TPI April 2009

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April 2009 Tube Products International 55
projects. Plastic tubes are gaining ground in the areas of
sanitary, air conditioning and heating technology, and are
increasingly displacing the traditional materials.
n How do the tubes differ, depending on their different areas
of use?
Generally, plastic tubes differ in the plastics used and in their
construction, profile, also known as design (ie the diameter,
wall thickness, etc). In the area of supply and waste disposal,
you will find mainly tubes of polyethylene (PE) and polyvinyl
chloride (PVC), and increasingly in recent years, polypropylene
(PP). Using the extrusion process, the plastics, which come
as granulates or powder, are first heated and plasticised, so
they can be shaped into tubes. These tubes can be made
of a single material (homogenous solid-wall tubes) or such
with two or multiple layers. Because of this, it is possible to
configure tubes that comply specifically with the respective
requirements of a certain medium and the external stresses in
the underground environment.
n Which special criteria must plastic tubes fulfil?
Plastics and plastic tube systems must comply with various
quality specifications, depending on their area of application,
so they can be used accordingly and answer to multiple
and varying demands. To this end, there are approval or
prototype tests for the plastics as well as for the various tube
systems. In addition to statutory requirements according to the
European product standards, there are added requirements
by authorities and users. In Germany, the Deutsches Institut
für Bautechnik (the Institute for Structural Engineering) grants
building inspection permits to manufacturers. Only after
receipt of such a permit may producers install their products
on private land. Specifications for potable water and gas
tube systems are listed in the technical regulations of the
Deutsche Vereinigung des Gas- und Wasserfaches (DVGW)
(German Association of the Gas and Water Industry), while
specifications for tubes for other uses are subject to the
certification programme under DIN Certco.
n Are there quality certificates for plastic tube systems?
As construction products, plastic tube systems must comply
with high safety standards. There are many marks in Germany
and Europe, however these marks do not necessarily speak
of the quality of the products. CE labelling for the plastic
tube industry is still pending in Europe. Once the statutory
requirements for the issuing of the CE-mark are fulfilled,
manufacturers are required to label their products accordingly.
However, the CE label is no guarantee of quality, but rather
an administrative label used for free movement of goods in
Europe. In Germany, users of plastic tube systems should pay
attention to the DVGW label (gas and water), the official ‘Ü’
mark and/or the DINplus mark, depending on the intended
use. Products with those labels can be used without worries.
n Do plastic tubes have advantages over concrete or steel
tubes?
All materials and the tubes made thereof have specific
characteristics. Compared to concrete or steel tubes, plastic
tubes are fairly new products, however their market share is
increasing. Publications of the DWA (Deutsche Vereinigung
für Wasserwirtschaft, Abwasser und Abfall eV, the German
Association for Water Management, Waste Water and
Waste) and the DVGW (Deutsche Vereinigung des Gas- und
Wasserfaches, German Association of the Gas and Water
Industry) show this. Plastic tubes are increasingly being
used in nominal diameters, which used to be the stronghold
of concrete and steel tubes. This is mainly due to the
advantageous characteristics of plastic tube systems. They
can be installed easily and inexpensively, last a long time
(about 100 years), are good when it comes to maintenance
and repairs, and can be used very well to remedy existing,
defective tube systems.
n Sustainability: What are the features of plastic tubes in this
regard?
Plastic tube systems are long lasting and can be recycled
at the end of their lifespan. In addition, a scientific study
confirmed that sewage pipes made of plastic offer better
ecological performance. Upon the initiative of the KRV and
the Europäischer Dachverband der Kunststoffrohr-Industrie
(TEPPFA), the European Association of the Plastic Tube
Industry, a study on environmental risks in communal sewage
systems was carried out. ‘Study of the performance of
different tube systems or tube materials for municipal sewage
systems with special consideration of the ecological effects
during the period of use’ by Prof Dr-Ing Stein & Partner GmbH
also included the cooperation of an external European expert
committee. According to Stein & Partner, the study, under
consideration of the limitations of the analysed data to pipes
with a maximum age of 30 years and a maximum diameter
of 800mm, concluded that “ sewage systems using bendable,
soft tubes show significantly better ecological performance
because of lower damage rates and risks with regards to
infiltration and exfiltration.”
n What are the current trends in plastic tube engineering?
Plastic tube systems are becoming more diverse and more
powerful. Further development of plastics and improved
production or process technology allow for products and
solutions tailored to specific demands. This leads to the fact
that the areas of use for plastic tube systems are expanding.
Further advances are expected in the area of remediation
of existing, defective sewage and potable water networks.
Here, the technological and economic advantages of plastic
tube systems are brought to bear. We also expect rising
demand for plastic tube systems in mechanical services for
buildings. There are many options in this area. In Germany,
there is more refurbishment than new construction. This
offers great opportunities for our products. As of late,
the technical pre-requisites for installation of gas pipes in
residential construction have been met. This offers excellent
opportunities for this sub-segment. Indeed, Germany’s future
lies with a functional infrastructure. This also includes the
creation of fibre optic networks. Plastic tube systems are
excellently suited for this purpose. The fibre optic strands
require long-lasting protective tubes, and the creation of the
supply networks still needs to happen in Germany.
Interview supplied by Messe Düsseldorf GmbH
Kunststoffrohrverband eV Fachverband der
Kunststoffrohr-Industrie – Germany
Messe Düsseldorf GmbH – Germany