One of the most important characteristics of a steel pipe is its diameter (D). Based on this parameter, all required calculations are made when designing an object. How to choose the diameter so as not to make a mistake?
The diameters of metal pipes are standardized and must correspond to the values of GOST 10704–91.
Conventionally, they are divided into several subgroups:
- Large – 508 mm and above;
- Medium – from 114 to 530 mm;
- Small – less than 114 mm.
When it is necessary to carry out plumbing, ordinary pipes are installed that can withstand a small load. In a private house, it is better to use welded metal water pipes. The cost of such products is somewhat lower than similar seamless ones. The technical characteristics and properties of such a product fully meet all the requirements for laying water pipes.
Main dimensions
Depending on this characteristic and its numerical value, the required diameter of the metal pipe is determined. All basic values are regulated by GOST and relevant technical specifications.
These include:
- Inner D;
- External D. Considered the main dimensional characteristic in accordance with GOST;
- Conditional D. Based on minimum value internal diameter;
- Wall thickness;
- Nominal D.
Metal products and their outer diameters
All types of metal pipes are manufactured at the factory, based on their outer diameter “Dн”. Standard diameters are shown in the table below.
In industry and construction, they mainly use products whose diameters are in the range of 426–1420 mm. Intermediate standard sizes of water pipes are taken from the table.
Small D metal products are mainly used for laying water pipes in residential buildings.
Middle D metal pipelines are used for laying city water supply. Such water pipes are used by industrial systems involved in the extraction of crude oil.
Big sizes steel pipelines have found application in the creation and laying of main oil pipelines. They are also used in the gas industry. Through such pipelines gas is supplied to every corner of the planet.
Inner diameter
This metal pipe size (Din) can have different values. Moreover, the value of external D always remains unchanged. To standardize the diameter of water supply pipes, designers use a special value called “nominal diameter”. This diameter has its own designation Dу.
In fact, the nominal diameter is the minimum value of the internal diameter of a given product, rounded to the nearest whole number. Rounding is always performed towards the maximum value only. The value of conditional D is regulated by GOST 355–52.
To calculate internal D, a special formula is used:
Din = Dn – 2S.
The internal diameters of steel products range from 6 to 200 millimeters. All intermediate values are shown in the corresponding table.
The diameter of metal pipes is also measured in inches, which is 25.4 millimeters. The table below shows the product diameters in both inches and millimeters.
Plastic
Nowadays, their plastic counterparts have become an alternative to metal pipes. Moreover, their sizes vary widely. The material for such a product is:
- Polypropylene;
- Polyethylene;
- Metal-plastic.
Each manufacturer of such pipes sets its own size chart. Therefore, if one system is being manufactured, it is advisable to use parts from the same manufacturer.
Of course, there will definitely be discrepancies, but they will be minimal and will not cause any particular difficulties for a good master. If a person has little experience, he will have to make some efforts to fit all the sizes.
The table of sizes of plastic pipes for water supply using polypropylene of various densities shows the most popular models.
When all kinds of communications are laid, builders also use other diameters of plastic water pipes.
The diameters of water pipes in the table help you select the appropriate product for repairs or other work.
Cast iron
Such products are used for installing water supply systems outside the building. In residential premises, cast iron water supply is installed extremely rarely. This material has high strength, but increased fragility. Its main disadvantage is its heavy weight and high cost. The operation of such cast iron products is designed for many years.
To compare the sizes of cast iron plumbing products, below is a table showing the dimensions of Class A cast iron pipe.
How to convert inches correctly
There are special tables for such calculations. Let's take, for example, a pipe with D = 1″. The outer diameter of the water supply pipe will not be 25.4 mm. The cylindrical pipe thread has an outer D = 33.249 mm. Why is this happening?
Thread cutting is performed only on the outer diameter. Consequently, the value of the nominal diameter of the cut thread in relation to the internal value becomes conditional. To calculate the diameter of a water supply pipe, you need to take 25.4 mm and add the wall thickness multiplied by 2, you get 33.249 mm. The conversion of inch values of water pipe diameters to mm can be found in the table below.
Standard diameters of steel pipes on the table with wall thickness and weight regulated by GOST. (For water pipes.)
Steel water and gas pipes (extract from GOST 3262-75)
Table of water pipe diameters
The data is shown in the table below
Conclusion
When laying a water supply system, all dimensions of the pipeline must be observed very precisely. Any slightest deviation, even a millimeter, will not allow you to create a tight, hermetically sealed connection. Such a system will not be reliable and durable. It will definitely flow.
Temporary water supply is intended to meet industrial, domestic and fire-fighting needs. Design of temporary water supply should be carried out in the following order:
· determine the estimated need;
· choose a source of supply; outline the network diagram;
· calculate pipeline diameters;
· tie the route and structures on the construction plan.
When installing a temporary water supply, it is necessary to make maximum use of permanent sources and water supply networks.
The temporary water supply system must be designed in such a way that drinking installations operating in the summer are located no further than 75 m from workplaces. Toilets, washrooms, showers and rooms for personal hygiene of women must be provided with water for domestic needs during all work shifts.
The total estimated water flow Qtot is determined by the formula
Q total = Q pr + Q household + Q pozh,
where Q pr, Q household, Q fire - respectively, water consumption for industrial, household and fire-fighting purposes.
Water consumption for production needs is determined by the formula
where 1.2 is the coefficient for unaccounted water consumption;
Q av - average production water consumption per shift;
R 1 - consumption unevenness coefficient, R1=1.6;
8.0 - number of hours of work per shift;
3600 is the number of seconds in 1 hour.
Water consumption for household needs Q households consists of water consumption for cooking, sanitary facilities and drinking needs:
where n p is the largest number of workers per shift;
n 1 - rate of water consumption per 1 person. per shift (for sites with sewerage 20-25 l, without sewerage 10-15 l);
n 2 - consumption rate for one shower (take - 30l);
R 2 - coefficient of uneven water consumption, R2=2.7;
R 3 - coefficient taking into account the ratio of shower users to the largest number working per shift (accepted 0.3 - 0.4).
The minimum water consumption for firefighting needs is determined based on the simultaneous action of two jets from hydrants of 5 l/s for each jet
(Q = 5 x 2 = 10 l/s).
Let's consider an example of calculation (Table 13).
Table 10 - Calculation of water requirements for construction site
|
Water flow direction |
Total consumption |
|
Production needs |
|
|
Household needs |
|
|
Fire safety needs |
|
Based on the data obtained, taking into account the maximum water consumption obtained, we will determine the diameter of the combined water supply
where Q max is the maximum water flow;
V - speed of water movement through pipes (2m/s)
d tr =v4*13.6/3.14*2*1000=93 mm
We accept Dtr = 100 mm, which corresponds to fire safety requirements. We accept this water supply for fire-fighting needs.
For industrial and household needs d tr =v4* (1.6+0.7) /3.14*2*1000=33 mm we accept a seamless hot-deformed steel pipe with a diameter of 42 mm.
Description of heat and compressed air requirements
It is carried out from transportable compressor units. We accept the mobile compressor station PKS-5.
Heat is supplied from electric heaters.
Supply of compressed air to the construction site - mobile compressor station PKS-5.
Design of a temporary sewer network on a construction site
The sewer network at the construction site is installed to ensure the removal of wastewater coming from sanitary facilities (canteens, buffets, toilets, washrooms, showers) and industrial installations.
This project provides for the installation of a temporary network to the nearest permanent sewer well from ceramic free-flow pipes with a diameter of 200 mm.
Description of the supervisory control tools used
The design of dispatch communications and signaling at a construction site is carried out in the following order:
a) the location of control centers is determined;
b) equipment is shown using symbols;
c) switching communication networks are plotted;
d) specifications for dispatch communication equipment are drawn up
Table 11 - Communications at the construction site
The initial data for determining the need for water are the measures taken for the production and organization of construction and installation work, their volumes and the timing of their implementation.
Water at a construction site is used for production, household needs and in case of fire extinguishing. The calculation is made for the construction period with the most intensive water consumption separately for production and economic purposes.
The calculation is completed by finding the required diameter of the main entrance of the temporary water supply to the construction site.
The total estimated water consumption in liters per second is determined by the formula:
Q full = Q production + Q utility + Q liquid, where (18)
Q proiv - water consumption for production needs, l/s;
Q utility service - water consumption for household needs, l/s;
Q fire - water consumption for fire extinguishing, l/s.
where (19)
V is the volume of construction and installation work where water is required;
q 1 - specific water consumption per unit volume of construction and installation works;
K 1 - coefficient of unevenness of water flow;
1.2 - coefficient for unaccounted expenses;
8.2 - number of hours of work per shift;
3600 is the number of seconds in an hour.
where (20)
N is the number of workers on the busiest shift (85 people),
B - water consumption per employee (10 l),
K 2 - coefficient of hourly unevenness of water flow (3),
Q 1 - water consumption rate for shower (40 l),
N 1 = 40% of N (34 people)
M 1 - duration of shower (50 min.),
Q 2 - water consumption rate for a dining room (15 l),
M 2 - duration of work of the canteen (50 minutes).
When the construction site area is less than 0.5 hectares, Ql is taken equal to 10 l/s.
Table 5.
Calculation of the need for temporary water supply
| Water consumers | Unit change | Quantity V | Specific water consumption q 1, l/s | Water flow unevenness coefficient K 1 | Water consumption, l/s | ||||||||
| Production needs | |||||||||||||
| Assembly crane | PC. | 1,1 | 0,0134 | ||||||||||
| Loader | PC. | 1,1 | 0,0067 | ||||||||||
| Trucks | PC. | 0,0055 | |||||||||||
| Compressor | PC. | 0,0032 | |||||||||||
| Painting works | 100 m2 | 77,07 | 1,25 | 1,9581 | |||||||||
| Plastering works | 100 m2 | 6,97 | 1,25 | 0,1771 | |||||||||
| Watering concrete | m3 | 691,2 | 1,3 | 3,6527 | |||||||||
| Total: | 5,8278 | ||||||||||||
| Household needs | |||||||||||||
| Are common | Person | 0,27 | |||||||||||
| for the shower | Person | 0,17 | |||||||||||
| to the dining room | Person | 0,16 | |||||||||||
| Total: | 0,6 | ||||||||||||
| Fire purposes | |||||||||||||
| - | - | - | - | - | |||||||||
| Total water consumption: | 16,4278 | ||||||||||||
Explanations for filling out column 3 of table 6:
1. Painting and plastering work
We take the volume from Table 2.
2. The volume of a concrete floor is equal to the floor area multiplied by its thickness (0.2 m).
We get 0.2 m * 3456 m 2 = 691.2 m 3.
3. The volume for all other water consumers (column 3) is left unchanged.
The diameter of the pipes of the external water supply network is determined by the formula:
where (21)
v is the speed of water movement in the pipes (0.9 m/s).
D = 2 * ((16.4278* 1000) / (3.14 * 0.9)) 1/2 = 152.5 mm.
In the specification of diameters of temporary water supply, the following pipe sizes are distinguished: 100, 150, 200, 250 mm. Therefore, we take the diameter of the external water supply = 200 mm.
Calculation of temporary power supply.
The initial data for organizing temporary power supply are the types, volumes and timing of construction and installation work, types of construction machinery and mechanisms, the area of temporary buildings and structures, the length of roads, the area of the construction site and the shift of roads.
Electricity at a construction site is spent on production needs (cranes, lifts, welding machines, etc.), technological needs (electric heating of concrete, soil, etc.) and lighting (external and internal).
For the calculation, we use the method of calculating loads based on the installed capacity of electrical receivers and the demand coefficient with differentiation by type of consumer.
where (22)
α - coefficient taking into account network losses;
K - demand coefficient;
сos j - power factor;
Р с - power of power consumers, kW;
R t - power for technological needs, kW;
Rov - required power for interior lighting, kW;
R no - required power for external security lighting, kW.
The construction process consumes a large amount of water. When designing a temporary water supply for a construction site, the need for water is carefully calculated, taking into account the materials of feasibility studies.
When designing a temporary water supply for construction at the stage of developing a construction organization project (CPO), the following issues are resolved:
- - determine the approximate construction need for water;
- - accept and provide the most rational schemes engineering communications and points for connecting temporary networks to existing ones;
- - select the most technically and economically efficient sources of water supply, establish locations for drilling artesian wells, determine the nature of water intake equipment and filtering and treatment devices, establish the capacity and quality of water sources;
- - coordinate with the relevant organizations the issues of providing construction with water in the required quantities and with the required parameters.
When developing PPR, based on the fundamental decisions made in the PIC, water supply networks are designed in accordance with current technical conditions and standards. At the same time, they resolve issues of connecting temporary networks to existing ones, draw up updated specifications and statements for the necessary units, engines and materials. When designing temporary engineering communications, measures are taken to minimize their length and cost.
Water at a construction site is spent for industrial, domestic and fire-fighting needs, and the calculation of temporary water supply is based on the calculation of water consumption for these needs.
The total calculated second water consumption for construction in liters is determined by the formula:
Q sum = Q pr +Q household +Q well,
where Q pr is water consumption for production needs, l/s;
Q households - the same for household needs, l/s;
Q well - the same for fire safety needs.
Water consumption for production needs Q pr, l/s, is calculated using the formula:
where 1.2 is the coefficient for unaccounted work;
Q av - average consumption water for production needs per shift, l;
K 1 - coefficient of unevenness of water consumption, K 1 = 1.5;
t - number of hours of work per shift (8 hours);
Q av = 210+6+10=226 l. - consists of: 210 l. - water consumption for cement-sand mortar; 6 l. - water consumption for plastering work; 10 l. - water consumption for roofing.
Water consumption for household needs Q households, l/s, consists of water consumption for cooking, for the needs of sanitary facilities and for drinking needs:
where n p is the largest number of workers per shift, people;
n 1 - norm of water requirement per 1 person. per shift (for sites with sewerage - 25 l., without sewerage - 15 l.);
n 2 - rate of water consumption for one shower (30 l.);
K 1 - coefficient of uneven water consumption, K 1 = 3.0;
K 2 - coefficient taking into account the ratio of those using the shower to the largest number of workers per shift, K 2 =0.3;
Water consumption for fire-fighting measures is determined based on the simultaneous action of two jets from hydrants, 5 l/s for each jet, i.e. Qf = 5×2 = 10 l/s. This consumption can be accepted for small objects with a building area of up to 10 hectares.
Then the total second water consumption will be:
Q sum = 0.014+0.087+10=10.101 l/s.
Temporary water supply networks are arranged in a ring pattern, which ensures uninterrupted water supply regardless of the occurrence of damage in one of the areas.
The diameter of temporary water supply pipes D in, mm, is determined by the formula:
where Q sum is the total second calculated water flow, m 3 /s;
n is the speed of water movement through the pipes (taken in the range from 0.7 to 1.2 m/s).
We round the resulting value to the nearest standard diameter, taking into account that the diameter of the external fire water supply must be at least 100 mm. Based on this, we accept a diameter of 120 mm.
Temporary water supply to a construction site is necessary to ensure construction and installation work, household services for workers and fire safety needs.
At the design stage of a complex of objects as part of the “Construction Organization” section, it is established based on aggregated indicators of water consumption per 1 million rubles. estimated cost annual volume of construction and installation work during the period of maximum intensity of their production.
Calculation standards establish the need for water for industrial and domestic needs. The obtained value is compared with the water consumption for fire-fighting needs Q, set according to the size of the construction site area.
Water consumption for these purposes is set in the following amounts:
with a building area of up to 10 hectares - 10 l/sec.,
with a building area of up to 50 hectares - 20 l/sec.,
With a larger area, for every additional 25 hectares, water consumption increases by 5 l/sec.
If Qfire is greater than the consumption for production and household needs, then the need for water is established according to the amount of consumption for fire-fighting needs.
When designing PPR, water consumption (Total is determined as the sum
Q total =Q pr +Q household +Q om
where Q is the need for water for industrial, domestic and fire-fighting needs.
Water consumption for production purposes consists of the following needs: for preparing a concrete mixture or solution, watering laid concrete, performing plastering and painting work, servicing and washing construction machines, etc. It is determined by direct counting in accordance with the volume of relevant work or the number of construction vehicles according to the data in Table. 8.5.
Calculation formula to determine Q pr, has the following form:
where: q - specific water consumption per unit of work or individual consumer, liters. n - volume of work or number of machines
Kn - coefficient of unevenness of water consumption - 1.5 - 2.0
The need for water for household needs Q households is determined by the standards for its consumption per person per day shift based on the number of workers using the formula
where: K and - consumption unevenness coefficient -2.7.
q household - water consumption per worker is approximately assumed to be 20 - 25 liters. for a site with drainage (sewage); 10 - 15 l. for sites without sewerage; 36 l. water for one shower per employee.
Qfire - the minimum water consumption for fire-fighting purposes is determined based on the simultaneous action of two jets from hydrants of 5 l/sec for each jet, i.e. 10 l/sec.).
The diameter of the water pipeline is determined:
where V is the speed of water movement through the pipes:
at high water flow - 1.5 - 2.0 m/sec; at low - 0.7 -1.2 m/sec. Calculated values are rounded to the nearest larger section according to GOST. In the case of laying a water pipeline only for fire safety purposes, the diameter of the pipeline is taken to be at least 100 mm.