RU2684518C1 - Method for protection of inner cavity of pipeline against corrosion and abrasive wear - Google Patents

Abstract

FIELD: transportation.SUBSTANCE: invention relates to pipeline transport. Method involves cleaning and drawing into the inner cavity of the polyethylene pipe. High-density polyethylene pipe with "shape memory" effect is used, with outer diameter making 2–3 % more than inner diameter of processed pipeline. First, pipe sections are welded, then pipe is drawn. Tube is preliminarily passed through crimping rolls with reduction of its diameter by 7–15 %. In order to temporarily stop pipeline restoration, clamping yokes are installed ahead of flange of treated pipeline section and polyethylene bushings are welded to pipe ends. For degassing of internal cavity of pipeline and annular space during installation of polyethylene pipe and prevention of its collapse in process of pipeline operation, ventilation standings are installed on it. Installation of pipeline sections is performed by connection of steel and polyethylene flanges by means of steel adjusting ring, and insulation of flange connection is performed by heat-shrinkage cuffs. Internal stresses of polyethylene pipe after installation are removed by thermal action of transported product.EFFECT: method increases resistance of pipeline walls to corrosion, abrasive wear and accumulation of solid deposits.1 cl, 2 dwg

Description

The invention relates to pipeline transport and can be used to protect both new pipelines and those that are in operation or decommissioned as a result of corrosion or abrasion, from exposure to highly corrosive fluids, such as sour oil and gas, salt and mineral water, hydrogen sulfide emulsions and pulps.

A known method for lining underground pipelines, comprising introducing into the existing pipeline a lining pipe having a length corresponding to the length of the pipeline being repaired and made of fusible polymer in a folded state, and unfolding the folds of the lining pipe for lining the pipeline. To form a cladding pipe, cladding layers are introduced into the pipeline being repaired, create increased pressure inside the layers and subsequently alloy them together, exposing each layer to the heat of fusion from a heat source that is moved along the inner surface of the innermost layer of the cladding formed before (application RU 98115004, IPC F16L 58/10, published on December 20, 2001).

A known method of sanitation of pipelines, which includes cleaning the inner surfaces of the pipeline, forming on a cleaned surface a highly elastic polymer coating and applying a concrete coating to it. Highly elastic polymer coating is formed by applying to the inner surface of the pipeline and subsequent curing of the composition containing the emulsion. The dispersion medium in the emulsion are oligomers with terminal isocyanate groups, and the dispersed phase is a solution or dispersion obtained by mixing a lime solution with a calcium hydroxide content of 10-70 wt. %, and glycerol in an amount of 1-250 wt. hours per 100 wt. including calcium hydroxide (patent RU 2482377, IPC F16L 58/06, F16L 55/162, publ. 05/20/2013).

A number of methods are known based on pulling polyethylene sleeves of a special U-shape into a repaired pipeline with its subsequent return to the original round shape. These methods are distinguished by the technology of work and the equipment used. They are conventionally called U-Liner methods. The U-shaped sleeve is made of polyethylene by thermomechanical formation in the factory or on the construction site. At the same time, the pipe acquires a U-shape, and its cross section decreases, which allows you to transport the sleeve in reels to the place of work and to lay pipelines with minimal technical costs (BACHELOR WORK "Trenchless rehabilitation of the gas pipeline" Primary water discharge unit No 4-Preparation gas No. 8 "at the crossing section through the old river Ob and the ducts of the Zondovskaya Sovetsko-Sosninskoye field" (Tomsk Polytechnic University, pp. 47-48, Internet link http://earchive.tpu.ru/bitstream/11683/27153/ 1 / TPU161076.pdf).

Taken as a prototype.

The disadvantages of this method are as follows:

- The length of the sanitized section is strictly limited by the volume of the polyethylene pipe (liner) wound around the reel: 100-200 m;

- A polyethylene pipe (liner) passes gas that collects between it and the inner surface of the pipeline, which leads to the collapse of the liner;

- there is no residual stress of the polyethylene pipe, which dampens the thermal longitudinal expansion and prevents the longitudinal collapse of the liner and the formation of corrugations;

- at low temperatures, the water used to restore the shape of the liner freezes.

The objective of the invention is to extend the life of steel pipelines.

The technical result is an increase in the resistance of the walls of the pipeline to corrosion, abrasion and the accumulation of solid deposits by increasing the reliability of the installation of a polyethylene pipe (liner) in the internal cavity of the pipeline with the possibility of its installation both at positive and negative temperatures.

The problem is solved, and the technical result is achieved by the method of protecting the inner cavity of the pipeline from corrosion and abrasive wear, including drawing into the inner cavity of the pipeline of a polyethylene pipe having a temporarily reduced cross section. In contrast to the prototype, a pipe made of high density polyethylene with the effect of “shape memory” is used, with an external diameter 2-3% larger than the inner diameter of the processed pipeline, while first the sections of the polyethylene pipe are welded together “into a string” corresponding to the length of the processed pipeline, then the welded pipe is pulled into the internal cavity of the pipeline by means of a hydraulic winch cable, while the polyethylene pipe is preliminarily passed through crimp rollers with a decrease in its diameter 7-15%, and while passing through the crimp rollers on the outer surface of the pipe along the entire length of the pipe, grooves are made by means of rollers, and in order to temporarily stop the restoration of the pipeline, clamping clamps are installed in front of the flange of the processed pipeline section, and plastic sleeves are welded to the pipe ends and then dismantle the clamps and fit the pipe sleeves on the steel flanges of the treated pipeline section, and to degass the internal cavity of the pipeline and the inside during installation of the polyethylene pipe and preventing its collapse during operation of the pipeline, ventilation risers are installed on it, while the installation of the pipe sections is carried out by connecting the steel flanges of the pipeline and the polyethylene pipe bushings to ensure a tight connection of the flanges during compression of the pipeline, and the isolation of the flange connection is carried out heat-shrink cuffs, and the internal stresses of the polyethylene pipe after installation are removed by thermal the impact of the transported product, and before processing the pipeline it is cleaned of deposits and burrs. According to the invention, the method is used for steel pipelines.

The technical result is achieved as follows.

Welding a polyethylene pipe into a “thread” corresponding to the length of the pipeline being processed allows the method to be used for pipelines of any length.

During the pulling through the rollers, grooves are cut on the outer surface of the polyethylene pipe, which allows the gas leaking through the polyethylene to be transported to the air outlet holes of the flange connection, which prevents the pipe from collapsing.

There is a residual stress of the polyethylene pipe, which dampens the thermal longitudinal expansion and prevents the longitudinal collapse of the polyethylene pipe and the formation of corrugation, which, after installation, is removed by the thermal effect of the transported product.

The polyethylene used has a pronounced effect of "memory", that is, with small deformations, the material returns to its original form after unloading. Those. the reversion process for this polyethylene proceeds independently, thereby there is no need for heating it with steam or applying pressure inside.

The absence of “wet” processes allows the processing of pipelines at both positive and negative temperatures.

All of the above allows us to achieve the claimed technical result.

The invention is illustrated by drawings, where:

in FIG. 1 shows the flange connection of the sections of the processed pipeline;

in FIG. 2 - shows the pulling of a polyethylene pipe (liner) into the internal cavity of the pipeline.

In FIG. 1 is indicated:

1 - steel adjusting ring,

2 - connection stud + two spring lock washers + two nuts (galvanized);

3 - steel collar flange;

4 - a polyethylene sleeve under the flange;

5 - ventilation riser;

6 - steel pipe support;

7 - processed pipeline;

8 - polyethylene pipe (liner);

9 - air hole (diameter 3-5 mm).

In FIG. 2:

10 - installation with crimp rollers;

11 - hydraulic winch;

12 - traction head of a polyethylene pipe (liner).

The inventive method is as follows.

First, polyethylene is selected for welding a polyethylene pipe in accordance with the characteristics of the pipeline. Then prepare the internal cavity of the pipeline 7 for broaching liner 8:

- weld ventilation struts 5;

- pass the pioneer steel cable into the internal cavity of the pipeline 7 by blowing the compressor of the foam rubber piston in the pipeline with the attached cable;

- pull the winch cable 11 into the pipeline;

- clean the in-pipe space of the pipeline from deposits, welding spatter, treatment devices using a winch 11.

Next, perform the following actions:

- broach the projectile to detect dents;

- elimination of dents by cutting a defective coil and inserting a repair coil;

- stripping of metal protrusions from the weld using broach projectile calibrator;

- welding of polyethylene pipe 8 into a "thread" (liner),

- installation of equipment from crimping rollers (rollers);

- drawing the liner through the rollers into the internal cavity of the pipeline;

- after pulling through a section of the pipeline, the installation of clamping clamps to temporarily stop the restoration of the liner;

- welding of polyethylene sleeves 4 to the ends of the liner 8;

- dismantling the clamps, landing bushings 4 liner on the steel flanges 3 of the treated area.

- installation of the ring 1 and the connection of the flanges on stainless bolts;

- insulation of the flange joint with heat-shrink cuffs.

Then produce a hydraulic test of the pipeline; dismantling of winch equipment.

For the degassing of the internal cavity of the pipeline (mainly steel) and the annular space during installation of the polyethylene pipe (liner) and to prevent the liner from collapsing during operation of the pipeline, ventilation risers 5 are installed.

The connection of the sections of the pipeline is carried out by connecting the steel flanges 3 of the pipeline and the polyethylene sleeve 4 of the pipe with a tight connection of the flanges during compression of the pipeline. Two lips of the sleeves absorb the cyclic loads of the sections of the processed pipeline. This flange unit is able to withstand pressures up to 25.0 MPa.

The pipeline should work as a unit during operation, that is, there should not be any layer between the liner and it, contracting or moving under the influence of high pressure transported through the pipeline to the field media (oil, gas and field wastewater). This is achieved through the use of polyethylene pipes with an outer diameter slightly exceeding the nominal inner diameter of the pipeline, which creates contact pressure that allows the polyethylene pipe to fit snugly against the inner surface of the pipeline. The described technology provides strength, tightness at overpressure, corrosion resistance and durability of the pipeline.

Thus, the application of the invention increases the resistance of the walls of the pipeline to corrosion, abrasion and the accumulation of solid deposits by increasing the reliability of the installation of a polyethylene pipe (liner) in the internal cavity of the pipeline with the possibility of its installation both at positive and negative temperatures.

Claims (2)

1. A method of protecting the internal cavity of the pipeline from corrosion and abrasive wear, including drawing into the internal cavity of the pipeline a polyethylene pipe having a temporarily reduced cross section, characterized in that a high density polyethylene pipe with the effect of “shape memory” with an outer diameter of 2 -3% more than the inner diameter of the processed pipeline, while first the sections of the polyethylene pipe are welded together “into a string” corresponding to the length of the processed pipeline, then Pull the welded pipe into the internal cavity of the pipeline by means of a hydraulic winch cable, preliminarily pass the polyethylene pipe through crimp rollers with a reduction of its diameter by 7-15%, and in the process of passing through the crimp rollers on the outer surface of the pipe along its entire length, make it through the rollers cutting of grooves, and in order to temporarily stop the restoration of the pipeline, clamping clamps are installed in front of the flange of the treated pipeline section, polyethylene welds are welded the sleeves to the ends of the pipe, after which the clamps are dismantled and the pipe sleeves are planted on the steel flanges of the pipeline section being treated, and for the degassing of the internal cavity of the pipeline and the annular space during installation of the polyethylene pipe and prevention of its collapse during operation of the pipeline, ventilation risers are installed on it, while the installation of the sections of the pipeline is performed by connecting the steel flanges of the pipeline and the polyethylene pipe bushings with a tight flange connections during pipeline compression, and the flange connection is insulated with heat-shrink cuffs, and the internal stresses of the polyethylene pipe after installation are removed by the thermal effect of the transported product, and before treatment of the pipeline it is cleaned of deposits and burrs. 2. The method according to p. 1, characterized in that it is used for steel pipelines.

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