RU2293901C1 - Bellows compensator for main pipelines - Google Patents

Abstract

FIELD: pipeline engineering.

SUBSTANCE: bellows compensator comprises rings mounted in the hollows of corrugations. The corrugations and rings are made of a reinforced composite material. The side surface of the ring is convex, e.g. is shaped into a torus, and the sizes of the ring and corrugation is determined from the equation proposed.

EFFECT: enhanced reliability.

11 dwg

Description

The invention relates to mechanical engineering and can find application in energy systems, pipeline structures and other areas of the national economy.

Known metal bellows expansion joints used in pipeline structures, while the expansion joints used in high-pressure lines have reinforcing rings (see book: Gusenkov AP and other "Unified flexible pipe elements. M., 1988) .

As a prototype, a reinforced bellows made of an elastic material with thickenings in the crests of the corrugations was selected, and reinforcing rings with a V-shaped cross section, the apex of which is facing the axis of the bellows, the outer diameter of the reinforcing rings being larger than the outer diameter of the corrugations, are installed in the troughs (invention SU 1536110 A1). Based on a brief description of the design, the reinforced bellows can only be used with a significantly limited range of axial compensation, when the gap between the reinforcing rings is small enough to reinforce the corrugations of the corrugations under pressure. Such a design cannot be used in main pipelines at high pressures and a significant range of required axial compensations in the main pipelines.

The main objective of the present invention is to provide a design of a bellows expansion joint made of composite materials for high-pressure pipelines, which provides reliable performance while increasing the compensating range without increasing the dimensions of the bellows.

The technical result that can be obtained from the use of a new technical solution: when using a bellows expansion joint for trunk pipelines having corrugations with reinforcing rings located in the corrugations of the corrugations, characterized in that the corrugations and reinforcing rings are made of reinforced composite material, while the lateral surface of the reinforcing the rings are convex (for example, toroidal), and the basic geometric parameters of the reinforcing ring and corrugation system should satisfy the relations

B _in ≥ (t _min + B _max ) (1-sinβ _in ),

where S _to - the length of the generatrix of the side wall of the reinforcing ring;

t _min is the distance between the side surfaces of adjacent reinforcing rings at the maximum allowable compression of the bellows;

β _about - the angle in radians between the tangent to the side surface at the base of the section of the reinforcing ring and the axis of rotation of the bellows;

β _in - the angle in radians between the tangent to the side surface of the upper part of the section of the reinforcing ring and the axis of rotation of the bellows;

P is the length of the midline of the variable cross section of the corrugation between the bases of adjacent reinforcing rings;

In _max - the maximum width of the section of the reinforcing ring;

In _in - the width of the upper part of the section of the reinforcing ring;

h is the thickness of the corrugation.

Figure 1-3 presents in three operating positions (at various degrees of tension-compression) section of the proposed design of the compensator.

Figure 4 presents the geometric diagram of the proposed design.

Figures 5-8 show, at various degrees of tension-compression, a section of a bellows expansion joint made of KM with reinforcing rings of rectangular cross section.

Figures 9-11 show, at various degrees of tension-compression, a section of a bellows expansion joint made of CM with reinforcing rings of a trapezoidal section.

The bellows compensator (figure 2) consists of corrugations and reinforcing rings 3 located in the hollows of the corrugations. The crest of the corrugation consists of two parts: one part of the corrugation 1 is free, the second part 2 is in contact with the reinforcing ring. With tension-compression of the compensator under pressure, the lengths of the corrugations 1 and 2 change, but their total length remains constant.

Figure 1-3 presents in three operating positions (with maximum compression (figure 1), in the middle position (figure 2), with maximum tension (figure 3)), the cross section of the proposed design of the compensator, in which the corrugations and reinforcing rings made of reinforced composite material. The lateral surface of the reinforcing ring 3 is convex and in cross section has a “barrel-shaped” shape, and the main geometric parameters of the reinforcing ring and corrugation system satisfy the above relations.

When the compensator is made from KM, the generatrix of the free surface of the corrugation 1 under pressure practically takes the form of a part of a circle, the radius of which depends on the distance between the reinforcing rings during tension-compression of the bellows compensator. When the compensator is compressed, the contact surface with the side wall of the reinforcing ring increases, with tension it decreases (up to zero at ultimate tension).

Figure 1 shows that in this design, with maximum compression, section 2 is in contact with the reinforcing ring 3 along the entire side surface. This eliminates the bending of the corrugation at the top of the cross section of the reinforcing ring 3 by smoothly mating corrugation sections 1 and 2 in zone A (Fig. 1). When stretching the compensator, the maximum opening of the corrugation is determined from the condition of smoothly matching the corrugation with the side surface of the corrugation 3 at a minimum radius without "straightening" the angle at the base of the cross section of the ring (figure 3). In this case, the length of the corrugation portion in contact with the ring is zero.

To derive the above dependencies, the fulfillment of which ensures smooth coupling in zone A of two sections 1, 2 of the corrugation, Fig. 4 is presented in cross section: half of the corrugation with sections 1, 2 and half of the reinforcing ring 3 of the bellows expansion joint from KM in the most compressed state . Since the destructive pressure of the bellows expansion joint for trunk pipelines is several times higher than the maximum working pressure, we can assume that in the range of working pressures the length of the corrugation section P (along the midline between the reinforcing rings, including sections 1 and 2) remains constant during the expansion (compression) of the bellows. The semi-perimeter P ₀₅ consists of two sections: free 1 with a radius R _g along the midline and 2 in contact with the generatrix of the side surface of the reinforcing ring 3 of length S _c also along the midline. Corrugation cross-sectional half-length

The length of the midline S _c can be expressed in terms of the length of the lateral section line of the ring S _k

here β _about , β _in are the angles in radians between the tangent to the side surface in the lower part and the upper part of the section of the reinforcing ring with the axis of rotation of the bellows, respectively;

h is the thickness of the corrugation.

The length of the segment c can be expressed both through the parameters of the free section of the corrugation 1, and through the parameters of the reinforcing ring 3

c = (R _g + h / 2) sinβ _in ,

c = t _min / 2 + (B _max / 2-B _in / 2),

here t _min is the minimum allowable gap between adjacent rings in a compressed state (the minimum value can be equal to two corrugations);

B _max , B _in - the maximum width of the cross section of the ring and the width of the cross section at the top.

From the formulas for the parameter c determines the radius R _g

From expressions (1) - (3) we finally obtain the relation that the geometric parameters of the reinforcing ring must satisfy for given basic corrugation parameters (cross-section along the midline and thickness)

In addition, in order to exclude contact between adjacent corrugations at the extreme lateral points of the section D, D 'with maximum compression of the bellows, it is necessary that the point D of the cross section of the free part of the corrugation (Fig. 4) does not go beyond the symmetry line of the section of the ring, i.e. the condition is satisfied

Using expressions (3), (4), this condition can be written in the form

Relations (4), (5) determine the geometric parameters of the section of the reinforcing ring, the fulfillment of which eliminates the bending of the corrugation at the maximum radius of the ring.

The maximum allowable stretching of the corrugation (without "straightening" the angle at the base of the cross section of the reinforcing ring in zone B) is determined by the angle β _about between the tangent to the side surface at the base of the cross section of the reinforcing ring and the axis of rotation of the bellows (figure 4).

For comparison with the proposed design, FIGS. 5–11 show sections of compensators made of KM with reinforcing rings 3, the lateral surfaces of which are made flat (rectangular section, FIGS. 5–7) or conical (in section — a trapezoid, FIGS. 8–10) .

When compressing the compensator with a reinforcing ring of rectangular cross section (Fig. 5), sharp corrugations of the corrugation (“kink”) are possible in the joint zone of the corrugation parts 1 and 2 (zone A). When the compensator is stretched, a sharp change in the corrugation of the corrugation is also possible (“straightening” of the initial angle) at the base of the ring section (zone B, Fig. 8). With multi-cycle tension-compression of the compensator, premature failure can occur during operation. For such a design, it is necessary to significantly reduce the range of variation of the width of the corrugation so that within the compensation range the direction of the section at the junction of the free part of the corrugation 1 with the contacting part 2 at a point of contact with the side surface is tangent to the side wall of the reinforcing ring. The limits of the allowable range of tension-compression, defined in this way, are presented in FIGS. 6 and 7. Moreover, the completion of the compensating range of the compensator as a whole entails an increase in the number of corrugations and, accordingly, an increase in the total length of the bellows.

The conical shape of the side wall of the reinforcing ring eliminates the "kink" of the corrugation during compression (Fig.9). However, to eliminate kinks of the corrugation at the base of the ring section in zone B (Fig. 11), it is necessary to reduce (compared with the rectangular section of the ring) the maximum stretch of the corrugation (Fig. 10) so that the direction of the corrugation section is tangent to the side wall of the reinforcing ring. The use of a trapezoidal section of the ring while maintaining the compensatory ability of the bellows as a whole also requires an increase in the number of corrugations and an increase in the total length of the bellows.

The table below shows the calculated data on the acceptable compensation ranges for one corrugation for the considered designs of bellows expansion joints. The length of the midline P of the corrugation sections for all structures is assumed to be the same. In the table, the values of the period T of the location of the corrugations along the length of the bellows at the extreme points of the allowable compensation range and in the middle position are assigned to the length of the middle line P of the corrugation section.

Cross sectional shape of reinforcing ring The relative period of the location of the corrugations along the length of the T / P bellows Valid Compensation Range Compensation range with respect to the design with a rectangular section of the reinforcing ring T _min / P T _ax / P T _sr / r Rectangular 0.576 0.830 0.703 ± 0.127 one Trapezoidal 0.271 0.697 0.484 ± 0.213 1.68 Barrel-shaped 0.240 0.942 0.591 ± 0.351 2.76

The table shows that the proposed design of the bellows significantly increases the allowable range of the compensating ability of the bellows (2.76 times relative to the bellows with a rectangular section of the reinforcing rings).

Thus, the use of this technical solution will improve the reliability of the bellows expansion joint for trunk pipelines, in which the corrugations and reinforcing rings are made of reinforced composite material, with minimal dimensions, ensuring the required value of the compensating range.

Claims (1)

A bellows expansion joint for trunk pipelines having corrugations with reinforcing rings located in the corrugations of the corrugations, characterized in that the corrugations and reinforcing rings are made of reinforced composite material, while the lateral surface of the reinforcing ring is convex (for example, toroidal), and the main geometric parameters of the system reinforcing rings and corrugation must satisfy the relations

B _in ≥ (t _min + B _max ) (1-sinβ _in ), where S _to - the length of the generatrix of the side wall of the reinforcing ring; t _min is the distance between the side surfaces of adjacent reinforcing rings at the maximum allowable compression of the bellows; β _about - the angle in radians between the tangent to the side surface at the base of the section of the reinforcing ring the axis of rotation of the bellows; β _in is the angle in radians between the tangent to the lateral surface of the upper part of the section of the reinforcing ring by the axis of rotation of the bellows; P is the length of the midline of the variable cross section of the corrugation between the bases of adjacent reinforcing rings; B _max - maximum sectional width of the reinforcing ring; In _in - the width of the upper part of the section of the reinforcing ring; h is the thickness of the corrugation.

Images