Fastening method of turbine fastener

Abstract

The invention relates to a fastening method, in particular to a fastening method of a turbine fastener. The invention aims to solve the problem that the existing fastening method is easy to cause steam leakage at the split of two connected pieces, so that the construction period progress and the installation quality of a steam turbine are influenced. According to the method, firstly, all nuts are tightened to 50% of the rated tightening torque T, it is guaranteed that a sealing gasket between two connected pieces is fully compressed, then 50% of the rated tightening torque T is removed one by one, and the nuts are tightened to the rated nut rotating angle phi through a rotating angle method again; and secondly, the tightening mode can meet the requirement for tightening flanges in the heaven and earth directions such as a cylinder and a partition plate sleeve, and is also suitable for the requirement for tightening flanges in the circumferential direction such as a steam turbine valve. A reliable and effective mode is provided for tightening the steam turbine bolt, it is guaranteed that the assembly process of the steam turbine is rapid and accurate, and meanwhile the installation quality of the steam turbine is guaranteed. The invention belongs to the technical field of building decoration construction equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to a fastening method, in particular to a fastening method of a steam turbine fastener, and belongs to the technical field of steam turbine fastening. BACKGROUND

[0002] In the steam turbine, bolts and nuts are installed as fasteners on various part covers such as partition cover, inner and outer cylinder, valve, etc. The current installation method is to directly tighten the nut to the required angle or torque. However, the joint surface of the connected parts usually has a sealing gasket structure. It is found in actual operation that the original tightening method cannot meet the installation requirements of various part covers, i.e.:

[0003] When there is no gasket between the two connected parts, the tightening torque is almost entirely used for bolt elongation and slight compression of the connected parts, and the nut angle and bolt elongation have a stable linear relationship.

[0004] However, due to the presence of the sealing gasket, its stiffness is much lower than that of the metal connected parts and the bolt. Only when the sealing gasket is compressed to the designed amount, the two connected parts can be attached. However, during the tightening process, the rated tightening torque applied will cause large compression deformation of the sealing gasket, so under the same bolt elongation, the corresponding nut angle will fluctuate greatly, the linear relationship between the rated torque, bolt elongation and nut angle is disrupted, resulting in inaccurate nut rotation angle and loss of measurement accuracy. Therefore, the current tightening method is prone to cause steam leakage at the center of the two connected parts, thereby affecting the construction progress and the installation quality of the steam turbine.

[0005] In view of the above technical problems, how to propose a new fastening method has become a problem to be solved by the technical personnel in the field. SUMMARY

[0006] The present application provides a fastening method of a steam turbine fastener to overcome the shortcomings of the prior art.

[0007] The technical scheme of the present application is as follows: a fastening method of a steam turbine fastener, comprising a plurality of double-headed studs, the double-headed studs being installed on the connected parts, and nuts being installed on the double-headed studs, and the method being specifically performed according to the following steps:

[0008] Step 1: tighten each nut to 50% of the rated tightening torque T by using a tightening tool;

[0009] Step 2: loosen one of the nuts in step 1 until the tightening torque disappears, and then manually rotate the loosened nut until the gap between the loosened nut and the connected part is less than 0.04 mm, and then draw a straight line mark on the surfaces of the loosened nut and the connected part.

[0010] Step 3: Tighten the loosened nut from Step 2 to the rated nut angle Φ using the angle-tightening method. The rated nut angle Φ when using the angle-tightening method is:

[0011]

[0012] In the formula:

[0013] P is the pitch of the double-ended stud;

[0014] F0 is the preload of the double-ended stud;

[0015] C L The stiffness of the double-ended stud;

[0016] C F The stiffness of the connected components;

[0017] Step 4: Tighten all remaining nuts on the connected parts to the rated nut angle Φ using the methods in Steps 2 and 3.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. This invention first tightens each nut to 50% of the rated tightening torque T, ensuring that the sealing gasket between the two connected parts is fully compressed. Then, 50% of the rated tightening torque T is removed one by one, and the nuts are tightened again to the rated nut angle Φ using the angle method, ensuring that the two connected parts fit tightly and avoiding air leakage. The operation process is standardized, improving work efficiency and providing technical support for the safe and stable operation of steam turbines.

[0020] 2. The tightening method of this invention can meet the tightening requirements of flanges in the vertical direction, such as cylinders and diaphragm sleeves, as well as the tightening requirements of flanges in the circumferential direction, such as turbine valves. It provides a reliable and effective way to tighten turbine bolts, ensuring that the turbine assembly process is fast and accurate, while also guaranteeing the installation quality of the turbine. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the present invention;

[0022] In the picture: 1. Double-ended stud; 2. Nut. Detailed Implementation

[0023] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings.

[0024] Specific implementation method one: Combining Figure 1This embodiment describes a method for fastening turbine fasteners, comprising a plurality of double-ended studs 1, each stud 1 being mounted on a connected component, and each stud 1 being fitted with a nut 2. The method is characterized by the following steps:

[0025] Step 1: Tighten each nut 2 to 50% of the rated tightening torque T using a tightening tool. Preferably, depending on the actual installation of the double-ended stud 1, tighten each nut 2 according to the tightening and loosening sequence of bolts in the "DL / T439-2018 Technical Guidelines for High-Temperature Fasteners in Thermal Power Plants".

[0026] Step 2: Loosen one of the nuts 2 from Step 1 until the tightening torque disappears. Then manually tighten the loosened nut 2 until the gap between the loosened nut 2 and the connected part is less than 0.04mm. Then draw a straight line mark through both the loosened nut 2 and the connected part. This straight line mark is used as the measurement zero point when the nut 2 is tightened.

[0027] Step 3: Tighten the loosened nut 2 from Step 2 to the rated nut angle Φ using the angle-tightening method. The rated nut angle Φ when using the angle-tightening method is:

[0028]

[0029] In the formula:

[0030] P is the pitch of the double-ended stud 1;

[0031] F0 is the preload force of the double-ended stud 1;

[0032] C L Let be the stiffness of the double-ended stud 1;

[0033] C F The stiffness of the connected components;

[0034] During the tightening process, a protractor is used to check whether the rotation angle of nut 2 reaches the rated nut rotation angle Φ. Preferably, the protractor is a type of protractor for checking the rotation angle of high-strength bolts disclosed in the existing announcement number CN203908429U.

[0035] Step 4: Tighten the remaining nuts 2 on the connected parts to the rated nut angle Φ using the methods in Steps 2 and 3.

[0036] Specific Implementation Method Two: Combining Figure 1 In this embodiment, the rated tightening torque in step one is T = 0.2 × F0 × d;

[0037] In the formula: F0 is the preload of the double-ended stud 1, and d is the nominal diameter of the double-ended stud 1.

[0038] The other components and connections are the same as in Specific Implementation Method 1.

[0039] Specific implementation method three: Combining Figure 1 In this embodiment, step two involves checking the gap between the loosened nut 2 and the connected component using a feeler gauge. Specifically, if the feeler gauge cannot penetrate the 0.04mm gauge, the nut 2 is considered to be properly tightened. Other components and connections are the same as in embodiment one or two.

[0040] Specific implementation method four: Combination Figure 1 In this embodiment, step three involves tightening nut 2 with a torque wrench. Other components and connections are the same as in specific embodiments one, two, or three.

[0041] Specific Implementation Method Five: Combining Figure 1 This embodiment describes a double-ended stud 1 with a performance grade of 8.8.

[0042] Furthermore, the double-ended stud 1 is made of alloy steel.

[0043] The other components and connections are the same as those in specific implementation methods one, two, three, or four.

[0044] Specific Implementation Method Six: Combination Figure 1 This embodiment describes a double-ended stud 1 made of carbon steel. Other components and connections are the same as in specific embodiments one, two, three, four, or five.

[0045] Specific implementation method seven: Combination Figure 1 In this embodiment, the tightening tool in step one is a torque wrench. Other components and connections are the same as in specific embodiments one, two, three, four, five, or six.

[0046] Specific implementation method eight: Combination Figure 1 In this embodiment, the tightening tool in step one is a torque wrench or a torque measuring wrench. Other components and connections are the same as in specific embodiments one, two, three, four, five, six, or seven.

[0047] The present invention has been disclosed above with reference to preferred embodiments, but it is not intended to limit the present invention. Any simple modifications, equivalent changes and alterations made by those skilled in the art to the above embodiments without departing from the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for fastening turbine fasteners, comprising a plurality of double-ended studs (1), the double-ended studs (1) being mounted on the connected parts, and nuts (2) being mounted on the double-ended studs (1), characterized in that: This method is specifically carried out in the following steps: Step 1: Tighten each nut (2) to 50% of the rated tightening torque T using a tightening tool; Step 2: First, loosen one of the nuts (2) from Step 1 until the tightening torque disappears; Then, manually tighten the loosened nut (2) until the gap between the loosened nut (2) and the connected part is less than 0.04mm; Then, draw a straight line through the loosened nut (2) and the surface of the connected parts. Step 3: Tighten the loosened nut (2) from Step 2 to the rated nut angle Φ using the angle method. The rated nut angle Φ when using the angle method is: In the formula: P is the pitch of the double-ended stud (1); F0 is the preload of the double-ended stud (1); C L The stiffness of the double-ended stud (1); C F The stiffness of the connected components; Step 4: Tighten the remaining nuts (2) on the connected parts to the rated nut angle Φ using the methods in Step 2 to Step 3.

2. The method for fastening turbine fasteners according to claim 1, characterized in that: In step one, the rated tightening torque T = 0.2 × F0 × d; In the formula: F0 is the preload of the double-ended stud (1); d is the nominal diameter of the double-ended stud (1).

3. The method for fastening turbine fasteners according to claim 1, characterized in that: In step two, the gap between the loosened nut (2) and the connected parts is checked by using a feeler gauge.

4. The method for fastening turbine fasteners according to claim 1, characterized in that: In step three, tighten the nut with a torque wrench (2).

5. The method for fastening turbine fasteners according to claim 1, characterized in that: The performance grade of the double-ended stud (1) is 8.

8.

6. The method for fastening turbine fasteners according to claim 1, characterized in that: The double-ended stud (1) is made of alloy steel.

7. The method for fastening turbine fasteners according to claim 1, characterized in that: The double-ended stud (1) is made of carbon steel.

8. The method for fastening turbine fasteners according to claim 1, characterized in that: The tightening tool in step one is a torque wrench.

9. The method for fastening turbine fasteners according to claim 1, characterized in that: The tightening tool in step one is a torque wrench.

10. A method for fastening turbine fasteners according to claim 1, characterized in that: The tightening tool in step one is a torque wrench.

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