PEX pipes

PE-Xa Pipe Uponor
PE-Xa Pipe (photo: Uponor)

Former: VPE = Vernetztes Polyethylen
Today:  PEX = Polyethylen crosslinked (X-linked)

We distinguish between 4 different methods:

  • PE-Xa = with peroxide (Engel, PAM, Fränkische, etc.)
  • PE-Xb = with Silane (Dow Corning/Sioplas)
  • PE-Xc = by electronic irradiation
  • PE-Xd = with AZO (Gustavsberg-Lubonyl) now extinct

Degrees of cross-linking

Contrary to popular belief, the degree is not a quality hallmark but has to be in tune with the material and method, therefore the suggested minimum is

  • 70% in PE-Xa (formerly 75%)
  • 65% in PE-Xb
  • 60% in PE-Xc (and PE-Xd)

PE-X (cross-linked Polyethylene) pipe systems are among the most robust piping systems currently on the market. PE-X material is created through cross-linking of PE-HD (high density Polyethylene) which itself is already well suited for potable water distribution pipe. The cross-linking process forms a chemical bond of molecular carbon chains in form of a 3-dimensional network. Thus stabilized, even high temperatures applied over a long time as well as mechanical and chemical stress don’t have negative impact on the operating life of PE-X pipe systems. For their industrial scale production, 3 main cross-linking methods are well-established. Since the differences between these methods are so significant, they are described in detail in chapter 2.) To achieve all other requirements for potable water distribution systems besides mechanical strength, special processes have to be considered depending on the cross-linking method. Particularly to ensure good organoleptic properties (the impact of the piping material on odor and taste of the foodstuff potable water) the chemical cross-linking methods Xa and Xb need special treatment. Those considerations have to be taken into account when calculating manufacturing costs for all PE-X types properly.

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