Filling the pipe with cement mortar technology. A method for sealing the interpipe space of pipe-in-pipe type pipelines. Stresses in three-layer pipes when cement stone perceives tangential tensile forces

During trenchless renovation of dilapidated pipeline networks By pulling new, smaller diameter, polymer and other materials into them, designers are given the task of determining the loads on the dragged pipeline and checking the load-bearing capacity of the two-layer pipe structure “old pipeline + dragged”, the space between which is filled cement mortar(CR).

To determine the loads on the reconstructed pipeline, it is necessary to solve one of the classical problems of hydrostatics, i.e., determine the magnitude and direction of the pressure of liquids (solutions of various consistencies) on the curved cylindrical surface of the pipes.

Backfilling of the interpipe space is mainly necessary for the stability of the restored pipeline and increasing strength building structure after repair using the trenchless method, as well as to prevent possible linear extensions of the polymer pipeline inside the old one under the influence of temperature environment and the transported liquid.

Solving the problem of determining the pressure of cement mortar in the annulus allows, taking into account the strength characteristics and geometric dimensions new drawn polymer pipes to identify their ability to withstand all types of loads and, thus, guarantee the absence of deformations while ensuring the load-bearing capacity and physical integrity of the resulting single three-layer pipe structure “old pipeline + cement mortar + polymer pipeline.” At the same time, in practice, to counteract the loads from the CR, the option of pre-filling is possible polymer pipe filler, for example water.

Below is a schematic representation of a fragment of a cross-section of a repair section of a three-layer pipe structure of a unit length (1 m).

Cross section of a repair section of a pipeline with backfilling of the interpipe space

1 - old pipeline to be renovated with internal diameter D int;
2 - new polymer pipeline with outer diameter d out and inner diameter d in; 3—cement mortar (CR) in the interpipe space.

In practice, the research task comes down to determining the magnitude and direction of the influence of the CR pressure on a cylindrical surface, which is taken to be the running edge of a polymer pipeline along the circumference of a diameter d int, minus the corresponding volume of polymer material between the outer and inner walls polymer pipe, i.e. a cylindrical ring enclosed between diameters d external and d internal.

The general approach to solving this problem is that the horizontal and vertical components of the pressure force on the coordinate axis are determined and, according to the rules of mechanics, the resultant of these forces is found, which represents the pressure force on the cylindrical surface. Below are options for solving the problem of determining the load on a pipeline for four typical cases:

• with uniform filling of the interpipe space of the CR, taking into account the wall thickness and material of the pipe in the absence of filler (water) in the polymer pipeline;
• the same if there is a filler (water) in the polymer pipeline;
• in case of uneven filling of the inter-pipe space of the CR (for example, on the left side of the polymer pipe), taking into account the wall thickness and material of the pipe in the absence of filler (water) in the polymer pipeline;
• the same if there is a filler (water) in the polymer pipeline.

Sample diagrams of the resulting pressures on the cylindrical surface of a polymer pipeline are presented in the figures below, where, for convenience and simplification of the image of a three-layer pipe structure, the contours of the old pipeline are removed and there is no horizontal shading showing the CR. It should be noted that for the first two options for solving the problem, the relationships between the vertical components (the difference between the positive and negative pressure bodies) are considered as the resulting pressure, and the horizontal components, uniformly acting on both sides on the cylindrical surface of the pipe, are the same and are subject to mutual exclusion.

On the left are diagrams of the vertical component of the resulting pressure of the CR on the cylindrical surface of the pipe with uniform backfilling and the absence of water

On the right is a diagram of water pressure on the inner cylindrical surface of the pipe

Diagram of the CR pressures on the left side of the cylindrical surface of the pipe with uneven filling with the coordinates of the center of pressure Td, the vector of the resulting pressure force and its inclination angle α

According to the figure above (taking into account the unit length of the pipeline under consideration), the positive “+” V 2 pressure body of the CR on the cylindrical surface (oblique hatching) is a certain volume V AKLBM. To determine this volume, it is necessary to calculate the volume V AKLBM minus half the area of ​​the circle with diameter d int. To take into account the pressure from the mass of the upper part of the polymer pipe (up to the horizontal diameter), it is necessary to subtract from the volume obtained above the volume of the cylindrical semi-ring limited by the generatrices of the polymer pipe AMVV "MA" A. After appropriate mathematical calculations, the volume “+” V 2 will be:

Taking into account the fact that the generatrix A"M"B" is affected by substances of different densities (CR and polymer material), the positive vertical component of the pressure force “+” P z on the cylindrical surface will be expressed taking into account various volumetric scales(densities) in the form of the product of the corresponding volumes of substances by their volumetric weight, i.e. γ tsr and γ pm:

In turn, the negative “-” V 2 body of pressure CR on a cylindrical surface (vertical hatching) is a certain volume V AKLB plus half the volume of a figure with a circle area of ​​diameter d minus the volume of a cylindrical ring limited by the generatrices of the polymer pipe AMVSS "AM" IN". After appropriate mathematical calculations, the volume “-” V 2 will be:

Taking into account various volumetric weights, the negative vertical component of the pressure force “-” P z on a cylindrical surface will be expressed as:

The resulting vertical component of the pressure force on a cylindrical surface after appropriate transformations will be:

The “-” sign for the resulting pressure force indicates that this force, in accordance with the adopted coordinate grid, symbolizes the buoyant (Archimedean) force.

If a polymer pipeline is filled with water during the period of filling the interpipe space, a uniformly distributed load counteracting the resulting force occurs on the inner surface of the pipeline, which reduces the magnitude of the resulting pressure force. According to the figure above and the above reasoning, the positive volume of the water pressure body “+” W consists of a certain volume W A" NSB" and half the volume of a figure with a circular area of ​​​​diameter d int:

Taking into account the volumetric weight of water y in, the positive vertical component of the water pressure force “+”P on the inner cylindrical surface will be expressed as:

Then, taking into account all the real loads on the cylindrical surface, excluding the horizontal components that balance each other on both sides of the pipeline, the resulting component of the pressure force will be:

Regarding the directions of the resulting force, it should be noted that for the first two solutions considered, the directions will coincide with vertical axis, passing through the centers of circles 0 and 0", and depending on the specific values ​​of the quantities included in the formulas above, they can be both positive and negative.

A special case of uneven pressure distribution when backfilling the inter-tube space is filling the space with CR from one of the sides, figure above. In this case, a horizontal component of the pressure force arises, acting on one side of the pipeline (for example, the left) and reaching a maximum at the moment the CR begins to overflow to the other side (right) of the cylindrical surface of the pipe. In this case, the horizontal component of the resulting pressure force per unit length of the pipeline is defined as the area of ​​the diagram per vertical plane (abc), multiplied by the volumetric weight of the CR:

P" x = (d ad 2 / 2) γ tsr.

The magnitude of the vertical component of the resulting pressure force on the pipeline is determined by the formula:

In other words, the value of the vertical component is half of the value calculated using the formula above. The formula presented above is valid for the case of an empty polymer pipeline.

According to the rules theoretical mechanics, the resultant pressure force on the cylindrical surface of the pipeline is determined from the formula:

P equal = √ (P" x 2 + P" z 2)

For the case of filling a polymer pipeline with water during the period of filling the interpipe space, the resultant pressure force is determined by the formula:

P equal = √ (P" x 2 + (P" z +P) 2)

It should be noted that in the formula above, the value P" z was taken with its own sign, i.e. “+” or “-” according to specific calculation results.

Having determined the magnitude of the resultant force, it is possible to determine the point of application and direction of the force, i.e., the angle α of its inclination to the horizon. Angle α is determined from a triangle of forces constructed along the legs P" z and P" x, for example, through the tangent of the angle according to the formula:

tgα= P" z / P" x

The point of application of the resultant pressure force T d (i.e., the center of pressure) for curved surfaces is determined according to the following rules: the horizontal component P" x passes through the center of gravity of the ABC diagram (figure above) and, according to the rules of mechanics for the case under consideration, is located at a distance z = d nar /3 upward from the comparison plane I-I. The vertical component P" z must pass through the center of gravity of the cross section of the pressure body. Using the rules of mechanics, for this case (volume of a semicircle), we calculate that point T d should lie at a distance x = 0.212d nar to the left of the comparison plane II-II. Thus, the coordinates of the center of pressure will be: x - 0.212d nar and z = d nar /3. To obtain the vector of the resultant pressure force from the coordinate point of the center of pressure T d, a straight line is drawn at an angle α to the horizon.

After determining the loads on the polymer pipeline, a strength calculation must be carried out, the essence of which is to check the bearing capacity of the new pipeline during the backfilling period according to several criteria, in particular, according to the condition of strength against impact internal pressure(I); the condition of the maximum permissible ovalization (deformation) of the cross-section of the pipe (II); stability condition round shape cross-section of the pipeline (III).

Below are considered methodological approaches to strength calculations with various options for carrying out construction work and a list of initial data for design.

Initial data:

Diameters: D = 0.4 m; dnar = 0.32 m; d int = 0.29 m.

Volumetric weights: γ central = 25 000 N/m 8 ; γ pm = 9500 N/m 3 ; γ B = 9800 N/m 3.

Design internal pressure of the transported substance corresponding to the reduced design stress σ pr = 0.8 MPa.

HDPE polyethylene pipes with a projected service life of 50 years are used as polymer pipes.

The old cast iron pipeline is located at a depth of 10 m from the ground surface and the groundwater level is Pgv = 10 m of water. Art. (OD MPa); the pipeline has numerous damages in the form of discrepancies in the joints of the sockets while the pipe skeleton is preserved.

Checking load-bearing capacity according to condition I

A new polymer pipeline, pulled into the old one and subjected to backfilling, must initially have design resistance material R* is greater than the total calculated reduced stress σ pr:

R* > σ ex.

The value of R* is determined by the formula:

R*=k 1 R n k y k c = 2.16 MPa,

where k 1 is the coefficient of laying conditions, 0.8; R n - standard long-term resistance of the pipe wall material, MPa (with operation for 50 years and a temperature of 20°C R n = 5 MPa); k y—working conditions coefficient, 0.6; k c — joint strength coefficient, 0.9.

Thus, the condition is met: 2.16 MPa >> 0.8 MPa.

Load-bearing capacity test according to condition II

The relative deformation of the vertical diameter of the pipeline (E, %) should not exceed the maximum permissible value ovalization of the cross section, which for polyethylene pipes is taken equal to 5%.

The value of E is determined by the formula;

E = 100ςP pr θ / 4P l d ad ≤ [E]

where ς is a coefficient taking into account the distribution of load and support reaction of the base, ς = 1.3; P pr - calculated external reduced load, N/m, determined accordingly according to the formulas above, for various options backfilling, as well as the absence or presence of water in the polyethylene pipeline; R l - parameter characterizing the rigidity of the pipeline, N/m 2:

where k e is a coefficient that takes into account the influence of temperature on the deformation properties of the pipeline material, k e = 0.8; E 0 is the tensile creep modulus of the pipe material, MPa (with 50 years of operation and a stress in the pipe wall of 5 MPa E 0 = 100 MPa); θ is a coefficient taking into account joint action base resistance and internal pressure:

where E gr is the modulus of deformation of the backfill (backfill), taken depending on the degree of compaction (for CR 0.5 MPa); P is the internal pressure of the transported substance, P< 0,8 МПа.

Consistently substituting the initial data into the main formulas above, as well as into the intermediate ones, we obtain the following calculation results:

Analyzing the obtained calculation results for this case, it can be noted that in order to reduce the value of P pr it is necessary to strive to reduce the value of P" z + P to zero, i.e. equality in absolute value values ​​P" z and P. This can be achieved by changing the degree of filling with water polyethylene pipeline. For example, with a filling equal to 0.95, the positive vertical component of the water pressure force P on the internal cylindrical surface will be 694.37 N/m at P" z = -690.8 N/m. Thus, by adjusting the filling, data equality can be achieved quantities

Summarizing the results of testing the load-bearing capacity under condition II for all options, it should be noted that maximum permissible deformations do not occur in the polyethylene pipeline.

Load-bearing capacity test according to condition III

The first stage of the calculation is to determine the critical value of the external uniform radial pressure P cr, MPa, which the pipe can withstand without losing its stable cross-sectional shape. The value of Pcr is taken to be the smaller of the values ​​calculated using the formulas:

P cr =2√0.125P l E gr = 0.2104 MPa;

P cr = P l +0.14285 = 0.2485 MPa.

In accordance with the calculations using the formulas above, a smaller value of P cr = 0.2104 MPa is accepted.

The next step is to check the condition:

where k 2 is the coefficient of pipeline operating conditions for stability, taken equal to 0.6; Pvac is the magnitude of the possible vacuum at repair area pipeline, MPa; Pgv is the external pressure of groundwater above the top of the pipeline, according to the conditions of the problem Pgv = 0.1 MPa.

The subsequent calculation is carried out by analogy with condition II for several cases:

• for the case of uniform filling of the interpipe space in the absence of water in the polyethylene pipeline:

thus, the condition is met: 0.2104 MPa>>0.1739 MPa;

• the same if there is a filler (water) in a polyethylene pipeline:

thus, the condition is met: 0.2104 MPa >>0.17 MPa;

• for the case of uneven filling of the interpipe space in the absence of water in the polyethylene pipeline:

thus, the condition is met: 0.2104 MPa >>0.1743 MPa;

• the same in the presence of water in a polyethylene pipeline:

thus, the condition is met: 0.2104 MPa >>0.1733 MPa.

Checking the load-bearing capacity according to condition III showed that the stability of the round cross-section of the polyethylene pipeline is observed.

As general conclusions, it should be noted that the implementation of construction work on backfilling the interpipe space for the corresponding initial design parameters will not affect the load-bearing capacity of the new polyethylene pipeline. Even in extreme conditions (with uneven filling and high level groundwater), backfilling will not lead to undesirable phenomena associated with deformation or other damage to the pipeline.

After drilling a well in loose sandy soils a stage begins aimed at strengthening the casing pipes. At the same time, the trunk should be protected from damage, aggressive effects of groundwater, corrosion and other negative phenomena. We are talking about a process such as cementing wells.

Carrying out cementing work on your own is quite difficult, but it is possible if you have knowledge about the technologies for carrying out the event. We will tell you why you need to carry out cementing and what you need to pay attention to when performing work. For clarity, the material contains themed photos and videos.

Well cementing is a process that follows immediately after completion. The cementing procedure consists of introducing a cement solution into the annular or annulus (if the casing pipe is placed in a wider polyethylene pipe), which hardens over time, forming a monolithic wellbore.

The cement mortar in this case is called “plugging”, and the process itself is called “plugging”. A complex engineering process called well cementing technology requires certain knowledge and special equipment.

In most cases, water sources can be plugged with your own hands, which is much cheaper than hiring specialists.

Well cementing is a set of measures aimed at strengthening the annulus and casing from destructive lateral pressure rocks and groundwater impacts

Correctly performed plugging of water wells contributes to:

• ensuring the strength of the well structure;
• protecting the well from ground and surface waters;
• strengthening casing pipe and protecting it from corrosion;
• increasing the service life of the water source;
• elimination of large pores, voids, gaps through which unwanted particles can enter the aquifer;
• displacement of drilling mud by cement, if the former was used during drilling.

The quality of the produced water and performance characteristics wells. Cementing is also carried out for abandoned wells that will no longer be in operation.

Image gallery

selection of pipes and materials for the construction and reconstruction of water supply pipelines

at the facilities of JSC Mosvodokanal

1. At the design stage, depending on the laying conditions and the method of work, the material and type of pipe are selected (pipe wall thickness, standard dimensional ratio (SDR), ring stiffness (SN), the presence of external and internal protective coating of the pipe), the issue of strengthening the laid pipe is resolved. pipes using a reinforced concrete clip or steel case. For all pipe materials, it is necessary to carry out a strength calculation for the influence of internal pressure of the working environment, soil pressure, temporary loads, the dead weight of the pipes and the mass of the transported liquid, atmospheric pressure during the formation of vacuum and external hydrostatic pressure of groundwater, determination of the axial pulling force (punching).

2. Before choosing a reconstruction method, technical diagnostics of the pipeline are carried out in order to determine its condition and residual life.

3. The choice of pipeline material must be justified by comparative technical and economic calculations. The calculation is carried out taking into account the requirements of Mosvodokanal JSC. When intersecting with existing engineering communications or the location of the pipeline in their security zone the requirements of third-party operating organizations are taken into account. A feasibility study and strength calculations of the pipeline are included in the design and estimate documentation and are presented when considering the project.

4. All materials used for laying water supply networks (pipes, thin-walled liners, hoses and internal spray coatings) must undergo additional tests for the general toxic effect of constituent components that can diffuse into water in concentrations hazardous to public health and lead to allergenic, skin-related irritating, mutagenic and other negative effects on humans.

5. When laying polyethylene pipes without reinforced concrete casing or steel casing in urbanized and industrial areas, the environmental safety of the surrounding soil along the design route must be confirmed. In case of unacceptable contamination in the soil and groundwater(aromatic hydrocarbons, organic chemicals, etc.) soil reclamation is carried out.

6. Steel pipes that were not previously used for drinking water supply pipelines are not allowed for the installation of water bypasses.

7. Restored previously used steel pipes are not allowed for new installation and reconstruction water pipelines(pipes for the working environment). They can be used to make cases.

8. Steel spiral-welded pipes (according to GOST 20295-85 with volumetric heat treatment) can be used when constructing cases and bypass lines.

9. When laying pipes in cases, the interpipe space is backfilled with cement-sand mortar.

10.For new construction steel pipes For open-laying water supply pipelines (without steel cases and reinforced concrete clips), provide, if necessary, for simultaneous protection of the pipe from electrochemical corrosion in accordance with GOST 9.602-2005.

11. When reconstructing steel pipelines (without steel cases and reinforced concrete cages) without destroying the existing pipe and when quickly restoring local and emergency sections of pipelines using methods that do not have bearing capacity, if necessary, provide for simultaneous protection of the pipe from electrochemical corrosion in accordance with GOST 9.602-2005.

12. It is allowed to use cast shaped parts made of ductile iron with internal and external epoxy powder coating, approved for use in drinking water supply systems (certificate of state registration, expert opinion on product compliance with the Unified Sanitary-Epidemiological and hygienic requirements to goods subject to sanitary and epidemiological supervision).

13. Specialists of Mosvodokanal JSC have the right to visit factories supplying pipes and get acquainted with the conditions for organizing production and quality control of products, as well as inspect the supplied products.

14. Tests of polyethylene pipes are carried out on samples made from pipes.

14.1. The characteristics of the pipe material must correspond to the following values:

Thermal stability at 200°C – at least 20 minutes;

Mass fraction of carbon black (soot) – 2.0-2.5%;

Distribution of carbon black (soot) or pigment – ​​type I-II;

Relative elongation at break of a pipe sample is not less than 350%.

14.2. When checking weld failure of the sample should occur when the relative elongation reaches more than 50% and be characterized by high ductility. The break line must run along the base material and not intersect the welding plane. The test results are considered positive if, when tested for axial tension at least 80% of the samples have type I plastic fracture. The remaining 20% ​​of the samples may have a type II fracture pattern. Type III failure is not permitted.

2.Technical requirements for the use of pipes and materials

for the construction and reconstruction of sewerage systems at the facilities of JSC Mosvodokanal

Vehicle for delivery of the coiling machine and accessories

Winding machine (transportation by truck)

Hydraulic unit for winding machine (transportation by truck)

Generator (transportation by truck)

Wheel Forklift

Tool:

Bulgarian

Chisel, chisel, chisel

Backing material (branded product Blitzd?mmer®)

Diluent (eluent) and pore-forming additive

2. Preparing the construction site

Preparation construction site implies security measures traffic, providing sites for machines and storage for equipment and materials, as well as water and electricity supplies.

Flow adjustment

During the winding process, depending on specific situation You can refuse to take safety measures if the reservoir being sanitized is filled with water up to 40%.

A small flow can be used subsequently for better movement of the pipe during the coiling process and for fixing the pipe during backfilling.

Cleaning the collector

Cleaning the collector when using the coiling method is usually carried out through high-pressure washing.

TO preparatory work Relining also includes the removal of obstacles such as hardened sediments, cut-ins of other communications, sand, etc. If necessary, their removal is carried out manually using a milling cutter, sledgehammer and chisel.

Insertions of other communications

Canal branches flowing into the collector to be rehabilitated must be plugged before restoration work begins.

Quality and quantity control of materials and equipment

Upon delivery to the construction site necessary materials and equipment, their completeness and quality are checked. In this case, for example, the profile is checked for compliance with the data according to the quality certificate for its marking, sufficient length, as well as possible damage arising as a result of transportation; The branded Blitzdämmer® filling material is in turn checked for sufficient quantity and proper storage conditions.

Before installing the winding machine, it may be necessary to partially or complete removal chamber base to ensure alignment between the machine and the manifold being refurbished. Removal is usually carried out by opening the base of the chamber using a hammer drill or manually using a sledgehammer and chisel.

Pipe winding can be carried out both along the flow and against the flow, depending on the size of the well chamber and the possibilities of access to it.

In our case, the pipe is wound against the flow, since the chamber of the well at the lowest point has big sizes, which greatly simplifies the installation process of the winding machine.

3. Installation of the winding machine

Delivery of the winding machine

The hydraulically driven winding machine used in our example is designed for lining pipelines with a diameter from 500 DN to 1500. Depending on the diameter of the pipeline into which the new pipe is wound, winding boxes of various diameters are used.

First, the winding machine, disassembled into constituent components, is delivered to the starting well. It consists of a tape drive mechanism and a winding box.

Lowering machine parts into the shaft and installing the winding machine

The components of the winding box are lowered manually into the starting shaft and installed there.

For diameters up to 400 DN the machine can be lowered into the shaft assembled.

Before lowering the hydraulically driven tape drive mechanism into the starting shaft, it is necessary to remove the transport feet of the tape drive mechanism.

A hydraulically driven tape transport mechanism is mounted on a winding box directly in the starting shaft. In this case, the receiving part of the winding machine must be below the level of the well neck to ensure unhindered feeding of the profile into the tape transport mechanism.

Installation work is completed by connecting the hydraulic drive of the winding machine to a hydraulic unit located near the launch shaft.

Then it is necessary to check the alignment of the coiling machine and the collector being sanitized; otherwise, during the coiling process, the coiled pipe may become stuck on the walls of the collector or experience strong resistance from them, which may negatively affect the length of the section being sanitized.

4. Profile preparation

Unwinding and cutting the profile

In order for the first turn of the wound pipe to be under right angle to the axis of the pipe, it is necessary to cut the profile using a grinder in accordance with the diameter of the pipe. To do this, it is necessary to unwind part of the profile from the reel located on the frame.

Profile submission

The cut profile is fed using a guide roller mounted on a manipulator boom or other device into the starting shaft.

First round

The profile is fed into the tape drive mechanism and passes along inside winding box (make sure that the profile fits into the grooves on the rollers; if necessary, adjust the profile manually) and then connect to each other using a so-called latch lock (loss in diameter due to the thickness of the profile is about 1-2 cm).

Profile available

Diameter range from DN 200 to DN 1500.

5. Coiling process

A small flow lifts the spooled pipe and reduces friction against bottom part collector being sanitized.

The profile forming the pipe is progressively fed from the winding box rotational movements in the direction of the collector being sanitized. In this case, it is necessary to ensure that the wound pipe is not subjected to strong friction against the walls of the old channel and does not cling to joints, tie-ins, etc.

Glue supply.

Long-term water resistance of the wound pipe is achieved by applying special PVC glue to the latches of individual profile turns.

Lock latching technologies.

The glue is fed into the groove on one side of the profile, after which the lock immediately snaps into place on the other side of the profile, thus creating a reliable adhesion of both parts of the latch lock. This type of connection is also called the “cold welding” method.

6. Backfilling/covering of the annulus space with mortar

Dismantling the machine and adjusting the pipe.

According to the footage marked on back side profile, you can calculate the length of the wound pipe. After winding a pipe of the required length, you should check whether the distance from the end of the pipe to the receiving well coincides with the length of the pipe protruding from the starting well.

If they match, then the wound pipe is cut in the starting well using a grinder.

The coiled pipe, supported by the flow in the manifold, is easily pushed by two workers from the starting well towards the receiving well, so that the edges of the pipe exactly coincide with the edges of both wells.

These actions allow you to save material, since the length of the coiled pipe exactly corresponds to the length of the collector being sanitized, taking into account the part of the pipe that protrudes into the starting well and is later pushed into the collector.

Then the winding machine is again dismantled into separate parts and removed from the starting well.

Covering the annulus

Covering the annulus between old pipe and a wound pipe is achieved by internal cementing with sulfate-containing cement mortar a space of about 20 cm from the edge of the well. Depending on the level groundwater and the diameter of the pipe, it may be necessary to have a larger number of pipes for filling the solution and releasing air.

Covering the interpipe space at the highest point.

First, the interpipe space is closed at the highest point (at in this case- this is the receiving well). After plugging the interpipe space and inserting air outlet pipes into the base and top of the cement slab, the waste flow is temporarily blocked (flow control), so that work in the well chamber can be carried out without interference from waste water. Waste water, which is still in the annulus, flows towards the lowest point, thus the annulus is emptied and ready for grouting. After completion of work on blocking the interpipe space, wastewater is released through the wound pipe of the collector being sanitized.

Raising the water level in a coiled pipe.

During this process the waste flow is also adjusted, during which the coiled pipe is closed by means of a so-called bubble with a through profiled pipe and a pipe for adjusting the water level in the coiled pipe. Thus, the water level in the wound pipe is raised and the pipe is fixed on the base of the old channel during the process of two-phase filling of the interpipe space. This ensures that the angle of inclination is maintained and the possibility of bending is eliminated.

Covering the annulus at the lowest point

Then the interpipe space is closed at the lowest point (in our case, this is the starting well).

If necessary, pipes for filling the solution are installed in the ceiling vault, and pipes are installed for venting air into the ceiling and the base of the ceiling. The pipe integrated into the bubble has a profiled outer coating and does not provide complete tightness, which allows a certain amount of wastewater to flow out. Using a water level detection tube, you can always monitor the level of wastewater in a coiled pipe.
The first stage of backfilling.

In our case, backfilling of the interpipe space is carried out from the lowest point in two stages. To do this, a tank is installed at the edge of the well for mixing the backing material, to which a hose is connected to supply the solution. Mixing of branded backing material of the Blitzd?mmer brand is carried out according to the manufacturer’s recommendations in special tanks of various volumes.

Next, the valve of the mixer tank opens, and the Blitzd?mmer solution without rendering external pressure flows freely into the interpipe space between the old channel and the new wound pipe. Wastewater filling the coiled pipe prevents it from floating.

The process of mixing and supplying the solution continues until the solution begins to flow out of the air exhaust pipe installed in the base of the ceiling at the lowest point.

By comparing the amount of backfill solution used with the calculated amount, you can check whether the solution remains in the interpipe space or goes into the ground through fistulas in the old channel. If the amount of solution consumed coincides with the calculated amount, the backfilling process continues until the solution begins to flow out of the air exhaust pipe installed in the ceiling vault at the lowest point. The first stage of backfilling is considered completed.

Second stage of backfilling.

Hardening of the backing material lasts 4 hours, with a slight sedimentation of the solution in the interpipe space. After the solution has hardened, mixing of the Blitzd?mmer backfill material begins for the second backfilling phase. The process of filling the interpipe space can be considered complete when the solution begins to flow out of the air outlet pipe mounted in the ceiling at the highest point.

For quality control, a sample of the backing solution flowing from the air exhaust pipe in the receiving well is taken.

Then the pipes for filling the solution and the air outlet pipes in the starting and receiving wells are dismantled. Through holes in the ceilings are cemented.

7. Final work

Sole restoration.

The partially cracked bottom of the well chamber is being restored.

Work on integrating tie-ins into new channel carried out by robot.

Quality control

To control the quality of pipeline restoration work, an inspection of the pipeline itself is carried out, as well as a leak test in accordance with DIN EN 1610.

The invention relates to the construction of pipelines. The method is intended to eliminate temperature stresses in pipelines of the “pipe-in-pipe” type in the operating sealed state of the internal pipeline (in the absence of overpressure in the annulus) without installing special compensators inside. The method consists of placing sealing units in the annulus space, made in the form of spiral sleeves tightly wound to each other. The hoses are made of elastic, air-impermeable material; they are wound with a small gap along the ends of the “pipe-in-pipe” type pipeline on internal pipeline in the form of two spirals, each with a length no less than the internal diameter of the pipeline. The spirals are inserted into the annulus, the hoses are filled with air, the ends of the annulus are closed with annular plugs rigidly connected to the outer pipeline, ensuring free movement of the outer and internal pipelines relative to each other in the absence of excess pressure in the annulus. The technical result of the invention is to increase the reliability of environmental protection. 2 salary f-ly.

The invention relates to the construction of pipelines, mainly underwater crossings, and is intended to eliminate temperature stresses in pipelines of the “pipe-in-pipe” type in operating condition without installing special compensators inside and to prevent liquid hydrocarbons pumped through the internal pipeline from entering the environment in the event of a leak in the internal pipeline .

It is known to construct pipelines of the “pipe-in-pipe” type, in which the interpipe space is sealed by filling spiral hoses loosely wound towards each other along the entire length of the internal pipeline with hardening cement mortar. Temperature stresses in the internal pipeline are suppressed by installing special compensators in the form of closed metal cavities spirally wound towards each other (A.S. USSR No. 1460512, class F16L 1/04, 1989).

The disadvantage of sealing the annulus in this case is mandatory installation compensators for temperature stresses inside a “pipe-in-pipe” pipeline, which significantly complicates and increases the cost of the entire known design of a “pipe-in-pipe” pipeline.

Closest in essence technical solution is the sealing of pipeline cavities, in which the seals are made in the form of tightly wound spiral hoses, the hoses are filled with incompressible fillers (RF patent, No. 2025634, Class F16L 55/12, 1994).

In this case, complete sealing of the space is not ensured with a sufficiently large excess pressure in front of the seal. Such pressure can be in front of the sleeve seal if it is installed in the annulus. If the internal pipeline of the “pipe-in-pipe” system is damaged (tightness is broken), the polluting liquid can leak through the spiral gaps between the tightly wound round, non-deformable under pressure cross section hoses with incompressible filler and enter the environment. This sealing of the pipeline cavity has limited area application and can only be used when the pressure in front of the hose seal is close to atmospheric, i.e. only when carrying out repair work to eliminate (cut out) damaged sections of conventional (not “pipe-in-pipe”) pipelines.

The purpose of the invention is reliable protection environment from spills of liquid hydrocarbons in case of violation of the tightness of the internal pipeline of the “pipe-in-pipe” system and ensuring compensation of temperature stresses in the internal pipeline in working condition (without violating its tightness) due to the free axial movement of the internal pipeline relative to the external one in good condition of the “pipe-in” system pipe."

Reliable environmental protection is achieved due to the fact that the sealing of the annulus space is carried out by installing tightly wound spiral-shaped hoses made of elastic air-tight material into the annulus space, which are filled with a compressible filler (air). If the tightness of the internal pipeline is broken, the excess pressure in the annulus increases, compresses and tightly presses the spirally wound hoses with air to the walls of the outer and internal pipelines, thus ensuring complete tightness of the annulus.

Providing compensation for temperature stresses of the internal pipeline in operating condition (in the absence of excess pressure in the interpipe space) is achieved due to the fact that air is supplied to the spirally wound hoses at low pressure, close to atmospheric pressure, at which there are practically no friction forces between the hoses and the walls of the internal pipeline , preventing the relative longitudinal movement of the external and internal pipelines in good condition.

The method is implemented as follows. The hoses are made of an elastic air-tight material, they are wound with a small gap along the ends of the pipe-in-pipe pipeline onto the internal pipeline in the form of two spirals, each with a length of at least the internal diameter of the pipeline, the spirals are inserted into the interpipe space, the hoses are filled with air, the ends of the interpipe space closed with ring plugs rigidly connected to the outer pipeline, ensuring free movement of the outer and inner pipelines relative to each other in the absence of excess pressure in the interpipe space. To eliminate temperature stresses in a “pipe-in-pipe” pipeline, impermeable hoses wound in the form of a tight spiral on the internal pipeline are filled with air at a pressure that ensures free movement of pipelines relative to each other in the absence of excess pressure in the interpipe space.

To prevent spontaneous unwinding of the spirals when inserting them into the annulus, the ends of the spirals are connected flexible connection or limit their ends with ring bushings.

CLAIM

1. A method for sealing the annular space of pipelines of the “pipe-in-pipe” type, including placement in pipelines of sealing units made in the form of spiral hoses with fillers tightly wound to each other, characterized in that the hoses are made of an elastic air-tight material, they are wound with a small gap at the ends of the “pipe-in-pipe” type pipeline onto the internal pipeline in the form of two spirals, each with a length no less than the internal diameter of the pipeline, insert the spirals into the annular space, fill the sleeves with air, the ends of the annular space are closed with ring plugs rigidly connected to the outer pipeline, ensuring free movement of external and internal pipelines relative to each other in the absence of excess pressure in the interpipe space.

2. The method according to claim 1, characterized in that to eliminate temperature stresses in a “pipe-in-pipe” pipeline, impermeable hoses wound in the form of tight spirals on the internal pipeline are filled with air at a pressure that ensures free movement of the pipelines relative to each other in the absence excess pressure in the annulus.

3. The method according to claim 1, characterized in that to prevent spontaneous unwinding of the spirals when inserting them into the annulus, the ends of the spirals are connected with a flexible connection or their ends are limited by annular bushings.