RU2604981C1 - Method of repairing oil pipeline using temporary overlap - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to operation of pipeline transport and is intended for shutting off an oil pipeline during repair. Method comprises cutting off a pumping product at faulty section, draining remains of product, cutting defective section using a fireless method, installing tampons-seals at ends of pipeline. Each tampon is made in form of cylindrical workpiece with clay coating at ends. Workpiece has a cavity for filling water reserve and a mass, capable of swelling under action of water coming from cavity. Prior to installation of tampons pipeline inner surface is cleaned via open ends from paraffin deposits by evaporation. Cavity of workpiece is filled with water until first signs of swelling of mass, then cavity is finally filled with water and tampons are installed in open ends of pipeline in zone cleaned from paraffin deposits. Tampons are left to swell to size and shape of sealing pipeline. After repair tampons are destroyed by oil flow and cleaning and diagnosis means are removed through chamber.

EFFECT: higher safety of repair, reduced labour intensiveness of repair.

1 cl, 4 dwg

Description

The invention relates to the field of operation of pipeline transport and is intended for overlapping for the period of repair of the cross section of the pipeline.

A known method of sealing the cavity of the oil pipe for repair work [Standards of the company OJSC AK TRANSNEFT clauses 8.1, 8.5, 8.7, 8.9, 8.16 of the Rules for cutting and inserting “coils” of connecting parts, plugs, valves and control valves and connecting sections of the main of oil pipelines RD 153-39.4-130-2002 published on INFOSITE.ru at the link http://www.infosait.ru/norma_doc/41/41407/index.htm], which consists in the fact that the cavity of the pipeline is sealed from the open end of the pipeline clay and unbaked to Irpicha. The tampon is created by layering and sealing by tampers, at least 2 diameters long (along the upper generatrix) of the oil pipeline. Before installing the sealant tampon through the open end of the pipe, the inner surface of the pipeline is cleaned of paraffin deposits and dirt to a length of at least 2D + 1 m, where D is the diameter of the pipeline, m

The disadvantage of this method is to carry out repair work in conditions of increased danger, due to the fact that the tampon is made (built) directly in the pipeline, which requires an employee to carry out its construction for a long time, and, as a result, the use of safety equipment and special equipment In addition, layering of the material from which the swab is made in the pipeline is a laborious process, which increases the pipeline downtime during repair .

A known method of repairing a pipeline [RF patent No. 2032124], adopted as a prototype, which consists in the fact that the product of pumping in the defective area is cut off. Then the product residues are poured through an existing defect or technological hole, and the defective section is cut out without fire. Install tampons (plugs) at the ends of the pipeline. Moreover, the plugs are made in the form of a cylinder with flanges, in one of which through holes are made. Before installing the plugs, in separate containers, the polymer is pre-soaked. The swollen polymine mixture is spread onto the indented portion of the plugs to the level of the largest diameter of the flange. Then the plugs are inserted into the ends of the pipeline, orienting with flanges with holes towards each other. After installing the plugs through the holes, water is fed to the polymine. The swollen mass of polymine continues to absorb moisture, increases in volume, thereby ensuring the creation of a dense impermeable overlap of the pipeline. After that, the products of pumping are burned on the inner walls of the pipeline before the plugs. Before welding a new section of the pipe, the water supply to the polymine is repeated through the holes in the flanges.

The disadvantage of this method is the repair work in conditions of increased danger, due to the fact that the products of pumping on the inner walls of the pipeline before the plugs are removed by burning, as well as by burning, the tightness of the created overlap is controlled. In addition, the method has a high complexity, due to the fact that it requires preliminary soaking of the polymine in separate containers and its subsequent application between the flanges, as well as an additional supply of water to feed the polymine after installing tampons at the ends of the pipeline before starting the welding process. After the start of welding, additional water supply is not possible, which can lead to shrinkage of polymine (sealing material) and premature loss of sealing. Destruction, after starting the pipeline under the influence of the internal pressure of the pumping product, only polymine is exposed, but not the material from which the cylinder with flanges is made, which creates a risk of harm to equipment installed on the pipeline, for example, valves.

The objective of the invention is to provide temporary overlap of the pipeline for the duration of the repair work, preventing the ingress of explosive product vapors into the welding zone.

The technical result of using the proposed method is to increase the safety level of repair work, reduce the complexity of repairing a pipeline, preserve equipment from the damaging effects of the remains of a tampon-sealant, when passing through a pipeline for disposal.

The specified technical result is achieved due to the proposed method of repairing an oil pipeline using a temporary overlap, namely, that the pumping product is initially cut off on the defective section, then the product residues are drained, the defective section is cut out by fire, the inner surface of the pipeline is cleaned from the open ends of the pipe to remove paraffin deposits by evaporation to a length L, calculated by the formula:

L≥2D + 1, m,

where D is the diameter of the pipeline.

Tampons are installed on the ends of the pipeline, after they are pre-prepared.

As tampons use prefabricated cylindrical billets with clay coating on the ends, containing a mass that can swell under the action of water and collapse after the repair is completed under the influence of a pumping product stream. The blanks have a cavity for storing water. The cavity has an opening for filling the water supply and is designed to be saturated with moisture to swell and maintain the mass in size and shape, sealing the pipeline.

Preliminary preparation of tampon-sealants (preforms) for installation consists in filling the preform cavity with water until the first signs of mass swelling. The water reserve in the cavity used up for swelling is restored, filling the cavity again with water. Then, billets filled with water are installed in the open ends of the pipeline with one of the ends with clay coating to the outside and an opening for filling the water up. Expect swelling swabs to sizes and shapes, sealing the pipeline.

The proposed method provides safety conditions for repair work by cleaning the inner surface of the oil pipeline from paraffin deposits by evaporation, the analysis of the air in the welding zone is carried out using control devices, the installation of tampons does not require a person inside the pipeline, clay coating is also used to comply with fire safety requirements the ends of the workpieces. Reducing the complexity of repair work is achieved by prefabricated cylindrical billets containing a mass capable of swelling under the action of water from a cavity located inside the billet for the supply of recharge water. The safety of the equipment from the damaging effects of the remains of tampon-sealers, when they pass through the pipeline for disposal, is ensured by the use of materials that are capable of swelling, materials that are destroyed by the flow of the pumping product.

In FIG. 1 shows a repaired pipeline section with installed tampon-sealers; in FIG. 2 shows a general view of the tampon-sealant, in FIG. 3 - tampon-sealant, end view, in FIG. 4 is a sectional view of a tampon-sealant.

Consider an example of a method for repairing a pipeline using temporary closure with a tampon-sealant.

The repair method is carried out in accordance with safety requirements established by the governing documents, for example, the standards of TRANSNEFT OJSC JSC “Rules for cutting and inserting“ coils ”of connecting parts, plugs, stop and control valves and connecting sections of main oil pipelines” RD 153 -39.4-130-2002, published on INFOSITE.ru at the link http://www.infosait.ru/norma_doc/41/41407/index.htm.

To implement the proposed repair method, the pumping product is initially cut off on the defective section 1 of the pipeline 2. Then, through the existing defect or technological hole (not shown), the product residues are drained. Next, they carry out the cutting of the defective section 1 (shown in dotted lines in Fig. 1) by the fireless method (using milling cutters at low speeds of revolution and other fireless cutting methods).

Simultaneously with the cutting of the defective section 1, tampons-sealants 3 are prepared for installation.

Moreover, as a mass capable of swelling from water, a mass is used in the tampon, which has the property of not only sealing the pipeline when swelling, but also collapsing after repair work under the influence of a pumped product stream, for example, a mixture of paper fragments and clay.

To implement the proposed method, for example, it is possible to use tampons-sealants 3, made in the form of pre-made cylindrical blanks with clay coating 4 at the ends. The blanks (tampon-sealants 3) include a cavity 5 for water supply with an opening 6 for its inlet (filling hole) and a mass 7, based on a mixture of paper fragments and clay that can swell under the action of water entering (seeping) from the cavity 5, having a clay coating 8 with holes 9 to saturate the mass 7 with water (moisture).

Before installing tampons 3, the inner surface of the pipe 2 is cleaned through the open ends of the pipe from paraffin deposits by evaporation by a length L, calculated by the formula:

L≥2D + 1, m,

where D is the diameter of the pipeline.

Evaporation of paraffin deposits is an explosion and fireproof method for cleaning paraffin deposits.

The cavity 5 of the workpiece 3 is filled with water through the filling hole 6, after which the water begins to flow (seep) through the holes 9 located in the clay coating 8 to the mass 7, saturating it with moisture. The cavity 5 of the workpiece 3 is filled with water to the signs of mass swelling 7. After the signs of mass swelling 7 appear, the water level in the cavity 5 is checked and it is completely filled with water immediately before installing the workpiece 3 (tampon) in the open end of the pipeline 2.

Tampons 3 filled with water are installed in the open ends of the pipeline 2 at a distance of at least 400 mm from the open ends of the pipeline 2, previously cleaned of paraffin deposits, orienting one of the ends with clay coating 4 outward (to comply with fire safety), and filling holes 6 - up. The installation of tampons 3 does not require the presence of a person inside the pipeline 2, the tampon 3 can be installed, for example, using a mounting rod, which helps to increase the safety level of repair work. After installing the tampons 3 wait for their swelling to the size and shape, sealing the pipe 2.

Before starting welding work, as required by safety rules, an analysis of the air in the welding zone (not shown) is performed to check the tightness of the created overlap on the overlapping section, which is carried out using control devices (not shown), which is an explosion and fireproof control method .

At the end of the repair work, the sealant tampons 3 are destroyed by the oil flow to the state of clay sediment and paper fragments, and then removed from the oil pipeline through the chambers of cleaning and diagnostics (SOD) (not shown) or discharged into a settling tank (not shown), providing equipment safety.

Reducing the complexity of repair work is achieved by prefabricated cylindrical billets 3 and the presence in them of a cavity 5 for a water supply that does not require additional water supply after installing tampon 3 in the pipeline 2. The installation of tampons 3 is technologically simple and does not require any additional installation works.

The manufacture of tampons 3 from materials that are destroyed by the action of pumping products eliminates the possibility of a stuck of the tampon or its fragments in the pipeline 2.

Claims (2)

1. A method of repairing a pipeline using temporary overlap, which consists in cutting off the product of pumping in the defective section, then draining off the product residues, cutting out the defective section in a non-fire way, installing sealing tampons at the ends of the pipeline, characterized in that, before installing the tampons, each of which is made in the form of a cylindrical billet with clay coating on the ends, having in its composition a cavity for supplying water and a mass capable of swelling under the action of water coming from the cavity and, the latter being made with the possibility of filling it with a supply of water and saturating the mass with moisture to swell and maintain it in the size and shape that seal the pipeline, the inner surface of the pipeline is cleaned from the open ends of the pipe by paraffin deposits by evaporation, and the billet cavity is filled with water until the first signs swelling of the mass, after which the cavity is finally filled with water, then preforms filled with water are installed in the open ends of the pipeline into the area purified from paraffin deposits and wait swelling swabs to sizes and shapes that seal the pipeline. 2. The method according to p. 1, characterized in that as a mass capable of swelling, use a mass based on a mixture of fragments of paper and clay.

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