GENERAL INFORMATION ON CROSS LINKED POLYETHYLENE 02
02_03
All aforementioned methods achieve the same results in PE-X pipes and meet the DIN 16892/16893 and the recent European EN ISO 15875-1/2 standards. Their only difference lies in the cross-linking degree specified in the DIN and EN standards. 70% for method –a, 65% for method –b, and -60% for method –c. For example, a pipe with a cross-linking degree of 68% that has been produced using method –a does not meet the specifications, while a pipe with the same cross-linking degree produced by method –b does. The Como-pex pipes of Interplast are produced using the –b method. It is a method that has managed to improve the characteristics of Pex pipes since the fact that cross-linking degree continues over time, which is considered as a huge advantage, leading as such to exceptional properties of the product during its use. Furthermore, -b method pipes, in varying degrees of cross-linking, are more homogenous in their behavior.
The applications of plastic pipes are so common in our daily life that these types of pipes have come to replace conven- tional pipes on a large scale. One of the most important breakthroughs is their use in hot water networks. The raw materials used are polypropylene (PP) and cross-linked polyethylene (PE-X) produced from a special composition of high density polyethylene (HDPE). In HDPE, a reaction is induced in the double bonds, so that many of them get connected and by the help of silane molecules, a three-dimensional homogenous network is created of high molecular weight. The final product (cross- linked polyethylene) has excellent performance at high temperatures combined with high pressures, has improved resistance to impact and to chemicals and has a longer lifespan. Today, 40 years after their first applications and based on their successful history, Pex pipes are constantly growing in demand gaining a significant market share.
Characteristic is the ever increasing demand of method –b in the markets, with ever increasing trends in the recent years compared to cross-linked manufactured products of the other alternatives.
GLOBAL CONSUMPTION IN TONS PEX
PE-X OVERALL
AREA
PE-Xa
PE-Xb
PE-Xc
Europe
24.000
38.000
20.000
82.000 11.100
Middle East
1.300
8.000
1.800
& Africa Russia
200
4.000
4.200
North America
9.000
14.000
23.000
Cross-linking methods
South America
5.000
5.000
3.000
20.000
23.000
Asia (Pacific)
The most common cross-linking methods used in industrial production are:
Total:
37.500
89.000
21.800
148.300
Consumption 2007, Source: Pex Association
Peroxide method or Pex-a method
Silane method or Pex-b method
Radiation method or Pex-c method
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