RU2616735C1 - Method for repairing defective pipeline section of aboveground gasket - Google Patents

Abstract

FIELD: machine engineering.

SUBSTANCE: cradle housing rise with a pipeline and installation of the anti-friction cushioning material between the base cradle housing surface and the upper surface of the table-raft foundation, are carried out in front of the defective pipeline part notch by the lifting mechanism. Then, pipe fixing is performed on the supports on the both sides of the cut places by the clamping devices, and defective pipeline section clipping is performed. The installation of the repair pipeline section is made by the welded joint means with the coaxial pipe ends, after bringing the pipeline ends in alignment with the clamping devices and the load-lifting mechanism. The clamping devices are designed as modular units comprising the upper and the lower portions consisting of steel profiles rigidly interconnected in the transverse direction.

EFFECT: preventing the loose pipe end movement adjacent to the cutting site in the pipe metal cooling process.

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Description

The invention relates to a method for repairing trunk pipelines of an overhead installation by the method of cutting / inserting a coil.

The prior art method for replacing a defective section of a trunk pipeline according to patent RU 2425273 (published: 03/27/2005; IPC: F16L 1/028).

The invention relates to the repair of pipelines, in particular to the repair of the pipeline with the rise in the trench and laying. When raising a pipeline to clean old insulation and applying new insulation, the determination of the lifting height, the choice of the number and placement of pipe layers is carried out based on the condition of limiting the deformation of the pipeline metal in places with a minimum radius of curvature to a value that causes the critical temperature of brittleness of the metal to reach ambient temperature.

The invention allows you to choose a lifting scheme (the height of the pipeline, the number and placement of pipe layers), limiting the value of the permissible bending moment taking into account the ambient temperature, to prevent the transition of the deformed pipeline to a brittle state when the ambient temperature decreases, its destruction during insulation and laying operations, therefore to increase the safety of repair work.

There is also a method of cutting a section of a pipeline (patent RU 2529972, published: 10/10/2014; IPC: F16L 1/024). Before starting the cutting according to the invention, the cut-out section of the pipeline is fixed by means of a lifting mechanism and supported until the end of the cutting. Pipe cutting is carried out simultaneously with two (or three, in the case of cutting a tee) pipe ends. Achieved simplification of the implementation of the method, increasing its efficiency and improving the quality of cutting.

However, the known methods do not exclude the displacement of the pipeline and the change in the planning and altitude position due to increased stresses in the pipeline during the cooling process of the repaired pipeline section, which entails a reduction in the safety of repair work.

This negative factor is manifested to the greatest degree during the repair of oil pipelines of elevated laying in extreme climatic conditions. Such pipelines are installed on specially designed metal structures that receive and transfer the weight of the pipeline with the pumped product and provide free movement of the pipeline on the support cushion at temperature extremes.

The objective of the invention is the provision of the safe execution of work on replacing a defective section of a pipeline in sections of above-ground laying at low ambient temperatures.

The technical result consists in preventing the movement of the free ends of the pipe adjacent to the cut during cooling of the pipe metal.

This problem is solved, and the technical result is achieved by the fact that the method of repairing a defective section of a pipeline of an overhead gasket according to the invention comprises the steps of lifting the cradle-box with the pipeline by means of a lifting mechanism and installing an antifriction gasket material between the support before cutting the defective section of the pipeline in the cut points the surface of the lodgement case and the upper surface of the grill table and lower the lodgement case onto the grill table; the pipeline is fixed on supports on both sides of the cut with the help of clamping devices, the defective section of the pipeline is cut out, then the clamping devices are loosened, the ends of the pipeline are aligned with the clamping devices and the lifting mechanism, and then the pipeline repair section is installed at help weld with the coaxial ends of the pipeline.

In addition, the method of repairing a defective section of an overhead gas pipeline is characterized by the following particular features:

- the clamping device is made in the form of a prefabricated device containing the upper and lower parts, consisting of steel profiles rigidly connected to each other in the transverse direction, while the upper part of the clamping device is placed in the gap between the base and the supporting surface of the cradle-box installed through the antifriction gasket material on the upper surface of the grill table, and the lower part under the lower surface of the grill table, the upper and lower parts of the clamping device rigidly with unite among themselves on both sides of a support;

- antifriction cushioning material is a sheet of reinforced rubber;

- fix the pipeline on three adjacent supports on both sides of the cut, and the clamping devices are installed, starting from the supports closest to the defective section of the pipeline;

- steel profiles, of which the upper and lower parts of the clamping devices are made, are bent closed welded square tubes;

- before installing the clamping device between the upper part and the supporting surface of the casing-lodgement place the insertion of a wooden beam;

- as a lifting mechanism using a pipe-laying crane or a truck crane.

The invention is illustrated by drawings, where in FIG. 1 shows a clamping device, front view, in FIG. 2 is a side view of the clamping device, in FIG. 3 - installation of the clamping device on the pipeline support, side view, in FIG. 4 is a view along section AA. Under the support of the pipeline is understood to be the lodgement case on which the pipeline is fixed, and the grill table on which the lodgement case is freely mounted.

In FIG. 1-4 is indicated:

1 - upper part;

2 - lower part;

3 - insert;

4 - tie pin;

5 - a nut;

6 - washer;

7 - stiffener;

8 - lodgement case;

9 - grill table;

10 - pipeline.

The clamping device is a collection device. It consists of the upper part 1 and the lower part 2, made of bent closed welded pipes of square section - steel profiles of square section 100 × 100 × 5 mm according to GOST 30245-2003.

The upper part 1 of the clamping device consists of five steel profiles, which are installed in the gap between the base and the supporting surface of the cradle case 8, and are interconnected using two tie rods 4, four washers 6 and four nuts 5. To reduce the bending moment between the upper part 1 and the supporting surface of the table-grill 9 provides for inserts 3 of a wooden beam.

The lower part 2 of the clamping device also consists of five steel profiles interconnected by two tie rods 4, four washers 6 and four nuts 5. The lower part 2 is inserted under the supporting surface of the grill table 9 and with four stiffeners 7, four tie rods 4, eight washers 6 and eight nuts 5 are pulled together with the upper part 1, providing a rigid connection on both sides of the support of the cradle box 8 and the pipeline 10 fixed thereon with a grill table 9. Stiffeners 7 made of steel Single provide uniformity of clamping the upper and lower clamping devices to the table 9-grillage.

The density of the screed of the assembled steel profiles is checked with a 0.3 mm thick probe, which, within the area limited by the washer, should not pass between the assembled parts to a depth of more than 20 mm. The bolt shaft should protrude from the nut by at least 3 mm.

The tightness of the bolts is checked by tapping them with a hammer weighing 0.4 kg, while the bolts should not be displaced.

The method is as follows.

Dismantling of heat-insulating and anticorrosive coatings is carried out in the places of cut along the entire circumference of the pipe to a width of at least 600 mm. The surface of the pipeline in the places of cutting must be cleaned of residual glue, primer, mastic.

Before cutting the defective section of the pipeline with previously dismantled heat-insulating and anti-friction coatings in the places of cut, the lodgement casing is raised with the pipeline by means of a lifting mechanism, the antifriction cushioning material is installed between the supporting surface of the casing-lodgement and the upper surface of the table-grillage and the casing-lodgement is lowered onto the table- grillage.

The pipeline is fixed on supports on both sides of the cut by means of clamping devices. The upper part 1 of the clamping device is placed in the gap between the base and the supporting surface of the lodgement case 8, installed through an antifriction cushioning material (not shown in the figures), on the upper surface of the grill table, and the lower part, under the lower surface of the grill table 9, the upper and lower parts of the clamping devices are rigidly connected to each other on both sides of the support.

The clamping devices are designed to fix the pipeline section on the supports in order to prevent a possible change in the planning and altitude position during the cutting of the defective pipeline section (coil). The mounting of the clamping devices is carried out immediately before the coil cutting work.

To eliminate the displacements of the pipeline and to change the planning and altitude position when cutting the coil, six clamping devices are used: on three adjacent supports on both sides of the cut points, and the clamping devices are installed starting from the supports closest to the defective section of the pipeline. The required number of clamping devices is determined by calculation with subsequent experimental confirmation.

Before installing the clamping devices between the supporting surface of the lodgement case and the upper (sliding) surface of the grill table, a cushioning material of reinforced rubber is installed, while lifting the pipeline is carried out by a lifting mechanism.

Cut the defective area (coil). The coil is cut at the same time by two machines for cutting pipes of the Volzhanka-2 type from a specialized installation site. After cutting the coils, the upper and lower parts are weakened (if necessary, dismantled) of the clamping devices on the supports to relieve longitudinal and transverse stresses.

Insert a new coil, installing the repair section of the pipeline using a welded joint with the coaxial ends of the pipeline. Immediately before the welding work on the insertion of the coil, the ends of the pipeline are brought into alignment using clamping devices and lifting mechanisms.

As a lifting mechanism, a pipe-laying crane or a truck crane is used. When obtaining alignment in plan, but also if there is a vertical difference, a second pipe-laying crane or a truck crane is used. After achieving alignment, welding is carried out to insert the coil into the pipeline. In this case, the clamping devices prevent the movement of the free ends of the pipe adjacent to the cutting place during the cooling of the welds. In conditions of low ambient temperatures, in the absence of fixation of the movement of the free ends of the pipe, significant stresses are caused in the weld, which threatens the safety of performing work on replacing the defective section of the pipeline in sections of overhead laying.

At the end of the welding and installation work, the welded joints are checked by non-destructive testing methods.

After the positive results of the quality control of the welded joints, work is carried out to restore the anticorrosion and heat-insulating coatings of the pipeline section being repaired, while the quality of applying the anticorrosion coating (ACP) of the areas free of thermal insulation is monitored, the AKP pipe sections and parts at the pipe ends (parts) are from thermal insulation, application of the welded joint AKP, installation of polyurethane foam shells and a protective casing.

Upon completion of the work, the clamping devices are dismantled from the grill tables.

Testing of the repair method for the defective section of the overhead gas pipeline was carried out at the under construction site of the overhead gas pipeline with a diameter of 820 mm with factory thermal insulation made of polyurethane foam with a thickness of 100 mm at the object of the Zapolyarye – OPS Pur-Pe pipeline system 3 stage. Stage 2 ”(the photograph of FIG. 4 shows the installation of a fixing device on the pipeline support of this section). A test section 448.51 m long was located between the fixed supports. During the testing of the repair technology, continuous working time was performed.

It was found that the proposed method of work provides the ability to repair the pipeline with above-ground laying by the method of cutting / tapping the coil. The adopted technology provides the ability to safely perform repair (replacement) of the oil pipeline in the sections of overhead laying. To bring the ends of the pipeline of the above-ground section in alignment with the further insertion of the coil, it is necessary to use at least one load-lifting mechanism with clamping devices. The total duration of the repair work performed in accordance with this method was 30 hours 05 minutes.

Based on the results of testing, this method was included in the draft guidance document “Trunk pipeline transport of oil and oil products. Repair (replacement) of the oil pipeline in sections of overhead laying. ”

The proposed method of repairing the pipeline, involving the use of clamping devices, prevents the movement of the free ends of the pipe adjacent to the cutting site during the cooling of the pipe metal and ensures the safety of replacing the defective section of the pipeline in sections of overhead laying at low temperatures in northern climatic conditions.

Claims (7)

1. A method of repairing a defective section of an overhead gasket pipeline, characterized in that it comprises the steps of lifting the cradle-box with the pipeline by means of a lifting mechanism, installing an anti-friction cushioning material between the bearing surface of the cradle and the upper surface of the grill table and lower the lodgement case onto the grill table; the pipeline is fixed on supports on both sides of the cut with the help of clamping devices, the defective section of the pipeline is cut out, then the clamping devices are loosened, the ends of the pipeline are aligned with the clamping devices and the lifting mechanism, and then the pipeline repair section is installed at help weld with the coaxial ends of the pipeline. 2. The method according to p. 1, characterized in that the clamping device is made in the form of a prefabricated device containing the upper and lower parts, consisting of steel profiles rigidly connected to each other in the transverse direction, while the upper part of the clamping device is placed in the gap between the base and the supporting surface of the cradle-case installed through the antifriction cushioning material on the upper surface of the grill table, and the lower part is under the lower surface of the grill table, the upper and lower h The parts of the clamping device are rigidly connected to each other on both sides of the support. 3. The method according to p. 1, characterized in that the antifriction cushioning material is a sheet of reinforced rubber. 4. The method according to claim 1, characterized in that the pipeline is fixed on three adjacent supports on both sides of the cut points, and the clamping devices are installed starting from the supports closest to the defective section of the pipeline. 5. The method according to p. 1, characterized in that the steel profiles of which the upper and lower parts of the clamping devices are made, are bent closed welded square tubes. 6. The method according to p. 1, characterized in that before installing the clamping device between the upper part and the supporting surface of the casing-lodgement place the insert of a wooden beam. 7. The method according to p. 1, characterized in that as a lifting mechanism using a pipe-laying crane or a truck crane.

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