development → sawing → heat treatment → turning → milling hexagon → rolling thread → silver palladium ion plating on the surface, wherein:

[0027] Materials: This utility model is made of ASTM A453 660B material;

[0028] Heat treatment: 980±14℃, keep warm for at least 1 hour, water quench; 720±14℃, keep warm for at least 16 hours, air cool;

[0029] Turning: rough turning + fine turning, processing of cylindrical boss section at one end of the stud;

[0030] Milling hexagonal: milling the other end of the stud to process the hexagonal structure section 1;

[0031] Thread rolling: Adopt self-made ACME thread rolling tools and inspection fixtures to carry out batch, automated processing and rapid inspection of thread rolling;

[0032] Surface treatment: Silver-palladium ion plating, the simple process of silver-palladium alloy ion plating is as follows: silver-palladium alloy is used as an evaporation source connected to the anode, and a fastener is connected to the cathode; when a high-voltage direct current of three to five kilovolts is applied, arc discharge is generated between the evaporation source and the workpiece; because the vacuum cover is filled with inert argon gas, part of the argon gas is ionized under the action of the discharge electric field, thereby forming an ion dark area around the cathode fastener, and the positively charged argon ions are attracted by the negative high voltage of the cathode and violently bombard the surface of the fastener, causing the surface particles and dirt of the fastener to be splashed out, so that the surface of the fastener to be plated is fully cleaned by ion bombardment; then, the evaporation source AC power supply is turned on, the evaporation material particles melt and evaporate, enter the glow discharge area and are ionized; the positively charged evaporation material ions, attracted by the cathode, rush to the workpiece together with the argon ions, and when the evaporation material ions plated on the surface of the workpiece exceed the number of splashed ions, they gradually accumulate to form a coating that firmly adheres to the surface of the workpiece.

[0033] Example 1: Manufacturing number: 2021-12-13; Quantity: 2151 pieces; User: China National Nuclear Corporation Su Valve Technology Industry Co., Ltd.; Service project: Guohe demonstration PV70 bursting valve project.

[0034] Example 2: Manufacturing number: 2024-1-8; Quantity: 3368 pieces; User: CNNC Suvalve Technology Industry Co., Ltd.; Service project: Sanmen Nuclear Power Unit 3 / 4 CAP1000 PV70 bursting valve project.

[0035] Example 3: Manufacturing number: 2024-4-59; Quantity: 280 pieces; User: CNNC Suvalve Technology Industry Co., Ltd.; Service project: Burst valve spare parts project for Unit 2 of the National Nuclear Demonstration Power Plant.

[0036] Based on the embodiments of the present utility model, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present utility model.

Claims

1. A special stud for flange in nuclear power bursting valve, characterized by: It comprises an integrally formed hexagonal structure section, a first threaded rod section, a threadless polished rod section, a second threaded rod section, and a cylindrical boss section, wherein the thread structure of the first threaded rod section and the second threaded rod section is an ACME trapezoidal thread with a tooth angle of 29°.

2. A stud for flange in a nuclear power explosion valve as claimed in claim 1, characterized in that: The surface of the special stud for flange in the nuclear power bursting valve is plated with a silver-palladium ion plating layer.

3. A stud for flange in a nuclear power explosion valve as claimed in claim 1, characterized in that: The thread structure of the first threaded rod segment and the second threaded rod segment has a thread height of 0.5P, a thread top width of 0.3707P, and a thread width at the mid-diameter of 0.5P, where P is the thread pitch.

4. A stud for flange in a nuclear power explosion valve as claimed in claim 1, characterized in that: The special studs for flanges in the nuclear power bursting valve are made of high-temperature corrosion-resistant alloy material with the grade ASTM A453 660B.

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