RU2677016C2 - Method of repair of pressure pipelines and flat shell therefor - Google Patents

Abstract

FIELD: transportation.SUBSTANCE: invention relates to pipeline transport and can be used to repair pressure water, sewage, heating, steam, etc. networks. In pipes (3) and (5) to be repaired, flat shell (1), glued with glue (4), is stretched. Flat shell, stratified by glue under the pressure of the working medium, is pressed against the pipe with the formation of a longitudinal fold, pressed against the pipe. Stock material in the glued part excludes the rupture of a flat shell when it hits a section where the internal diameter of the pipe being repaired is greater than the original one. Variants of manufacturing a flat shell of various materials are indicated.EFFECT: invention restores the tightness of pipes having a large residual structural strength, allows repairing pipelines consisting of pipes with different diameters, it can be used as a universal emergency facility for repair of different diameter pipelines.7 cl, 4 dwg

Description

The invention relates to methods for repairing pressure pipelines and can be used in utilities for repairs of pressure networks of water supply and sewerage, hot water and heating, in oil and gas production, chemical production during repairs of process pipelines, and trenchless repairs of underground pipelines.

There is a method of repairing pressure pipelines by drawing inside an old pipe that has lost its tightness, a new polyethylene pipe of smaller diameter with a wall thickness calculated for the required pressure of the working medium.

The disadvantages of this method are the large consumption of materials and the cost of a new pipe, a large reduction in the cross section of a new pipe, the difficulty of drawing a new pipe due to the small gap between the old and new pipes, and the high cost of transporting new pipes.

Pressure pipelines made of steel and cast iron usually lose their tightness due to fistulas, electrocorrosion, pitting corrosion, cracks, joint leakages, etc., but having lost their tightness, the pipeline, with rare exceptions, has a large residual structural strength. Repair of the pipeline by replacing it with a new pressure pipe leads to an overspending of material and funds. To repair the pipeline in such cases, it is enough to restore its tightness.

One of such methods for restoring tightness is the well-known method of repairing pressure pipelines using Subterra sanitation technology by pulling inside an old polyethylene "stocking" pipe - a new thin-walled polyethylene pipe with a diameter equal to the inner diameter of the old pipe. "The outer diameter (strictly speaking, the circumference) of the lining stocking is chosen so that it is slightly smaller than the minimum diameter of the receiving pipe channel to be lined" (p. 4, article "RECENT ACHIEVEMENTS IN THE FIELD OF PIPELINES SANITATION TECHNIQUE BY TIGHT LEASTING) ". 29th International Conference and Exhibition international No-Dig 2011", Berlin, May 5, 2011, [Electronic resource], access mode: http://subterra-pipelines.com/uploadedfiles/knowledge-bank/12- 1419269337-recent_advances_in _close-fit_pe_pipe_lining_technology_080311_russ.pdf).

The closest analogue of the proposed technical solution is a stocking company Subterra.

The disadvantage of this method is the need for accurate selection of the diameter of the new thin-walled pipe to the repaired pipe. If the thin-walled coarse, spreading out, does not lie on the walls of the old pipe, it, when the pumped medium is supplied under pressure, will either stretch to the required size or break. Stretching the walls of a thin-walled pipe will reduce their thickness and create stresses in the material, which can subsequently lead to its rupture, i.e. accident.

Steel pipes of the same diameter can have different wall thicknesses, the inner diameter of which changes due to this, and given that steel pipelines may have sections of pipes with different diameters installed during the construction or repair of the pipeline, changes in diameters even between the nearest pipe diameters can reach up to 60%. Naturally, the wall of a thin-walled pipe will not withstand such changes, and it is impossible to make inserts of different diameters in a thin-walled pipe. In addition, it is very expensive to make dies for extrusion of a thin-walled polyethylene pipe of every possible diameter. Therefore, in the method of the company Subterra allowed the extension of a thin-walled pipe, both for the smallest and for the largest diameter, but these changes are allowed very small. This leads to an increase in the wall thickness of a thin-walled pipe and makes special demands on the material, it must stretch and remain in this state for a very long time.

A thin-walled extruded polyethylene pipe is manufactured at the factory, after which it must be delivered to the place of work without breaking the thin walls at the bend in width and length, which creates certain problems and limits the possible length of the thin-walled pipe for transportation.

The main objective of the invention is to find a method of repairing pressure pipelines, by pulling into the repaired coarse thin-walled folded pipe, free from the above disadvantages, namely:

1) the possibility of stretching the material of a thin-walled pipe around the perimeter should be completely excluded so as not to create stress in the wall of the thin-walled pipe, which will increase the reliability of the repaired pipe during operation;

2) it should be possible to repair pipelines with different internal diameters with a thin-walled pipe of the same size, the change in the internal diameter of which occurs due to the use of pipes with different wall thicknesses and with different diameters;

3) the wall thickness of a thin-walled pipe should be as thin as possible, only on the basis of the strength of the material, the internal pressure of the pumped medium, the size of the overlapped holes and the safety factor;

4) there should be other ways of manufacturing a thin-walled pipe, except for the extrusion of polyethylene, more suitable for the manufacture of a thin-walled pipe at the place of work;

5) it should be possible to manufacture a thin-walled pipe from other materials.

The main task is solved, and the technical result is achieved due to the fact that:

1. The method of repair of pressure pipelines, which consists in pulling inside the repaired pipe a rolled thin-walled pipe, characterized in that the thin-walled pipe is made in the form of a flat shell with a wall of flat rolled material folded in half, the folded walls of the flat shell are interconnected from the edge to the Inflection line , with the unconnected part at the inflection line, the flat shell is expanded by the pressure of the working medium inside the unconnected part, with the delamination of the connected walls from the breaking force into the flat casing until the straightened part of the flat casing increases to the diameter of the pipe being repaired and completely lies on its walls, after which the breaking force from the pressure of the working medium disappears and the delamination of the connected walls of the flat casing ceases, the longitudinal fold formed by the remaining connected part of the flat casing , it turns out to be pressed against the wall of the repaired pipe by the straightened wall of the flat shell and does not interfere with the flow of the working medium, the stock of material in the connected part of the flat shell is excluded It means a rupture of the wall of a flat shell or complete delamination when a flat shell hits a section where the internal diameter of the pipeline being repaired is larger than the original.

This solution makes it possible to use a flat shell of the same size to repair the entire pipeline with different internal diameters, the size of the flat shell should be sufficient for the largest diameter of the pipeline being repaired. This solution allows repairing a number of pipe diameters with one flat shell, for example, from a pipe with a diameter of 133 mm, with a wall thickness of 5.5 mm, to a pipe with a diameter of 325 mm, with a wall thickness of 3.5 mm. Between these extreme sizes are standard pipe diameters - 159 mm, 219 mm, 273 mm. In addition, each specified pipe diameter has a number of pipes with different wall thicknesses, which also changes the internal diameters.

Of course, there can be no such diameter changes in one pipeline, but the nearest pipe diameters are often used. Due to such universality of a flat shell, it becomes possible to repair different pipelines of different diameters with the same size of a flat shell. One flat shell can be used as an emergency tool for repairing pipes of various diameters.

This possibility of a wide change in the diameters of the pipes being repaired is available due to the walls of the flat shell glued or otherwise bonded and the longitudinal folds pressed when the flat shell is expanded under the pressure of the working medium in the repaired pipe. The force from the pressure of the working medium on the walls of the expandable part of the flat shell is directed to tear off the connected walls of the flat shell from each other along the entire length of the flat shell along the pipe being repaired, the characteristic of such a gap for glued walls is the term "adhesive strength during delamination" (GOST 28789-90 , p. 7, p. 50, Moscow, USSR State Committee for Product Quality and Standards Management, 1990). This separation force acts until the delaminated part of the flat shell under the pressure of the working medium increases and completely lies on the walls of the pipe being repaired. As soon as this happens, all the pressure of the working medium will be transferred to the pipe being repaired and the effort directed to delamination will disappear, delamination of the flat shell will stop. Where the inner diameter of the pipe being repaired is larger, the delamination of the wall connection will continue until the layered part of the flat shell increases its perimeter to the size of the pipe being repaired, etc.

The value of the bond strength of the walls of the flat shell during delamination should be much less than the tensile strength of the flat shell material so as not to create residual tensile stresses in the wall of the flat shell. Since after the free part of the flat shell lay on the repaired pipe and the separation of the walls ceased, only the force equal to the pressure of the working medium on the seam area acts on the connection of the walls, given the small thickness of the seam and the fact that the remaining connected part of the flat shell is sandwiched between the wall the pipe being repaired and the wall of the flat shell pressed by the pressure of the working medium, the pressure of the working medium cannot break the connection of the walls. At any value of the joint strength other than zero, the joint strength the walls should be minimal, but strong enough from delamination of the flat shell during the tightening of the pipe to be repaired, rupture of the clamps and expansion of the rolled flat shell.

The longitudinal fold eliminates the occurrence of tangential stress in the flat shell, which makes it possible to reduce the wall thickness of the flat shell, the minimum wall thickness is calculated from the maximum fistula (holes) in the pipe being repaired, internal pressure, strength of the material of the flat shell and safety factor.

The size of the bending radii of the material of the flat shell in a longitudinal fold depends on the strength of the material in bending, its thickness and internal pressure in the pipe.

2. The method of repairing pressure pipelines according to claim 1, characterized in that the flat shell is made of polyethylene, or polypropylene, or polyvinyl chloride, or polyethylene terephthalate, or reinforced rubber, or polyurethane, or stainless foil, or brass foil.

The absence of stretching of the flat shell makes it possible to use different materials for the manufacture of a flat shell, these materials must be flexible enough to form a longitudinal fold in the repaired pipe. This makes it possible to produce a flat shell using materials with special properties that can be used to repair pipes for hot water and steam, high pressure, chemical products, etc.

3. The method of repairing pressure pipelines according to claim 1. characterized in that the flat shell is made of double folded flat roll material, where the edges of the material are shifted relative to each other for a more smooth bending of the wall of the flat shell when it is applied to this place.

4. The method of repairing pressure pipelines according to claim 1, characterized in that the flat shell is made of double folded flat roll material, where the edges of the material are rounded for a more smooth bending of the wall of the flat shell when it is applied to this place.

The solutions according to p. 3 and p. 4 are aimed at increasing the bending radius of the wall of the flat shell at the junction of the edge of the flat shell, increasing the radius creates a smoother transition, reduces the load on the wall of the flat shell at the junction and increases the reliability of the repaired pipe.

5. The method of repairing pressure pipelines according to claim 1, characterized in that the flat shell is made of double folded flat roll material, where the edges of the material are additionally welded together along the length.

Welding the edges of the material increases the reliability of the flat shell in the case of through pores in the connecting layer, protects the flat shell from sticking from the edges during mechanical impact during transportation or during work.

6. The method of repairing pressure pipelines according to claim 1, characterized in that the flat shell for drawing into the pipe being repaired is folded C-shaped or spiral.

The minimum wall thickness and the shape of the flat shell makes it possible to fold it for tightening into the pipe being repaired C-shaped or more tightly-helix, which gives great advantages when tightening and reduces the risk of damage to the flat shell. In addition, a decrease in wall thickness reduces the number and thickness of annular retainers that hold the flat shell in a folded state and tear when it is straightened.

7. A method of repairing pressure pipelines according to claim 1, characterized in that the folded walls in a flat shell are connected by gluing, or stitching, or soldering, or welding.

This makes it possible to use other materials, for example, for the manufacture of a flat shell of copper foil in the manufacture of a flat shell using solder, etc.

The glue used for bonding the flat shell must be resistant to the influence of the working environment, flexible, smooth and not sticky in open areas where peeling of the flat shell occurred, the glue should not damage the material of the flat shell during peeling, it must withstand the parameters of the working medium, for example temperature .

The methods for manufacturing a flat shell according to Claims 1, 3, 4, 5 are very simple and make it possible to produce a flat shell at the place of work, to fold a flat roll material, to glue it if it is necessary to weld an edge, fold a flat shell, fasten with ring clips from thin ribbons or packaging film, from unrolling and tightening into the pipe being repaired. These operations can be mechanized to produce a flat shell at the place of work.

A brief description of the drawings.

In FIG. 1 shows a glued flat shell 1, with a wall thickness of 2 mm. The flat shell 1 is glued from t.C to t.V along the entire length. The edges of the flat shell 1 are shifted relative to each other.

In FIG. 2, the flat shell 1 is folded helically into a compact sleeve with a maximum diameter of 95 mm and is fixed around the perimeter by ring clips 2, made of thin ribbons or packaging film, from being deployed. A flat shell 1, rolled up in a spiral manner, is tightened into a steel pipe 3 with an outer diameter of 133 mm, with a wall thickness of 5.5 mm.

In FIG. 3, the flat shell 1 is straightened by internal pressure and, with the formation of a longitudinal fold, lies on the wall of steel pipe 3 with an outer diameter of 133 mm, with a wall thickness of 5.5 mm, and steel pipe 5 with an outer diameter of 273 mm, with a wall thickness of 9 mm. Glue 4, gluing the walls of a flat shell and remaining on one wall, after delamination of the glued walls, is shown shaded and increased in thickness. Without magnification, adhesive 4 is not visible in the drawing. Steel pipes are placed concentrically for clarity of proportions and sizes.

In FIG. 4, the flat shell 1 is straightened by internal pressure and, with the formation of a longitudinal fold, lies on the wall of the steel pipe 8 with an outer diameter of 159 mm, with a wall thickness of 9 mm, on the wall of the steel pipe 7 with an outer diameter of 219 mm, with a wall thickness of 9 mm, - on the wall of steel pipe 5 with an outer diameter of 273 mm, with a wall thickness of 9 mm, - on the wall of steel pipe 6 with an outer diameter of 325 mm, with a wall thickness of 3.5 mm. Steel pipes are placed concentrically for clarity of proportions and sizes.

Note: In all the drawings, the flat shell has the same perimeter and wall thickness, i.e. it is the same flat shell, but in different positions.

The implementation of the invention.

Tests of the invention were made on the experimental section of the pipeline, assembled from segments of steel pipes with welded transitions and flanges. The following steel pipes are used:

- outer diameter 219 mm, with a wall thickness of 4 mm;

- outer diameter 273 mm, with a wall thickness of 8 mm;

- an outer diameter of 325 mm, with a wall thickness of 3.5 mm.

The required wall thickness of the flat shell is calculated.

Since the flat shell transfers all the pressure to the walls of the repaired pipe, the load on the walls of the flat shell lies only in areas adjacent to the holes (fistulas) on the repaired pipe, where:

r is the radius of the fistula opening;

D is the diameter of the hole of the fistula;

P is the internal pressure in the pipe;

δ is the wall thickness of the flat shell;

σ is the yield strength of HDPE under tension;

Ssv is the fistula opening area;

S side is the wall area of a shear sheath;

F ₁ - ultimate force which the material of a flat shell will withstand;

F ₂ - the force that acts on the area with a given pressure;

τ is the shear strength of the flat shell material.

F1 is larger than F2, therefore, the material of the flat shell will withstand the load. Moreover, with a wall thickness of a flat shell of 2 mm, there is an almost six-fold safety margin.

The flat shell is glued from low-pressure polyethylene (HDPE) 2.0 mm thick, manufactured as a MEAPLAST geomembrane. The sheet with a width of 1080 mm is doubled bent, the width of the glued part is 230 mm. Adhesive of the brand "DP-8005 Structural adhesive for plastics" with a peeling strength of 28 N / cm, the type of joint failure is cohesive, i.e. on glue without damaging the material.

The flat sheath is spirally folded into a roll with a diameter of 150 mm and tied with packing tape. After laying in the pilot pipeline, the flat shell is straightened with a water pressure of 6 atm. and kept under pressure for 72 hours. It can be seen in the holes drilled in the pipes that the flat shell everywhere densely laid along the perimeter of the pipes, there is no leak in any hole, holes with a diameter of 6 mm. After depressurizing and draining the water, the pipeline is disassembled. It was found that the flat shell in each pipe was laid according to calculations, the bending radius of the shell stacks on the fold remained within 5 mm (without pressure), small wrinkles up to 10 mm high were formed only at the transition points of the steel pipe diameters.

Claims (7)

1. A method of repairing pressure pipelines, which consists in pulling a rolled-up thin-walled pipe inside the pipe being repaired, characterized in that the thin-walled pipe is made in the form of a flat shell with a wall of flat rolled material folded in half, the folded walls of the flat shell are interconnected from the edge to the inflection line with the unconnected part at the inflection line, the flat shell is smoothed out by the pressure of the working medium inside the unconnected part with the delamination of the connected walls from the breaking force in the plane casing until the expanded part of the flat casing increases to the diameter of the pipe being repaired and completely lies on its walls, after which the breaking force from the pressure of the working medium disappears and the delamination of the connected walls of the flat casing ceases, the longitudinal fold formed by the remaining connected part of the flat casing , it turns out to be pressed against the wall of the repaired pipe by the expanded wall of the flat shell and does not interfere with the flow of the working medium, I exclude the supply of material in the connected part of the flat shell It causes a rupture of the wall of a flat shell or complete delamination when a flat shell hits a section where the internal diameter of the pipeline being repaired is larger than the original. 2. The method of repairing pressure pipelines according to claim 1, characterized in that the flat shell is made of polyethylene, or polypropylene, or polyvinyl chloride, or polyethylene terephthalate, or reinforced rubber, or polyurethane, or stainless foil, or brass foil. 3. The method of repairing pressure pipelines according to claim 1, characterized in that the flat shell is made of double folded flat roll material, where the edges of the material are shifted relative to each other for a more smooth bending of the wall of the flat shell when it is applied to this place. 4. The method of repairing pressure pipelines according to claim 1, characterized in that the flat shell is made of double folded flat roll material, where the edges of the material are rounded for a more smooth bending of the wall of the flat shell when it is applied to this place. 5. The method of repairing pressure pipelines according to claim 1, characterized in that the flat shell is made of double folded flat roll material, where the edges of the material are additionally welded together along the length. 6. The method of repairing pressure pipelines according to claim 1, characterized in that the flat shell for drawing into the pipe being repaired is folded C-shaped or spiral. 7. A method of repairing pressure pipelines according to claim 1, characterized in that the folded walls in a flat shell are connected by gluing, or stitching, or soldering, or welding.

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