RU2718099C1 - Dismantling method of decommissioning gas or oil pipeline - Google Patents

Abstract

FIELD: transportation.

SUBSTANCE: invention relates to pipeline transport, namely, to technologies for dismantling of decommissioned (worn) gas- and oil pipeline in places of passage of technological racks of gas- and oil pipelines. Method of dismantling of decommissioned gas or oil pipeline includes ground opening to upper generatrix of pipe, pipe cutting and its transportation. Note here that said dismantled pipe is marked by length defined by permitted lifting weight of gas or oil pipeline for its transportation. In marked points process holes are drilled, through which is discharged excess pressure in pipeline. Thereafter, a component is supplied into the inner cavity of the pipe to create sealing "plugs" in all marked places and the pipe is cut along the center of the formed plugs. Component for creating sealing plugs is represented by filling foam isolator with density from 18 to 60 kg/m³ of carbamide foam plastic. Foam isolator is fed into the inner cavity of the pipe in all marked places through a tube located vertically in the pipe at depth of 0.25–0.75 of the diameter of the pipe.

EFFECT: invention ensures prevention of spilled oil products remaining in the pipe due to reliable sealing of the empty pipe inner cavity in the specified sections.

1 cl, 3 dwg

Description

The invention relates to pipeline transport, and in particular, to technologies for the dismantling of decommissioned (worn out) gas and oil pipelines at the places of passage of technological flyovers of gas and oil pipelines.

The gas and oil pipeline to be decommissioned must be prepared for dismantling. Preparation consists in freeing the gas and oil pipelines from oil, cleaning the pipe cavity from dirt and paraffin-tar deposits. Gas and oil pipelines decommissioned and put into a safe condition do not require preparatory work, as they must be disconnected from neighboring sections, emptied and cleaned of petroleum hydrocarbons. As a rule, in the process of cleaning an oil pipeline, it is not possible to completely free the pipeline from oil residues and asphalt-tar deposits, which during pipe dismantling leads to the outflow of oil, which has a negative impact on the state of the components of the natural environment. In such cases, soil contaminated with oil products is recultivated, especially in marshy and waterlogged areas, which is a laborious and expensive process. Oil spill response is an urgent problem. Therefore, one of the most important tasks is to prevent oil spills during the dismantling of gas and oil pipelines.

Known dismantling the linear part of the main pipelines as a set of technical measures aimed at removing the pipeline from the soil, cutting into parts and transporting pipes to the storage location (OST153-39.4-027-2002). The method of dismantling a decommissioned gas and oil pipeline involves removing the surface horizon of the soil (turf), opening the soil to the upper generatrix of the pipe, cutting the pipe and transporting it. Mark the dismantled pipe into sections with a length determined by the permitted load-carrying mass of the gas and oil pipelines for its transportation. Technological holes are drilled in marked places through which penocarbamide (penoizol) is fed into the internal cavity of the oil pipeline to create “plugs”. The pipe is cut along the centers of the formed traffic jams. When using the invention provides reliable sealing of the internal cavity of the gas and oil pipelines and the absorption of residual petroleum hydrocarbons with penoizol.

There is a method of opening a trench and lifting an underground pipeline during the overhaul of main pipelines or during the dismantling of decommissioned inactive pipelines (patent RU2389930, IPC F16L1 / 028, published on 05/20/2010). The method of opening the trench and lifting the underground pipeline during dismantling and overhaul includes loosening and removing vegetable and mineral soil backfill, raising the pipeline and laying it on the soil surface along the axis of the trench, moreover, loosening and removing vegetable and mineral soil backfill is carried out simultaneously by moving the multi-row trolley suspension and lifting the pipeline with rippers attached to the tractors.

A known method of dismantling a decommissioned oil pipeline (patent RU2585158, IPC F16L1 / 028, published on 05.27.2016), which includes opening the soil to the upper generatrix pipe, marking the dismantled pipe into sections with a length determined by the permissible lifting weight of the gas and oil pipelines its transportation. During dismantling, technological holes are drilled through which excess pressure is removed in the pipeline and polyurethane foam is fed into the internal cavity of the pipeline to create “plugs”. Pipes are cut along the centers of formed plugs and pipes are transported. Taken as a prototype.

Known methods for dismantling disabled gas, oil pipelines using devices for sealing the internal cavity of the pipeline are ineffective and labor-intensive. In addition, polyurethane foam in accordance with GOST 30244 is assigned to group G4 - highly combustible, in accordance with GOST 30402 - B3 - highly flammable; according to GOST 12.1.044 - D3 - with high smoke generating ability and T4 - extremely toxic when burning.

The technical problem solved by the invention is to simplify the process of dismantling a decommissioned (worn out) gas and oil pipeline while preserving the vegetation of the surface soil horizon by preventing the spill of oil products remaining in the pipe, ensuring fire and explosion safety.

The technical result is the prevention of the spill of oil products remaining in the pipe of the gas and oil pipelines due to reliable sealing of the inner cavity of the emptied pipe in predetermined areas.

The problem is solved, and the technical result is achieved by the method of dismantling the decommissioned gas or oil pipeline, including opening the soil to the upper forming pipe, cutting the pipe and transporting it, while marking the dismantled pipe into sections with a length determined by the permitted lifting weight of the gas or oil pipeline for its transportation, technological holes are drilled in marked places, through which excess pressure is removed in the pipeline, after which it is fed into the internal cavity component tubes to create sealing "plugs" in all marked places and conduct pipe cutting in the center of the formed plugs. In contrast to the prototype, as a component for creating sealing "plugs", pouring penoizol with a density of 18 to 60 kg / m³ of urea foams is used, while the penoizol is fed into the internal cavity of the pipe in all marked places through a pipe located vertically in the pipe to a depth of 0 , 25-0.75 of its diameter.

The choice of component to create a sealing "plugs" due to the following. Penoizols with a density of up to 18 kg / m³ are impractical to use, since the compressive strength, bending and stretching become lower than 0.4, 0.2, 0.1 kg / cm³, respectively, and the vapor permeability increases (V.P. Gerasimenya, K.Z. Gumargalieva, С .V. Zakharov, I.G. Kalinina, L.A. Sobolev // Plastics, 2015, No. 1-2, p. 59). With a density above 60 kg / m³, the application becomes economically inexpedient.

In addition, it was experimentally established that the supply of penoizol through a tube located vertically in the pipeline to a depth of 0.25-0.75 of the pipe diameter ensures uniform distribution of penoizol, since it hardens from bottom to top and the tube provides penoizol to the bottom of the pipe, which eliminates the formation of through voids in the cork for its entire length.

The essence is illustrated by drawings, which show the inventive method:

Fig 1 - schematically shows the drilling of technological holes;

Figure 2 - shows the screwing to the welded nozzle of the ball valve;

Figure 3 - shows the flow into the cavity of the pipe under the pressure of penoizol from a mechanical installation.

In the drawings indicated:

1 - upper forming pipe of a gas or oil pipeline,

2 - drill

3 - technological hole,

4 - pipe

5 - ball valve,

6 - tube for supplying penoizol,

7 - sleeve for supplying penoizol,

8 - installation for the supply of penoizol,

9 - foam insulation plug.

The method is as follows.

The dismantled pipe 1 is marked into sections of a certain length along which the pipe will be cut. The mass of one section of the pipe must not exceed the permitted load-carrying mass of the conveyor.

 The length of one pipe section is calculated by the formula:

L = (m-3): [π · (ds) · s · ρ · 10 ^-6 ],

where L is the length of the pipe section (m),

m - load capacity of the mechanism (kg),

3 - cork mass (kg),

π = 3.14 (constant value),

d is the outer diameter of the pipe (cm),

s is the wall thickness (cm),

ρ is the density of the pipe material, g / cm ³ .

After marking the pipe sections in the marked places, a hole 3 with a diameter of 1.0-1.5 cm is drilled on the upper forming pipe 1 to determine the level of oil residue in the pipeline with a metal probe and to remove excess pressure (Fig. 1). The working pressure in the oil pipeline at the place of work should not exceed 2.5 MPa. In case of detection of excess pressure in the pipeline, which poses a threat to the safety of welding, appropriate measures are taken to divert excess pressure. A pipe 4 is welded to the holes 3 - a metal cylinder with a diameter of 100 to 150 mm with internal thread. A ball valve 5 is screwed to the welded pipe 4 (Fig. 2). A sleeve 7 is screwed to a ball valve, through which a pipe is supplied into the cavity under the pressure of penoizol from a special mechanical installation 8 (Fig. 3).

Sealing the internal cavity of the pipelines with penoizol should be carried out in accordance with the following technology.

Penoizol is fed into the internal cavity of the gas pipeline under pressure. The length of the filled section of the internal cavity of the pipeline should be at least one meter. To control the filling of the gas and oil pipelines with penoizol, the MG2-XT ultrasonic thickness gauge (Panametrics, USA) is used. The amount of penoizol for the formation of one sealing plug (1 meter) in the cavity of the pipeline is calculated by the formula:

M = 1.4 · 3.14 · ρ · r ² ,

where M is the amount of penoizol required for the manufacture of one tube, kg;

- 1.4-coefficient of mass loss of penoizol, kg;

π = 3.14 (constant value),

d is the diameter of the pipe (m),

ρ is the density of penoizol, kg / m ³ .

An example of a specific implementation of the method of dismantling a decommissioned gas pipeline.

An example of calculating the required number of penoizol and penoizol plugs for their manufacture for a pipe with a diameter of 219 mm and a length of 2 km. 1. The amount of the initial penoizole feedstock is calculated for the manufacture of 1 cork 1 meter long by the formula: M = 1.4 · 3.14 · ρ · r ² = 1.4 · 40 · 0.03765 = 2.1084≈2.1 kg

2. The weight of 1 meter of this pipe according to the assortment table is 41.63 kg, and the carrying capacity of the mechanism is 10 tons, so the length of the pipe section that the transporter can lift is 10000: (41.63 + 2.1) = 228.7 m. The number of such sections along the length of the pipeline will be equal

2000: 228.7 = 8.75 pcs. ≈ 9 pcs

3. For 9 sites, 10 plugs of penoizole are needed, for the manufacture of which 10 · 10.1084 = 21.084 kg of raw materials are needed.

Form sealing caps in all marked areas of the gas pipeline. After the formation of sealing plugs, the pipe is cut. Pipe cutting is carried out in the center of the formed cork (i.e. half its length). After cutting, the edges of the gas pipeline are completely sealed, the pipes are transported to the storage location.

The preparation of the pipeline for dismantling is to ensure conditions that exclude the spill of oil products and paraffin-tar deposits from the cavity of the pipeline, and increase the rigidity of the pipe to prevent fractures.

The method of dismantling a decommissioned gas and oil pipeline includes the following technological operations:

- clarification of the position of the pipeline and underground utilities crossing the pipeline, installation of milestones;

- removal of the surface soil horizon (turf) to a depth of not less than 60 mm;

- removing the fertile soil layer and moving it to a temporary dump;

- development of trenches to the upper and lower generatrix of the pipeline;

- marking the pipeline into sections of a given length along which the pipe will be cut;

- drilling of technological holes in the oil pipeline, for gas analysis of the air and supplying the foam pipe to the internal cavity, measuring the concentration of hot water in the pipeline cavity;

- connecting a specialized mechanical installation for supplying penoizol to form a plug and feeding penoizol into the internal cavity of the oil pipeline under pressure in accordance with the scheme;

 - cutting the pipeline in the centers of the formed traffic jams;

- removing pipes from the trench and transporting them to the storage location;

- backfilling of the trench;

- laying of the removed surface soil horizon (turf);

- reclamation.

Before cutting the pipeline into parts before transportation, it is necessary to carry out the following actions, which are aimed at sealing those sections of the pipeline where it will be cut, in order to prevent spillage of oil residues during transportation of pipes after they are cut:

1. The dismantled pipe is marked into sections of a given length along which the pipe will be cut. The number of sections and its length into which the pipeline will be divided is calculated taking into account the condition that the mass of one section should not exceed the permissible load-lifting mass for its transportation by special equipment to the prepared site.

2. Sealing of the internal cavity of pipelines with penoizol should be carried out in accordance with the following. The length of the foamed section of the internal cavity of the gas and oil pipeline should be at least 0.8 ÷ 1.2 meters, depending on the diameter of the pipeline. To control the filling of the gas and oil pipelines with penoizol, the MG2-XT ultrasonic thickness gauge (Panametrics, USA) is used. Form sealing caps of penoizol in all marked places of the gas and oil pipelines in accordance with the scheme. After the formation of sealing plugs, the pipe is cut along the centers of the formed plugs. After cutting, the edges of the gas and oil pipelines are completely sealed, the residual oil in the pipe cavity is transported to the storage location.

To prevent oil spills from decommissioned gas and oil pipelines, a pipe length of 3 km requires only 44.7 kg of penoizol, which is 17.9 kg less than when using polyurethane foam. The dismantling of the decommissioned gas and oil pipelines by the claimed method allows to prevent spillage of oil product residues during transportation of pipes after their cutting, which reduces the risk of environmental pollution. In addition, it should be noted that penoizol will absorb oil with high efficiency, since its oil absorption capacity is 40-60 g of oil / g of penoizol (Veprikova E.V., Tereshchenko EA, Chesnokova N.V., Schipko M .L., Kuznetsova B.N. J. Siberian Fed. Univer. Chemistry. 2010.3 (3). 285-304., Stepanova E.V., Chaplina T.O. Monitoring. Science and Technology. 2017. No. 1 (30). 62-68. Thus, the dismantling of decommissioned gas and oil pipelines by the claimed method is simpler and more effective in comparison with existing methods. conduct land reclamation, contaminated by petroleum products, provided that the preservation of environmentally friendly land, reduction of anthropogenic pollution from oil spills.

Of the 4 parameters of the combustibility of penoizol (urea foam), 2 correspond to the indicators for the combustibility group G1 (GOST 30244-94). These include: the parameter "duration of independent burning" - it amounted to zero seconds and the parameter "degree of damage along the length" - from 42 to 57% when the standard for the combustibility group G1 is not more than 65%. The parameter "degree of damage by weight" is found in all tests from 22% to 36% with a standard for the flammability group G2 not more than 50%. Urea foam is made from resins belonging to the group of thermosets in which the reverse reaction does not occur and the material cannot again go into liquid form, i.e. during a fire, it does not melt, but only loses mass, releasing water, carbon dioxide and nitrogen, which are not dangerous to humans. The material is resistant to the action of microorganisms and rodents.

Thus, the invention provides the prevention of spillage of oil products remaining in the pipe of the gas and oil pipelines due to reliable sealing of the inner cavity of the emptied pipe in predetermined areas.

Claims (1)

A method of dismantling a decommissioned gas or oil pipeline, including opening the soil to the upper forming pipe, cutting the pipe and transporting it, marking the pipe to be dismantled into sections of length determined by the permissible load-carrying mass of the gas or oil pipeline for its transportation, drilled in marked places technological holes through which excess pressure is removed in the pipeline, after which a component is fed into the internal cavity of the pipe to create sealing "plugs" in in marked places and pipe cutting is carried out in the center of the formed plugs, characterized in that as a component for creating sealing "plugs", filling penoizol with a density of 18 to 60 kg / m ^{3 of} urea foams is used, while the penoisol is fed into the inner cavity of the pipe all marked places through a tube located vertically in the pipe to a depth of 0.25-0.75 of its diameter.

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