services

Abza Engineering Technical Company was established in 1370 and is a well-known company in the field of designing and implementing pressurized irrigation systems.

This company has provided services to the country's agricultural industry by relying on expert forces with high executive power and using modern science and technology.

The company's activities are carried out in four units as follows:

Providing design and engineering services
Construction and production of equipment and connections
Inspection, repair and maintenance of equipment
Quality control and compilation of technical documents
Supplying the required materials

- Installation steps of polyethylene pipes

Pipe cutting
Cleaning pipes and accessories
Installation of pipes and accessories
Installation of valves and accessories
Back straps and concrete harnesses
Preliminary excavation on the installed pipes
Cleaning pipelines
Hydrostatic test of installed pipelines
Test result
Completion of earthworks on the installed pipes

Pipe cutting

In water transmission or irrigation networks, it is common to use smaller branches. In these cases, they convert large branch pipes into smaller pieces according to the design. Pipe cutting should be done in such a way that the ends of the pipes resulting from cutting are complete and healthy and no damage is done to the pipe. The cut section of the pipe must be completely perpendicular to the pipe axis.

The use of a fine-toothed hand saw is allowed only for cutting polyethylene pipes up to 100 mm in diameter. To cut larger pipes, special machines and tools for cutting plastic pipes should be used.

When cutting, to keep the pipe steady, a clamp should not be used, because the operation of the clamp causes the pipe to shrink and its wall to be damaged at the place of the clamp. When working with a cutting machine with special tools for polyethylene pipes, it is necessary to follow instructions and recommendations. The manufacturer of said equipment should be fully observed about how to use this equipment and safety tips.

To cut the pipe, devices should be used that create the least shavings and chips in the place. After finishing the cut, it is necessary to completely flatten the cut surface using a suitable file and remove all chips and chips to be ready for butt welding.

Cleaning the pipe and accessories

Before installation, the inside and outside of the simple head of each pipe branch and the head of accessories should be completely cleaned with a dry cloth.

Installation of pipes and accessories

The contractor is obliged to place the pipes that must be installed in the trench in accordance with the plan next to the trench, in the order in which they must be installed. The butt welding connection of pipes and accessories must be done outside the trench. In order to meet this purpose, the contractor must provide enough timber with the appropriate thickness, width and length. These timbers should be aligned at certain intervals on the trench and in the perpendicular direction along the trench. Polyethylene pipes that are supposed to be welded to each other should be placed on these timbers in one stretch. After each branch of the pipe and each of the accessories is placed on the timber, it should be visited immediately and made sure that the inside of the pipe is clean and free of foreign objects.

Installation of faucets and accessories

If the connection of faucets intended for installation in the polyethylene pipeline is of the flange type. The installation of this type of faucet is exactly the same as the installation of other fittings in pipelines. If the connection of these chirals is of another type, then it is possible to use polyethylene conversion, which turns this connection into a flanged connection.

Back straps and concrete harnesses

Back straps and concrete restraints of polyethylene pipelines are used for the establishment of transmission pipelines.

Preliminary excavation on the installed pipes

Before the hydrostatic test of the installed pipelines, it is necessary to fill and compact the surrounding and on the pipe with suitable soil, so that the pipeline stays in place and does not move due to the internal pressure during the tests. Considering that during the hydrostatic test of the pipeline, it is necessary to see all the connections in the place of faucets and accessories, so that in case of water leakage, the location of the leak can be easily found. The minimum height of preliminary earthwork on the top of the pipe is 30 cm.

Cleaning pipelines

The general washing of the pipeline should be done with clean water containing chlorine with the following conditions after completing the test and disinfection. The amount of chlorine water used for general washing should be three grams per cubic meter, but it should never be less than one gram per cubic meter. In addition, due to the presence of water with a high concentration of chlorine in the disinfected line, it is necessary to wash the line as soon as possible and within 24 hours after the end of the test.

Hydrostatic test of installed pipelines

In the hydrostatic test of polyethylene pipes, it is necessary to be sensitive to the exit of all the trapped air in the pipeline. The reason for this is the presence of viscoelastic property in these pipes. This means that after applying the internal pressure, creep will occur in the pipe wall and therefore the internal pressure will change. When the polyethylene pipe is subjected to the test pressure and the pressure supply pump is stopped, the pressure inside the pipe gradually decreases. Even in the case of a piece of pipe that is 100% sealed, due to the viscoelastic properties of the pipe and pipe creep, this pressure reduction will occur. This pressure reduction is non-linear, that is, at the beginning of the work, the amount of pressure drop will be more and gradually fixed.

The maximum test pressure is 1.5 times the nominal pressure of the pipeline, but in special circumstances, the consulting engineer may reduce this value to 1.5 times the working pressure of the pipeline. Polyethylene pipes should be tested in lengths appropriate to the diameter and local conditions. The length of the pipe under test in small diameter pipes is about 800 meters and in larger diameter pipes, less than

The above is recommended.

If the heat of polyethylene pipe is more than 30 degrees Celsius, it should not be subjected to hydrostatic test.

Test result

After disconnecting the manual pressure pump into the pipeline under pressure and after a period of one hour, the result of the test will be accepted if the amount of water required to provide the pressure to the initial amount, from the amount of 3 liters per kilometer of the pipeline for each The inner diameter of the pipe should not exceed 25 mm for every 3 atmospheres of test pressure in 24 hours. All test activities should be confirmed and recorded based on the formats defined in the test package that has been prepared in advance.

The duration of the test should be inquired from the manufacturer when the pipe is procured.

If the pressure drop during the test time is significant and water leakage is practically not observed, it means that the amount of air trapped in the pipeline is high, and this air should be discharged and hydrostatic testing of the pipe should be done again.

If during the test, the amount of illegal leakage is shown, first the mechanical accessories and then the polyethylene welds should be controlled and after fixing the problems, the test should be performed again.

After the test, the pressure inside the pipe should be gradually reduced to reach the pre-test conditions. If, for any reason, re-testing is desired, an appropriate time interval should be considered between the two tests. In any case, this distance should not be less than 5 times the time that the pipe has been under test

Completion of earthworks on the installed pipes

After obtaining the permission of the consulting engineer, the contractor is obliged to carry out additional earthworks by following the points explained below:

Parts of the pipeline in the place of connections and valves, which are kept open for hydrostatic testing, should be covered and compacted with high-quality soil such as that determined in the case of preliminary excavation.
With the high-quality soil accepted by the consultant engineer, continue the excavation operation inside the trench in 15 cm thick layers and compact each layer up to 90% of the proctor, until the surface amount resulting from this final excavation reaches such a level that the engineer The consultant has determined according to the type and specifications of the pavement layers.
In order to compact the final earthworks inside the trench, the contractor can obtain the desired density by flooding the trench instead of using the compaction method, provided that he has obtained the approval and permission of the consulting engineer. In these cases, the thickness of the additional earthen layers inside the trench can be more than 15 cm.
In cases where the pipeline that is the subject of the agreement is installed in a crossing that is exposed to the traffic of heavy vehicles, the thickness of the soil cover of the pipe (from the top of the pipe to the bottom of the pavement layers of the crossing) should not be less than 60 cm. But in cases where the crossing is a place for light vehicles, about 30 to 45 centimeters of soil cover on the pipe will be enough, provided that the necessary controls have been made in terms of the depth of the glaciers.
Installation guide for polyethylene pipes

On a buried pipeline, various forces are applied, some of them such as the force caused by the weight of the soil, the weight of underground water (if any), internal pressure (in pressurized flows) and specific and calculable traffic forces and It is an estimate and another part is uncertain and ad hoc. To consider the above forces, there are different methods that depend on the conditions and conditions of the place where the pipeline is used; But their general principles are similar. In general, there are two main guidelines in the world, from which the rest of the methods and guidelines are derived: ATV A-129 and AASHTO M252, M294.

Among the points that must be observed during installation, the following can be mentioned:

The width of the trench is a function of the diameter of the pipe, the method of tapping, the ease and the soil behind the dam. Taking into account the mentioned factors, the width of the trench should be selected at the minimum allowed level; Because the wider the trench, the greater the soil pressure on the pipe. According to section 30 of the AASHTO guidelines, the minimum width of the trench is one and a half times the outer diameter of the pipe.
Wetting of the trench during the installation of pipes should be strictly avoided.
How to prepare the trench bed is extremely important. The bottom of the trench should be smooth and free of any stones and lumps. It is suggested that if the trench floor soil is not suitable, higher quality soil that is provided from another place should be used for bedding.
The soil behind the embankment should be beaten well to increase the hardness of the soil. The better the soil pounding next to the pipe is done, the better and more suitable the behavior of the pipe will be under external pressures.
Appropriate tools and equipment should be used for tamping the soil above the pipe (initial and final backfill).