Transmission lines and water distribution networks are referred to as a set of facilities, including piping, fittings and valves which are designed to transfer fluids (liquids and gases) from one point to another.
The most important parts of a water distribution network or transmission lines include a pipe of various types, a pumping station to supply line pressure and valves for controlling and operating the transmission line. In designing a distribution network or water transmission lines, the most important parameters are the difference between the height of the origin and delivery point, the length of the route, the rate of water flow, and mainly the transfer lines are carried out in the depth of the earth (and in the form of a funeral).
Design, implementation and installation of a variety of transmission lines, water distribution networks and pumping stations and concrete storage tanks are implemented in the TARHOKAR engineering company in different sizes and in the form of EPC contractors. The design of the transmission lines is simulated in the Water Gems Engineering Software and also the Regulation of No. 3-117 from the planning and budget organization is considered for the water supply networks.
A general overview of the water transmission lines
Whenever we want to transfer water or other fluids from the negative height (at the lowest point of the earth) to a higher point or if we want to transfer water from one location to another so we use water transmission lines. That is, if the location of the storage of fluids containing water or wastewater at the place of use or refining it at a lower altitude should be used to transfer water from the pressure transmission network or a transmission line. Therefore, in a water storage at the low level, the pumping station is constructed and the head or pressure required for the transmission lines is provided. In some cases, there is no height difference between the water source and destination however, there are many longitudinal distances that cause water pressure to drop along the route; thus, transmission lines are also applicable. Several issues play a role in the design and implementation of optimal water pipelines and water distribution networks including selecting the appropriate flow or transmission line capacity.One of the important parameters is determining and calculating the pressure drop along the path of the water pipelines which is done with accurate mathematical calculations and attention to the size and shape of the pipes and the water flow. The route map of the transmission lines and its length and height difference are also estimated at this rate and the drop of the pressure is significant.
The choice of appropriate tube pipe for water transmission lines due to salinity or its physical properties, depth of pipe burial and soil texture and its impact on pipes are the most important factors in the design and implementation of water pipelines. The sum of these factors should also be the selection of suitable valves along the path of transmission lines including one-way valves, interrupting and connecting gates and the most important is air discharge valves.
Distribution of network design and water transmission lines
In the design of a water distribution network or transmission lines, the first stage is the estimate of the discharge or the capacity of water transmission in the network or lines. As an example, in a manufacturing plant with different water consumption levels in different seasons, transmission lines are designed and constructed based on the Dubai or their capacities or in a water distribution network and urban water transmission lines that use water in different hours of the day are different, Dubai or the capacity of the transmission lines are selected on the same basis. In particular, the design of transmission scenarios or different modes of discharge can be imagined from Dubai which based on this factor, capacities and water transmission lines are designed.After selecting the Dubai transmit lines, the route of transportation of water and consumables (delivery points) are determined; thus, to the map of topography of the Earth is provided. At this stage, the earth's length and path are carefully measured and calculated. Then according to the physical and chemical properties of the water, the genus of the pipeline are determined and according to the genus, the amount of pressure drop along the route can be calculated. In the topographic map, the points of contact of the transmission lines which are likely to be in contact with the rail network, roads and other lines, are identified and in order to prevent the siphoning phenomenon, necessary measures and appropriate valves are designed.
Since the pressure lines are pressurized, the entire pipe surface is in contact with water, so the water velocity near the pipes (the boundary conditions) is very small but in the center of the tube is greater. This issue is due to the friction between the fluid (water) and the pipe in the transmission lines, this friction depends on the tube material, its diameter, and on the physical properties of the water, such as temperature, viscosity and density. In designing the process of water transmission lines, modeling of the whole lines takes place and the amount of pressure drop through the effect of internal friction of the pipe, the height difference, the pressure drop of the valves and the connections are calculated and based on the required pressure is designed for the transmission line.
In the final stage, the valve of the transmission lines is designed and finally the depth of intubation along the path is selected. Transmission lines are completed according to the climate conditions of the project site and calculation of the depth of freezing water.
Selection of pipes in the water transmission lines
As mentioned, the choice of pipe material in the transmission lines depends on the characteristics of the soil and water. Since water is in constant contact with the internal surfaces of the pipe; therefore, its physical and chemical properties are effective on the inner surface of the pipes in the long time. Also, Soil effects on the outer surface of the tubes. In cases where the soil contains high levels of sulfate, it causes corrosion on the outer surface of the pipe, especially in GRP pipes.Generally, the following pipes are used in the water transmission lines:
Steel (including fusing and mechanical connection)
Ductile iron
Asbestos cement
Reinforced concrete
GRP or GREV
Poly-ethylene
Each of the pipes has its own unique features which along with the economic and technical issues are selected by the designer of the transmission lines.
Parameters for selecting pipes in the water transmission line
In order to select the pipe material in addition to the economic parameters, the physical and chemical properties of water should be considered in order to improve the useful life of the tube. Some of the most important factors include:The amount of suspended particles in the water measured with the TSS parameter or opacity. The greater the amount of suspended particles in water, next the friction of the inner surface of the tube increases, and thus the roughness of the tube will increase as a result of its pressure drop.
When the velocity gradient in the pipeline is higher in the level, causes numerous problems, such as increased corrosion, stresses and increases the relative roughness of the pipe in the lines.
The amount of water salinity that is measured by the TDS parameter and the higher the amount causes the problem of corrosion or sediment inside the surface of the tube. Of course, some pipes such as polyethylene pipes have the highest corrosion resistance in the water pipelines.
The pipeline pressure parameter is also selected based on calculations in the design section. Typically, polyethylene pipes are classified according to the nominal pressure PN6, PN10, PN16 and steel pipes according to SCH10, SCH20, and SCH40 grades. The type of pressure of pipes are identified based on the standard tables.
Selection of valves in the water transmission line
The choice of valves in the transmission lines are designed for the ease of operation as well as control of possible risks of design and installation lines Choosing the right place for the valve, the type and size of the valves and the pressure bearing in them are applied all by simulating the water pipelines by an engineer software. Some of the commonly used valves in the transmission line and its applications are listed here:Air drain valve: In order to allow the air to enter the pipeline or to enter the air in order to prevent stiffening or bursting in the effect of pressure on the water transmission lines.
One-way valve: In order to prevent the water from returning to the beginning of the line and control the hit of the ram inside the line.
Disconnect and connect valve: To maintain the system and lines.
Safety valve: In order to control and eliminate positive pressure along the line and control the ram's impact.
Discharge Valves: In order to wash and disinfect water lines especially when it used in drinking industrial.
Selection of anks and manholes in water transmission lines
Other essential elements in the water supply lines are manholes and reservoirs. In general, access manholes in places that a series of valves are embedded to allow operators to use the transmission lines and to easily access it.The selection of storage tanks and their locations are also designed and built on the basis of various economic and engineering parameters along the way. The use of these reservoirs is the control and adjustment of flow along the path. These reservoirs are sometimes concrete on the ground and sometimes in metal and are designed in the appropriate height.
An example of Implementation Projects of TARHOKAR Company in the field of water transmission lines
One of the projects of the work and design company designed and operated by the water engineering department of this company,Water lines were used for water supply to mines.
The general characteristics of this sewage treatment project are as follows.
| flow | 75 liters per second |
| water TDS | 40000 mg / l |
| Pipe material | Polyethylene PE100 |
| Working pressure | 6 bar |
| Length of the pipeline | 8 km |
| The height difference | 20 meters |
| The power of the pumping station | 90 kW |
| Number of pumps | 4 |
| Number of manholes | 2 |
| Air discharge valves | 4 inches |