To select the right pipelines, it is imperative to take into account their geometric parameters. One of the most important indicators is the diameter of PVC, PPE, and cast iron sewer pipes.
A smoothly functioning sewer system is very important in a comfortable human home. The quality of life of each of us directly depends on the correctness of its installation. Only a well-designed and stably operating wastewater disposal system can guarantee cleanliness in a private home and in the larger city.
Type of pipes
For properly organized drainage of wastewater, pipes must be stable, durable and smooth on the inside. There are 2 main materials for making such products: metal and plastic. The latter are divided into 3 types:
- PVC – polyvinyl chloride. Durable and UV resistant, but cannot withstand high temperatures of hot water and exposure to aggressive environments. Used for internal and external sewers.
- PET – polyethylene. Operating functionality within temperatures of -40 +40 C°, not recommended for use in a hot water drain system.
- PP – polypropylene. They can last 100 years and are highly resistant to temperature changes and harsh chemicals. Used in domestic wastewater systems.
The cast iron drainage system is an outdated option. Despite the fact that it is durable and strong, it is completely replaced with plastic. This is not due to the disadvantages of metal, but due to the advantages of PVC.
Plastic pipes are also divided according to density and hardness. It depends on which highway they will be used:
- SN-2. Products made of lightweight material are used in areas with minimal load. The installation is carried out shallowly and not under transport roads.
- SN-4. They have a denser material and can be laid under roads with little traffic.
- SN-8. The densest and heaviest products are intended for use under highways and industrial enterprises.
PVC – polyvinyl chloride pipes
It is important to note that a PVC drainage system is not as durable as a cast iron one, but it is more flexible and easy to install. When properly installed, it can last 50 years.
Main types and their features
The described products can be socketed, socketless, pressure and non-pressure. Pipes, which are designated by the abbreviation VShChG, have found widespread use in many industries. Such a pipe contains spherical graphite, which makes the product more elastic and viscous. Such pipes replace their gray cast iron counterpart. Their properties can be compared to cast and forged steel. In terms of mechanical characteristics, these pipes can compete with steel products due to their high corrosion resistance coefficient. Their service life is 8 times longer than their analogues. Pressure products can be used to work with aggressive substances. They perform well in winter. They are not afraid of frost.
The pipes are high-strength, which means they can be laid under highways, and the installation depth can be quite impressive. Such a cast iron sewer pipe, the dimensions and GOST of which were mentioned above, can be socketed or have rubber seals.
Pipe dimensions and area of use
There are certain standards according to which the size of a sewer pipe depends on the area of its use. Thus, a pipeline with a diameter of 40–50 mm is installed in kitchen and sink drains, and 75–100 mm in diameter in the sewer leading from the toilet.
Dependence of diameter and area of use
Standard parameters depend on the volume of water that must leave the container in a certain time. For example, in an apartment in a multi-storey building there are standard toilets, from which a large volume of water along with waste must come out in a short period of time. Therefore, in most cases, for toilets, the diameter of plastic or cast iron pipes is chosen to be at least 110 mm.
Table on how to choose the internal diameter for a sewer pipe depending on the use of the outlet:
| For dishwasher, washing machine | 25 mm |
| For connecting pipelines to the drain of a bathroom, shower box, sink, kitchen sink | 32 mm |
| Ensuring the installation of a sewerage system in the premises | 50 mm |
| Installation of pressure pipes for external water supply, sewerage, drainpipes, selection of diameter for the toilet | From 110 to 200 mm |
If you have non-standard parameters of water supply systems, then before installing a sewer system you need to determine the relationship between the amount of wastewater and the rate of its discharge. For this, certain geometric parameters are calculated.
In addition to the fact that the correct diameter allows you to calculate the water drainage rate, pipe cleaning is also carried out taking this parameter into account. For example, the technology of sewer cleaning with Kärcher systems is now very popular, but they are used only on pipes with a diameter of 100 mm or more.
Advantages and disadvantages
The popularity of cast iron pipes for sewer installation is explained by their high wear resistance. The main positive qualities of communications include:
- long trouble-free service life, which reaches up to 100 years;
- environmental safety;
- noiselessness;
- possibility of installation in any soil without the use of additional protective boxes;
- possibility of installation at great depths;
- possibility of combination with modern plastic pipes;
- low cost of maintenance of communications after commissioning;
- resistance to temperature changes and low temperatures;
- a wide range of installation possibilities - socket connections, welding, using fittings or special clamps.
We recommend that you read: How to build a plasterboard box yourself to disguise pipes in a toilet?
The disadvantages of cast iron sewer pipes include:
- fragility;
- heavy weight;
- high cost.
Note! The fragility and heavy weight of cast iron pipes make them difficult to install and transport independently. When purchasing sewerage products for an individual home, you should choose pipes with a thin wall.
Cast iron socket products of class A or LA have sufficient strength for an individual sewer system.
Pipe calculation
To individually select a pipe for installation in houses, cottages or in the country, it is necessary to calculate the permeability. To calculate the useful pipe diameter (internal d), you need to know the following parameters:
- D – outer (external) diameter, mm;
- B – wall thickness, mm;
- m – mass of a linear meter of pipe, g (necessary to take into account the number and type of fastenings if a complete replacement of the pipeline is needed);
- S – cross-sectional area, mm2.
Formulas for calculation:
d = D – 2 b;
S = π/4 (D2 – d2);
V = S * L;
m = ρ * V.
Pipe sizes
Many manufacturers of polyethylene pipes mark most of the required parameters on the communication. But, as a standard, only the outer diameter (D) and wall thickness of the outlet are initially known. The most important parameter is the internal diameter; it is used to connect the pipe to the main and to lay out the sewer system, select additional elements, fittings, etc.
Manufacturer's markings on pipes
Moreover, unlike polypropylene plastic pipes, cast iron sewer lines are initially specified by the manufacturer with a useful internal diameter. Like steel, it is designated DN. It can have different values, in whole numbers, for example, DN 110 or DN 200. This means that this pipe has a nominal water drainage diameter of 110 or 200 millimeters, respectively.
Application of cast iron pipes
The scope of application of cast iron pipes is outlined by the characteristics described above.
And if you look closely at the acquired and “innate” qualities of such products, it becomes clear that cast iron pipes can be used in the following situations:
- When installing industrial pressure sewer networks
- During the construction of non-pressure domestic sewer networks
- When installing pressure or non-pressure pipelines in the food industry.
- In the process of constructing drainage channels on farms or poultry farms.
- During the construction of laboratory pipelines.
- In the process of constructing pressure water pipelines.
Moreover, the scope of application of cast iron pipes is influenced not only by their quality, but also by the presence (or absence) of a protective coating on the walls of the product. In addition, the scope of application of pipes also depends on the dimensions of the products.
Determination of nominal diameter
Regardless of the material from which sewer pipes are made and the scope of their purpose, they have the current standard dimensions:
- D – outer diameter;
- d – diameter from the inside;
- S – wall thickness;
- Dy – conditional pass.
The internal diameter sign is placed on the marking of cast iron products, while the external dimensions are most often indicated on plastic products. The external width of the product for all categories remains unchanged, only the wall thickness changes. For example, if a pipe has D = 33.5 mm, then S can vary within 2.8-4 mm. The level of strength of the product and resistance to internal and external pressure depend on the thickness of the walls. Fluid dynamics engineers, for all internal diameters, use one approximate figure of 25 mm and call it the nominal bore.
Conditional diameter is the maximum throughput of the pipeline. The efficiency and performance of the structure directly depends on its size. If you know the dimensions of the internal lumen, you can choose the right connecting elements so that the sewage system has a holistic appearance without the threat of depressurization.
All products of domestic and foreign production have a nominal diameter that is most suitable to the nearest standard according to GOST 28338-89 and GOST 3262-75.
Determination of nominal diameter
In addition to the sewerage capacity, it is also necessary to calculate its angle of inclination. These parameters directly depend on the size of the product and the material it is made of. Formula for calculating the angle of inclination: V× (H / D)½ ≥ K. Where:
V – speed of wastewater movement; H – degree of filling; D – outer diameter; K is the roughness value of the internal walls, for polymers = 0.5.
Pipe diameter with slope
The greater the slope, the higher the waste flow rate. The sewage system is less clogged and is able to serve a larger number of premises.
Some advice from experts:
Despite the fact that the riser is located vertically, it must have the largest diameter, at least 100 mm. This ensures unimpeded drainage of the maximum volume of wastewater. The outlet design should have a minimum number of turns to minimize the likelihood of clogging. Since it is in these places that hardening most often occurs. The recommended slope should not be less than 12 mm per linear meter. This applies to all categories of sewer pipes. If possible, a 90°C turn should be replaced with two 45°C turns, this reduces the likelihood of solid deposits building up inside the structure.
Compliance with generally accepted rules for organizing wastewater disposal guarantees uninterrupted functionality of the system. In modern projects, a hidden type of installation of the structure is increasingly being practiced. This means that if the installation is carried out incorrectly, difficulties will arise during repair work.
Technologies for installing cast iron pipelines
The assembly of cast iron pipelines is carried out by joining individual elements either into a coupling or a socket. Moreover, all products from standardized assortments end with bell-shaped thickenings. And shaped elements (couplings, tees, etc.) for assembling pipelines are manufactured in strict accordance with the standardized diameter.
Simply put, the standard diameters of cast iron pipes (from 50 to 150 mm and from 63 to 1000 mm) correspond to the dimensions of only one end of the product, since there is a socket on the opposite side of the pipe.
At the same time, cast iron pipes and fittings for them correspond to each other almost 100% . After all, the dimensions of the ends of the shaped elements are adjusted to the diameters of the sockets and smooth ends of the pipes. And the production of all connecting elements is carried out taking into account the special GOST 5525-88, which normalizes the range of such fittings.
And according to this regulatory document, there are 18 standard sizes of shaped elements, classified according to the nominal diameter of the end holes. The values of this diameter, in this case, vary from 65 to 1200 millimeters. Well, according to their functional purpose, the GOST 5525-88 assortment is divided into 31 types of products. Moreover, this number includes such types of fittings as cross, tee, bend, coupling, plug, and so on. Moreover, the ends of these shaped elements will be designed either in the form of a socket or a flange connection.
General information about the installation process of cast iron pipelines
As a result, any sewer system made of cast iron pipes can be dismantled and reassembled from old and new components. After all, all its parts are interchangeable.
Well, the process of assembling a cast iron pipeline is as follows:
- At the very beginning, we simply insert the smooth end of the next pipe into the socket of the previous one. Moreover, the bell must be directed against the flow of liquid.
- Next, the lower and upper pipes are fixed to the supporting surface. Moreover, the lower part of the pipeline is attached tightly, and the upper part with a gap that allows the pipe to rotate.
- After fixing, we have to start insulating the joints between the pipe and the socket. Moreover, the connection of cast iron pipes is fixed using a rather complex technique, which involves the use of an organic sealant - an oiled rope (cable). This rope is driven (hammered) into the joint between the pipe and the socket using a wooden wedge and a hammer.
- After embossing is completed, the upper pipe is fixed to the supporting surface as tightly as possible. And they begin to install the next section, inserted into the socket of the just fixed pipe.
The pipe is installed in the socket of the shaped element in a similar way. Or installation of a shaped element into a pipe socket. The quality of the connection will depend on the joint embossing procedure. Therefore, we will consider this method of arranging the connection of cast iron sewer pipes in as much detail as possible.
Chasing joints of cast iron pipes
To emboss a joint, we will need the following tools and materials: several meters of oiled rope (heel), a metal plate or a wooden wedge (preferably made of hard wood), a hammer or mallet.
The minting process itself is as follows:
- After installing the smooth part of the pipe into the socket, we must center the connection using special calibration plates inserted into the gap between the pipe and the socket. Such plates will move the pipes in the desired direction after they are driven into the gap. After calibration is completed, the plates are removed from the joint.
- Having calibrated the pipes, we can begin minting the seal. To do this, you need to roll the rope into a ring (around the pipe) and push it into the inside of the gap using a wooden wedge and a mallet. After immersing the first loop to ¾ of the depth of the bell, you can fold the second loop and repeat the entire procedure.
- As a result, the joint is considered “stamped” after the last loop no longer fits into the gap. In this case, we cut the rope and seal the joint (filled with cable) with cement mortar.
This method of fixation, despite the archaic nature of the process, makes it possible to obtain a fairly tight connection that is not inferior in strength and reliability to the best modern analogues (with rubber or silicone seals). The only disadvantage of this method of fixation is the complicated dismantling of hammered joints. Caulking joints is one of the most difficult operations in plumbing.
How to choose the right PVC pipes for sewerage
On the sketch of the future sewer system, it is recommended to indicate the length and width of the pipe, angle of inclination, connection points with plumbing, etc. Based on the drawing, calculate the number of plumbing fittings, connecting elements, fittings. Transfer the diagram to the walls and floor, double-check its meaning and calculations. After this, you can begin gating ditches for the structure. Their dimensions must match the diameter of the pipes.
How to choose the right PVC pipes for sewerage
The exiting private pipe must match the width of the riser into which it enters. In multi-storey buildings, the diameter of the main line can be either 110 mm or 200 mm, depending on the number of apartments in the building. If several houses are connected to an underground communication, the diameter can reach 300 mm or more. Underground connections are most often flanged, and above-ground connections are socket-type.
Positive and negative qualities
Today, cast iron pipes are installed in most sewer systems. The properties of these products allow them to be installed in any type of soil. The main advantages are:
- very high strength;
- not afraid of temperature changes;
- long service life;
- does not burn;
- meets modern environmental requirements, does not emit toxic substances;
- has excellent soundproofing properties;
- does not react with aggressive substances;
- not afraid of corrosion.
Unfortunately, in addition to such a large number of positive properties, cast iron products also have a number of characteristic disadvantages. Some factors greatly influence the labor intensity when installing a sewer system:
- large mass;
- increased fragility;
- installation requires special equipment and additional materials;
- very high cost;
- repair work requires large financial investments.
How to determine pipe sizes
Foreign-made polypropylene, polyvinyl chloride and other plastic communications are most often designated by inches. It may also be that you need to install fasteners on the pipeline, but its dimensions are also given in inches, while the pipe is indicated in mm.
Pipe inch thread
To do this, you need to convert the known inch dimensions into millimeter ones. According to the data, 1 inch is 25.4 mm. It turns out that a pipe with a diameter of 2 inches = 50.8 mm, etc. Fractional values are very often used, this is how clamps, fittings, couplings and communications are marked.
Let's look at their meaning in the table:
| In inches | In millimeters | In inches | In millimeters |
| 1/8 | 3,2 | 1 1/8 | 28,6 |
| 1/4 | 6,4 | 1 1/4 | 31,8 |
| 3/8 | 9,5 | 1 3/8 | 34,9 |
| 1/2 | 12,7 | 1 1/2 | 38,1 |
| 5/8 | 15,9 | 1 5/8 | 41,3 |
| 3/4 | 19 | 1 3/4 | 44,4 |
| 7/8 | 22,2 | 1 7/8 | 47,6 |
| 2 1/8 | 54 | 3 1/8 | 79,4 |
| 2 1/4 | 57,2 | 3 1/4 | 82,6 |
| 2 3/8 | 60,3 | 3 3/8 | 85,7 |
| 2 1/2 | 63,5 | 3 1/2 | 88,9 |
| 2 5/8 | 66,7 | 3 5/8 | 92,1 |
| 2 3/4 | 69,8 | 3 3/4 | 95,2 |
| 2 7/8 | 73 | 3 7/8 | 98,4 |
PVC pipes of different diameters
But, when measuring a socket manually, for example, with a ruler, the nearest minimum size is always taken. For example, the diameter in millimeters of a sewer pipe for a sink is 34. It turns out that the outer diameter is 1 ¼ inches. Be careful when selecting sizes, otherwise you will have to buy additional spacers or adapters. But the coupling is selected based on the nearest larger indicator, i.e., 34 mm will be considered 1 3/8 inches.
Video: Joining pipes of different diameters in the sewer system.
Steel two-way communications may have different indicators on different sides; you need to double-check the data. This can be done by experimental measurements with a caliper or plug gauge.
Table: Diameters of ceramic pipes
More information about cast iron pipes
Gray cast iron is used by manufacturers to make domestic sewerage pipes. The surfaces of such products are coated with anti-corrosion bitumen both inside and outside. It becomes soft when the heating temperature exceeds 60 degrees.
The presence of cracks and the appearance of air bubbles on such a coating is prohibited. It has a smooth and very durable surface. Moreover, the solid surface of the bitumen should not stick to the pipe wall. It is strictly forbidden to have traces left from transportation devices.
The presence of dents and drips is not allowed. The quality of the product is checked on special technological stands directly at the production site that produces cast iron pipes.
The tightness test is carried out by visual inspection of the pipeline section after it is filled with water under a pressure of about 0.1 MPa. The joints should not have leaks. External surfaces must be free of fogging.
If there are no such defects, the product is considered sealed. Overall dimensions are checked with special reference instruments. Deviations from the nominal value must be within acceptable values. To determine the mass of the pipe, it must be weighed. When purchasing such a product, the consumer can check it for compliance with any verified indicator.
The pipes have markings that are located directly on the socket. It is applied with indelible paint. Sometimes it is cast together with the pipe. The marking must have:
- product icon;
- GOST numbers;
- release article.
Finished products can have very different packaging:
- containers;
- cassette;
- packages;
- bundles secured with wire.
The sockets are laid in different directions. According to regulatory requirements, manufacturers are required to produce products:
- with a guaranteed shelf life of 3 years;
- with a service life of 2 years.
List of sewer fittings
Only fittings are capable of combining pipes of different types and sizes. Used to connect branches and when turning a structure. The reliability of the system's sealing depends on correctly selected connecting parts.
| Name of the connecting element | Functionality |
| Tee 110×110 mm | Large fitting, used to connect to the central riser and toilet. |
| Reduction 110×50 mm | A special type of fitting that connects pipes with a diameter of 50 mm to a diameter of 110 mm. |
| Bends | Elbows designed to change the direction of pipelines. Suitable for all sewer sizes. Can be installed at an angle of 90° or 45°. |
| Tees | Several pipes are connected into one system. Can be all sizes identical or different. |
| Audit | Designed for places with an increased risk of contamination, equipped with special removable covers. |
| Stubs | They are selected for a certain pipeline diameter and installed at the ends. |
Features of installation and docking
During installation, special attention is paid to the joining of products. In order to achieve an ideal result, you should prepare the putty without wood waste and impurities. Before filling the socket with an asbestos-cement mixture, it is necessary to fill it with tarred hemp strands. Then it is rolled up into a rope and caulked into the slit of the bell. You must act carefully.
The thickness of the strand should be greater than the width of the slit, the length should be such that the strand fits into the socket 30 mm from the edge. To obtain a mixture of cement and asbestos, mix 400 grade Portland cement and asbestos fiber. These ingredients are mixed in a ratio of 70 to 30.
Before use, the mixture is moistened by adding water in a volume of 12% by weight. The joining of shaped parts to cast iron pipes is carried out by sealing the gaps that appear between the inner surface of the socket and the shaped part or the end of the pipe. When installing a pipe, the direction of the socket must be ensured in the opposite direction from the movement of the liquid.
