Polymeric device to protect pipe coupling

Abstract

A polymeric device for protection of the connecting pipe coupling contains a stepped bushing having a medium part with an increased diameter and two lateral parts with a smaller outside diameters, which is installed between end faces of pipes with a conic thread, and connected by means of a coupling and having sealing rings made of an elastomer, which are on parts of the bushing with the small diameter. The device has an additional stepped bushing, and the first stepped bushing has a constant outside diameter and two parts with small and large internal diameters, and the second stepped bushing has a constant internal diameter and two parts with small and large diameters.

Claims

1. A device for protection of a pipe-connecting coupling, the device comprising: a first stepped bushing having a large internal diameter part, a small internal diameter part with an internal diameter smaller than the large diameter part, and having a constant outer diameter; a second stepped bushing having a constant internal diameter, a large outer diameter part, and a small outer diameter part with a diameter smaller than the large outer diameter part; the two bushings being installed between end faces of pipes with a conic thread, the pipes connected via the thread to a coupling; wherein the small internal diameter part of the first bushing and the internal diameter of the second bushing are equal to each other and to an internal diameter of the pipes, and wherein the outer diameter of the first bushing and the large outer diameter part of the second bushing are equal to each other and to an internal diameter of the coupling; wherein the first bushing large internal diameter part is connected to the second bushing small outside diameter part by having an overlapping and frictional contact; wherein the value of possible lengthwise displacement of the bushings relative to each other is greater than the displacement of the pipe ends when tightening a threaded connection of the pipes; and wherein the first bushing large internal diameter part and the second bushing small outside diameter part each have projections, which are spiral annular projections with a semicircular shape on their faces, these projections are configured to interface during connection of the two bushings, while preventing their separation when disassembling the threaded connections of the pipes.

2. The device of claim 1 wherein one of the bushings is formed from a material having a smaller modulus of elasticity than the other bushing.

3. The device of claim 2 wherein one of the bushings is formed of high-pressure polyethylene, and wherein the other bushing is made of low-pressure polyethylene.

4. The device of claim 2 wherein one of the bushings is made of polycaprolactam, and the other bushing is made of polyethylene.

5. A device for protection of a pipe-connecting coupling, the device comprising: a first stepped bushing having a large internal diameter part, a small internal diameter part with an internal diameter smaller than the large diameter part, and having a constant outer diameter; a second stepped bushing having a constant internal diameter, a large outer diameter part, and a small outer diameter part with a diameter smaller than the large outer diameter part; the two bushings being installed between end faces of pipes with a conic thread the pipes connected via the thread to a coupling; wherein the small internal diameter part of the first bushing and the internal diameter of the second bushing are equal to each other and to an internal diameter of the pipes, and wherein the outer diameter of the first bushing and the large outer diameter part of the second bushing are equal to each other and to an internal diameter of the coupling; wherein the first bushing large internal diameter part is connected to the second bushing small outside diameter part by having an overlapping and frictional contact; wherein the value of possible lengthwise displacement of the bushings relative to each other is greater than the displacement of the pipe ends when tightening a threaded connection of the pipes; and wherein the first bushing large internal diameter part and the second bushing small outside diameter part each have projections, which are spiral annular projections with a semicircular shape on their faces, these interfaced projections connecting the two bushings, while preventing their separation when disassembling the threaded connections of the pipes from the coupling, wherein the interfaced spiral annular projections allow a shiftable connection of the two bushings, the two bushings shiftable from a first assembly position to a second assembly position by movement of the spiral annular projections of each of the two bushings over each other upon application of a force by at least one end face of the pipes.

6. The device of claim 5 wherein one of the bushings is formed from a material having a smaller modulus of elasticity than the other bushing.

7. The device of claim 6 wherein one of the bushings is formed of high-pressure polyethylene, and wherein the other bushing is made of low-pressure polyethylene.

8. The device of claim 6 wherein one of the bushings is made of polycaprolactam, and the other bushing is made of polyethylene.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 provides the structural layout of an embodiment of the device.

(2) The invention is realized as follows:

(3) The pipe coupling 1 serves to connect two pipes 2 and 3 (e.g. tubing strings) having tapered threads at their ends. The internal surface of the pipes 2 and 3 may have protective coating providing their insulation from aggressive media. The internal coating of the pipes may be: lacquer, enamel, glass, epoxy resin.

(4) There are two stepped bushings in the internal cavity of the coupling. The first stepped bushing 4 has constant outside diameter O.sub.d and two sections with small d.sub.1 and large d.sub.2 internal diameters; the second stepped bushing 5 has constant internal diameter d.sub.1′ and two sections with small d.sub.2′ and large O′.sub.d diameters, whereas the small internal diameter of the first bushing d.sub.1 and the internal diameter d.sub.1′ of the second bushing are equal to the internal diameter of the pipes being connected d.sub.int, the outside diameter of the first bushing O.sub.d and the larger outside diameter O.sub.d′ of the second bushing are equal to the internal diameter of the coupling ‘in the clear’; the first bushing at the section of the larger internal diameter is connected with the section of the smaller outside diameter of the second bushing with standoff, and the value of possible shift of the bushings relative to each other exceeds shift of the pipe ends at tightening of the threaded connection at maximally allowed value of the threads wear.

(5) The surfaces 6 and 7 where the interaction of the first 4 and the second 5 bushings have spiral annular ridges and troughs e.g. of semicircular profile providing their tight contact and preventing their detachment during disassembly of the threaded connection, i.e. at unscrewing of one of the pipes 2 (3) out of the coupling 1.

(6) The option of the structure implementation would be manufacture of the bushings 4 and 5 with smooth surfaces 6 and 7 to interact along the whole length. At that the sizes of the contacting surfaces are manufactured in such a way as to provide standoff.

(7) Independently of the bushings 4 and 5 design, one of them may be made of the material having smaller elastic modulus than the first one.

(8) The device operates as follows:

(9) Prior to assembly of the coupling connection, the coupling 1 is to be screwed on one of the pipes, e.g. the right one 2, and tightened with the torque ensuring sealing of the connection. Then the pre-assembled bushings 4 and 5 are installed into the internal cavity of the coupling 1. The right bushing 5 is installed in the opening of the left bushing 4 at the depth of about 5-10 mm, (depending on the diameter of the bushings) in such a manner that they would make a single assembly.

(10) If necessary, the thread is pre-lubricated with grease or sealant—depending on the operating conditions of the threaded connection.

(11) Then, the pipe 3 is screwed in the coupling 1. Screwing of the tapered threads consists of two stages—the actual screwing and further tightening of the threaded connection. During screwing the end of the pipe 3 props against the end of the bushing 5 and shifts it relative to the bushing 4. At the same time the surfaces of the bushings 5 and 6 slide relative to each other, the annular ridges of one bushing interact with the troughs of another bushing which provides for tight sealed connection. In case the surfaces of the bushings 6 and 7 are made smooth, the sealing of the gap is provided due to standoff.

(12) When the thread is tightened, the final embedding of the bushing 5 into the bushing 4 takes place, and the values of the gap becomes that determined for existing wear of tapered threads. Thus, there is no adjustment of the axial sizes of the bushings, for these are self-set relative to each other.

(13) When unscrewing of the threaded connection one of the pipes is unscrewed, and the bushings 4, 5 remain in the cavity of the coupling 1 due to friction forces. If necessary the bushings can be removed from the coupling cavity with a tool capturing the bushings at their ID. Separation of the bushings is after they have been removed out of the coupling by rotation relative to each other.

(14) Since tubing strings are laid on the scaffolding in strict order while the column is raising, when lowering them down into the well the unscrewed pair of the parts ‘coupling-pipe’ will be re-assembled. As a result of wear of the threaded connection surfaces the end of the pipe 3 will be positioned deeper in the coupling 1 then at the previous connection. Therefore, the bushing 5 would be embedded deeper into the bushing 4 providing full joint with the end of pipe 3.

(15) In process of wear and tear of the threaded cone connection, pipe 3 will be deeper and deeper screwed into the coupling, and bushing 5 will be deeper and deeper enter the opening of bushing 4. At the same time, the tightness at the end face of pipe 3 will be constant, or at least no smaller than the tightness at the initial stage, and will ensure leak-tightness of the connection.

(16) In case of limiting wear of the thread, (this value is to be determined by practical consideration based on the experience of operation of threaded pipe joints) the value of gap will take the minimum value close to zero. During the whole service life period of the thread connection, the suggested device will ensure isolation of the internal surface of the coupling and threads against any liquid or gas which is in the internal cavity of pipes.

(17) In such a way, the declared technical result consisting in increasing durability of the thread union joint during the whole service life period due to excluding corrosion of the coupling, its thread, and pipeline threads connected thereto.

(18) While several variations of the present invention have been illustrated by way of example in preferred or particular embodiments, it is apparent that further embodiments could be developed within the spirit and scope of the present invention, or the inventive concept thereof. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present invention, and are inclusive, but not limited to the following appended claims as set forth.