RU2178856C1 - Method for repairing gas pipeline - Google Patents

Abstract

FIELD: construction of gas mains. SUBSTANCE: device may be used for repairing gas pipelines by sectionalizing them followed by cutting out defective pipes and replacing them by new ones. Defective section is disconnected from pipeline, released from gas, sectionalized so that all sections are assigned equal scope of repair work, boundaries of these sections passing through defective pipes; auxiliary holes are made in defective pipes; spherical pugs are welded to the latter. Separators are passed through auxiliary holes to seal pipeline sections. The latter are blown down and defective sections are replaced by good ones. EFFECT: enhanced reliability of pipeline. 9 dwg

Description

 The invention relates to the operation of main pipelines and can be used in the repair of main gas pipelines by sectioning them into sections by shutting off valves (linear valves), followed by cutting out the defective pipes and replacing them with new ones.

 The main and most expensive element of the main gas pipeline is pipes welded into a continuous thread, which are the pipeline itself, which is divided into sections by shutoff valves (linear valves). The length of these sections can reach up to thirty kilometers. As a rule, gas pipelines are buried in the ground, usually to a depth of at least 0.8 m to the upper generatrix of the pipe. Underground gas pipelines are affected by corrosive soils. Despite the anticorrosive insulation coating of the gas pipeline, the presence of cathodic and drainage protection stations, the metal of the pipes undergoes wear and tear over a long period of operation. Within one section of the gas pipeline, pipes subject to corrosion can be three or more, and they can be located from each other at a distance of several kilometers.

 Under the influence of corrosive metal wear, the pipe wall thickness decreases, which leads to emergencies in gas pipelines. To eliminate emergencies, it is necessary to carry out preventive repairs, including the simultaneous replacement of three or more damaged pipes in one section of the gas pipeline with the implementation of hot work. Hot work on the gas pipeline is carried out after sectioning the pipeline, namely after disconnecting the emergency section from the gas pipeline and cutting off the site of hot work from the gas pipeline section itself.

 A known method of repairing an existing pipeline with its sectioning by blocking its cross section with a device such as a gel-like visco-elastic dividing overlapping piston (see RF patent 2005951, class F 16 L 55/18, 1990).

 The disadvantage of this method of repairing a pipeline with its sectioning by means of the indicated locking device is the low reliability of sealing the internal cavity of the pipe during hot work on large diameter pipelines, as well as the difficulty of installing electromagnets in an underground pipeline.

 As a prototype, a method of repairing an existing gas pipeline was selected (see. "Typical Instructions for the Safe Conduct of Hot Operations at Gas Objects of the USSR Mingazprom." M., 1989.). In accordance with this method, hot work is carried out after sectioning the pipeline, namely, disconnecting the emergency section from the main gas pipeline by means of shut-off valves (linear valves), releasing the emergency section of the gas pipeline from natural gas and installing inflatable rubber balls to cut off the site of direct hot work from the emergency section gas pipeline. Then hot work is carried out to replace the defective pipe in compliance with safety requirements.

 The disadvantage of this method of repairing a gas pipeline is that this method eliminates the possibility of carrying out hot work at the same time in several places on the same emergency section of the gas pipeline without separating these places among themselves with shutoff valves or without interfering with the influence of hot work carried out simultaneously in several places on the same emergency section of the gas pipeline (see. "Typical instructions for the safe conduct of hot work at gas facilities of the USSR Ministry of gas and oil industry." M., 1989, paragraph 3.1.15). This leads to the organization of long-term repair work on the consecutive replacement of defective pipes in the emergency section of the gas pipeline, to the cutting of additional technological holes in pipes that cannot be replaced, and, as a result, the subsequent welding of patches for these technological holes, to the irretrievable loss of significant volumes of natural gas, repeatedly discharged into the environment from the cavity of the emergency section of the gas pipeline, as well as to increase the total time to eliminate the emergency situation on the gas pipeline and, as a result s to reduce the gas supply to the consumer due to prolonged inoperability emergency pipeline section.

 The technical effect of the proposed invention is to increase the productivity of repair work carried out with the execution of hot work on the emergency section of the gas pipeline, to reduce the total downtime of the gas pipeline for repair, to reduce the number of technological holes made on pipes that cannot be replaced, and, as a result, reducing the number of patches for these technological holes, as well as reducing the discharge of natural gas from the internal cavity of the emergency section of the pipeline into the environment.

 This goal is achieved by the fact that the gas pipeline repair method, consisting of disconnecting the emergency section of the gas pipeline from the main gas pipeline by closing the shut-off valves (linear valves), releasing the emergency section from natural gas, installing inflatable rubber balls to cut off the location of the hot work from the emergency section of the gas pipeline of direct hot work to replace defective pipes, according to the invention, the emergency section of the gas pipeline disconnected from the main is divided gas pipeline by means of shutoff valves (linear valves), per section, depending on the number of defective pipes to be cut, the distance between the defective pipes to be cut, and the route profile of the emergency section of the gas pipeline, the section sizes being assigned equal to each other in terms of physical volumes of repair work and therefore, equal in time of repair work, while the boundaries of these sections pass through defective pipes to be cut, and technological holes, with the exception of the first and last the same technological holes are prepared on the defective pipes to be cut, and all spherical plugs are welded to the defective pipes to be cut, and these spherical plugs are removed together with these defective pipes.

 Comparison of the claimed technical solution with the prototype made it possible to establish compliance with its criterion of "novelty." In the study of other well-known technical solutions in this technical field, the features that distinguish the claimed invention from the prototype were not identified and therefore they provide the claimed technical solution with the criterion of "significant difference".

 The invention is illustrated by drawings.

 In FIG. 1 shows an emergency section of a gas pipeline, and FIG. 2 - 9 - technological stages of preparation of the emergency section of the pipeline for repair work with the replacement of defective pipes. The gas pipeline 1 contains valves (linear valves) 2 and 3, the emergency section of the gas pipeline 4, defective pipes to be cut, 5, 6 and 7, technological holes 8, 9 and 15, inflatable rubber balls 10, 11, 13, 14 and 17 , sections of the emergency section of the gas pipeline 12, 16, 18 and 19, spherical plugs 20, as well as two independent half-sections (21) and (22) of the emergency section of the gas pipeline (4).

 The following is a specific procedure for implementing the proposed method.

 The gas pipeline (1) is examined in any known manner, for example, using in-line diagnostic shells. As a result of the inspection of the gas pipeline (1), the emergency section of the gas pipeline (4) is determined, on which there are pipes (5), (6) and (7) damaged by corrosion and to be replaced.

 Repair work is carried out with the emergency section of the gas pipeline (4) disconnected from the gas pipeline (1) by means of shut-off valves (linear valves) (2) and (3), and the emergency section of the gas pipeline (4) is released from natural gas. Natural gas is vented into the atmosphere through process candles strapping shutoff valves (linear valves) (2) and (3).

 Then, depending on the number of defective pipes to be cut, (5), (6) and (7), the distance between these defective pipes (5), (6) and (7) and the vertical profile of the route of the emergency section of the gas pipeline (4) , the boundaries of sections (12), (16), (18) and (19) are determined into which the emergency section of the gas pipeline (4) disconnected from the main gas pipeline (1) by means of shut-off valves (linear valves) (2) and (3). The lengths of sections (12), (16), (18) and (19) of the emergency section of the gas pipeline (4) are assigned so that sections (12), (16), (18) and (19) are equal in physical volumes of repair work and, therefore, are equal in time of repair work, and their boundaries passed through defective pipes to be cut, (5), (6) and (7). Then, the number of defective pipes to be cut is made (5), (6) and (7), technological holes (8), (9) and (15) and sections (12), (16), (18) and (19 ) emergency section of the gas pipeline (4). Numbering is performed starting from stop valves (linear valves) (2) located at the beginning of the emergency section of the gas pipeline (4) along the course of the movement of natural gas in the main gas pipeline (1).

 Then earthwork is carried out. First, the pipes of the emergency section of the gas pipeline (4) are opened, on which the technological holes (8), (9) and (15) will be cut for the subsequent installation of inflatable rubber balls (10), (11), (13) and (15). Next, the defective pipes to be cut are opened, (5), (6) and (7).

 Before the start of hot work, the cathodic protection stations are turned off. Hot work on the emergency section of the gas pipeline (4) begins with cutting the first technological hole (8), which is located on the pipe, which cannot be replaced, but in the closest proximity to the beginning of the first defective pipe to be cut, the first section (12) of the emergency section of the gas pipeline ( 4). An inflatable rubber ball (10) is installed in the technological hole (8). The next process hole (9) is prepared on the last defective pipe to be cut, (5) the first section (12) of the emergency section of the gas pipeline (4) (Fig. 2).

 After installing an inflatable rubber ball (11) in the technological hole (9), the inner cavity of the first section (12) of the emergency section of the gas pipeline (4) is purged with air and then the internal cavity of the section (12) of the emergency section of the gas pipeline (4) is filled with inert gas, for example, exhaust gases. In this case, the technological hole (8) serves to supply air and exhaust gases to the cavity of the pipeline, and the technological hole (9) - to discharge residual natural gas, and then air from the internal cavity of section (12) of the emergency section of the gas pipeline (4) into the atmosphere (see Fig. 2).

 After filling the inner cavity of the section (12) of the emergency section of the gas pipeline (4) with exhaust gases, the rubber balls are reinstalled in the following order: into the technological holes (8) and (9) from the opposite side to the already installed rubber balls (10) and (11) ) install new inflatable rubber balls (13) and (14) (Fig. 3). Then, the previously installed inflatable rubber ball (10) is removed (Fig. 4). Thus, within the section (12) of the emergency section of the gas pipeline (4), bounded by inflatable rubber balls (13) and (14), the internal cavity of the gas pipeline was filled with exhaust gases.

 Then, on the other defective pipe (6), located at the end of the second sections (16) of the emergency section of the gas pipeline (4), the next process hole (15) is cut out. In this technological hole (16), a previously removed inflatable rubber ball (10) is installed (Fig. 5). In this case, an inflatable rubber ball (11) is removed from the technological hole (9) (see Fig. 6). Then, the internal cavity of the second section (16) is purged of the emergency section of the gas pipeline (4) located between the process openings (9) and (15), and the cavity is subsequently filled with exhaust gases. In this case, the technological hole (9) serves to supply air and exhaust gases to the cavity of the pipeline, and the technological hole (15) - to discharge residual natural gas, and then air from the internal cavity of section (16) of the emergency section of the gas pipeline (4) into the atmosphere (see Fig. 6).

 After completing this work, reinstallation of the inflatable rubber balls in the technological holes (9) and (15), namely in the technological holes (9) and (15), additional inflatable rubber balls (11) and (17) are installed. Thus, in the redistribution of section (16) of the emergency section of the gas pipeline (4), limited by inflatable rubber balls (11) and (17), the internal cavity of the gas pipeline was filled with exhaust gases (Fig. 7).

 In this order, air is purged and filled with exhaust gases of the internal cavities of the subsequent sections (18) and (19) of the emergency section of the gas pipeline (4) and the installation of inflatable rubber balls (Fig. 8). Reinstallation of inflatable rubber balls according to the proposed scheme eliminates the blowing of exhaust gases from the internal cavities of sections of the emergency section of the gas pipeline (4), as well as the possible penetration of natural gas into the cavities of these sections. At the same time, the last technological hole of the last section (19) of the emergency section of the gas pipeline (4) is located on a pipe that cannot be cut, but in the maximum proximity to the end of the last defective pipe to be cut (7).

 Upon completion of filling the internal cavities of the sections of the emergency section of the gas pipeline (4) with exhaust gases, hot work is performed to cut the defective pipe (6) located in the middle of the emergency section of the gas pipeline (4), and a boundary separating two adjacent pipes passes through this defective pipe (6) sections (16) and (18) (Fig. 9). Spherical plugs (20) are welded to the ends of two half-sections formed as a result of this technological operation. In this case, the spherical plugs (20) are welded to the defective pipe to be cut (6). Thus, instead of one section of the gas pipeline (4), two semi-sections (21) and (22) are independent from each other, on which simultaneous fire operations are possible in compliance with safety requirements and which are cut off from the main gas pipeline (1) as shut-off valves (linear cranes) (2) and (3), and spherical plugs (20).

 If necessary, in the above order, the subsequent division of the semi-sections (21) and (22) into independent parts is performed. In this case, all previously prepared technological holes (8), (9) and (15) and the inflatable rubber balls installed in them are used, and all spherical plugs (20) are welded to the defective pipes to be cut, and these spherical plugs (20) in repair work, as defective pipes are replaced, are removed along with the defective pipes.

 The subsequent stages of repair work with simultaneous hot work to replace defective pipes in independent from each other half-sections (21) and (22) of the emergency section of the gas pipeline (4) are carried out using well-known technologies for replacing pipes in existing gas pipelines. In this case, the number of technological holes prepared in the emergency section of the gas pipeline decreases with the number of defective pipes removed. All welded joints on newly welded pipes are subjected to flaw detection by non-destructive testing methods.

 At the end of the hot work, the exposed sections of the gas pipeline are isolated, and the pipeline is backfilled with soil. The site is tested and, after switching on the cathodic protection stations, it is put into operation.

 The gas pipeline repair method is supposed to be implemented on the Urengoy-Surgut-Chelyabinsk two-line gas pipeline system, which operates in a busy mode of gas transportation to consumers and does not have reserve looping sections of the gas pipeline. When one section of any gas pipeline is put into repair, a significant decrease in the throughput capacity of the entire two-thread system of the main gas pipelines occurs. As a result of the implementation of the proposed method for repairing a gas pipeline, a significant increase in the productivity of repair work carried out with the implementation of hot work on the emergency section of the gas pipeline is expected, a reduction in the total idle time of the gas pipeline for repair, a decrease in the number of process holes made on pipes that cannot be replaced, and, as a result, reduction in the number of patches for these technological openings, as well as reduction of discharges of natural gas into the environment from the internal cavity of the emergency section of the gas water.

Claims (1)

 The method of repairing a gas pipeline, which consists in disconnecting the emergency section of the gas pipeline (AUG) from the main gas pipeline using shutoff valves - linear valves, releasing the disconnected AUG from natural gas, installing inflatable balloons to cut off fire work sites in the AUG when replacing defective pipes, characterized in that AUGs are sequentially divided into sections, taking into account the equality in them of the volume of repair work, for which technological holes are made at the beginning and end of each section at its borders, the sections are cut off inflate it with inflatable balls and fill it with exhaust gases, after which the AHG is cut at the section boundary into half sections with plugs installed at their ends, and hot work and the replacement of defective pipes are carried out simultaneously on each section, and depending on the amount of repair work, the AHU is assigned a number there are at least two half-sections, and technological holes within the AUG except for the first and last are performed on defective pipes to be replaced, while plugs are installed on the ends of defective pipes to be replaced and joint it is natural to remove the plugs with them.

Images