Integral structural elements of the sewer system are pipes. Since external sewage pipes must withstand both static and dynamic loads, special requirements are imposed on them.
Pipes of PVC for the external sewerage perfectly cope with the task. The main thing before buying is to correctly select the optimal size and take into account a number of nuances in the installation process. This is what we will be talking about in our article. Separately, we highlight the main advantages and disadvantages of PVC pipes, we indicate the main characteristics by which they differ from other polymer pipes.
We also describe the features of connecting the pipes to each other during the assembly of the sewer pipeline and pay attention to the laying rules.
What are PVC pipes made of?
In the installation of both aboveground and underground sewer systems, polyvinyl chloride pipes are rightfully considered to be leaders among similar polymer products.
The basis for the manufacture of polyvinyl chloride cylindrical products is the eponymous thermoplastic. It is advantageous in that it retains its shape after heat treatment and extrusion.
Due to the high quality characteristics, polymer pipes for domestic use have almost irrevocably displaced metal and concrete analogues
The two main components of polyvinyl chloride are ethylene and stabilized chlorine.
In order to improve the operational parameters of products during the manufacturing process, various additives are added to thermoplastic compositions.
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Polyvinyl chloride pipes are actively used in the construction of all types of sewer pipelines: in laying a domestic sewage system, drainage and stormwater
In the construction of external sewer lines laid in the ground, pipes of a red (orange) color are used. They are designed to resist ground weight and external loads.
Lines leading sewer drains from private houses and baths are built from PVC pipes. Their only drawback is the weakening of the strength during transportation of water more than + 80ºС, and this temperature is unusual for domestic wastewater of any category
When selecting pipes from polyvinyl chloride for the construction of external sewer lines, you should focus on the group for stiffness. In the range of plastic products, there are positions for arranging branches with a traffic load
Sewer system of any kind without problems can be assembled with your own hands on the site. Technological material is easy to cut and join
For plastic pipes, an extensive range of connecting parts, tees, crosspieces, corners, adapters is produced, allowing you to mount any type of shutoff valves
It is permissible, but undesirable to arrange ventilation risers made of PVC products. Sun rays act destructively on PVC products
PVC pipes do not rust, do not oxidize, do not give in to aggressive groundwater, do not collapse in the ground with an acid or alkaline background
Pipes for laying underground utilities
Color of PVC pipes for underground installation
Polymer pipe connected to a septic tank
Laying in place of transport load
Assembling a plastic pipeline in the area
Use of fittings and fittings
Inappropriate use of PVC pipes
Piping in an aggressive environment
Advantages and disadvantages of PVC products
Polyvinyl chloride after processing under the action of high pressure at the outlet forms an ultra-strong composite compound. And therefore, products from this polymer have many advantages.
These include:
- Affordable cost. In comparison with concrete and cast iron counterparts, the price of polymer products is relatively low, which makes them affordable for any consumer.
- High performance. Corrosion does not form on the walls of polymer pipes. Products are resistant to aggressive environments. Due to the smooth inner surface, deposits are not formed on them and no growths are formed.
- Light weight products at a fairly high level of strength.
- Easy installationnot involving the use of special equipment.
- A wide variety of mounting elements. This greatly simplifies the design of branched complex pipelines.
Polymer pipes are frost resistant. So, with complete freezing, provided that there is no water in the pipeline, it does not even undergo cracking. The service life of polymer cylindrical products over half a century
It is convenient to install polymer pipes as well as to dismantle them if necessary, which is also relevant, taking into account the specifics of their use
High rates of corrosion resistance give the go-ahead for the installation of polymer pipes underground. And this factor is key, since 90% of sewer pipelines run there.
With strict adherence to the installation technology, even when the groundwater level changes, polymer structures are not displaced in the area of the docking nodes, thereby minimizing the risk of system depressurization.
The only drawback of polymer pipes is their low resistance to UV rays and temperature limits from -10 ° C to +65 ° C. Direct contact with UV rays reduces product performance. In this regard, they lose to steel and cast iron counterparts, which ultraviolet can not cause harm.
Main types and sizes
Depending on the conditions of use, PVC pipes are available in three versions, which correspond to the main sizes:
- SDR51; SN-2; S25 series - products of light type are laid under the sidewalk, green zone and in places where no traffic loads are expected.
- SDR41; SN-4; S20 series - middle-type products are chosen for laying in places where the traffic is not so great.
- SDR34; SN-8; S16.7 series - heavy type products are chosen for laying in industrial areas and places with a saturated traffic flow.
Pipes used for laying external pipelines are one-, two- and three-layer. In the latter embodiment, the inner layers of the product are made of foam material with a porous structure, which is obtained by recycling. And the top layer is from primary unplasticized PVC.
The most common when laying on the street were two-layer corrugated pipes. The outer layer of such products has a corrugated surface with stiffeners. Thanks to this, the corrugation acquires increased strength.
The inner surface of the profiled products created by the extrusion method is ideally smooth, which minimizes the resistance of the walls during the advancement of drains
Both walls of profiled products are made simultaneously. Due to the fact that they are connected by the "hot" method, the finished cylindrical products are a holistic design. The cavities formed between the inner and outer walls facilitate the weight of the structure, and the wavy wall on the outside gives the necessary ring stiffness.
If we take the class of ring stiffness as the basis for the classification of polymer products, then PVC pipes are of three types:
- "L" - light pipes for laying in ditches, the depth of which does not exceed 0.8-2.0 meters.
- "N" - medium-hard products are designed for laying to a depth of 2-6 meters.
- "S" - rigid with a maximum wall thickness that can be laid in trenches up to 8 meters deep.
The parameter of ring stiffness of products is indicated by the abbreviation "SN". It is a significant quantity because it determines the initial deformation during laying and lateral support.
In the private construction sector, products of the stiffness class “SN2” are most demanded, which can be laid in trenches up to 2 meters deep
In systems involving forced drainage, where pumping equipment is involved, pressure PVC pipes are installed. The basis for their manufacture is unplasticized polyvinyl chloride PVC-U, which is famous for the highest possible performance.
The main difference between pressure pipes is that they can withstand significant loads on the walls. On sale there are three types of pressure pipes that can withstand pressure of 6, 10 and 12.5 kg / cm2.
In gravity-type sewer systems, the movement of wastewater is effected by gravity. For the arrangement of such systems, ordinary PVC pipes are used, created on the basis of a simpler PVC polymer. The temperature range of these products is from 0 ° C to +45 ° C.
The depth to which it can be laid directly depends on how rigid the polymer pipe for sewage has
The size range of PVC pipes for outdoor sewage is also quite wide:
- 110 mm - products of minimum diameter are designed for the discharge of domestic wastewater in suburban construction.
- 315 mm - pipes of this size are used if necessary to build a common sewer system that unites several houses.
- 630 mm - pipes of maximum diameter are used for the construction of a general settlement sewage line.
Cylindrical products are produced in segments of 500/1000/2000/3000 / ... 6000 mm. Some sizes can be produced in twelve-meter segments. We talked about the characteristics of PVC pipes in more detail in this article.
Competent selection criteria
When choosing sewer pipes, they are guided only by two parameters: wall thickness and internal diameter of the product. The mechanical strength of the product largely depends on the wall thickness.
The inner diameter of the polymer cylindrical products must fully correspond to the predicted volume of effluents that will fill the pipeline
For internal sewerage, PVC pipes painted in gray are used. When arranging gravity systems, the wall thickness of such products should be at least 1.8 mm.
For an outdoor gasket, which involves more stringent conditions, choose orange and yellow shades. In such products, each size corresponds to its own indicator of wall thickness.
As an example, we give the correspondence of parameters for pipes D 200 mm:
- SN2 - for light conditions with a depth of pipe laying within 2 meters, pipes with a wall thickness of 3.9 mm are selected.
- SN4 - for medium hardness conditions with a pipe laying depth of around 4 meters, products with a wall thickness of 4.9 mm are selected.
- SN6 - for severe conditions, with a pipeline laying depth of up to 6 meters, pipes with a wall thickness of 5.9 mm are used.
In addition to products of orange color for laying external sewage, you can use polymer pipes painted in red-brick color. Which sewer pipes do you prefer? This is the issue we examined in detail here.
The main thing is to take into account the surface load and maximum working pressure when choosing products, and withstand the slope of the pipeline during installation
Corrugated pipes designed for external sewage have dimensions on the outer diameter in the range from 160 to 630 mm, and in terms of nominal diameter - from 139 to 542 mm. They are available in the form of six-meter segments. The ring stiffness parameter of the product is SN8 or SN16.
Difference of PVC products from other polymer pipes
Polyvinyl chloride is far from the only polymer used in the manufacture of pipes.
Along with it, these types of plastic are also used:
- RE polyethylene - plastic is used to create pipes designed for transporting cold water.
- RE-S cross-linked polyethylene - polymer has temperature limits of the order of +95 ° C. And therefore it is used both for cold and hot water. It is famous for its resistance to mechanical stress and UV radiation.
- PPE polypropylene - characterized by good chemical and mechanical resistance.
- PVDF - Semicrystalline thermoplastic, which is famous for its resistance to the effects of a chemical environment. It is mainly used in the pharmaceutical industry for the transport of drugs.
- PB polybutylene - cross-linked polyethylene. It is produced in small quantities, because it is not very durable.
Many of these types of plastic pipes can compete with PVC products, but polyvinyl chloride pipes do not have competitors in terms of the range of advantages and the price-quality ratio.
Features of mounting an external PVC sewer
Pipes made of polymer are famous for their ease of installation. To create a pipeline based on PVC pipes and fittings, no special tools are required. Yes, and work on the assembly and laying of the pipeline can be performed even by a novice master.
Methods of connecting products
PVC sewer pipes can be connected in one of two ways:
- Glue - involves connecting the elements by applying to the fittings a special adhesive composition.
- Bell-shaped - involves joining the elements by deepening the straight sections in the sockets, pre-treated with sealing compounds.
The adhesive joint, also known as "cold welding", allows for 100% tightness.
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PVC sewer pipes for gluing
Glue application on the processed surface
Bonding PVC parts
Rules for joining plastic parts
With the adhesive mounting method, compositions are used that are methods of “welding” adjacent to each other elements at the molecular level.
When joining pipes with shaped elements, one end of the nozzle is coated with silicone grease and inserted into the socket until it stops. Docking of elements is performed manually.
To be able to make a socket connection at one end of the products, an expansion is provided, the inner walls of which are supplemented by a rubber sealing ring
Basic laying rules
The key to the smooth operation of the sewer system is strict adherence to installation technology. And laying polymer pipes is no exception.
When constructing an external PVC pipeline, it is important to observe a number of basic rules:
- At the bottom of dug trenches, a cushioning "pillow" should be laid. Crushed-sand sanding will help protect the pipes from damage that may occur due to seasonal movements of the soil.
- Pipes must be laid at a slope towards the intake manifold. The slope angle largely depends on the diameter of the pipes and can vary from 2 to 15%.
- If necessary, change the direction of the collector apply taps of 15-30 °.
- When laying the external pipeline, inspection hatches are installed for every 15 meters.
When backfilling a pipe laid in a ditch, the soil is tamped only from the sides. There is no need to ram directly over the highway.
For thermal insulation, molded material is used in the form of a “shell” made of foamed polyethylene or rolls of fabric, which require winding in place
If it is impossible to deepen the polymer pipes to the required depth, they should be insulated.This is especially true for products made of unpolymerized polyvinyl chloride, as they become fragile in the cold.
An important point: after the pipeline has been insulated, it is necessary to re-measure the angle of inclination and, if it meets the norm, proceed with the final filling with earth.
In addition to choosing high-quality pipes for external sewage and their proper installation, it is equally important to choose the best pipes for arranging the internal sewer system and install in accordance with the norms and rules.
Options for sewer pipes and fittings:
Subtleties and nuances of installing a sewer pipeline:
With a competent approach to choosing products and observing the installation technology, the life of the pipeline will be commensurate with the duration of the "life" of the house itself.
Do you have an external sewage system made of PVC pipes and want to share your experience in installing and operating the system? Or maybe you noticed a mistake in the material presented or want to supplement our article with valuable comments and recommendations? Write your comments, ask questions, share your opinion in the block below.