SU1809230A1 - Pipeline joint - Google Patents

Description

The invention relates to mechanical engineering and can be used in cryogenic engineering, shipbuilding, aircraft construction, etc., in particular in high pressure cryogenic systems.

The aim of the invention is to reduce the mass of the connection and increase the resource by reducing the tightening force.

Figure 1 shows the connection of pipelines; figure 2-4 - comparative analysis of the prototype and the proposed connection; figure 5 - node A in figure 1; 6 is a specific example of a ferrule.

The connection of pipelines contains a fitting 1 with an internal conical bore, which turns into a cylindrical one, which includes a pipe 2, a union nut 3 and a metal seal in the yid of the compression ring 4, having concentric edges 5-7 formed by the groove. The number of edges is determined by the size of the connection. The contact surfaces 8 of the crimp ring and the union nut are made torus, and the center of the circumference of the torus surface with radius r is aligned with the center of gravity of the section of the crimp ring (c.t.), and the edges of the grooves are located on a conical surface tangent to the inner surface of the torus with a radius equal to the distance from the center of gravity of the section of the ferrule to the axis of the ring and the radius of the circle equal to the distance from the center of gravity of the section of the ring to the surface of the pipe, while the axes of the conical surface, the ferrule and the pipe coincide.

Considering the deformation scheme of const. The hands of the crimp ring in the prototype, you can see (see figure 2) that the deformation proceeds in the following stages:

1. All-round compression of the ring (by means of two wedge surfaces A and B, the ring is pressed by surface C to the pipe and wedges, excluding the rotation of the section).

JS U <> 1809230 A1. 1809230

5 'simulating the crimp ring in the prototype, received the same level of displacement, at the beginning of the cylinder W = 0.3 mm, while the greatest are the meridional stresses outside and inside the cylinder, equal to Si = 2.6-10 ⁴ kgf / cm ² with a force GR = = ЭООООкгс, which is 5.3 times more than in the case of a cylinder simulating the proposed crimp ring. For such a stress level (Si = 2.6-10 ⁴ 'kgf / cm ⁴ ^ = 260 kgf / .mm ² , which exceeds the ultimate strength of steels ЗОХГСА and 07Х16Н6 by 2.3 times), it is almost impossible to choose a material for making crimp rings with a given geometry and deformation, so that the ring works in the elastic zone.

Based on the above, comparative conclusions can be drawn:

1. Identical movements in the proposal. Compared to the prototype, a female ferrule can be achieved with significantly lower tightening forces with an elastic rotation of the proposed ring. The calculation did not take into account the reduction in the shoulder on which the load acts, due to jamming of a part of the ring in the prototype, and additional efforts were not taken into account.

2. Bend the remaining free part Then sequentially, using the perpetuation method over the line 1-1. _? the increase in the applied load to the cylinder.

In the proposed technical solution, the crimp ring (see Fig, 3) has the ability to rotate relative to the center of gravity of the ring section due to the torus surface.

This can be clearly seen from the printouts obtained as a result of a computer calculation by the finite element method. The calculation was carried out for steel rings with a modulus of elasticity E = 2x x10® gs / cm ² , for various geometries. size ratios and various applied loads. In all cases, practically the same results were obtained; ratio of efforts, deformations and stresses .. One of the cases. calculation is given below. For clarity and simplification of the calculation for the basic (for the prototype * type and the proposed technical solution) the crimp ring was taken as a hollow cylinder 1.5 cm high with an average radius of 6 cm and a thickness of 0.8 cm. Applied load Pr (see Fig. 2 , 3, '4) acts along the upper edge of the cylinder.

In the proposed technical solution, the crimp ring simulates a cylinder with free horizontal movement Wcm, and the freedom of the angle of rotation - TETA, glad. ,. ... ,.

In the prototype, the crimp ring simulates 30. pulling already in contact with the same cylinder, but with a limitation of the horizontal movement and the angle of rotation at the end of the cylinder.

Figure 4 explains the designations adopted in the calculation, where:

Hnach and Hkoi - coordinates of the beginning and end of the cylinder;

H - cylinder thickness ;.

•. R is the average radius of the cylinder;

P _g - applied load:

THETA-angle of rotation of the cylinder start:

V-vertical movement; W - horizontal movement; 1,2,3 ..... 21- elements of the section of the cylinder section.

A distributed force GR = 17000 kg was applied to a cylinder simulating the proposed crimp ring. The largest tensile strains were obtained, stresses S2 = 9.1 Ί0 ³ kgf / cm ² and horizontal displacement at the beginning of the cylinder W = 2.8Ί0 ² cm = 0.3 mm per side. At this level of stress, for the manufacture of a crimp ring, you can use, for example, ZOHGSA, and for media that cause corrosion, for example, 07XT6N6. For the displacements obtained on the ferrule, grooves can be made with a diameter difference of about 0.2 mm. which is technologically feasible.

pipe part of the ring, which would lead to an even greater difference in tightening forces for the proposed connection and the prototype.

2. A significant reduction in the acting stresses inside the ferrule will avoid crushing and destruction of the ferrule, and will also increase the service life of the ring with reusable use.

3. A significant reduction in the effort of e- ¹ heavy will lead to a decrease in the mass of the connection parts.

\ All this will lead to a decrease in the mass of the connection and an increase in the resource in comparison. prototype, ¹ The predominance of the components of the rotary deformation of the ring over others makes it possible to assume that the deformation of the ring occurs only due to the rotation of the section relative to the center of gravity. For ¹ explanation of the location of the edges of the grooves, consider Fig. 5; which shows a cross-section of the ferrule and pipe. Since during deformation the section rotates around the center of gravity, it means that every 55 point of the section moves in a circle with the Center at the center of gravity of the section. In order to, when Rotating the section, all edges. the grooves simultaneously touched the pipe, which would eliminate additional efforts to pull the already contacting surface of the torus with a radius equal to the distance from the center of gravity of the crimp ring section to the ring axis and a circle radius equal to the distance from the center of gravity of the crimp ring section to the pipe surface.

The seal will be sealed and effectively tightened up to the point where

Pr = (1.1-1.2) 2 lj-5r _P Or + Pd (see figure 5). where l _£ = h + I2 + 1h:

b) _p - pipe wall thickness;

From is the compressive yield strength of the pipe material:

R _d - force for deformation of the ring in a free state by an angle,

With an even greater tightening of the connection, plastic deformation of the pipe will occur, and then the ring (it is assumed that the material of the ring is two or more times stronger than the material of the pipe), which limits the possibility of reusing the connection and will not give a greater sealing effect.

Based on the above, conclusions can be drawn. Since the deformation of the ferrule when tightening the connection occurs around the center of gravity of the section of the ring, therefore, the ferrule can be considered 30 as a free ring loaded with a uniformly distributed linear moment from the forces arising from the tightening by the joints acting along the contact line of the end of the ferrule and 35 of the conical bore of the fitting on shoulder from the point of contact to the line perpendicular to the axis of rotation of the ring and passing through the center of gravity of the section of the ring, in this case we will obtain the maximum displacements of the compression ring. The friction force arising over the toric contact surface of the ferrule and the union nut when tightening the connection is small compared to the running torque on the ferrule. Therefore, 45 when calculating the connection, the friction force can be neglected. To reduce the friction force on the toric surface of the contact between the ferrule and the union nut, you can use a lubricant or an anti-friction 50 coating.

To clarify the above, we present the procedure for calculating the ferrule and a specific example of a ferrule with a geometry similar to a ring in a comparative calculation.

Previously, based on the dimensions of the pipelines to be connected and the mating parts of the connection, the following work is performed (see Fig. 6):

with the pipe part of the ring, the edges of the grooves 5-7 should be located on a tangent line to a circle with a radius and equal to the distance from the center of gravity of the ring section to the pipe surface. Moving from the 5th section to the joint as a whole, in the general case, we find that the timing of the grooves should be located on a conical surface tangent to the inner surface of the torus with a radius equal to the distance from the center of gravity of the section of the ferrule to the ring axis and a radius of the circle equal to the distance from the center the severity of the section of the ferrule to the pipe surface, while the axes of the conical surface, the ferrule 15 and the pipe coincide.

The proposed device works as follows.

When tightening the connection from the forces arising along the line of contact of the end of the compression ring 4 and the tapered bore of the fitting 1, the section of the compression ring turns around the center of gravity of the section with the simultaneous movement of the ring towards the conical bore of the fitting. 25 After turning the section of the ferrule, at an angle a (see f'ig. 5), all edges 5-7 will simultaneously touch the pipe. With further tightening of the connection, the edges 5-7 will begin to embed into the pipe body. Maximum implementation - 30. Edge 5 is inserted into the pipe body. As the most distant from the center of the section rotation, the least other edges will penetrate the edge 7 as the closest to the center of the section rotation. That is, the introduction of the edges occurs in proportion to their distance from the center of the section turning, therefore, the forces from the contact of the edges with the pipe surface are distributed from the maximum at the most distant edge 5 from the center. the cross-section gate to the minimum at the edge 7. This distribution of forces also corresponds to the distribution of forces from the component of the tightening force Pg. since races. the distribution of forces along the edges from P _g goes according to the 45 law of a triangle. Considering the law of distribution of forces from the penetration of the ring edges into the pipe and from the force P _g , while taking into account that the material of the ring is stronger than the material of the pipe, it can be argued that, until the moment of effective sealing of the joint, the deformations from the reversal of the section will prevail over all others. Based on the foregoing, we can conclude that in the 55 untight state, i.e. before deformation, and in tightened, i.e. after deformation, or in any other intermediate state, the edges of the grooves will be located on a conical surface tangent to the inner

1. The section of the ferrule is being constructed.

2. The center of gravity of the ring section is found.

3. The torus surface is determined from the center of gravity with radius R equal to X _o .

4. After calculating the geometric characteristics of the section for a given load, we determine the angle of rotation of the section of the ring.

_d 5. We draw a tangent to the circle with a plod angle to the pipe surface slightly less than the calculated one (taking into account the implementation of the calculated angle of rotation when tightening the connection until complete sealing.

6. Conduct the construction of grooves taking into account the location of the edges on the found tangent.

7. Specify the coordinates of the center of gravity of the section.

8. Perform calculations on points 20 2-7 to tech lore. until the coordinates of the center of gravity of the section of the subsequent calculation coincide with the coordinates of the center of gravity 'of the section of the previous calculation. Calculations for items 1-8 are conveniently performed using a computer. '

In the example presented (see fig. B), the calculation of geometric characteristics and their refinement were carried out on a computer. After calculating the final received: the material of the compression ring 03X11N10M2T-VD with a tensile strength σ _Β = = 125 kgf / mm ² and a yield strength oo 2 = 115 kgf / mm ^2, the load P = 10,000 kgf. Moment of inertia l _z = 0.12 cm ⁴ , moment of resistance

Claims (2)

Claim of invention Connection of pipelines containing a fitting with an internal conical bore, a union nut and a compression ring located between them, on the inner surface of which there are stepped grooves, characterized in that the contacting surfaces of the compression ring and union nut are torus, and the center of the circumference of the torus surface is aligned with the center of gravity of the section of the ferrule, and the edges of the grooves are located on a conical surface tangent to the inner surface of the torus with a radius equal to the distance from the center of gravity of the section of the ferrule to the axis of the ring, and a radius of a circle equal to the distance from the center of gravity 50 of the section of the ferrule to the surface = 9663 kgf / cm ² = 96.6 kgf / mm ² <00.2 ": pipes, while the axes of the conical surface, the compression ring and the pipe coincide. torque m = = “213.4 kgf cm / cm. 2 7ΓΟ, 34 .. „-F'Hz.t. Ring stresses σ - 213.4 * 6.34 0.14 The angle of rotation of the section is θ ⁼ · ~ ^ -ηρ ¹ = - ^2ι3 v ⁴ : 6.34 ² _{= 3} θ. ₁₀ -2 ₌ 2.05 °. 1Ί0 ⁶ '0.12 The calculation is presented in a simplified form. Thus, the proposed connection of pipelines has, in comparison with the prototype, the following technical and economic advantages: the crimp ring has a greater ability to move in comparison with the double-cone crimp ring of the same geometry in the prototype, which is subjected to comprehensive compression. Additional efforts are eliminated for pulling the part of the ferrule that has already come into contact with the pipe in the direction of the fitting, since all the edges cut into the pipe at the same time. All this leads to a decrease in the forces when tightening the joint by approximately 5 times, and, consequently, to a decrease in the mass of the joint, also approximately 5 times. A decrease in the stress level in the crimp ring 'will lead to an increase in its resource, and hence' to an increase in the resource of the connection as a whole with reusable use, since of all the connection parts, the crimp ring is the most loaded.