RU215812U1 - Coupling to ensure the tightness of the connection of the caisson and the casing - Google Patents

Abstract

The utility model relates to couplings that are used to ensure the tightness of the connection of the caisson 6 and the casing 7. The coupling contains a housing 1, hermetically connected to the hole at the bottom of the caisson 6, a sealing element 2, put on the casing 7 with the necessary relative tension and placed inside the housing 1 in a wedge-shaped annular cavity, a cylindrical thrust sleeve 3 with a slope at its lower end, installed in the body 1 between the sealing element 2 and the flange 4 centered on the outer diameter, the adjustable threaded connection 5 creates a compression force and, thereby, provides the necessary relative degree compression of the sealing element 2 between the outer diameter of the casing 7 and the inner wedge-shaped annular cavity of the housing 1, the relative degree of compression of the sealing element 2 is controlled by the size δ.

Description

The utility model relates to couplings (MPK F16L 21/02), which are used to ensure the tightness of the connection of the caisson and the casing.

Known "Coupling for sealing the connection of the casing and the caisson", the patent of the Russian Federation for utility model No. RU No. 172773 U1, priority dated February 03, 2017, IPC F16L 21/25 (2006.01), which is the prototype of the claimed utility model. The prototype contains located coaxially: a sealing element made of elastic material for installation on the casing, a cylindrical sleeve for permanent connection with the bottom of the caisson, the first flange connected to the end of the cylindrical sleeve, and the second flange, while the sealing element is made in the form of a ring and is placed between the first and second flanges, which are connected by means of an adjustable connection, with the possibility of compression of the specified sealing element, and the ratio of the diameter d of the opening of the flanges to the diameter D of the sealing element is from 0.7 to 1.2.

The disadvantage of the prototype is the impossibility of qualitatively providing the claimed technical result, which consists in "increasing the tightness of the caisson at the place where the hole is made for the passage of the casing pipe through it" with the ratio of the diameter d of the flange hole to the diameter D of the sealing element (the average cross-sectional diameter of the ring) indicated in the formula of the utility model of the prototype ) in the range from 0.7 to 1.2 without taking into account the relationship of this ratio with the outer diameter of the casing pipe d _OD , the inner diameter d _{id_oring of the} sealing element in the form of a toroidal O-ring made of elastic material, the cross-sectional diameter of this ring d _oring , diametrical clearance Δ between the hole of the sleeve (first flange) d and the outer diameter of the casing d _OD .

This drawback is confirmed by a study of the ratio of parameters d to D as an essential feature, and their influence on the claimed technical result in conjunction with other parameters

[d _{id_oring} , d _oring , d _OD , Δ] subject to the mathematical formulas and explanations below.

Inner diameter of the sealing element (ring):

where D is the average diameter of the cross section of the ring;

d _oring is the cross-sectional diameter of the ring;

d - inner diameter of the bushing hole (first flange);

k is the ratio of the parameters d to D (in the range from 0.7 to 1.2);

d _OD - outer diameter of the casing;

Δ - diametrical clearance (d _OD -d).

Relative degree of stretching of the sealing element (ring) when it is put on the casing pipe, %:

Relative compression ratio of the sealing element (ring) between the casing and the first flange, %:

where d' _oring is the cross-sectional diameter of the ring in a compressed state.

1. The first necessary condition for ensuring the tightness, reliability and durability of a fixed connection is the relative degree of stretching of the sealing element (ring) made of elastic elastic material δ _{id_oring} from 0% to 3% when this ring is put on the casing.

2. The second necessary condition for ensuring the tightness, reliability and durability of a fixed connection is the relative degree of compression of the sealing element (ring) from an elastic elastic material ε _oring from 15% to 35%.

From the mathematical study carried out for the most commonly used rings with _doring cross-sectional diameters in the range from 15 to 40 mm and casing pipes used in practice with outer diameters d _OD from 125 to 140 mm, it follows that with a ratio of parameters d to D equal to 0 ,7 the first necessary condition for ensuring the tightness of the connection is not met and δ _{id_oring} takes values from -26% to -15%, i.e. in the connection between the outer diameter of the casing pipe d _OD and the inner diameter of the ring d _{id_oring} , a gap is formed. When the ratio of parameters d to D is equal to 1.2, the first necessary condition for ensuring the tightness of the connection can theoretically be fulfilled, however, it is associated with significant relative stretching of the rings δ _{id_oring} , reaching 33÷85%.

With the ratio of parameters d to D equal to 1.2, the relative degree of stretching of the ring δ _{id_oring is} about 33% or, moreover, about 85%, it is practically impossible to perform manually without a special device at the installation site of the coupling with the caisson.

The relative degree of stretching of the ring δ _{id_oring} more than 5% and the subsequent relative degree of compression of the ring ε _oring more than 35% lead to a significant reduction in the service life of the elastomer seal, the appearance of large internal stresses in it, and the acceleration of the accumulation of residual compression deformation in operation. As a result, the contact pressure decreases at the junctions of the ring surfaces with the flanges and the outer surface of the casing, which subsequently leads to the inevitable loss of the joint tightness.

In addition, the claimed technical result also cannot be achieved using all the essential features of the independent claim of the utility model of the prototype without the mandatory use of "bevels in the form of bevels facing the sealing element", which are mentioned only in the dependent third claim of this utility model. In the absence of "chamfers in the form of bevels facing the sealing element" and without specifying the specific geometry of these elements and their relationship, the implementation of the above-mentioned second necessary condition for ensuring the tightness of the connection is also not possible. When the elastomer ring is compressed, due to the preservation of its volume, this ring will inevitably be squeezed out to the periphery - into the open outer space between the flanges with a decrease in the relative degree of compression of the ring ε _oring values significantly less than 15%, which will subsequently lead to a drop in contact pressure in the inner connection zone surface of the ring with the outer surface of the casing and the inevitable loss of tightness of the connection.

Based on the essential features of the independent claim of the utility model of the prototype and its description, when installing the upper (second) convex flange in an inverted state, regardless of the size of the sealing element, with subsequent application of force to this flange in order to press it against the sealing element, as a result of the impact distributed load on the sealing element, it will be gradually squeezed out to the periphery - into the open outer space between the flanges, with a decrease in the relative degree of compression of the ring ε _oring to values significantly less than 15%, which will lead to a drop in contact pressure in the junction of the inner surface of the ring and the outer surface of the casing pipes and the inevitable loss of tightness of the connection.

Practice confirms the calculation and theoretical conclusions: when installing and operating caissons with couplings according to patent No. RU No. 172773 U1, silicone sealant must be additionally used to eliminate joint leaks.

The set of essential features, expressed in the independent claim of the prototype utility model, does not provide the condition of the tightness of the connection (the first and second necessary conditions for the tightness of the joint) when using a sealing element made of an elastic material that does not have elastic properties.

Based on the foregoing, it follows that the totality of essential features contained in the independent claim of the utility model of the prototype does not ensure the achievement of the claimed technical result [fulfillment of the first and second necessary conditions for the tightness of the connection], the utility model of the prototype is not properly disclosed.

The technical result of the proposed utility model is to ensure the tightness, reliability, durability and maintainability of the connection of the caisson and the casing using a coupling.

To achieve the technical result claimed in the utility model, the problem is solved by the fact that in order to ensure the tightness, reliability, durability and maintainability of the connection, the coupling contains a housing with a through hole located coaxially with the casing, forming between the outer surface of the casing an annular cavity with a constant diametrical clearance in the upper part of the housing, a wedge-shaped annular cavity with a decreasing diametrical clearance in its middle part and an annular cavity with a minimum allowable diametrical clearance in the lower part of the housing, a sealing element made of an elastic elastic material, put on with a relative tension δ _{id_oring} from 0% to 3% on the casing pipe and placed inside the body in a wedge-shaped annular cavity; a cylindrical thrust sleeve with a slope at its lower end, put on a casing pipe with a minimum allowable clearance, installed in the body between the sealing element and the flange centered on the outer diameter.

Adjustable threaded connection creates the necessary compression force between the body and the flange with the transfer of this force to the end face of the cylindrical thrust sleeve. The slope made at the lower end of the cylindrical thrust sleeve, directed upwards towards the casing pipe, ensures the transfer of a distributed load to the sealing element, as a result of which it moves into a wedge-shaped annular cavity closed from the outside between the outer diameter of the casing pipe and the inner wall of the casing, as well as additional pressing sealing element to the outer surface of the casing pipe with a relative degree of compression of the sealing element ε _oring from 15% to 35%.

The cylindrical stop sleeve can be connected to the flange, for example by welding. On the outer surface of the lower part of the body, a cylindrical groove with a shoulder can be made to ensure alignment, with a hermetic connection of the body with a hole at the bottom of the caisson. As a sealing element, a toroidal o-ring can be used, or a cuff of a special shape, made of an elastic elastic material, for example, rubber with a hardness of 50÷65 IRHD.

The utility model is illustrated by a figure.

The figure shows a section along the axis of the casing pipe 7 with a sleeve put on it, the lower part of which is hermetically connected to the hole at the bottom of the caisson 6. The sleeve contains a housing 1 with a through hole located coaxially with the casing pipe 7, forming an annular ring between the outer surface of the casing pipe 7 a cavity with a constant diametrical clearance in the upper part of the housing 1, a wedge-shaped annular cavity with a decreasing diametrical clearance in the middle part of the housing 1 and an annular cavity with a minimum allowable diametrical clearance in the lower part of the housing 1; a sealing element 2 made of an elastic elastic material, put on with a relative stretch δ _{id_oring} from 0% to 3% on the casing 7 and placed inside the housing 1 in a wedge-shaped annular cavity; a cylindrical thrust sleeve 3 put with a gap on the casing pipe 7 with a slope at its lower end, installed inside the housing 1 in its upper part between the sealing element 2 and the flange 4 centered on the outer diameter, with the possibility of moving and subsequent compression of the sealing element 2 in a closed outside the wedge-shaped annular cavity between the outer surface of the casing 7 and the inner wall of the housing 1.

The installation of the clutch is performed as follows.

In the hole at the bottom of the caisson 6, the lower part of the body 1 is installed until it stops against the shoulder, after which it is hermetically connected, for example, by welding with the caisson 6. When operating the coupling with the caisson, including in heaving soils, to further improve reliability, ensure durability and maintainability, reducing friction, and increasing the degree of tightness of the connection, a grease is applied to the sealing surfaces of the joints and the sealing element 2. Placed in the inner space of the caisson 6, the previously prepared and cleaned outer surface of the casing pipe 7 is put on with a relative tension δ _{id_oring} from 0% to 3% of the sealing element 2 and installed in the wedge-shaped annular cavity of the body 1, put on the casing pipe 7 cylindrical thrust sleeve 3 until its lower end, which has a slope, comes into contact with the sealing element 2, as well as the flange 4. After that, the flange 4 and the upper part of the housing 1 are evenly pulled together by means of an adjustable threaded connection 5, with the necessary controlled gap δ between the upper part of the housing 1 and the lower part of the flange 4 (along its entire circumference), corresponding to the relative degree of compression ε _oring 15% to 35% for the sealing element 2 in order to avoid subsequent unacceptable deformation of the plastic casing pipe 7.

Adjustable threaded connection 5 creates the necessary compression force between the body 1 and the flange 4 with the transfer of this force to the cylindrical thrust sleeve 3 for the subsequent movement of the sealing element 2 into a wedge-shaped annular cavity closed from the outside between the outer diameter of the casing 7 and the inner wall of the body 1, and additional pressing sealing element 2 to the outer surface of the casing 7 with the first and second conditions for ensuring the tightness of the connection.

The required controlled gap δ is determined in the process of designing and performing engineering calculations of the seal and coupling elements, is interconnected with the physical and mechanical characteristics of the materials used, the relative degree of compression ε _{oring of the} sealing element 2, is indicated in the working design documentation, as well as in the instructions for installing and operating the caisson with clutch.

Claims (1)

Coupling for ensuring the tightness of the connection of the caisson and the casing pipe, including a sealing element, a flange, an adjustable threaded connection, characterized in that it contains a body with a through hole located coaxially with the casing pipe, forming an annular cavity between the outer surface of the casing pipe with a constant diametrical clearance in the upper parts of the body, a wedge-shaped annular cavity with a decreasing diametrical clearance in the middle part of the body and an annular cavity with a minimum allowable diametrical clearance in the lower part of the body, a sealing element made of an elastic elastic material, put on with a relative tension δ _{id_oring} from 0% to 3% on the casing and placed inside the body in a wedge-shaped annular cavity, a cylindrical thrust sleeve put on the casing pipe with a slope at its lower end, installed inside the body in its upper part between the sealing element and the flange centered on the outer diameter, with the possibility of displacement and subsequent compression of the sealing element in a wedge-shaped annular cavity closed from the outside between the outer surface of the casing and the inner wall of the casing, ensuring a relative degree of compression of the sealing element ε _oring from 15% to 35%.

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