Polyethylene (PE) as pressure pipe material. Its classification
In recent times, the importante of Polyethylene (PE) plastic pipes in the design of public networks, private and industrial water supply, sanitation and gas pressure has considerably increased. This trend confirms the confidence in the PE as pipe material, mainly due to increased knowledge and experience about it which actually exists worldwide.
Most plastics are derived from oil therefore, it can be interested to know how to distribute oil consumption in the in the world. Just 4% of oil is used for plastics manufacture, while 96% is “burnt” in transportation, heating etc. Besides, plastic products are recyclable, allowing us to have several lives, while “burnt” material becomes smoke and it no longer comes back.
Townships require that pipes lifetime used in its infrastructure is at least 50 years, in order to redeem 2% annually. PE pipes have a safety factor after 50 years of 1.25, which means that the total period is much higher, talking that last PE generations reach 100 years.
When subjecting them to mechanical stresses, plastics tend to plastid-deformed (cold flow), such as occurs with metals at high temperatures. To determine the limits of plastic pipes resistance subjected to constant loads, should be studied to determine its mechanical behavior over a long period, which you have to set the resistance curve regarding timing for (reference curve) according to the standard:
– UNE-EN ISO 9080:2003 Plastics piping and ducting systems. Determination of the long-term hydrostatic strengh of thermoplastics materials in pipe form by extrapolation.
PE is obtained by ethylene polymerization by subjecting it to pressure and temperature. At reactors outlet PE is a fine white powder, where additives are added to improve light and heat resistance, then transforming into pellets by Extrusion.
Since PE pipes were firstly introduced, about 50 years ago, it has significantly increased its market in pressure piping, as above mentioned. The reason for this increase should be found in the PE pipe properties, such as corrosion, flexibility, weldability, chemical resistance and fast and easy joining techniques, which provide an important cost saving.
PE raw material used in pressure pipes manufacture, must be certified therefore, it must comply with part 1 of the standard:
– UNE-EN 12201: 2012 Plastics piping systems for water supply, and for drainge and sewerage under pressure. Polyethylene (PE).
Founded on Feb. 24, 1999, the PE 100+ Association is an industry organisation of several polyethylene (PE) manufacturers whose objective is to promote consistent quality at the highest level in the production and the use of polyethylene for PE100 pipes.
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