RU2325581C2 - Pressure-tight detachable joint for tubing - Google Patents

Abstract

FIELD: mechanics.

SUBSTANCE: pressure-tight detachable joint for tubing incorporates a body, which is a female coupling for joining threaded tube ends, displacement of which is either limited or not by a stopper portion inside the said coupling. Elastic sealing elements are a female nut installed in a counterbore. Each sealing element is vulcanisation-installed in the sealing nut counterbore, which is threaded onto tube to the coupling. Diameter of the sealing element thread crest and root, to contact with the coupling end, is larger than corresponding diameter of the tube thread being sealed, and corresponding thread being sealed may be filled in case of sealing element contraction.

EFFECT: enhanced reliability of tubing joint.

3 dwg

Description

The present invention relates to hermetic detachable joints for fixed pipe elements and can be used, for example, to create a tight joint for threaded pipes at the ends.

Structural and technological gaps in threaded pipe joints under the influence of excessive internal or external pressure lead to a violation of the tightness of the joints and their permeability to the medium. To reduce permeability, various sealants are used for such gaps. At least two types of methods can be distinguished for creating a dense state of a threaded joint in such assemblies: a seal achieved inside a threaded joint and achieved outside it.

The most common are elastomeric seals that are installed between the surfaces to be sealed in special grooves (Seals and sealing technique. Handbook, Moscow: Engineering, 1994, p. 131). In this case, smooth surfaces are compacted together.

However, the creation of a sealed detachable connection with this form of gaskets requires a sufficiently large wall thickness of the coarse and, therefore, is not suitable for thin-walled pipes with ordinary threads. Even more complex types of sealing are described there, for example, with a cutting ring according to GOST 15763-91, where metal or combined types of gaskets are used.

Another known detachable joint for sealing uses a sealing material in the form of a tape made of a plastic polymer - fluoroplastic, produced under the name of the sealing tape FUM no TU 6-05-1388-86 by the Kirov-Chepetsk Chemical Combine (see the list "Fluoroplastic Products - 4D". 1992 city, AOO "Kirov-Chepetsk Chemical Plant"). The disadvantage of such a seal is a one-time use and high cost. Another disadvantage of the FUM tape is that, having a low coefficient of friction, it is easily extruded from the thread when it is screwed up.

A connection is known where, as a sealing part, a connecting part with sealing elements made on it is used (patent RU No. 2256115, C2, 7 F16L 21/00, from 2000.10.19). The specified part requires additional space for installation and is mainly suitable for thick steppe rough, not subjected to stress.

It is known to seal threaded joints of the metal-metal type when tightness is achieved due to tight inter-turn contact in a special shape conical thread (GOST 633-80, Fig. 4). The surface roughness of the thread should not exceed 25 microns. Special greases to increase the tightness of the threaded connection can also be used in combination with additional gaskets installed at the point of contact of the coupling and pipe in the area without thread.

Tapered threads in combination with a trapezoidal type profile require a wall thickness of at least 5 mm for a minimum pipe diameter. That is, this type of seal is not suitable for thinner threaded pipe joints.

Known sealed detachable connection in the form of a screw screw assembly containing an assembly of several threaded elements and with a housing for the sealing element in the form of a nut made of elastic material mounted on one of the threaded elements (SU, AS No. 1311338 A1, F16J 15/00 , from 1985.10.18) with a bandage on the outer surface of the sealing element, with radial protrusions on the outer surface of the sealing element, and an annular protrusion located respectively in axial grooves and an annular bore of the body a. Sealing is achieved by compressing the thread of the sealing element between the screw thread and the surface portion of the threaded hole, and the housing limits the expansion of the sealing element to the outer diameter. To achieve tightness, a rather complicated prefabricated design is used here. And the gap between the external thread of the screw and the outer diameter of the thread of the sealant is selected in accordance with the ratio only for trapezoidal thread, which limits the scope of the above assembly.

Known sealed detachable connections with a thread seal when connecting thick-walled pipes inside the area of direct contact of assembly parts (US 4703959, ЕВВ 17/042 В; F16L 15/04; F16L 15/06, from 1987.11.03, US 4828294, F16L 15/04; F16L 15/06, dated 1989.05.09, SU No. 1555587, F16L 15/04, dated 1988.01.06) or on one of the connected pipes of the assembly made in the form of a sleeve (female part) and a threaded end of the pipe (male part) connected to one of the ends of the coupling (SU No. 1555587). The disadvantage of the above solutions is the high degree of wear of the seal when performing several cycles of connection and disconnection of the assembly. A tapered thread is performed only on thick-walled pipes.

The closest to the claimed can be considered a sealed detachable connection with a thread seal when connecting thick-walled pipes inside the area of direct contact of assembly parts (US 4969671, ЕВВ 17/08; F16L 15/04; F16L 15/06, from 1989.05.09.). The elastomeric seal has several turns of tapered thread and is installed on the threaded section in the groove of the coupling from its opposite sides. Since the tightness effect is achieved by filling the depressions with the peaks of the sealing element inserted into the groove, the above-mentioned disadvantages are also inherent in it.

The technical result of the invention is to achieve reliable tightness of the detachable connection for the pipeline.

This technical result is achieved due to the fact that a sealed detachable connection for pipelines, having a housing made in the form of a sleeve with an internal thread for connecting the threaded ends of pipes, the movement of which is limited or not by an emphasis located inside (in the middle) of the specified sleeve having two sides on the internal threaded surface of the groove for elastic (elastomeric) sealing elements made in the form of a nut with an internal thread that is part of the internal thread of the coupling, according to the invention The sealing element is rigidly fixed (for example, by vulcanization) in the groove of the sealing nuts, which are screwed onto the outer surface of the pipes to the coupling, while the diameter of the ends and troughs of the thread of the sealing element of the nut before contact with the end of the coupling is made larger than the diameter of the corresponding vertices and troughs of the sealing thread pipes, with the possibility of filling the corresponding sealing thread during compression of the sealing element with full tightening of the sealing nuts.

In addition, the sealing nut may have an additional sealing element in the groove of the sealing nuts with an additional external thread.

In addition, the sealing nut may have additional sealing elements symmetrically located relative to each other on both sides of these nuts.

The proposed design of the detachable connection is illustrated by drawings, in which Fig. 1 shows a connection designed for external thread with pipes of different diameters, and Fig. 2 and Fig. 3 show particular applications of a sealing nut with a different arrangement of sealing elements relative to the previously presented (in fng. one). The ratio for the peaks and troughs of the sealing and sealing threads of the pipe sealing element is given in the formula. The pipe connection contains the ends of the pipes 1 with an external thread at the ends in the body in the form of a coupling with an internal thread 2. At the end of this coupling connecting the two pipes, a sealing nut 3 is installed. An elastomeric sealing element 4 with an internal thread is inserted by vulcanization in the groove ( figure 1). In this case, until the contact with the end face of the coupling, the thread of the sealing element does not come into contact with the sealing thread of the pipe and can fill it only when the sealing element is compressed. The pipe of small diameter is blocked due to the stop 5 at the end of the thread of small diameter, touching its surface with full screwing. A stop for threading a pipe of larger diameter 6 is another inner wall of the stop 5. A nut with a sealing element 7 is also screwed from the outer end of this part of the sleeve 7. Locking nuts can be used to fix the position. The connection shown in figure 2, contains inside and outside the nut 3 two grooves containing sealing elements 4 with internal and external threads. Figure 3 shows an example of the connection of two pipes using a sealing nut with an external and internal thread, while the sealing elements are located at two opposite ends of the nut.

Sealing is achieved as follows. Nuts with sealing elements in the form of a nut with a female thread are screwed onto the pipe threads and, in particular, we used vulcanized rubber sealing elements. Then, a female threaded sleeve is screwed. By tightening the nuts all the way, a tight connection is obtained, since the thread, being compressed on the elastic element, enters the corresponding pipe thread along the outer diameter and fills it when the sealing element is compressed. In other configurations of the threaded assembly, the tightness can be carried out by a sealing nut 3, which also has an external thread (figure 2). It is screwed up to the stop with the coupling 8, as in FIG. 1, while the external coupling 9 is additionally used. Using grooved sealing elements located on the end of the nut allows this type of threaded seal to be achieved. Alternatively, it is possible to install a sealing element in the groove on both sides of the coupling 8, which does not have an external thread, and to press the end face of the sealing nut 3 without sealing elements. In addition, it is possible at both ends of the sealing nut 3 (FIG. 3), playing the role of the coupling 8, to form sealing elements, and to compress them with the surface of the threaded element 8, imposing on it the function of the sealing nut without sealing elements.

The proposed technical solution is implemented for an experimental batch of nuts with vulcanized rubber sealing element. The check showed no leakage for the working pressure of the brake line of the rolling stock.

Claims (1)

An airtight detachable connection for pipelines, comprising a housing made in the form of a sleeve with an internal thread for connecting the threaded ends of pipes, the movement of which is limited or not by a stop located inside the specified sleeve, elastic sealing elements made in the form of a nut with an internal thread installed in the groove, characterized in that each of the sealing elements is installed by vulcanization in the groove of the sealing nut, which is screwed onto the outer surface of the pipes to the coupling, Diameter of the thread peaks and valleys of the sealing member into contact with the end face of the coupling, is greater than the diameter of the respective peaks and valleys of the sealing pipe thread with the possibility of filling and sealing a corresponding thread during compression of the sealing element.

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