RU2484359C1 - Method of pipeline repair and device to this end - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: coupling composed of two semi-rings is fitted at pipeline damaged section to make annular clearance. Coupling ends are sealed by paste. Composite material is fed via inlet pipe into said annular clearance between coupling and pipeline unless it appears in outlet pipes. Said paste contains the following components in wt %: epoxy-diane resin - 20-35, hardener consisting of the mix of aliphatic amines - 8-15, aerosil - 2-4, mineral filler - 50-65. Composite material contains the following components in wt %: epoxy-diane resin - 20-35, hardener consisting of the mix of aliphatic amines - 4-10, plasticiser - 3-7, active diluent - 0.04-0.08, mineral filler - 50-70.

EFFECT: higher quality of repair, possibility to carry out repair at negative temperatures.

2 cl, 8 dwg

Description

The invention relates to pipeline transport and can be used in the repair of operating pipelines with defects, mainly crack-like, in particular gas pipelines and oil pipelines. The invention is aimed at hardening a correlated or otherwise damaged section of the pipeline without stopping the pumping of the product.

Similar to the claimed method is a method of preventing the development of corrosion defects of the walls of the pipelines along the pipe generatrix, which consists in determining the location and nature of the defect, opening the pipeline, removing the insulation coating and stripping the defect, reducing the pressure in the pipeline, installing a detachable sleeve on the defect, welding with horizontal longitudinal seams half of the coupling, the injection of a hardening non-corrosive polymer material into the space between the coupling and the pipe, while itelno reduce the line pressure (for example, see RF patent №2097646, IPC F16L 57/00, 58/16, published 27/11/97;.. Bul №33.).

The disadvantages of this method is the following. Installing the coupling on a defect does not guarantee the prevention of the development of crack-like defects. The operating pipeline is in a difficult state, therefore, reducing the sleeve annular stresses in the defect area cannot always prevent the development of a crack-like defect, for example, when bending stresses occur in the pipeline.

Similar to the claimed method is a method for preventing the development of crack-like and corrosion defects of the walls of the pipelines along the pipe generatrix, which consists in determining the location and nature of the defect, opening the pipeline, removing the insulation coating and cleaning the defect, reducing the pressure in the pipeline, installing a detachable sleeve, welding with horizontal longitudinal seams of the halves couplings, the injection of hardening non-corrosive-active polymer material into the space between the coupling and the pipeline (see. Example, RF patent No. 2295088, IPC F16L 57/00 (2006.01), publ. 10.03.2007).

The disadvantages of this method are as follows. The method implements repair of gas pipelines with an axial arrangement of crack-like defects. The application of this method requires complex calculations performed after opening the pipeline with testing on tensile testing machines. The coupling length is calculated each time based on these calculations, which does not allow the coupling to be prepared for repair in advance, the repair time and the pipeline operating time at reduced pressure increase (which gives additional economic losses).

The closest analogue to the claimed method is a method of repairing pipelines, including installing a cylindrical coupling, consisting of two half shells, with nozzles on the damaged section of the pipeline with the formation of a gap between them, sealing the ends of the coupling on the pipeline and feeding into the annular gap between the coupling and the pipeline through its inlet nozzles a composite material based on epoxy resin before the composite material appears in the outlet pipes (see, for example, RF patent No. 2191317, IPC F16L 55/18, published on 10/20/2002).

The disadvantages of this method are as follows. Limited temperature range in which repairs can be carried out, namely at a temperature not lower than + 5C °. Increased curing time of the composite material.

The technical result is expressed in preventing the growth of crack-like defects of pipelines not only axial, but also radial, in restoring the working capacity of gas pipelines, oil pipelines and oil product pipelines after repair using composite-coupling technology, reducing the repair time of the pipeline and the possibility of repairing at low temperatures of the pumped product and ambient air .

The essence of the claimed method is expressed in the fact that they carry out the installation of a cylindrical coupling, consisting of two half shells, with nozzles on the damaged section of the pipeline with the formation of an annular gap between them, sealing the ends of the coupling on the pipeline with mastic and feeding it into the annular gap between the coupling and the pipeline through its inlet pipe a composite material based on epoxy resin until a composite material appears in the outlet pipes, characterized in that the mastic contains in wt.%:

Epoxy Diane Resin 20-35

Hardener mixture of aliphatic amines 8-15

Aerosil 2-4

Mineral filler 50-65

and the composite material contains in wt.%:

Epoxy Diane Resin 20-35

Hardener mixture of aliphatic amines 4-10

Plasticizer 3-7

Active diluent 0.04-0.08

Mineral filler 50-70

The essence of the claimed device for repairing the pipeline according to the claimed method is characterized in that it contains a cylindrical sleeve, consisting of two half-shells connected to each other along the longitudinal sections by welding or bolt joints, mastic located at the ends of the sleeve from the ends and on the inner end parts of the inner surface of the sleeve with providing tight contact with the outer surface of the pipeline, and a composite material located on the inner side of the coupling with ensuring tight contact with the outer surface of the pipeline, and differs from the closest analogue in that the mastic contains in wt.%:

epoxy diane resin 20-35

hardener mixture of aliphatic amines 8-15

Aerosil 2-4

mineral filler 50-65

and the composite material contains in wt.%:

epoxy diane resin 20-35

hardener mixture of aliphatic amines 4-10

plasticizer 3-7

active diluent 0.04-0.08

mineral filler 50-70

The essence of the claimed method of repairing the pipeline and the device for repairing the pipeline, through which the claimed method is carried out, is illustrated by the drawings, which show the following.

Figure 1 is a side view of the coupling located on the pipeline;

figure 2 is a cross-sectional view of the coupling and the pipeline;

figure 3 is a view A of the exhaust valve and bolt in the control hole;

figure 4 is a view of the coupling half from the end;

figure 5 is a top view of the coupling half;

Fig.6 is a view of a coupling half in section AA;

Fig.7 is a view of a coupling half in section BB;

Fig. 8 is a side view of a coupling with a bolted connection of half shells.

From the theory of the development of crack-like defects in pipeline transport, it is known that radial defects are the most dangerous for disruption of the pipeline. Due to the fact that main gas pipelines, oil product pipelines and oil pipelines do not work at a constant pressure of the pumped product (technological pressure surges occur in certain strictly controlled parameters), internal forces directed radially outward, which have a certain cyclicity, act on the wall of the pipeline. In addition, bending stresses very often also act on the pipeline. Since the crack tip is a stress concentrator, such a spatial combination of adverse factors increases the likelihood of crack development, which can lead to further destruction of the pipeline.

The claimed method is as follows. After identifying the location of the defect on the pipeline, the pipeline section is opened by performing a trench, the pipeline section is cleaned of insulation, if necessary, the location of the defect is clarified and the actions of the claimed method are carried out. A cylindrical coupling is installed, consisting of two half shells 1, 2, with nozzles 6, 7 on the damaged section of the pipeline 4 with the formation of an annular gap between them (Figs. 1, 8). Half-shells 1, 2 are connected along longitudinal sections by welding (Fig. 1) or bolted joints (Fig. 8). By means of the installation bolts 11 screwed into the half-shells 1, 2, a uniform clearance is set between the pipe 4 and the coupling. The ends of the coupling are sealed on the pipe 4 with a previously prepared mastic 3 containing in wt.%:

epoxy diane resin 20-35

hardener mixture of aliphatic amines 8-15

Aerosil 2-4

mineral filler 50-65

After the hardening of the mastic 3 is fed into the annular gap between the coupling and the pipe 4 through its inlet pipes 6 composite material 5 based on epoxy resin until the appearance of composite material 5 in the output pipes 7 (Fig.1, 8). Composite material 5 pre-prepared before being fed into the annular gap contains in wt.%:

epoxy diane resin 20-35

hardener mixture of aliphatic amines 4-10

plasticizer 3-7

active diluent 0.04-0.08

mineral filler 50-70

Given that the temperature of the pumped gas can reach minus 12 degrees Celsius, the above composite material 5 based on epoxy resin ED-20 was developed with the addition of the necessary additives, which allows repairs at these temperatures. In addition, the gel time (for pumping under the sleeve) has been increased to one hour. It was also created for repair using composite-coupling technology mastic 3 for sealing on the basis of epoxy resin ED-20 of the above composition. The curing time of the specified mastic 3 is 20 minutes.

The use of ED-20 resin as a basis in composite material 5 and in mastic 3 was not chosen by chance. This is done to eliminate the appearance of possible temperature and other stresses at the junction of the mastic 3 with the composite material 5 during repair work. In addition, the developed mastic 3 works, like the composite material 5, at low temperatures up to -12 C °. Famous analogues (such as, for example, the method of repairing pipelines, RF patent No. 2191317, IPC F16L 55/18, published on October 20, 2002), the minimum temperature at which the composite material is injected, plus 5 degrees Celsius, and the gelatinization time is 0, 5 hours, which with a large volume of injected composite material makes quality repair of the pipeline problematic. Used in the specified similar method for sealing a mastic 3 based on a polyester resin has a curing time of one hour, three times longer than that of the mastic in the claimed method, and can also be used in work at low temperatures.

A device for repairing a pipeline according to the claimed method comprises a cylindrical sleeve consisting of two half shells 1, 2 (Figs. 1, 2, 4, 5, 8), connected to each other along longitudinal sections by welding or bolted joints 9, mastic 3 located at the ends couplings from the ends and on the inner end parts of the inner surface of the coupling to ensure tight contact with the outer surface of the pipe 4, and composite material 5 located on the inside of the coupling to ensure tight contact with the outer surface of the pipe pipeline 4, which differs from the closest analogue in that the mastic 3 contains in wt.%:

epoxy diane resin 20-35

hardener mixture of aliphatic amines 8-15

Aerosil 2-4

mineral filler 50-65

and composite material 5 contains in wt.%:

epoxy diane resin 20-35

hardener mixture of aliphatic amines 4-10

plasticizer 3-7

active diluent 0.04-0.08

mineral filler 50-70

The coupling to the pipeline is not welded. The lateral edges of both half shells 1, 2 are cut for welding with the option of joining them by welding (Figs. 4, 6, 7).

The coupling consists of two cylindrical half-shells 1, 2, which are installed on the repaired pipeline 4, completely covering it (figure 1). Then both half-shells 1, 2 are butt welded with longitudinal seams with preliminary cutting of the edges of the longitudinal sides (Figs. 1, 4, 6, 7). The inner diameter of the coupling exceeds the outer diameter of the pipe 4 by an amount sufficient to form an annular gap between them.

In the lower half-shell 2 there are steel inlet pipes 6 (Figs. 1, 2, 8) designed to connect flexible hoses to them, through which composite material 5 is fed.

In the upper half-shell 1 there are output steel pipes 7 (Figs. 1, 2, 3, 8). In addition, in the coupling itself there are control holes 8 with a thread (Figs. 1, 3, 4, 5, 8), designed to release air and control the level of composite material 5 during pouring. As the coupling is filled with composite material 5, bolts are screwed into the control holes 8 (Figs. 1, 2, 3, 5, 6, 8).

In addition, in both half-shells 1, 2 there are threaded holes 10 into which mounting bolts 11 are screwed (Fig. 2), designed to adjust the gap between the coupling and the pipe 4 until the ends of the coupling are filled with mastic and perform the function of supports when installing the coupling on the pipe 4 .

The device operates as follows.

After installing the coupling with a gap and on the pipe 4, two steel half shells 1, 2 are welded together, installed on the pipe 4 symmetrically with respect to the defect with an annular gap by means of bolts 11 screwed into the holes 10 (Figs. 1, 2, 8). The tolerance on the size of the annular gap allows repairing pipelines 4 with geometry defects in the cross section and bending of the longitudinal axis. The ends of the coupling are filled with quick-setting mastic 3 to seal the annular gap at the ends of the half shells 1, 2 between them and the pipeline. The resulting volume between the pipeline 4 and the coupling through the inlet pipes 6 in the lower half-shell 2 is filled with a composite material 5 based on epoxy resin, hardening to the required strength within 24 hours. The location of the inlet nozzles 6 along the edges of the half-shell 2 and the outlet nozzles 7 along the edges of the half-shell 1 allows you to control the process of filling the volume 5 between the pipeline 4 and the sleeve with composite material 5. In the upper half-shell 1 there are several control threaded holes 8, designed to control the level of the composite material 5, into which the screws are screwed after the release of air bubbles and filling the volume of the composite material 5 between the pipe 4 and the sleeve.

Composite material 5 is prepared immediately before filling the volume between the pipe 4 and the sleeve. The composite material hardens and the bolts 11 are turned out to prevent electrical contact between the sleeve and the pipe. To obtain a smooth surface of the half shells 1, 2 after cutting all the bolts, the remaining bolts can be left in the holes 8, 10 of the pipeline 4 and flush cleaned.

As a result of the studies, it was found that the gap between the coupling and the pipe 4 should be at least 6 millimeters and not more than 40 millimeters. The wall thickness of the coupling should be increased by 20% of the wall thickness of the pipeline of the repaired gas pipeline, oil pipeline or oil product pipeline. The coupling in the form of two half shells 1, 2 must be manufactured in the factory by rolling and subsequent thermal tempering in furnaces at a temperature of 700-900 degrees Celsius or by hot stamping (when a sheet of metal is heated to a temperature of 700-900 degrees Celsius with subsequent shaping in a stamp) . Thermal tempering is carried out to relieve residual stresses in the half-shells 1, 2. The material for the manufacture of half-shells 1, 2 of the coupling is used the same as the material of the pipeline 4. It is permissible to use steel similar to the steel of the pipeline being repaired (with equivalent mechanical characteristics). With a large value of the defect, the use of a multi-section (composite) coupling is allowed. But its length should not exceed 10.5 meters.

If it is impossible to carry out fire (welding) work during the repair of the pipeline 4, steel half shells 1, 2 are performed with bolted joints 9 (Fig. 8). At the place of work, the steel half-shells 1, 2 of the coupling are connected to each other by the longitudinal sides of the bolted joints 9 (Fig. 8). All other steps of the method are carried out similarly to the case of connecting half-shells 1, 2 by welding. The installation of a device for implementing the inventive method, comprising a coupling with half shells 1, 2, interconnected by bolt joints 9 (Fig. 8), is carried out similarly to the case of connecting half shells 1, 2 by welding.

In all known repair methods for composite-coupling technology, the possibility of the appearance of stray currents and the appearance of electrochemical corrosion is not taken into account. If necessary, for cathodic protection of the repair structure, a copper cable connection is made with fastening to two bolts, which are welded (one to the body of the pipeline 4, the other to the coupling) by heat welding.

As a result of numerous laboratory experiments and field, field tests, it was found that to prevent the development of a defect, the length of the repair sleeve should be: for axial defects, it is increased on each side of the crack edge by 0.6 times the diameter of the pipeline 4 being repaired; for radial defects - by 1.3 times the diameter of the pipeline being repaired 4. At the same time, the repair structure will allow it to take on the arising loads and stop the development of crack-like defects. As an illustration of this, we can cite the data obtained during the testing of a tubular whip with crack-like defects deposited on it and repaired according to the inventive composite-coupling technology. Defects were applied both axially and radially (cuts to a depth of 50% of the pipe wall thickness).

The test program is as follows.

1. Pressure testing of a whip with a pressure of 55 atm.

2. Cyclic loading of a whip by a hydro pulsator in two stages:

the first stage - 9800 loading cycles with a pressure of 60.5 / 50 atm;

the second stage - 200 loading cycles with a pressure of 70.5 / 50 atm.

3. Static loading of the whip to failure.

As a result of the repair of artificial surface cuts by composite MK-1 couplings, the pipe lash withstood 10,000 loading cycles (which corresponds to 30 years of operation of the pipeline), during which the lash was not destroyed, and leaks and water leaks under the coupling were not inspected by external inspection.

The elongation of the perimeters in various sections of the pipe and coupling did not occur. The destruction of the lash as a result of static loading occurred at a pressure of 120.5 atm. The destruction occurred on the base metal of the pipe. The destruction center was located at a distance of 1600 mm from the edge of the coupling. The spread of destruction under the coupling did not occur. The destruction of the composite material did not occur. Detachment of the composite material in places of artificial defects did not occur. Destruction of steel coupling half shells did not occur. During the tests, measurements were made of the emerging loads on the coupling and on the pipe. The values of the relative deformations arising on the coupling are 1.86 times less than in the pipe.

The claimed method of repairing the pipeline and the device for its implementation due to the distinguishing features in the form of specific mastic materials and composite material with the specified compositions provide improved adhesion of the mastic and composite material with the material of the pipeline and steel half shells 1, 2 of the coupling.

Since the claimed method for repairing a pipeline and a device for its implementation are designed primarily for repairing pipelines with crack-like defects, which are the most difficult when carrying out repairs on a gas pipeline, oil pipeline or oil product pipeline, it can also be recommended for repairing pipelines with other types of defects.

Claims (2)

1. A method of repairing a pipeline, including the installation of a cylindrical sleeve consisting of two half shells, with nozzles on the damaged section of the pipeline with the formation of an annular gap between them, sealing the ends of the sleeve on the pipe with mastic and supplying an annular gap between the sleeve and the pipe through its composite material inlet pipe based on epoxy resin until a composite material appears in the outlet pipes, characterized in that the mastic contains, wt.%:
epoxy diane resin 20-35 hardener mixture of aliphatic amines 8-15 aerosil 2-4 mineral filler 50-65,
and the composite material contains, wt.%:
epoxy diane resin 20-35 hardener mixture of aliphatic amines 4-10 plasticizer 3-7 active diluent 0.04-0.08 mineral filler 50-70 2. A device for repairing a pipeline according to the method of claim 1, comprising a cylindrical sleeve consisting of two half-shells connected to each other along longitudinal sections by welding or bolt joints, a mastic located at the ends of the sleeve from the ends and at the inner end parts of the sleeve inner surface with tight contact with the outer surface of the pipeline, and a composite material located on the inner side of the coupling to ensure tight contact with the outer surface of the pipeline, characterized it that the mastic comprises wt.%:
epoxy diane resin 20-35 hardener mixture of aliphatic amines 8-15 aerosil 2-4 mineral filler 50-65,
and the composite material contains, wt.%:
epoxy diane resin 20-35 hardener mixture of aliphatic amines 4-10 plasticizer 3-7 active diluent 0.04-0.08 mineral filler 50-70

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