The plastics industry is over 100 years old, but polyethylene was not invented until the 1930s. Since its discovery in 1933, polyethylene (PE) has grown to be one of the most widely used and recognized thermoplastic materials in the world. Today’s modern PE resin is highly improved for much more rigorous applications such as high pressure gas and water pipes, landfill membranes, automotive fuel tanks and other demanding applications.
Polymers that consist only of carbon and hydrogen are called polyolefins. Polyethylene (PE) belongs to this group. It is a semi-crystalline thermoplastic. Polyethylene is the best known standard polymer. The chemical formula is (CH2-CH2) n. It is an environmentally friendly hydrocarbon.
TYPES OF PE MATERIALS
The physical properties of PE materials are specific for each grade or type and can be modified in variations in density and in molecular weight distribution. A large number of grades of polyethylene materials are used in pipe systems and fittings and the specific properties are tailored for the particular application.
The most general types of PE materials are listed below.
LOW DENSITY PE (LDPE)
The density of LDPE varies between 0.910 and 0.940 g / cm3 and exposes great flexibility and retention of properties at low temperatures. The major use of LDPE in pipelines is in micro-irrigation or in irrigation drip tube applications with measurements up to 32mm in diameter.
LDPE materials can be modified with elastomers (elastically modified) to improve environmental stress crack resistance (ESCR) values in micro-irrigation applications, where pipelines operate in unprotected environments while carrying agricultural chemicals.
MEDIUM DENSITY PE (MDPE)
The MDPE based resin is manufactured using a low pressure polymerization process and the structural chain with limited lateral branching results in a material with a density range between 0.930 and 0.940 g / cm3. MDPE materials are rated PE63 and PE80.
MDPE materials provide pipes with improved properties when compared to older high-density materials used in pipes.
These properties include life, flexibility, ductility, resistance to slow growth and crack propagation. These properties of MDPE materials are used in gas networks, small diameter pipe coils, mobile irrigation coils, and water network applications.
HIGH DENSITY PE (HDPE)
HDPE based resins are produced in a low pressure process, resulting in a structural chain with small lateral ramifications and a material density range between 0.930 and 0.960 g / cm3. HDPE is rated as PE80 or PE100 according to ISO4427.
HDPE is widely used in pressure and non-pressure applications, such as water supply, drains, drains and sewers in pipes up to 2500 mm in diameter. The increased stiffness of HDPE is used to take advantage of applications such as electrical and communication conduits, subsurface drains, sewers, and surface water.
FIELDS OF APPLICATION
FIELDS OF APPLICATION
Drinking water pipe networks for water supply to cities and municipalities.
Gas distribution networks.
Storm water drainage.
Pipe networks for swimming pool installations.
Pipe networks for heating and air conditioning. HDPE VASEN pipe systems and fittings are used in geothermal applications.
Pipe networks for irrigation.
Transport of suspended solids in the mining industry, etc.
- Light weight.
The density of the pipe and fittings is only 0.93-0.96 g / cm3. The weight of HDPE pipe is much less than that of concrete, iron or steel. HDPE piping systems are easy to handle and install and the reduction in labor and equipment requirements can result in installation savings.
In some cases the flexibility of the pipeline could significantly eliminate the use of fittings and greatly reduce the cost of installation. HDPE pipe can be bent to a minimum radius between 20 and 40 times the pipe diameter, which depends mainly on the SDR of the pipe.
- Chemically inert and good resistance to corrosion.
HDPE VASEN pipes and fittings have excellent corrosion resistance against most chemicals in drinking water, irrigation, sanitation and drainage systems. HDPE is anticorrosive and does not rust in the long term.
- Odorless and tasteless.
- Electrical insulator.
HDPE is an electrical conductor and does not deteriorate, rust or corrode by electrolytic action.
- Good thermal insulator.
- Low coefficient of friction.
- Abrasion resistance.
The high abrasion resistance, flexibility, light weight and robustness of HDPE VASEN pipes and fittings has led to its wide use in applications such as transportation of mining waste.
- Ease of installation and union.
By electrofusion or butt welding.
- Long useful life.
When the working temperature is 20 ° C, its useful life is 50 years.