Discussions - Sessions 1-6

Mr. J. Kuik (Ethylene Plastique): Would polypropylene co-polymer pipes have a longer service life compared to the homo-polymers? If so could this explain the fact that British pipes seem to be made from co-polymers?

Dr. W.F. Mueller: The difference between them is the impact resistance and this is also fixed in different specifications and also in the newest ISO documents, It depends in which case you are using the homo-polymer or the co-polymer. For instance, I know some examples from the chemical industry when people have said we prefer, for instance, the homo-polymer with a little bit higher stiff ness, concerning installation and another department perhaps of the same company saying we prefer the co-polymer because we are anxious concerning impact resistance.

Mr. Coad (Melbourne Board of Works): Those pressure ratings that you quoted in your table how were they derived? mathematically or dimensionally?

Mr. M. Littlewood: These dimensions are taken from International recommendation, or | believe it is now elevated to the position of International Standard number 3, which is a series of preferred numbers these are the so called Renard numbers which are widely used in a variety of different selection of tables for mathematical numbers, they are basically geometrical progressions of numbers and you will see roughly that the increase in these values are in steps of, for example, 50% in an RS series of 25% in an R1O series or 12*%2% in the case of an R20 series, but these numbers are all detailed in ISO standard number 3.

Mr. Sprecher (Owens Corning Fibreglass Europe, Brussels): Considering that extruded thermoplastic large diameter pipes could be considered as flexible pipes could Dr. Mueller outline for us some precautions that should be taken during installation procedure, and also the impact on economics.

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