7 Tips For Choosing PVC Pipes For SewerageAugust 30, 2018
Our century, many scientists call the era of plastic. The polymers created by mankind are used absolutely in all spheres of life, often showing themselves much better than traditional materials. A vivid example is the arrangement of a sewage system. Another couple of decades, there was simply no alternative to cast-iron pipes. Today they are actively replaced by polyvinylchloride analogs, which are not susceptible to corrosion, do not overgrow, weigh less, and are cheaper. The excitement around such products can be understood. It remains only to figure out how to choose PVC pipes for sewage, and what their features are important to take into account when operating.
№1. What are the PVC sewer pipes?
Often PVC pipes are called simply plastic, which is not entirely true. Plastic pipes – this is a whole group of products, where you can also include polypropylene pipes, pipes made of cross-linked polyethylene and, in fact, pipes made of polyvinyl chloride (PVC). The latter is made of polyvinyl chloride thermoplastic, which also includes special additives, which provide additional strength to the product. Pipes from the prepared mass are created by extrusion, they keep the shape well.
Depending on the characteristics of production, there are two types of PVC pipes:
- Pipes made of plasticized PVC (PVC) are notable for their low price, good elasticity, but they can not boast of high strength. Such pipes for the organization of separate sites of the water drain;
- pipes made of unplasticized PVC (PVC-U) are more expensive, but also more rigid, resistant to all kinds of external influences, perfectly suited for the arrangement of internal and external sewerage, provide sufficient durability of the system. Such pipes can be used even in pressure sewers.
PVC pipes are actively used in the arrangement of internal and external sewerage, they are also used to install a cold water system, to create drainage systems, when laying cables for the Internet and telephony. Such a wide scope of distribution is a consequence of the huge number of advantages of this type of product.
№2. Pvc pipes: advantages and disadvantages
Before choosing anything, every sane person weighs all the pros and cons. Sewage pipes will not be an exception.
Advantages of PVC sewer pipes:
- democratic value. The arrangement of sewerage with the help of PVC pipes will cost several times cheaper than the organization of the same pipeline of cast iron;
- resistance to corrosion. Plastic does not rust, unlike the same cast iron, which means that PVC will allow creating a more durable sewerage system;
- the resistance of both external and internal surfaces to aggressive environments;
- high tightness. Since the material is not afraid of corrosion and other negative factors, you can not be afraid that the underground pipe will lose its integrity, and wastewater will fall into the ground;
- a smooth inner surface minimizes the probability of overgrown pipes and their obstruction by fecal fractions ;
- resistance to low temperatures. Polyvinylchloride pipes are not deformed even with prolonged exposure to negative temperatures;
- lightweight, which greatly facilitates the transportation and installation of PVC pipes;
- sufficiently high strength and environmental safety;
- durability. Manufacturers speak of a service life of up to 50 years ;
- plastic does not conduct wandering currents, and this is another plus in terms of your safety;
- a huge selection of pipes of different diameters and lengths, there are also a sufficient number of adapters and mounting elements, so installing a sewer system from PVC pipes is a relatively simple task.
There were no shortcomings:
- sensitivity to high temperatures. The maximum working temperature for PVC pipes is +40 0 C. The products withstand heating to +80 0 C, but such impacts should be rare and short-lived. With prolonged contact with hot liquids, the material loses a number of useful performance characteristics and quickly breaks down;
- polyvinylchloride pipes behave better than cast-iron ones, but in time, even on their smooth walls, plaque begins to form. With a regular, albeit short-term exposure to high temperatures, around the tube starts to transform into an elliptical tube. All this in combination can lead to a reduction in capacity or even the formation of leaks, so it is important to follow the rules during the installation and operation of pipes;
- low fire resistance;
- Despite the fact that manufacturers say that PVC is completely inert to aggressive substances, individual compounds can still corrode the walls of pipes. For the sake of justice, we note that such compounds are usually not found in domestic sewer systems.
No. 3. The Main Types Of Pvc Sewer Pipes
Polyvinylchloride pipes are used for laying internal and external sewerage, are used under different conditions, therefore manufacturers offer us several types of products that differ not only in performance but also in appearance.
For the arrangement of sewage the following types of pipes are used:
- Hard gray pipes are used for laying internal sewerage. The thickness of the walls varies from 1 to 3.2 mm, the diameter varies from 32 to 160 mm, and the length of the segments ranges from 0.3 to 3 m;
- hard orange pipes are designed for laying the outside of the sewer. The diameter of such products ranges from 110 to 500 mm, length – from 1.2 to 3 m, and the walls have a thickness of 3 mm. These pipes are strong enough to withstand the load of the soil. They have a small expansion coefficient, so they are not able to deform strongly even with a significant temperature difference. Between each other, individual sections are connected by a bell-like method;
- Corrugated sewer pipes of gray color and small diameter are used for connection to the sewerage of washing machines and dishwashers. Two- and three-layer orange pipes are used for external sewerage. They are strong enough and elastic, withstand decent loads, can be mounted to a depth of up to 15 m. Such strength properties are achieved due to the presence of numerous stiffeners. Corrugated pipes are also used for laying rain sewage systems, the arrangement of drainage pipelines.
№4. Class of strength of PVC sewer pipes
About what the load can withstand the PVC pipe, says its strength class. This information is most needed when it comes to pipes for external sewerage. Strength and resistance of the pipe to external pressure indicate the depth to which it can be buried, without being afraid for its integrity.
There are three classes of a strength of sewage pipes:
- light pipes ( SN2) withstand pressure up to 630 Pa, have a wall thickness of up to 2.3 mm. Such pipes are used inside the apartment, buried at a shallow depth (up to 2 m), and where there are not expected to be heavy loads, for example, under the lawn, flower garden, pedestrian zone and in other places where there is no traffic load;
- pipes of medium gravity ( SN4) have walls 2.5-12.3 mm thick, withstand pressure 600-800 Pa, can be used for laying under the road part with a small load, depth 2-6 m;
- heavy pipes ( SN8) with a wall thickness of 3.2-15.3 mm withstand a load of 800-1000 Pa, are designed for laying under roads with heavy traffic, buildings. The maximum depth is 8 m.
In the most difficult areas, naturally, it is better to use unplasticized PVC pipes that can withstand pressures up to 1.6 MPa.
№5. Pressurized And Non-Pressure Sewerage System
The pressure on the pipes can be provided not only from the outside but also from the inside. Depending on how the flow is organized, the pressure will be different. There are non-pressure sewer systems when the drains move by gravity. In a similar way, the sewage system in the apartment works. Also, water flow in a private house is organized when the site is on a slope. On the main sewer pipes, the drains move under pressure. In a flat area, drains to the septic also have to be forcibly driven. In this case, we can not do without pressure equipment, the work of which will expose the pipes to an additional load.
The type of sewage system leaves an imprint on the choice of PVC pipes:
- for non-pressure internal sewage pipes with a wall thickness of 1.8-3 mm are suitable, plastic pipes are used. For non-pressure external sewer take pipes with a wall thickness of 3.2 mm (for a diameter of 110 mm) to 12 mm (with a diameter of 500 mm);
- pipes for pressure sewage are made of unplasticized PVC. Such products, depending on the wall thickness, can withstand a pressure of 0.8-1.6 MPa. The wall thickness varies from 2.2-6.6 mm for a pipe 90 mm in diameter to 12.3-23.9 mm for pipes with a diameter of 500 mm.
№6. Size of sewage PVC pipes: diameter, thickness, length
The selection of the diameter of the sewage pipe is a matter of increased importance. If you take pipes less than what is required, they will not provide enough bandwidth. What this means, probably, should not be explained. At best, the wastewater will go badly, at worst – in some places they will start to go outside. For fear of encountering similar consequences, many decide to be reinsured and take pipes with a diameter significantly higher than required. Efficiency compared to pipes with a properly selected diameter will increase insignificantly, but the cost and area to be allocated for these pipes, greatly increase.
Before going for a purchase, it is necessary to draw up a scheme of the sewage system and mark on it all the points of the discharge of the liquid. The larger the drainage points, the larger the drainage pipe. However, when selecting pipes, it is necessary to take into account not only their diameter but also the length, as well as the wall thickness.
In order to properly select the diameter of a sewage PVC pipe, ideally it is necessary to calculate the expected volume of waste, but this calculation is often neglected using the parameters checked by millions:
- pipes from the shower, bath, washbasin, and bidet can be 40-50 mm in diameter;
- for kitchen sink – 32-50 mm;
- for the toilet – 110 mm;
- for dishwasher and washing machines – 25 mm;
- central riser – 110-160 mm;
- pool – 200-300 mm.
The diameter of the sewer pipe that leaves the apartment must be at least the diameter of the common highway. For houses up to 5 floors, pipes are 110 mm in diameter, for tall buildings – 160-200 mm. External sewage can not have a diameter of less than 110 mm, which must be remembered in the arrangement of the sewage system of a private house. As a rule, pipes in a diameter of 110-200 mm are used in suburban areas and in out-of-town houses to equip the outside of the sewage system. If a sewer system is being built to service several houses, it is better to take a bigger diameter – about 315 mm. Pipes with a diameter of 630 mm are suitable for equipping the main sewerage for servicing a small village.
The thickness of the walls depends on the loads on the pipes. For internal pressureless sewage pipes with walls, 1,2-2,2 mm will suit. They have a diameter of up to 110 mm and belong to the strength class SN2. The SN4 pipes are the most widespread. They are used for the arrangement of both external and internal sewerage. Such pipes with a diameter of 50 mm have a wall of 2.6 mm, with 110 mm – already 3.2 mm. Suitable for the organization of a common house riser, as well as external non-pressure drainage in a private house. If it is necessary to equip the pressure sewer, it is better to take pipes with the thickest walls (class SN8). With a diameter of 90 mm, the wall thickness is 3-6.6 mm.
The choice of length depends on the length of the pipeline. It is better to keep all connections to a minimum, but unnecessarily long pipes should not be bought – it is economically unprofitable, and inconvenient. Usually, PVC pipes are sold in sections of 0.5 m, 1 m, and 2 m, but you can find products with a length of 3 m and 0.3 m. Some manufacturers offer pipes with a length of 6 m and even 12 m, it is convenient to equip them with external sewerage.
Remember that the junction points of the individual sections are the most dangerous, so try to make the installation so that the connections are as small as possible. Here, a competent preliminary calculation will help. In which case the length of the pipe can be reduced using a hacksaw for metal.
With the help of PVC pipes, it is possible to assemble a sewage system of any complexity. Not only different diameters of pipes come to the rescue, but also all kinds of adapters, swivel bends, tees, crossings, reducers, plugs, etc.
№7. Features of installation of PVC sewer pipes
If you have certain skills, then you can manage the installation of internal sewerage yourself, because the main advantage of PVC pipes is the ease of installation. The sequence of actions will be as follows:
- Prepare all pipe sections and connecting elements, if necessary, sign them, so as not to confuse them later;
- PVC pipes are connected by the socket method. Before starting the installation, it does not stop to check whether the ends of one pipe enter the socket of the others. Ideally, the pipe should easily go into the landing slot for 2/3;
- then the connection itself follows immediately. The end of the pipe is lubricated with glue and injected into the socket. To glue better, you can scratch the surface of the pipe a little before the appearance of small scuffs. Once the glue is applied, a connection is made, and a small force will be required to fully insert the pipe into the socket;
- tees, crosses and other elements are mounted exactly according to the same scheme;
- do not forget about the bias necessary for gravity drainage. The smaller the diameter of the pipe, the greater the angle of incline is needed. For pipes with a diameter of 40 mm, the slope should be 3.5 cm per running meter, for pipes 50 mm – 3 cm, for 80 mm – 2 cm, for 100 mm – 1.5 cm. The slope is formed by means of clamps that are mounted to the wall;
- when the glue dries (indicated on the package), the system is checked for leaks;
- Do not discard the remains of pipes – you can make useful things from them.
If the existing sewerage system in the apartment is being repaired, then first it will be necessary to dismantle the old cast-iron pipes. Before this, it is necessary to warn the neighbors from above so that they do not temporarily use sewerage. It will be necessary to act quickly since such inconveniences are unlikely to be tolerated for long. In the sections of cast-iron pipes, rubber sealing cuffs are inserted, an adapter and a tee are installed.
The outside of the sewer is best entrusted to professionals. It is important to correctly perform the thermal insulation, provide for inspection wells, create a sand pillow, take care of the slope of the pipes and the correct angle of rotation of the knees. Details of the installation of internal and external sewage can be seen in the video.
Of course, polyvinylchloride sewer pipes will not last for centuries, but from what the market offers us, it is almost the most durable option, and if you take into account the cost, performance, and ease of installation, PVC pipes can be considered the best option for sewerage.