RU2585158C1 - Method of dismantling decommissioned oil pipeline - Google Patents

Abstract

FIELD: pipe.

SUBSTANCE: invention relates to pipeline transport, particularly, to technologies of dismantling decommissioned (worn-out) oil pipeline in places of passage of technological dock oil pipelines. Method of dismantling decommissioned pipeline includes opening ground to upper generatrix of pipe, cutting pipe and its transportation. Collapsible sections are marked on pipe length, determined by allowed load lifting weight oil pipeline for its transportation. In marked points process holes are drilled, through which is discharged excess pressure in pipeline. Foamed polyurethane is fed into inner cavity of oil pipeline to create “plugs” in all marked points. Pipeline is cut along centres of formed plugs.

EFFECT: invention provides reliable sealing of inner cavity empty oil pipeline.

4 cl, 4 dwg

Description

The invention relates to pipeline transport, and in particular to technologies for dismantling decommissioned, subject to repair and replacement of oil pipelines in their places.

Dismantling the linear part of the main pipelines is a set of technical measures aimed at removing the pipeline from the soil, cutting into parts and transporting the pipes to the storage location (OST 153-39.4-027-2002).

The oil pipeline to be decommissioned must be prepared for dismantling. Preparation consists in freeing the oil pipeline from oil, cleaning the pipe cavity from dirt and paraffin-tar deposits.

Oil pipelines decommissioned and put into a safe state do not require preparatory work, so they must be disconnected from neighboring sections, emptied and cleaned of oil.

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 product outflow and pollution of the surrounding soil.

Also, excess pressure is generated in the decommissioned oil pipeline.

No other harmful factor can be compared with the spills of oil and oil products - the raw materials of petrochemical processes - in terms of the extent of distribution and the number of sources of environmental pollution.

The elimination of spills of various petrochemical products is an urgent problem.

In such cases, soil contaminated with oil products is reclaimed, especially in marshy and waterlogged areas, which is a laborious and expensive process.

Therefore, one of the most important tasks is to prevent spills of various petrochemical products.

Known methods and devices for dismantling oil pipelines.

There is a method of opening a trench and lifting an underground pipeline during major repairs of main pipelines or when dismantling decommissioned inactive pipelines. The method 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 with moving the multi-row trolley suspension and lifting the pipeline with cultivators attached to the tractors (RF Patent for invention No. 2389930, priority date 03.24.2008).

A known method of repairing a pipeline (RF patent No. 2332610, dated 22.12.2004), which can be used in the operation and repair of the linear part of the main pipelines. The proposed method consists in examining a pipeline with the location on the locality of the pipeline section being repaired, dismantling it and constructing a new pipeline section, while inspecting the pipeline, the section to be repaired before identifying it on the local area is determined as a section of the pipeline predisposed to corrosion cracking of pipes under KRC voltage, which discover by finding the zone of intersection of the pipeline with the watercourse, opening the pipeline with a hole, starting from the intersection zone, in opposite directions from the center of the watercourse and revealing at the same time in the open pit diagnostic signs of the occurrence of SCC, which are the presence of gleying of soil around the pipeline, the presence of delamination of the insulation coating of the pipeline, the presence of more than 10% siderite in the total mass of corrosion products under insulating coating of the pipeline. In the places where the detection of the indicated diagnostic signs in the open pit has ceased, the boundaries of the section of the pipeline predisposed to SCC, which are considered as the boundaries of the repaired section of the pipeline, are established. Then, the repaired section of the pipeline is dismantled within the established boundaries, in which a new section of the pipeline is constructed by erecting an elevated passage of the pipeline or by laying it below the boundary of the penetration of the watercourse into the ground.

The well-known "Method of sealing a pipe cavity using a clay swab and device for its implementation" (RF patent No. 1832879 from 04/07/1989, publ. 03/20/1996).

The invention relates to methods for pipeline transportation of liquid products, in particular petroleum products, and is intended to block the cavity of the pipeline during emergency and scheduled repairs. The device comprises a cap, a loading removable quick-detachable container mounted on a mechanized jaw grip, through which the device is mounted on the free ends of the pipeline after cutting the defective area. The maxillary grip has an upper non-rotatable and a lower rotatable jaw, forming an airtight cavity when a pipeline closes.

Clay is supplied to the pipeline cavity via an elbow tap installed on the upper jaw of the mounting unit, due to the force developed by the cap hydraulic cylinder. The complete assembly is mounted on a boom of a material handling vehicle.

Disadvantage: the method and the device are designed to block the cavity of the pipeline during emergency and scheduled repairs. The device is very bulky and expensive.

It is known "Device for sealing the internal cavity of the pipeline" SU No. 1643852 from 05/30/1988, publ. 04/23/1991).

A device for sealing the internal cavity of the pipeline contains a polyurethane foam swab and a channel for introducing the composition of the polyurethane foam into the pipeline. New in the device is that the tampon is a cylinder turning into a truncated cone, while a groove is made in the cylindrical part of the tampon, in which two channels are diametrically opposed along the generatrix - a channel for introducing the polyurethane foam composition and a channel for removing gases generated in the process foaming polyurethane foam, the inner part of the tampon is hollow and has the shape of a cone, the base of which is the end face of the tampon, and the diameter of the tampon is less than the diameter of the sealed tube gadfly.

Disadvantage: this device is used to temporarily seal the pipeline.

Known methods of dismantling disabled pipelines using devices for sealing the internal cavity of the pipeline are ineffective and labor-intensive.

Currently, the dismantling of oil pipelines is carried out in accordance with OCT 153-39.4-027-2002 (PROTOTYPE).

The technical task of the invention is to simplify the process of dismantling a decommissioned (worn out) oil pipeline, to prevent the spill of oil products remaining in the pipe, and its further transportation to the storage location.

Effect: reliable sealing of the internal cavity of the emptied oil pipeline in certain areas, which prevents the spill of oil products remaining in the pipe, and thereby eliminates the need for land reclamation contaminated with oil products, i.e. conservation of ecologically clean lands, reduction of anthropogenic pollution of the environment from oil spills and oil products

The technical result is achieved by the fact that the method of dismantling a decommissioned oil pipeline involves digging 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 pipeline for its transportation; technological holes are drilled in marked places through which excess pressure is removed in the pipeline, and then polyurethane foam is fed into the internal cavity of the pipeline to create sealing "plugs" in all marked places, the pipe is cut in the center of the formed plug.

The implementation of the method of dismantling a decommissioned oil pipeline.

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 oil pipeline includes the following process steps:

- extraction of the pipeline from the soil,

- cutting into pieces,

- transportation of pipes to the storage location.

Before cutting the pipeline into parts before transportation, the following steps must be taken. These actions are aimed at sealing those sections of the pipeline where it will be cut, in order to prevent spillage of oil product residues during transportation of pipes after their cutting.

To do this:

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

- drilling a control hole in the upper generatrix of the pipe to determine the level of oil residue in the pipeline and to divert excess pressure;

- welding of the nozzle and installation of a ball valve;

- cutout holes for supplying foam to the pipe cavity;

- connecting a specialized mechanical installation for supplying PUF for the formation of a plug providing sealing of a given section, in the absence of the possibility of directly connecting the unit with PUF to the nozzle, installation is carried out by means of an elastic sleeve

- pipe cutting;

- lifting and laying the pipeline for transportation.

The dismantled pipe is marked into sections of a certain length along which the pipe will be cut. The number of sections and its length into which the pipeline will be divided is calculated mathematically, 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.

The mass of one section of the pipeline should not exceed the permitted lifting weight of the conveyor.

The mass of one meter of pipes for general use, manufactured by the outer diameter, wall thickness and length, is calculated by the formula:

m = π * (ds) * s * ρ * 10 ^-6 ,

where m is the theoretical mass of one linear meter of pipe, kg,

π = 3.14 (constant value),

d is the outer diameter of the pipe, mm

s is the wall thickness, mm

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

After marking the pipe sections in marked places, a control hole of small diameter (5-10 mm in diameter) is drilled on the upper forming pipe to determine the level of oil residue in the pipeline and to relieve excess pressure.

Measurement of the level of oil residue is determined by lowering a metal dipstick into the drilled hole (see Fig. 1 (1 - pipeline; 2 - drill; 3 - oil product residues; 4 - control hole); Fig. 2 (1 - pipeline; 3 - oil product residues; 4 - control hole, 5 - probe)).

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 (“glass”) is welded to the holes - a metal cylinder with a diameter of 100 to 200 mm with internal thread. A ball valve of the corresponding diameter or a valve with a flange is screwed to the welded branch pipe ("glass") (see Fig. 3 (1 - pipeline; 3 - oil product residues; 6 - pipe; 7 - ball valve)).

A ball valve or gate valve with a flange is installed with the aim of overlapping the drilled hole.

After drilling due to the difference in external and internal pressure, oil residues can rise, to prevent spillage of rising oil residues, the hole is closed with a ball valve. Drilling the cavity of the upper part of the pipe is carried out by lowering the drill into the nozzle ("glass").

The drilled hole serves as an exhaust valve through which air is blown, which forms an air plug in the interior of the pipeline, thereby ensuring uniform distribution of fluid in this area.

The working pressure in the oil pipeline should be no more than 2.5 MPa in the presence of at least 0.1 MPa overpressure.

A sleeve is screwed onto the ball valve (corrugated or from another material), through which polyurethane foam (PUF) is supplied from the special mechanical installation of FIG. 4 (1 - pipeline; 3 - oil product residues; 6 - pipe; 7 - ball valve; 8 - sleeve for supplying PUF; 9 - installation for supplying PUF; 10 - PPU stopper).

Under conditions where it is not possible to access a specialized mechanical installation with PPU, a probe made of metal or other resistant materials with a length of 200 m is inserted directly into the nozzle opening.

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

After establishing the pressure in the pipeline, polyurethane foam (PUF) is fed under pressure into the internal cavity of the oil pipeline.

The length of the filled section of the internal cavity of the oil pipeline should be at least one meter (experimentally identified), and the volume is calculated depending on the diameter (radius) of the pipeline.

To control the filling of the PPU oil pipeline, holes of small diameter are drilled on both sides of the welded pipe at a distance of 45 cm.

Visual control of filling the PPU pipe. The exit of the PUF from these holes confirms the filling of the cavity.

Polyurethane foam (PPU) grade is selected for pouring polyurethane foam with the number of closed pores of 90-95% and a density of 55-60 kg / m ³ . Foaming time 2-3 min.

The amount of polyurethane foam (PUF) for the formation of one sealing plug in the cavity of the pipeline is calculated by the formula:

M = m _PPU + m _p

where M is the amount of polyurethane foam required for the manufacture of one cork, kg;

m _p - the mass of losses, which is from 30% to 50% of the estimated mass of polyurethane foam, kg;

m _PPU - estimated mass of polyurethane foam, kg.

m _PUF = ρ * V

where ρ is the density of polyurethane foam, kg / m ³ ;

V is the volume of the pipeline section that needs to be foamed, m ³ .

V = π * r ² * b

r is the radius of the pipeline, m;

b - the length of the section of the pipeline, which must be foamed, m;

π = 3.14 (constant value).

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

An example of calculating the required number of PPU plugs and raw materials for their manufacture for a pipe with a diameter of 219 mm and a length of 3 km.

1. The volume of the pipeline section (1 meter long) is determined, which must be foamed:

V = π ∗ r2 ∗ b = 3.14 ∗ 0.1095 ^∧ 2 ∗ 1 = 0.03765 m ³ .

2. The mass of raw materials required for 1 (one) cork, 1 meter long, is calculated:

m _PUF = ρ * V = 55 * 0.03765 = 2.0658 kg.

3. The amount of feedstock - polyurethane foam (PUF) for the manufacture of 1 tube is calculated by the formula:

M = m _PUF + m _p = 2.0658 + 1.0329 = 3.0987≈3.1 kg,

where m _p - the mass of losses, which is from 30% to 50% of the estimated mass of PPU = 1,0329 kg

4. 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, it follows that the length of the pipe section that the mechanism can lift will be:

10000: (41.63 + 3.1) = 223.6 m.

The number of such sections along the length of the pipeline will be equal

3000: 223.6 = 13.4 pcs. ≈15 pcs.

5. For 15 sites, 16 PPU plugs are needed, for the manufacture of which 16 * 3.1 = 49.6 kg of raw materials are needed.

Forming sealing plugs from polyurethane foam in all marked areas of the 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 pipeline are completely sealed, the residual oil in the pipe cavity is transported to the storage location.

Thus, to prevent a spill of oil from a decommissioned oil pipeline for a 3 km long pipe, only 49.6 kg of polyurethane foam are required, which is much cheaper when compared with the harm of environmental pollution.

Dismantling the decommissioned oil pipeline by the claimed method allows to prevent spillage of oil product residues during transportation of pipes after cutting, which reduces the risk of environmental pollution.

In addition, the dismantling of a decommissioned pipeline by the claimed method is simpler and more effective in comparison with existing methods.

When dismantling a decommissioned oil pipeline, PPU was used to form sealing plugs inside the cavity of the emptied oil pipeline and to prevent spillage of oil product residues.

Compared with the known methods of dismantling oil pipelines, which work effectively only in favorable conditions with normal access roads, the inventive method is more simplified, since it uses mobile equipment and it is even possible to seal the internal cavity of the pipeline with two people.

Claims (4)

1. A method of dismantling a decommissioned oil pipeline, including opening the soil to the upper generatrix of the pipe, cutting the pipe and transporting it, characterized in that the dismantled pipe is marked up into sections of length determined by the permitted load-carrying mass of the pipeline for its transportation, technological holes are drilled in marked areas through which excess pressure is removed in the pipeline, after which polyurethane foam is fed into the internal cavity of the oil pipeline to create sealing side "in all marked locations, cutting is performed on the center tube formed tube. 2. The method of dismantling a decommissioned oil pipeline according to claim 1, characterized in that a pipe is welded to the drilled technological holes of the pipe to which a ball valve or valve with a flange is screwed. 3. The method according to p. 1, characterized in that they use filling polyurethane foam with a number of closed pores of 90-95% and a density of 55-60 kg / m ³ . 4. The method according to p. 1, characterized in that the length of the sealing tube is at least 1 m

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