Oesterholt, Scholten, Roebers
# 2001 Munich
Worldwide more and more buildings are connected to natural gas. Until recently the gas within the building was exclusively distributed through metal pipe systems, such as straight copper pipes, soldered together and straight steel pipes, screwed together. About six years ago some pilot projects with PEX (crosslinked polyethylene) piping systems in domestic buildings were started in the Netherlands. These projects are still in operation and no problems have occurred up to this moment. Subsequently other projects followed and nowadays the use of plastic (and multilayer) pipes in The Netherlands is common indoor installation practice. In this paper the suitability of PEX, PEX/Al/PEX and PE/Al/PE pipe systems for indoor gas installations with respect to technological aspects is discussed in more detail. Next to the technological suitability, the suitability of these systems also depends on other aspects, such as safety and economical aspects. These items are addressed as well. When it comes to the technological suitability of flexible pipe systems containing plastic, these can be divided into physical, chemical and mechanical aspects. The systems made of PEX, PEX/Al/PEX and PE/Al/PE are all suitable with respect to these aspects, as far as the system requirements are met. In The Netherlands these pipe systems have to meet the requirements written down in the relevant GASTEC QA Approval Requirements. A very important aspect to cover is the resistance against odorant permeation. Summarised, the following conclusions can be drawn from the results of the extensive research programme on the permeation of odorant, carried out by Gastec : • In the case of multilayer pipes consisting of PEX-aluminium-PEX and PE-aluminiumPE the permeation of odorant through the pipe wall is zero. Pipe systems made of these pipes are therefore suited for use in indoor gas installations, as far as the resistance to odorant permeation concerns. • In the case of PEX pipes containing an EvOH layer, present in or as a coating on the outside or inside of the pipe, the permeation of odorant through the pipe wall is negligible. Pipe systems made of these pipes are therefore suited for use in indoor gas installations, as far as the resistance to odorant permeation concerns.