Pipelines for the transport of various liquids are an integral part of units and installations in which work processes related to various fields of application are carried out. When selecting pipes and piping configuration great importance has the cost of both the pipes themselves and pipeline fittings. The final cost of pumping a medium through a pipeline is largely determined by the dimensions of the pipes (diameter and length). The calculation of these quantities is carried out using specially developed formulas specific to certain types operation.
A pipe is a hollow cylinder made of metal, wood or other material used for transporting liquid, gaseous and granular media. The transported medium can be water, natural gas, steam, oil products, etc. Pipes are used everywhere, from various industries to domestic use.
For the manufacture of pipes the most different materials, such as steel, cast iron, copper, cement, plastic such as ABS plastic, polyvinyl chloride, chlorinated polyvinyl chloride, polybutene, polyethylene, etc.
The main dimensional indicators of a pipe are its diameter (external, internal, etc.) and wall thickness, which are measured in millimeters or inches. A value such as nominal diameter or nominal bore is also used - nominal value internal diameter pipes, also measured in millimeters (denoted DN) or inches (denoted DN). The values of nominal diameters are standardized and are the main criterion when selecting pipes and connecting fittings.
Correspondence of nominal diameter values in mm and inches:
A pipe with a circular cross-section is preferred over other geometric sections for a number of reasons:
- A circle has a minimum ratio of perimeter to area, and when applied to a pipe this means that with equal bandwidth pipe material consumption round shape will be minimal compared to pipes of other shapes. This also implies the minimum possible costs for insulation and protective covering;
- Round cross section most advantageous for moving a liquid or gaseous medium from a hydrodynamic point of view. Also, due to the minimum possible internal area of the pipe per unit of its length, friction between the moving medium and the pipe is minimized.
- The round shape is most resistant to internal and external pressures;
- The process of making round pipes is quite simple and easy to implement.
Pipes can vary greatly in diameter and configuration depending on their purpose and application. Thus, main pipelines for moving water or oil products can reach almost half a meter in diameter with a fairly simple configuration, and heating coils, which are also pipes, have a small diameter complex shape with many turns.
It is impossible to imagine any industry without a pipeline network. The calculation of any such network includes the selection of pipe material, drawing up a specification that lists data on the thickness, size of pipes, route, etc. Raw materials, intermediate products and/or finished products pass through production stages by moving between various apparatuses and installations, which are connected by pipes and fittings. Correct calculation, selection and installation of the pipeline system is necessary for the reliable implementation of the entire process, ensuring safe pumping media, as well as to seal the system and prevent leakage of the pumped substance into the atmosphere.
There is no single formula or rules that could be used to select a pipeline for any possible application and work environment. In each individual application of pipelines there are a number of factors that require consideration and can have a significant impact on the requirements for the pipeline. So, for example, when working with sludge, the pipeline big size will not only increase the installation cost, but also create operational difficulties.
Typically, pipes are selected after optimizing material and operating costs. The larger the diameter of the pipeline, that is, the higher the initial investment, the lower the pressure drop and, accordingly, the lower the operating costs. Conversely, the small size of the pipeline will reduce the primary costs of the pipes themselves and pipe fittings, but an increase in speed will entail an increase in losses, which will lead to the need to spend additional energy on pumping the medium. Speed limits fixed for various applications are based on optimal design conditions. The size of pipelines is calculated using these standards taking into account the areas of application.
Pipeline design
When designing pipelines, the following basic design parameters are taken as a basis:
- required performance;
- entry and exit points of the pipeline;
- composition of the medium, including viscosity and specific gravity;
- topographic conditions of the pipeline route;
- maximum permissible operating pressure;
- hydraulic calculation;
- pipeline diameter, wall thickness, tensile yield strength of the wall material;
- number of pumping stations, distance between them and power consumption.
Pipeline reliability
Reliability in pipeline design is ensured by adherence to proper design standards. Also, staff training is a key factor in ensuring long term pipeline service and its tightness and reliability. Continuous or periodic monitoring of pipeline operation can be carried out by monitoring, accounting, control, regulation and automation systems, personal production monitoring devices, and safety devices.
Additional pipeline coating
A corrosion-resistant coating is applied to the outside of most pipes to prevent the damaging effects of corrosion from the external environment. In the case of pumping corrosive media, a protective coating can also be applied to the inner surface of the pipes. Before being put into service, all new pipes intended to transport hazardous liquids are checked for defects and leaks.
Basic principles for calculating flow in a pipeline
The nature of the flow of the medium in the pipeline and when flowing around obstacles can vary greatly from liquid to liquid. One of important indicators is the viscosity of the medium, characterized by such a parameter as the viscosity coefficient. Irish engineer-physicist Osborne Reynolds conducted a series of experiments in 1880, based on the results of which he was able to derive a dimensionless quantity characterizing the nature of the flow of a viscous fluid, called the Reynolds criterion and denoted Re.
Re = (v·L·ρ)/μ
Where:
ρ—liquid density;
v—flow velocity;
L is the characteristic length of the flow element;
μ - dynamic viscosity coefficient.
That is, the Reynolds criterion characterizes the ratio of inertial forces to viscous friction forces in a fluid flow. A change in the value of this criterion reflects a change in the ratio of these types of forces, which, in turn, affects the nature of the fluid flow. In this regard, it is customary to distinguish three flow regimes depending on the value of the Reynolds criterion. At Re<2300 наблюдается так называемый ламинарный поток, при котором жидкость движется тонкими слоями, почти не смешивающимися друг с другом, при этом наблюдается постепенное увеличение скорости потока по направлению от стенок трубы к ее центру. Дальнейшее увеличение числа Рейнольдса приводит к дестабилизации такой структуры потока, и значениям 2300
| Flow velocity profile | ||
|---|---|---|
| laminar mode | transitional regime | turbulent regime |
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| Character of the current | ||
| laminar mode | transitional regime | turbulent regime |
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The Reynolds criterion is a similarity criterion for the flow of a viscous fluid. That is, with its help it is possible to simulate a real process in a reduced size, convenient for study. This is extremely important, since it is often extremely difficult, and sometimes even impossible, to study the nature of fluid flows in real devices due to their large size.
Pipeline calculation. Calculation of pipeline diameter
If the pipeline is not thermally insulated, that is, heat exchange is possible between the fluid being moved and the environment, then the nature of the flow in it can change even at a constant speed (flow). This is possible if the pumped medium at the inlet has a sufficiently high temperature and flows in turbulent mode. Along the length of the pipe, the temperature of the transported medium will drop due to heat losses to the environment, which may lead to a change in the flow regime to laminar or transitional. The temperature at which a regime change occurs is called the critical temperature. The value of liquid viscosity directly depends on temperature, therefore, for such cases, a parameter such as critical viscosity is used, corresponding to the point of change of flow regime at the critical value of the Reynolds criterion:
v cr = (v D)/Re cr = (4 Q)/(π D Re cr)
Where:
ν cr - critical kinematic viscosity;
Re cr - critical value of the Reynolds criterion;
D - pipe diameter;
v - flow speed;
Q - consumption.
Another important factor is the friction that occurs between the pipe walls and the moving flow. In this case, the friction coefficient largely depends on the roughness of the pipe walls. The relationship between the coefficient of friction, the Reynolds criterion and roughness is established by the Moody diagram, which allows one to determine one of the parameters knowing the other two.
The Colebrook-White formula is also used to calculate the friction coefficient of turbulent flow. Based on this formula, it is possible to construct graphs from which the friction coefficient is determined.
(√λ ) -1 = -2 log(2.51/(Re √λ ) + k/(3.71 d))
Where:
k - pipe roughness coefficient;
λ - friction coefficient.
There are also other formulas for approximate calculation of friction losses during pressure flow of liquid in pipes. One of the most commonly used equations in this case is the Darcy-Weisbach equation. It is based on empirical data and is mainly used in system modeling. Friction losses are a function of fluid velocity and pipe resistance to fluid movement, expressed through the value of the pipeline wall roughness.
∆H = λ L/d v²/(2 g)
Where:
ΔH - pressure loss;
λ - friction coefficient;
L is the length of the pipe section;
d - pipe diameter;
v - flow speed;
g is the acceleration of free fall.
Pressure loss due to friction for water is calculated using the Hazen-Williams formula.
∆H = 11.23 L 1/C 1.85 Q 1.85 /D 4.87
Where:
ΔH - pressure loss;
L is the length of the pipe section;
C is the Heisen-Williams roughness coefficient;
Q - flow rate;
D - pipe diameter.
Pressure
The operating pressure of a pipeline is the highest excess pressure that ensures the specified operating mode of the pipeline. The decision on pipeline size and number of pumping stations is usually made based on pipe operating pressure, pump capacity and costs. The maximum and minimum pipeline pressure, as well as the properties of the working medium, determine the distance between pumping stations and the required power.
Nominal pressure PN is a nominal value corresponding to the maximum pressure of the working medium at 20 °C, at which long-term operation of a pipeline with the given dimensions is possible.
As the temperature increases, the load capacity of the pipe decreases, as does the permissible excess pressure as a result. The pe,zul value shows the maximum pressure (gp) in the piping system as the operating temperature increases.
Permissible excess pressure chart:
Calculation of pressure drop in a pipeline
The pressure drop in the pipeline is calculated using the formula:
∆p = λ L/d ρ/2 v²
Where:
Δp - pressure drop across the pipe section;
L is the length of the pipe section;
λ - friction coefficient;
d - pipe diameter;
ρ - density of the pumped medium;
v - flow speed.
Transported working media
Most often, pipes are used to transport water, but they can also be used to move sludge, suspensions, steam, etc. In the oil industry, pipelines are used to transport a wide range of hydrocarbons and their mixtures, which differ greatly in chemical and physical properties. Crude oil can be transported over greater distances from onshore fields or offshore oil rigs to terminals, intermediate points and refineries.
Pipelines also transmit:
- petroleum products such as gasoline, aviation fuel, kerosene, diesel fuel, fuel oil, etc.;
- petrochemical raw materials: benzene, styrene, propylene, etc.;
- aromatic hydrocarbons: xylene, toluene, cumene, etc.;
- liquefied petroleum fuels such as liquefied natural gas, liquefied petroleum gas, propane (gases at standard temperature and pressure but liquefied using pressure);
- carbon dioxide, liquid ammonia (transported as liquids under pressure);
- bitumen and viscous fuels are too viscous to be transported by pipeline, so distillate fractions of oil are used to dilute these raw materials and obtain a mixture that can be transported by pipeline;
- hydrogen (short distances).
Quality of the transported medium
The physical properties and parameters of the transported media largely determine the design and operating parameters of the pipeline. Specific gravity, compressibility, temperature, viscosity, pour point and vapor pressure are the main parameters of the working environment that must be taken into account.
The specific gravity of a liquid is its weight per unit volume. Many gases are transported through pipelines under increased pressure, and when a certain pressure is reached, some gases can even be liquefied. Therefore, the degree of compression of the medium is a critical parameter for designing pipelines and determining throughput.
Temperature has an indirect and direct effect on pipeline performance. This is expressed in the fact that the liquid increases in volume after increasing temperature, provided that the pressure remains constant. Lower temperatures can also have an impact on both performance and overall system efficiency. Typically, when the temperature of a fluid decreases, this is accompanied by an increase in its viscosity, which creates additional frictional resistance on the inner wall of the pipe, requiring more energy to pump the same amount of fluid. Very viscous media are sensitive to changes in operating temperatures. Viscosity is the resistance of a medium to flow and is measured in centistokes cSt. Viscosity determines not only the choice of pump, but also the distance between pumping stations.
As soon as the fluid temperature drops below the pour point, the operation of the pipeline becomes impossible and several options are taken to restore its operation:
- heating the medium or insulating pipes to maintain the operating temperature of the medium above its fluid point;
- change in the chemical composition of the medium before entering the pipeline;
- dilution of the transported medium with water.
Types of main pipes
Main pipes are made welded or seamless. Seamless steel pipes are produced without longitudinal welds in steel sections that are heat treated to achieve the desired size and properties. Welded pipe is produced using several manufacturing processes. The two types differ from each other in the number of longitudinal seams in the pipe and the type of welding equipment used. Welded steel pipe is the most commonly used type in petrochemical applications.
Each length of pipe is welded together to form a pipeline. Also in main pipelines, depending on the application, pipes made of fiberglass, various plastics, asbestos cement, etc. are used.
To connect straight pipe sections, as well as to transition between pipeline sections of different diameters, specially manufactured connecting elements (elbows, bends, valves) are used.
| elbow 90° | 90° bend | transition branch | branching |
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| elbow 180° | bend 30° | adapter fitting | tip |
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Special connections are used to install individual parts of pipelines and fittings.
| welded | flanged | threaded | coupling |
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Temperature expansion of the pipeline
When a pipeline is under pressure, its entire internal surface is exposed to a uniformly distributed load, which causes longitudinal internal forces in the pipe and additional loads on the end supports. Temperature fluctuations also affect the pipeline, causing changes in pipe dimensions. Forces in a fixed pipeline during temperature fluctuations can exceed the permissible value and lead to excess stress, which is dangerous for the strength of the pipeline both in the pipe material and in the flange connections. Fluctuations in the temperature of the pumped medium also create temperature stress in the pipeline, which can be transmitted to fittings, a pumping station, etc. This can lead to depressurization of pipeline joints, failure of fittings or other elements.
Calculation of pipeline dimensions with temperature changes
Calculation of changes in the linear dimensions of the pipeline with temperature changes is carried out using the formula:
∆L = a·L·∆t
a - coefficient of thermal expansion, mm/(m°C) (see table below);
L - pipeline length (distance between fixed supports), m;
Δt - difference between max. and min. temperature of the pumped medium, °C.
Table of linear expansion of pipes made of various materials
The numbers given represent average values for the listed materials and for calculating a pipeline made of other materials, the data from this table should not be taken as a basis. When calculating the pipeline, it is recommended to use the linear elongation coefficient indicated by the pipe manufacturer in the accompanying technical specification or data sheet.
Thermal elongation of pipelines is eliminated both by the use of special compensation sections of the pipeline, and with the help of compensators, which can consist of elastic or moving parts.
Compensation sections consist of elastic straight parts of the pipeline, located perpendicular to each other and secured with bends. During thermal elongation, the increase in one part is compensated by the bending deformation of the other part on the plane or by the bending and torsion deformation in space. If the pipeline itself compensates for thermal expansion, then this is called self-compensation.
Compensation also occurs thanks to elastic bends. Part of the elongation is compensated by the elasticity of the bends, the other part is eliminated due to the elastic properties of the material of the area located behind the bend. Compensators are installed where it is not possible to use compensating sections or when the self-compensation of the pipeline is insufficient.
According to their design and operating principle, compensators are of four types: U-shaped, lens, wavy, stuffing box. In practice, flat expansion joints with an L-, Z- or U-shape are often used. In the case of spatial compensators, they usually represent 2 flat mutually perpendicular sections and have one common shoulder. Elastic expansion joints are made from pipes or elastic disks, or bellows.
Determining the optimal size of pipeline diameter
The optimal pipeline diameter can be found based on technical and economic calculations. The dimensions of the pipeline, including the size and functionality of the various components, as well as the conditions under which the pipeline must be operated, determine the transport capacity of the system. Larger pipe sizes are suitable for higher mass flows, provided that other components in the system are properly selected and sized for these conditions. Typically, the longer the section of main pipe between pumping stations, the greater the pressure drop in the pipeline is required. In addition, changes in the physical characteristics of the pumped medium (viscosity, etc.) can also have a great impact on the pressure in the line.
The optimum size is the smallest suitable pipe size for a particular application that is cost effective over the life of the system.
Formula for calculating pipe performance:
Q = (π d²)/4 v
Q is the flow rate of the pumped liquid;
d - pipeline diameter;
v - flow speed.
In practice, to calculate the optimal pipeline diameter, the values of the optimal velocities of the pumped medium are used, taken from reference materials compiled on the basis of experimental data:
| Pumped medium | Range of optimal speeds in the pipeline, m/s | |
|---|---|---|
| Liquids | Gravity movement: | |
| Viscous liquids | 0,1 - 0,5 | |
| Low viscosity liquids | 0,5 - 1 | |
| Pumping: | ||
| Suction side | 0,8 - 2 | |
| Discharge side | 1,5 - 3 | |
| Gases | Natural craving | 2 - 4 |
| Low pressure | 4 - 15 | |
| Great pressure | 15 - 25 | |
| Couples | Superheated steam | 30 - 50 |
| Saturated steam under pressure: | ||
| More than 105 Pa | 15 - 25 | |
| (1 - 0.5) 105 Pa | 20 - 40 | |
| (0.5 - 0.2) 105 Pa | 40 - 60 | |
| (0.2 - 0.05) 105 Pa | 60 - 75 | |
From here we get the formula for calculating the optimal pipe diameter:
d o = √((4 Q) / (π v o ))
Q is the specified flow rate of the pumped liquid;
d - optimal pipeline diameter;
v is the optimal flow rate.
At high flow rates, pipes of smaller diameter are usually used, which means reduced costs for the purchase of the pipeline, its maintenance and installation work (denoted by K 1). As the speed increases, pressure loss due to friction and local resistance increases, which leads to an increase in the cost of pumping liquid (denoted by K 2).
For large diameter pipelines, the costs K 1 will be higher, and the operating costs K 2 will be lower. If we add the values of K 1 and K 2, we obtain the total minimum costs K and the optimal pipeline diameter. Costs K 1 and K 2 in this case are given in the same time period.
Calculation (formula) of capital costs for a pipeline
K 1 = (m·C M ·K M)/n
m - pipeline mass, t;
C M - cost of 1 t, rub/t;
K M - coefficient that increases the cost of installation work, for example 1.8;
n - service life, years.
The indicated operating costs associated with energy consumption are:
K 2 = 24 N n day C E rub/year
N - power, kW;
n DN - number of working days per year;
S E - costs per kWh of energy, rub/kW * h.
Formulas for determining pipeline dimensions
An example of general formulas for determining the size of pipes without taking into account possible additional impact factors such as erosion, suspended solids, etc.:
| Name | The equation | Possible restrictions |
|---|---|---|
| Flow of liquid and gas under pressure | ||
| Loss of head due to friction Darcy-Weisbach |
d = 12 [(0.0311 f L Q 2)/(h f)] 0.2 |
Q - volumetric flow, gal/min; d - internal diameter of the pipe; hf - loss of pressure due to friction; L - pipeline length, feet; f - friction coefficient; V - flow speed. |
| Equation of total fluid flow | d = 0.64 √(Q/V) |
Q - volumetric flow, gal/min |
| Pump suction line size to limit frictional head loss | d = √(0.0744·Q) |
Q - volumetric flow, gal/min |
| Total gas flow equation | d = 0.29 √((Q T)/(P V)) |
Q - volume flow, ft³/min T - temperature, K P - pressure lb/in² (abs); V - speed |
| Gravity flow | ||
| Manning's equation for calculating pipe diameter for maximum flow | d = 0.375 |
Q - volumetric flow; n - roughness coefficient; S - slope. |
| Froude number is the relationship between the force of inertia and the force of gravity | Fr = V / √[(d/12) g] |
g - free fall acceleration; v - flow speed; L - pipe length or diameter. |
| Steam and evaporation | ||
| Equation for determining pipe diameter for steam | d = 1.75 √[(W v_g x) / V] |
W - mass flow; Vg - specific volume of saturated steam; x - steam quality; V - speed. |
Optimal flow rates for various piping systems
The optimal pipe size is selected based on the minimum cost of pumping the medium through the pipeline and the cost of the pipes. However, speed limits must also be taken into account. Sometimes, the size of the pipeline must match the requirements of the process. Also often the size of the pipeline is related to the pressure drop. In preliminary design calculations, where pressure losses are not taken into account, the size of the process pipeline is determined by the permissible speed.
If there are changes in the direction of flow in the pipeline, this leads to a significant increase in local pressures at the surface perpendicular to the direction of flow. This kind of increase is a function of fluid velocity, density, and initial pressure. Because velocity is inversely proportional to diameter, high-velocity fluids require special consideration when selecting piping size and configuration. The optimal pipe size, for example for sulfuric acid, limits the velocity of the medium to a value at which erosion of the walls in the pipe elbows is not allowed, thereby preventing damage to the pipe structure.
Gravity fluid flow
Calculating the size of a pipeline in the case of a gravity flow is quite complicated. The nature of the movement with this form of flow in the pipe can be single-phase (full pipe) and two-phase (partial filling). Two-phase flow is formed when liquid and gas are simultaneously present in the pipe.
Depending on the ratio of liquid and gas, as well as their velocities, the two-phase flow regime can vary from bubbly to dispersed.
| bubble flow (horizontal) | projectile flow (horizontal) | wave flow | dispersed flow |
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The driving force for a liquid when moving by gravity is provided by the difference in the heights of the starting and ending points, and a prerequisite is that the starting point is located above the ending point. In other words, the difference in height determines the difference in the potential energy of the liquid in these positions. This parameter is also taken into account when selecting a pipeline. In addition, the magnitude of the driving force is influenced by the pressure values at the starting and ending points. An increase in pressure drop entails an increase in the fluid flow rate, which, in turn, makes it possible to select a pipeline of a smaller diameter, and vice versa.
If the end point is connected to a pressurized system, such as a distillation column, it is necessary to subtract the equivalent pressure from the existing height difference to estimate the actual effective differential pressure generated. Also, if the starting point of the pipeline is under vacuum, then its effect on the overall differential pressure must also be taken into account when selecting the pipeline. The final selection of pipes is carried out using differential pressure, taking into account all of the above factors, and is not based solely on the difference in height between the starting and ending points.
Hot liquid flow
Process plants typically face various challenges when handling hot or boiling media. The main reason is the evaporation of part of the hot liquid stream, that is, the phase transformation of the liquid into vapor inside the pipeline or equipment. A typical example is the phenomenon of cavitation of a centrifugal pump, accompanied by point boiling of a liquid with the subsequent formation of steam bubbles (steam cavitation) or the release of dissolved gases into bubbles (gas cavitation).
Larger piping is preferred due to the reduced flow rate compared to smaller piping at constant flow, resulting in a higher NPSH at the pump suction line. Also, the cause of cavitation due to loss of pressure can be points of sudden change in flow direction or reduction in the size of the pipeline. The resulting vapor-gas mixture creates an obstacle to the flow and can cause damage to the pipeline, which makes the phenomenon of cavitation extremely undesirable during pipeline operation.
Bypass pipeline for equipment/instruments
Equipment and devices, especially those that can create significant pressure drops, that is, heat exchangers, control valves, etc., are equipped with bypass pipelines (to allow the process not to be interrupted even during technical maintenance work). Such pipelines usually have 2 shut-off valves installed in the installation line and a flow control valve parallel to this installation.
During normal operation, the fluid flow, passing through the main components of the apparatus, experiences an additional pressure drop. Accordingly, the discharge pressure for it created by the connected equipment, such as a centrifugal pump, is calculated. The pump is selected based on the total pressure drop in the installation. During movement along the bypass pipeline, this additional pressure drop is absent, while the operating pump delivers the flow of the same force, according to its operating characteristics. To avoid differences in flow characteristics between the apparatus and the bypass line, it is recommended to use a smaller bypass line with a control valve to create a pressure equivalent to the main installation.
Sampling line
Typically, a small amount of liquid is sampled for analysis to determine its composition. Sampling can be done at any stage of the process to determine the composition of the raw material, intermediate product, finished product, or simply the transported substance, such as wastewater, coolant, etc. The size of the piping section from which sampling occurs typically depends on the type of fluid being analyzed and the location of the sampling point.
For example, for gases under high pressure conditions, small pipelines with valves are sufficient to collect the required number of samples. Increasing the diameter of the sampling line will reduce the proportion of media sampled for analysis, but such sampling becomes more difficult to control. However, a small sampling line is not well suited for the analysis of various suspensions in which solid particles can clog the flow path. Thus, the size of the sampling line for suspension analysis depends largely on the size of the solid particles and the characteristics of the medium. Similar conclusions apply to viscous liquids.
When selecting the size of the sampling pipeline, the following are usually taken into account:
- characteristics of the liquid intended for sampling;
- loss of the working environment during selection;
- safety requirements during selection;
- ease of operation;
- location of the sampling point.
Coolant circulation
High speeds are preferred for circulating coolant lines. This is mainly due to the fact that the coolant in the cooling tower is exposed to sunlight, which creates the conditions for the formation of an algae layer. Part of this algae-containing volume enters the circulating coolant. At low flow rates, algae begins to grow in the piping and, after a while, makes it difficult for the coolant to circulate or pass into the heat exchanger. In this case, a high circulation rate is recommended to avoid the formation of algae blockages in the pipeline. Typically, the use of heavily circulating coolant is found in the chemical industry, which requires large piping sizes and lengths to supply power to various heat exchangers.
Tank overflow
Tanks are equipped with overflow pipes for the following reasons:
- avoiding fluid loss (excess fluid goes into another reservoir rather than spilling out of the original reservoir);
- preventing unwanted liquids from leaking outside the tank;
- maintaining liquid levels in tanks.
In all of the above cases, the overflow pipes are designed to accommodate the maximum permissible fluid flow entering the tank, regardless of the fluid flow rate at the outlet. Other principles for selecting pipes are similar to the selection of pipelines for gravity liquids, that is, in accordance with the availability of available vertical height between the starting and ending points of the overflow pipeline.
The highest point of the overflow pipe, which is also its starting point, is located at the point of connection to the tank (tank overflow pipe) usually almost at the very top, and the lowest end point can be near the drain gutter almost at the ground. However, the overflow line may end at a higher elevation. In this case, the available differential pressure will be lower.
Sludge flow
In the case of mining, ore is usually mined from inaccessible areas. In such places, as a rule, there are no railway or road connections. For such situations, hydraulic transportation of media with solid particles is considered the most appropriate, including in the case of mining processing plants located at a sufficient distance. Slurry pipelines are used in various industrial applications to transport solids in crushed form along with liquids. Such pipelines have proven to be the most cost-effective compared to other methods of transporting solid media in large volumes. In addition, their advantages include sufficient safety due to the absence of several types of transportation and environmental friendliness.
Suspensions and mixtures of suspended solids in liquids are stored in a state of periodic stirring to maintain homogeneity. Otherwise, a separation process occurs in which suspended particles, depending on their physical properties, float to the surface of the liquid or settle to the bottom. Mixing is achieved through equipment such as a tank with a stirrer, while in pipelines, this is achieved by maintaining turbulent flow conditions.
Reducing the flow rate when transporting particles suspended in a liquid is not desirable, since the process of phase separation may begin in the flow. This can lead to clogging of the pipeline and changes in the concentration of the transported solids in the stream. Intensive mixing in the flow volume is facilitated by the turbulent flow regime.
On the other hand, excessive reduction in the size of the pipeline also often leads to blockage. Therefore, choosing the size of the pipeline is an important and responsible step that requires preliminary analysis and calculations. Each case must be considered individually as different slurries behave differently at different fluid velocities.
Pipeline repair
During the operation of the pipeline, various types of leaks may occur in it, requiring immediate elimination to maintain the operability of the system. Repair of the main pipeline can be carried out in several ways. This can range from replacing an entire segment of pipe or a small section that is leaking, or applying a patch to an existing pipe. But before choosing any repair method, it is necessary to conduct a thorough study of the cause of the leak. In some cases, it may be necessary not just to repair, but to change the route of the pipe to prevent repeated damage.
The first stage of repair work is to determine the location of the pipe section that requires intervention. Next, depending on the type of pipeline, a list of necessary equipment and measures required to eliminate the leak is determined, and the necessary documents and permits are also collected if the section of the pipe to be repaired is located on the territory of another owner. Since most pipes are located underground, it may be necessary to remove part of the pipe. Next, the pipeline coating is checked for general condition, after which part of the coating is removed to carry out repair work directly on the pipe. After repair, various inspection measures can be carried out: ultrasonic testing, color flaw detection, magnetic particle flaw detection, etc.
Although some repairs require a complete shutdown of the pipeline, often only a temporary interruption of work is sufficient to isolate the area being repaired or prepare a bypass route. However, in most cases, repair work is carried out when the pipeline is completely disconnected. Isolating a section of pipeline can be done using plugs or shut-off valves. Next, the necessary equipment is installed and repairs are carried out directly. Repair work is carried out on the damaged area, freed from the environment and without pressure. Upon completion of the repair, the plugs are opened and the integrity of the pipeline is restored.
Laying a pipeline is not very difficult, but quite troublesome. One of the most difficult problems in this case is calculating the pipe capacity, which directly affects the efficiency and performance of the structure. This article will discuss how pipe capacity is calculated.
Throughput is one of the most important indicators of any pipe. Despite this, this indicator is rarely indicated in pipe markings, and there is little point in this, because the throughput capacity depends not only on the dimensions of the product, but also on the design of the pipeline. That is why this indicator has to be calculated independently.
Methods for calculating pipeline capacity
- External diameter. This indicator is expressed in the distance from one side of the outer wall to the other side. In calculations, this parameter is designated Day. The outer diameter of the pipes is always indicated in the markings.
- Nominal diameter. This value is defined as the diameter of the internal section, which is rounded to whole numbers. When calculating, the nominal diameter is displayed as Dn.
Calculation of pipe permeability can be carried out using one of the methods, which must be selected depending on the specific conditions of pipeline laying:
- Physical calculations. In this case, the pipe capacity formula is used, which allows taking into account each design indicator. The choice of formula is influenced by the type and purpose of the pipeline - for example, sewer systems have their own set of formulas, as do other types of structures.
- Spreadsheet calculations. You can select the optimal cross-country ability using a table with approximate values, which is most often used for arranging wiring in an apartment. The values indicated in the table are quite vague, but this does not prevent them from being used in calculations. The only drawback of the tabular method is that it calculates the throughput of the pipe depending on the diameter, but does not take into account changes in the latter due to deposits, so for pipelines prone to build-up, such a calculation will not be the best choice. To get accurate results, you can use Shevelev’s table, which takes into account almost all factors affecting pipes. This table is perfect for installing highways on individual plots of land.
- Calculation using programs. Many companies specializing in pipeline laying use computer programs in their activities that allow them to accurately calculate not only the pipe capacity, but also a host of other indicators. For independent calculations, you can use online calculators, which, although they have a slightly larger error, are available free of charge. A good option for a large shareware program is “TAScope”, and in the domestic space the most popular is “Hydrosystem”, which also takes into account the nuances of pipeline installation depending on the region.
Calculation of gas pipeline capacity
Designing a gas pipeline requires fairly high precision - gas has a very high compression ratio, due to which leaks are possible even through microcracks, not to mention serious ruptures. That is why correct calculation of the capacity of the pipe through which gas will be transported is very important.
If we are talking about gas transportation, then the throughput of pipelines, depending on the diameter, will be calculated using the following formula:
- Qmax = 0.67 DN2 * p,
Where p is the value of the working pressure in the pipeline, to which 0.10 MPa is added;
DN – the value of the nominal diameter of the pipe.
The above formula for calculating the capacity of a pipe by diameter allows you to create a system that will work in domestic conditions.
In industrial construction and when performing professional calculations, a different formula is used:
- Qmax = 196.386 DN2 * p/z*T,
Where z is the compression ratio of the transported medium;
T – temperature of the transported gas (K).
To avoid problems, professionals also have to take into account the climatic conditions in the region where it will pass when calculating the pipeline. If the outer diameter of the pipe is smaller than the gas pressure in the system, then the pipeline is very likely to be damaged during operation, resulting in loss of the transported substance and an increased risk of explosion in the weakened section of the pipe.
If necessary, you can determine the permeability of a gas pipe using a table that describes the relationship between the most common pipe diameters and the operating pressure level in them. By and large, the tables have the same drawback that the pipeline capacity calculated by diameter has, namely, the inability to take into account the influence of external factors.
Calculation of sewer pipe capacity
When designing a sewer system, it is imperative to calculate the throughput of the pipeline, which directly depends on its type (sewage systems are either pressure or non-pressure). Hydraulic laws are used to carry out calculations. The calculations themselves can be carried out either using formulas or using appropriate tables.
For the hydraulic calculation of the sewer system, the following indicators are required:
- Pipe diameter – DN;
- The average speed of movement of substances is v;
- The magnitude of the hydraulic slope is I;
- Filling degree – h/DN.
As a rule, when carrying out calculations, only the last two parameters are calculated - the rest can then be determined without any problems. The magnitude of the hydraulic slope is usually equal to the slope of the ground, which will ensure the movement of wastewater at the speed necessary for self-cleaning of the system.
The speed and maximum level of filling of domestic sewerage are determined from a table that can be written out as follows:
- 150-250 mm - h/DN is 0.6 and speed is 0.7 m/s.
- Diameter 300-400 mm - h/DN is 0.7, speed is 0.8 m/s.
- Diameter 450-500 mm - h/DN is 0.75, speed is 0.9 m/s.
- Diameter 600-800 mm - h/DN is 0.75, speed is 1 m/s.
- Diameter 900+ mm - h/DN is 0.8, speed – 1.15 m/s.
For a product with a small cross-section, there are standard indicators for the minimum pipeline slope:
- With a diameter of 150 mm, the slope should not be less than 0.008 mm;
- With a diameter of 200 mm, the slope should not be less than 0.007 mm.
To calculate the volume of wastewater, the following formula is used:
- q = a*v,
Where a is the open cross-sectional area of the flow;
v – speed of wastewater transportation.
The speed of transport of a substance can be determined using the following formula:
- v= C√R*i,
where R is the value of the hydraulic radius,
C – wetting coefficient;
i is the degree of slope of the structure.
From the previous formula we can derive the following, which will allow us to determine the value of the hydraulic slope:
- i=v2/C2*R.
To calculate the wetting coefficient, a formula of the following form is used:
- С=(1/n)*R1/6,
Where n is a coefficient that takes into account the degree of roughness, which varies from 0.012 to 0.015 (depending on the material of the pipe).
The R value is usually equated to the usual radius, but this is only relevant if the pipe is completely filled.
For other situations, a simple formula is used:
- R=A/P,
Where A is the cross-sectional area of the water flow,
P is the length of the inner part of the pipe in direct contact with the liquid.
Tabular calculation of sewer pipes
You can also determine the permeability of sewer system pipes using tables, and the calculations will directly depend on the type of system:
- Gravity sewerage. To calculate free-flow sewer systems, tables are used that contain all the necessary indicators. Knowing the diameter of the pipes being installed, you can select all other parameters depending on it and substitute them into the formula (read also: " "). In addition, the table indicates the volume of liquid passing through the pipe, which always coincides with the patency of the pipeline. If necessary, you can use the Lukin tables, which indicate the throughput of all pipes with a diameter in the range from 50 to 2000 mm.
- Pressure sewer. Determining the throughput in this type of system using tables is somewhat simpler - it is enough to know the maximum degree of filling of the pipeline and the average speed of liquid transportation. Read also: "".
The capacity table for polypropylene pipes allows you to find out all the parameters necessary for arranging the system.
Calculation of water supply capacity
Water pipes are most often used in private construction. In any case, the water supply system is subject to a serious load, so calculating the pipeline capacity is mandatory, because it allows you to create the most comfortable operating conditions for the future structure.
To determine the permeability of water pipes, you can use their diameter (read also: " "). Of course, this indicator is not the basis for calculating cross-country ability, but its influence cannot be excluded. The increase in the internal diameter of the pipe is directly proportional to its permeability - that is, a thick pipe almost does not interfere with the movement of water and is less susceptible to the accumulation of various deposits.
However, there are other indicators that also need to be taken into account. For example, a very important factor is the coefficient of friction of the liquid against the inside of the pipe (different materials have their own values). It is also worth considering the length of the entire pipeline and the pressure difference at the beginning of the system and at the outlet. An important parameter is the number of different adapters present in the design of the water supply system.
The throughput of polypropylene water pipes can be calculated depending on several parameters using the tabular method. One of them is a calculation in which the main indicator is water temperature. As the temperature in the system increases, the fluid expands, causing friction to increase. To determine the permeability of the pipeline, you need to use the appropriate table. There is also a table that allows you to determine the permeability in the pipes depending on the water pressure.
The most accurate calculation of water based on pipe capacity can be made using the Shevelev tables. In addition to accuracy and a large number of standard values, these tables contain formulas that allow you to calculate any system. This material fully describes all situations related to hydraulic calculations, which is why most professionals in this field most often use the Shevelev tables.
The main parameters taken into account in these tables are:
- External and internal diameters;
- Pipeline wall thickness;
- System operation period;
- Total length of the highway;
- Functional purpose of the system.
Conclusion
Calculation of pipe capacity can be done in different ways. The choice of the optimal calculation method depends on a large number of factors - from pipe sizes to purpose and type of system. In each case, there are more and less accurate calculation options, so both a professional who specializes in laying pipelines and an owner who decides to lay a pipeline at home can find the right one.
Shevelev table calculation method theoretical hydraulics SNiP 2.04.02-84
Initial data
Pipe material: New steel without an internal protective coating or with a bitumen protective coating New cast iron without an internal protective coating or with a bitumen protective coating Non-new steel and cast iron without an internal protective coating or with a bitumen protective coating Asbestos-cement Reinforced concrete vibrohydropressed Reinforced concrete centrifuged Steel and cast iron with internal. plastic or polymer-cement coating applied by centrifugation Steel and cast iron, with an internal cement-sand coating applied by spraying Steel and cast iron, with an internal cement-sand coating applied by centrifugation Polymer materials (plastic) Glass
Estimated flow
L/s m3/hour
Outside diameter mm
Wall thickness mm
Pipe length m
Average water temperature °C
Eq. internal roughness pipe surfaces: Heavily rusted or with large deposits Steel or cast iron old rusty Galvanized steel. after several years Steel after several years Cast iron new Galvanized steel new Welded steel new Seamless steel new Drawn from brass, lead, copper Glass
Sum of local resistances
Calculation
Dependence of pressure loss on pipe diameter
HTML5 doesn't work in your browserWhen calculating a water supply or heating system, you are faced with the task of selecting the diameter of the pipeline. To solve this problem, you need to make a hydraulic calculation of your system, and for an even simpler solution, you can use online hydraulic calculation, which is what we will do now.
Operating procedure:
1. Select the appropriate calculation method (calculation according to Shevelev tables, theoretical hydraulics or according to SNiP 2.04.02-84)
2. Select pipe material
3. Set the estimated water flow in the pipeline
4. Set the outer diameter and wall thickness of the pipeline
5. Set the pipe length
6. Set the average water temperature
The result of the calculation will be the graph and the hydraulic calculation values given below.
The graph consists of two values (1 – water pressure loss, 2 – water speed). The optimal pipe diameter values will be written in green below the graph.
Those. you must set the diameter so that the point on the graph is strictly above your green values for the pipeline diameter, because only with such values will the water speed and pressure loss be optimal.
Pipeline pressure loss shows the pressure loss in a given section of the pipeline. The higher the losses, the more work will have to be done to deliver water to the right place.
The hydraulic resistance characteristic shows how effectively the pipe diameter is selected depending on the pressure loss.
For reference:
- if you need to find out the speed of liquid/air/gas in a pipeline of various sections, use
Capacity is an important parameter for any pipes, canals and other heirs of the Roman aqueduct. However, the throughput capacity is not always indicated on the pipe packaging (or on the product itself). In addition, the layout of the pipeline also determines how much liquid the pipe passes through the cross-section. How to correctly calculate the throughput of pipelines?
Methods for calculating pipeline capacity
There are several methods for calculating this parameter, each of which is suitable for a particular case. Some symbols important when determining pipe capacity:
Outer diameter is the physical size of the pipe cross-section from one edge of the outer wall to the other. In calculations it is designated as Dn or Dn. This parameter is indicated in the labeling.
Nominal diameter is the approximate value of the diameter of the internal section of the pipe, rounded to the nearest whole number. In calculations it is designated as Du or Du.
Physical methods for calculating pipe capacity
Pipe throughput values are determined using special formulas. For each type of product - for gas, water supply, sewerage - there are different calculation methods.
Tabular calculation methods
There is a table of approximate values created to make it easier to determine the capacity of pipes in apartment wiring. In most cases, high precision is not required, so the values can be applied without complex calculations. But this table does not take into account the decrease in throughput due to the appearance of sedimentary growths inside the pipe, which is typical for old highways.
| Type of liquid | Speed (m/sec) |
| City water | 0,60-1,50 |
| Water pipeline | 1,50-3,00 |
| Central heating water | 2,00-3,00 |
| Pressure system water in pipeline line | 0,75-1,50 |
| Hydraulic fluid | up to 12m/sec |
| Oil pipeline line | 3,00-7,5 |
| Oil in the pressure system of the pipeline line | 0,75-1,25 |
| Steam in the heating system | 20,0-30,00 |
| Steam central piping system | 30,0-50,0 |
| Steam in a high temperature heating system | 50,0-70,00 |
| Air and gas in the central piping system | 20,0-75,00 |
There is an exact table for calculating capacity, called the Shevelev table, which takes into account the pipe material and many other factors. These tables are rarely used when laying water pipes in an apartment, but in a private house with several non-standard risers they can be useful.
Calculation using programs
Modern plumbing companies have special computer programs at their disposal to calculate pipe capacity, as well as many other similar parameters. In addition, online calculators have been developed, which, although less accurate, are free and do not require installation on a PC. One of the stationary programs “TAScope” is a creation of Western engineers, which is shareware. Large companies use “Hydrosystem” - this is a domestic program that calculates pipes according to criteria that affect their operation in the regions of the Russian Federation. In addition to hydraulic calculations, it allows you to calculate other pipeline parameters. The average price is 150,000 rubles.
How to calculate the capacity of a gas pipe
Gas is one of the most difficult materials to transport, in particular because it tends to be compressed and therefore is able to leak through the smallest gaps in pipes. There are special requirements for calculating the capacity of gas pipes (as well as for designing the gas system as a whole).
Formula for calculating the capacity of a gas pipe
The maximum throughput of gas pipelines is determined by the formula:
Qmax = 0.67 DN2 * p
where p is equal to the operating pressure in the gas pipeline system + 0.10 MPa or absolute gas pressure;
Du - nominal diameter of the pipe.
There is a complex formula for calculating the capacity of a gas pipe. It is usually not used when carrying out preliminary calculations, as well as when calculating a household gas pipeline.
Qmax = 196.386 DN2 * p/z*T
where z is the compressibility coefficient;
T is the temperature of the transported gas, K;
According to this formula, the direct dependence of the temperature of the moving medium on pressure is determined. The higher the T value, the more the gas expands and presses on the walls. Therefore, when calculating large highways, engineers take into account possible weather conditions in the area where the pipeline runs. If the nominal value of the DN pipe is less than the gas pressure generated at high temperatures in summer (for example, at +38 ... + 45 degrees Celsius), then damage to the line is likely. This entails the leakage of valuable raw materials and creates the possibility of an explosion in a section of the pipe.
Table of gas pipe capacities depending on pressure
There is a table for calculating gas pipeline throughputs for commonly used pipe diameters and nominal operating pressures. To determine the characteristics of a gas pipeline of non-standard sizes and pressures, engineering calculations will be required. The pressure, speed and volume of gas are also affected by the outside air temperature.
The maximum speed (W) of the gas in the table is 25 m/s, and z (compressibility coefficient) is 1. The temperature (T) is 20 degrees Celsius or 293 Kelvin.
| Work.(MPa) | Pipeline capacity (m?/h), with wgas=25m/s;z=1;T=20?C=293?K | |||||||
|---|---|---|---|---|---|---|---|---|
| DN 50 | DN 80 | DN 100 | DN 150 | DN 200 | DN 300 | DN 400 | DN 500 | |
| 0,3 | 670 | 1715 | 2680 | 6030 | 10720 | 24120 | 42880 | 67000 |
| 0,6 | 1170 | 3000 | 4690 | 10550 | 18760 | 42210 | 75040 | 117000 |
| 1,2 | 2175 | 5570 | 8710 | 19595 | 34840 | 78390 | 139360 | 217500 |
| 1,6 | 2845 | 7290 | 11390 | 25625 | 45560 | 102510 | 182240 | 284500 |
| 2,5 | 4355 | 11145 | 17420 | 39195 | 69680 | 156780 | 278720 | 435500 |
| 3,5 | 6030 | 15435 | 24120 | 54270 | 96480 | 217080 | 385920 | 603000 |
| 5,5 | 9380 | 24010 | 37520 | 84420 | 150080 | 337680 | 600320 | 938000 |
| 7,5 | 12730 | 32585 | 50920 | 114570 | 203680 | 458280 | 814720 | 1273000 |
| 10,0 | 16915 | 43305 | 67670 | 152255 | 270680 | 609030 | 108720 | 1691500 |
Sewer pipe capacity
The throughput of a sewer pipe is an important parameter that depends on the type of pipeline (pressure or free-flow). The calculation formula is based on the laws of hydraulics. In addition to labor-intensive calculations, tables are used to determine sewer capacity.
For hydraulic calculation of sewerage, it is necessary to determine the unknowns:
- pipeline diameter Du;
- average flow velocity v;
- hydraulic slope l;
- degree of filling h/Dn (calculations are based on the hydraulic radius, which is associated with this value).
In practice, they are limited to calculating the value of l or h/d, since the remaining parameters are easy to calculate. In preliminary calculations, the hydraulic slope is considered to be equal to the slope of the earth's surface, at which the movement of wastewater will not be lower than the self-cleaning speed. Speed values, as well as maximum h/DN values for household networks can be found in Table 3.
Yulia Petrichenko, expert
In addition, there is a standardized value for the minimum slope for pipes with a small diameter: 150 mm
(i=0.008) and 200 (i=0.007) mm.
The formula for volumetric fluid flow looks like this:
where a is the open cross-sectional area of the flow,
v – flow velocity, m/s.
Speed is calculated using the formula:
where R is the hydraulic radius;
C – wetting coefficient;
From this we can derive the formula for hydraulic slope:
This parameter is used to determine this parameter if calculation is necessary.
where n is the roughness coefficient, having values from 0.012 to 0.015 depending on the pipe material.
The hydraulic radius is considered equal to the normal radius, but only when the pipe is completely filled. In other cases, use the formula:
where A is the area of the transverse fluid flow,
P is the wetted perimeter, or the transverse length of the inner surface of the pipe that touches the liquid.
Capacity tables for free-flow sewer pipes
The table takes into account all the parameters used to perform the hydraulic calculation. The data is selected according to the pipe diameter and substituted into the formula. Here the volumetric flow rate of liquid q passing through the cross-section of the pipe has already been calculated, which can be taken as the throughput of the line.
In addition, there are more detailed Lukin tables containing ready-made throughput values for pipes of different diameters from 50 to 2000 mm.
Capacity tables for pressure sewer systems
In sewer pressure pipe capacity tables, the values depend on the maximum degree of filling and the calculated average wastewater velocity.
| Diameter, mm | Filling | Acceptable (optimal slope) | Speed of movement of waste water in the pipe, m/s | Consumption, l/sec |
| 100 | 0,6 | 0,02 | 0,94 | 4,6 |
| 125 | 0,6 | 0,016 | 0,97 | 7,5 |
| 150 | 0,6 | 0,013 | 1,00 | 11,1 |
| 200 | 0,6 | 0,01 | 1,05 | 20,7 |
| 250 | 0,6 | 0,008 | 1,09 | 33,6 |
| 300 | 0,7 | 0,0067 | 1,18 | 62,1 |
| 350 | 0,7 | 0,0057 | 1,21 | 86,7 |
| 400 | 0,7 | 0,0050 | 1,23 | 115,9 |
| 450 | 0,7 | 0,0044 | 1,26 | 149,4 |
| 500 | 0,7 | 0,0040 | 1,28 | 187,9 |
| 600 | 0,7 | 0,0033 | 1,32 | 278,6 |
| 800 | 0,7 | 0,0025 | 1,38 | 520,0 |
| 1000 | 0,7 | 0,0020 | 1,43 | 842,0 |
| 1200 | 0,7 | 0,00176 | 1,48 | 1250,0 |
Water pipe capacity
Water pipes are the most commonly used pipes in a home. And since they are subject to a large load, calculating the throughput of the water main becomes an important condition for reliable operation.
Pipe patency depending on diameter
Diameter is not the most important parameter when calculating the patency of a pipe, but it also affects its value. The larger the internal diameter of the pipe, the higher the permeability, and also the lower the chance of blockages and plugs. However, in addition to the diameter, it is necessary to take into account the coefficient of friction of water on the pipe walls (tabular value for each material), the length of the line and the difference in fluid pressure at the inlet and outlet. In addition, the number of elbows and fittings in the pipeline will greatly influence the flow rate.
Table of pipe capacity by coolant temperature
The higher the temperature in the pipe, the lower its throughput, since the water expands and thereby creates additional friction. For plumbing this is not important, but in heating systems it is a key parameter.
There is a table for calculations of heat and coolant.
| Pipe diameter, mm | Bandwidth | |||
|---|---|---|---|---|
| By warmth | By coolant | |||
| Water | Steam | Water | Steam | |
| Gcal/h | t/h | |||
| 15 | 0,011 | 0,005 | 0,182 | 0,009 |
| 25 | 0,039 | 0,018 | 0,650 | 0,033 |
| 38 | 0,11 | 0,05 | 1,82 | 0,091 |
| 50 | 0,24 | 0,11 | 4,00 | 0,20 |
| 75 | 0,72 | 0,33 | 12,0 | 0,60 |
| 100 | 1,51 | 0,69 | 25,0 | 1,25 |
| 125 | 2,70 | 1,24 | 45,0 | 2,25 |
| 150 | 4,36 | 2,00 | 72,8 | 3,64 |
| 200 | 9,23 | 4,24 | 154 | 7,70 |
| 250 | 16,6 | 7,60 | 276 | 13,8 |
| 300 | 26,6 | 12,2 | 444 | 22,2 |
| 350 | 40,3 | 18,5 | 672 | 33,6 |
| 400 | 56,5 | 26,0 | 940 | 47,0 |
| 450 | 68,3 | 36,0 | 1310 | 65,5 |
| 500 | 103 | 47,4 | 1730 | 86,5 |
| 600 | 167 | 76,5 | 2780 | 139 |
| 700 | 250 | 115 | 4160 | 208 |
| 800 | 354 | 162 | 5900 | 295 |
| 900 | 633 | 291 | 10500 | 525 |
| 1000 | 1020 | 470 | 17100 | 855 |
Table of pipe capacity depending on coolant pressure
There is a table describing the capacity of pipes depending on pressure.
| Consumption | Bandwidth | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Du pipe | 15 mm | 20 mm | 25 mm | 32 mm | 40 mm | 50 mm | 65 mm | 80 mm | 100 mm |
| Pa/m - mbar/m | less than 0.15 m/s | 0.15 m/s | 0.3 m/s | ||||||
| 90,0 - 0,900 | 173 | 403 | 745 | 1627 | 2488 | 4716 | 9612 | 14940 | 30240 |
| 92,5 - 0,925 | 176 | 407 | 756 | 1652 | 2524 | 4788 | 9756 | 15156 | 30672 |
| 95,0 - 0,950 | 176 | 414 | 767 | 1678 | 2560 | 4860 | 9900 | 15372 | 31104 |
| 97,5 - 0,975 | 180 | 421 | 778 | 1699 | 2596 | 4932 | 10044 | 15552 | 31500 |
| 100,0 - 1,000 | 184 | 425 | 788 | 1724 | 2632 | 5004 | 10152 | 15768 | 31932 |
| 120,0 - 1,200 | 202 | 472 | 871 | 1897 | 2898 | 5508 | 11196 | 17352 | 35100 |
| 140,0 - 1,400 | 220 | 511 | 943 | 2059 | 3143 | 5976 | 12132 | 18792 | 38160 |
| 160,0 - 1,600 | 234 | 547 | 1015 | 2210 | 3373 | 6408 | 12996 | 20160 | 40680 |
| 180,0 - 1,800 | 252 | 583 | 1080 | 2354 | 3589 | 6804 | 13824 | 21420 | 43200 |
| 200,0 - 2,000 | 266 | 619 | 1151 | 2486 | 3780 | 7200 | 14580 | 22644 | 45720 |
| 220,0 - 2,200 | 281 | 652 | 1202 | 2617 | 3996 | 7560 | 15336 | 23760 | 47880 |
| 240,0 - 2,400 | 288 | 680 | 1256 | 2740 | 4176 | 7920 | 16056 | 24876 | 50400 |
| 260,0 - 2,600 | 306 | 713 | 1310 | 2855 | 4356 | 8244 | 16740 | 25920 | 52200 |
| 280,0 - 2,800 | 317 | 742 | 1364 | 2970 | 4356 | 8566 | 17338 | 26928 | 54360 |
| 300,0 - 3,000 | 331 | 767 | 1415 | 3076 | 4680 | 8892 | 18000 | 27900 | 56160 |
Table of pipe capacity depending on diameter (according to Shevelev)
The tables of F.A. and A.F. Shevelev are one of the most accurate tabular methods for calculating the throughput of a water pipeline. In addition, they contain all the necessary calculation formulas for each specific material. This is a lengthy piece of information that is most often used by hydraulic engineers.
The tables take into account:
- pipe diameters – internal and external;
- wall thickness;
- service life of the water supply system;
- line length;
- purpose of pipes.
Hydraulic calculation formula
For water pipes, the following calculation formula is used:
Online calculator: calculation of pipe capacity
If you have any questions or have any references that use methods not mentioned here, please write in the comments.
This characteristic depends on several factors. First of all, this is the diameter of the pipe, as well as the type of liquid, and other indicators.
For hydraulic calculation of a pipeline, you can use the hydraulic pipeline calculation calculator.
When calculating any systems based on fluid circulation through pipes, there is a need to accurately determine pipe capacity. This is a metric value that characterizes the amount of liquid flowing through pipes over a certain period of time. This indicator is directly related to the material from which the pipes are made.
If we take, for example, plastic pipes, they differ in almost the same throughput throughout their entire service life. Plastic, unlike metal, is not prone to corrosion, so a gradual increase in deposits is not observed in it.
As for metal pipes, they throughput decreases year after year. Due to the appearance of rust, the material inside the pipes peels off. This leads to surface roughness and the formation of even more plaque. This process occurs especially quickly in hot water pipes.
The following is a table of approximate values, which was created to make it easier to determine the throughput of pipes in apartment wiring. This table does not take into account the reduction in throughput due to the appearance of sedimentary build-ups inside the pipe.
Table of pipe capacity for liquids, gas, water vapor.
|
Type of liquid |
Speed (m/sec) |
|
City water |
|
|
Water pipeline |
|
|
Central heating water |
|
|
Pressure system water in pipeline line |
|
|
Hydraulic fluid |
up to 12m/sec |
|
Oil pipeline line |
|
|
Oil in the pressure system of the pipeline line |
|
|
Steam in the heating system |
|
|
Steam central piping system |
|
|
Steam in a high temperature heating system |
|
|
Air and gas in the central piping system |
Most often, ordinary water is used as a coolant. The rate of decrease in throughput in pipes depends on its quality. The higher the quality of the coolant, the longer the pipeline made of any material (steel, cast iron, copper or plastic) will last.
Calculation of pipe capacity.
For accurate and professional calculations, you must use the following indicators:
- The material from which pipes and other elements of the system are made;
- Pipe length
- Number of water consumption points (for water supply system)
The most popular calculation methods:
1. Formula. A rather complex formula, which is understandable only to professionals, takes into account several values at once. The main parameters that are taken into account are the material of the pipes (surface roughness) and their slope.
2. Table. This is a simpler way by which anyone can determine the throughput of a pipeline. An example is the engineering table of F. Shevelev, from which you can find out the throughput capacity based on the pipe material.
3. Computer program. One of these programs can be easily found and downloaded on the Internet. It is designed specifically to determine the throughput for pipes of any circuit. In order to find out the value, you need to enter initial data into the program, such as material, pipe length, coolant quality, etc.
It should be said that the latter method, although the most accurate, is not suitable for calculating simple household systems. It is quite complex and requires knowledge of the values of a wide variety of indicators. To calculate a simple system in a private house, it is better to use tables.
An example of calculating pipeline capacity.
Pipeline length is an important indicator when calculating throughput. The length of the pipeline has a significant impact on throughput indicators. The greater the distance water travels, the less pressure it creates in the pipes, which means the flow speed decreases.
Here are some examples. Based on tables developed by engineers for these purposes.
Pipe capacity:
- 0.182 t/h with a diameter of 15 mm
- 0.65 t/h with pipe diameter 25 mm
- 4 t/h with a diameter of 50 mm
As can be seen from the examples given, a larger diameter increases the flow rate. If the diameter is doubled, the throughput will also increase. This dependence must be taken into account when installing any liquid system, be it plumbing, drainage or heat supply. This is especially true for heating systems, since in most cases they are closed, and the heat supply in the building depends on the uniform circulation of the liquid.