Types of drainage pipes

Just a few decades ago, problem of choosing the type sewer pipe did not arise - steel or cast-iron pipes and fittings are purchased usually. But now everything has changed - the building materials market offers a wide variety types of pipes for drainage systems, and their main characteristic can be called the manufacturing material. The pipes and fittings can be divided into several types:

Steel pipes - for a long time this pipes and fittings for drainage systems are used in heating systems and water supply systems, but for installation of drainage systems they was used more rarely because the steel is nonresistant to corrosion;
Cast iron pipes - this pipes for decades was the main typies of pipes when installing drainage systems. Now cast iron systems is fast-growing in the market, because they have a long service life - up to 80 years;
Plastic pipes - they was used for installation of domestic and outdoor drainage systems only recently, but very quickly they gained popularity due to high capacity which is provided by the smooth internal walls, and flexibility, so they are not damaged even when the deformation coefficient exceeds of 3 %.

Features cast iron pipeline systems

Manufacturers produce several types of cast iron drainage pipes:

Pressure pipes with socket (CPS);
Pipes with are made of cast iron with nodular graphite (ductile iron);
Socketless SML systems;
Non-pressure pipes (CD - cast iron drainage pipes).

Pressure pipes with socket is most often used when installing of underground and ground drainage systems, and they are characterized by durability, also they can withstand high pressure - up to 16 bar, so that they can be used in heating systems. Most often the pressure pipes are used at industrial facilities.

Cast iron raw materials for ductile iron is improved by adding magnesium - it ensures the absence of cracks on the pipeline. Other advantages of ductile iron are:

Anti-corrosion properties;
High bending strength;
Frost resistance (characteristics of ductile iron do not change at temperatures up to -60 °C);
Endurance under the influence of aggressive environments;
Low breakdown susceptibility.

Non-pressure pipes are suited for systems which do not suffer extreme stress: they are recommended for domestic drainage systems of low-rise residential buildings and industrial facilities.

SML systems have one important difference from other types of cast iron equipments for drainage systems - the internal walls are covered by special epoxy layer, which eliminates the probability of formation of deposits. This prolongs the service life of the pipeline and reduces the risk of clogging.

Cast iron pipes are not recommended for installation of drainage systems in areas with saline soils or with weak ground.

Types of plastic pipes and fittings

Plastic (polymer) pipes and fittings are gaining in popularity because they have indisputable advantages. All drainage pipes and fittings of the polymers can be divided into several types:

Polyethylene;
Polypropylene;
PVC.

Polyethylene pipeline is made of high-strength polyethylene, and manufacturers produce the conventional, and two-layer, and corrugated pipes. Plastic pipes are characterized by:

Excellent flexibility;
High capacity;
High ring stiffness.

However, they have a drawback - the presence of high linear expansion under the influence of temperature. Also this type of pipeline equipment is suitable for disposal effluents with temperature no higher than +40 °C. Accordingly, PE pipes should not be used for installation of the hot water supply systems.

HDPE pipes are made of high density polyethylene. This type of pipeline equipment has the following advantages:

Durability;
Corrosion resistance;
Low thermal conductivity;
Resistance to water hammer;
Operation of the pipeline at temperatures down to -70 °C;
Low weight;
Resistance to aggressive environments;

HDPE pipes have disadvantages. Thus, they lose their properties under ultraviolet light. Also they have low mechanical strength and low resistance to high temperature - the material begins to soften at temperature +80 °C and it melts at temperatures above +105 °C. However, manufacturers produce pipes which are made of cross-linked polyethylene that can withstand temperatures up to +400 °C.

Polypropylene pipes are the most common among the different types of plastic equipment for drainage systems. They have the following advantages:

Long service life - up to 100 years;
High temperature resistance – PP pipeline can be used for the disposal of effluents with temperatures up to +100 °C;
Flexibility, so that they are deformed without breaking under the influence of mechanical factors;
Resistance to alkalis and chemicals;
Diffusion resistance;
Environmental security.

Drawbacks of products from PP includes:

Low resistance to UV radiation;
High elasticity, which is why the installation of pipes under ground requires thickening of the walls.

Installation of PP pipe should be at temperature not below +5 °C, but some manufacturers add to the raw low-temperature plasticizers, so that the pipes can be installed at temperatures down to -10 °C.

PVC products are used for installation of gravity drainage systems, ie those systems in which wastewater moves by itself due to small deviation of pipes, as well as the weight of the waste masses. The main advantages of PVC products include:

Resistance to UV light;
Strength;
Resistance to aggressive environments.

However, there is a significant drawback this type of pipeline equipment, which is why it is not recommended to use when installing domestic drainage systems - if ignited PVC pipes release toxic gas phosgene into the environment

Features of multilayer pipes

Multilayer pipes consist of several layers, and internal layer is made of plastic which increases capacity due to absolute smoothness of the internal walls. Also the smoothness of the internal walls reduces the likelihood of deposits.

The external layer is made of cross-linked polyethylene, and the middle layer is made of aluminum. All elements are connected together using glue mixture. So that the pipeline is resistant to internal and external influences.

The main advantages of multilayer pipes:

Resistance to aggressive environments and corrosion;
Ease of installation;
Low weight;
The pipes can be bended, so that you can reduce amount of connecting elements when assembly;
Noise abatement;
Resistance to mechanical damage;
Long service life (about 50 years).

Multilayer pipes have several drawbacks, and one of the main is low resistance to temperature extremes – it can result to stratification of glue mixture. Also multilayer pipes are inflammable materials.

When choosing drainage pipes and fittings you should give special consideration to material from which they are made - it determines the service life of the pipeline and the cost of its installation.

Published At: 14.07.2015

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