Design & Testing
Plastic Pipes Conference Association # 1998 Gothenburg
Plastic Pipes have been successful now for over 60 years. The first pipes with solid wall designs were used for pressure applications. Example: In the city of Berlin, the buried drinking water PVC pipes installed in private housing areas during 1935 are still in use.
Test methods and Standards in the early years were drafted on the basis of the pressure resistance of both the material and long term performance requirement. Non-pressure pipes and fittings followed during the years and their Standards today still tend to follow these early pressure design requirements. Example: Pipe series and wall thickness of these non-pressure pipes are sometimes still linked to pressure and not to stiffness design.
More than 20 years ago, the first structured wall pipes in cormgated single wall designs entered various markets, the products design depending more on process possibilities than application needs. They have been very successful in the low-demanding land drainage field. A further development was a twin wall version of this pipe with the advantage of smooth inner wall which was applied successfully in storm water and farm and forest use.
In the early years it was only in France that structured wall pipes were successful in the field of sewer applications. Here the solid wall PVC pipes were changed to pipes with a foamed core, but the system was kept unchanged.
All these pipe designs depended more on process possibilities and economical effectiveness rather than on the demands from the field of application.
This changed, when, more than 10 years ago, Ultra Rib entered the market, designed with focus on the demands of 100 years of usage in the field of municipal sewerage. Based on this quality level, this pipe system has entered the sewer market worldwide for structured wall pipes. Now all the others are trying to tollow.
A Standard for structured wall pipes has now been under discussion for more than 15 years; first in IS0 and continued in CEN. A first draft will now be sent out for voting ' , field of application is the area of Municipal Sewerage. Bearing in mind, that CEN - Rules prescribe EN Standards are not to exclude existing products, one question is important: Are the requirements in the standard sufficient for the demands of sewerage applications with 100 years life time expectancy?