By Thomas Huelsmann, European
Vinyl Corporation (Deutschland)
and Reinhard E.Nowack,
ALPHACAN Omniplast
18” pipe being installed in Varennes,
Québec, in 1967.
Today, PVC-U pipes are used in
a wide variety of applications,
such as sewage, potable water,
drainage and gas. In these areas
plastic pipes often replace traditional
materials and by 2000, the polymer
consumption for pipe production had
grown to about 2.5 million tonnes in
Europe.
The roots of
industrial PVC
pipe production
date back to the
1930s. The first
pipes were produced
in 1934 in
the Bitterfeld-
Wolfen chemical
industry area.
These pipes
were used for
different applications
such as
potable water
pipes, transparent
food contact pipes (brewery applications)
as well as industrial pipes
(chemical laboratory and plant applications).
The annual pipe production
capacity reached about 550 tonnes in
1941.
In parallel to the increasing production
volumes, the first norms for plastic
pipes were developed and products
were made to meet these new standards.
Although the plastics industry is a
rather young materials segment, production
of industrial volumes of PVC
polymer and PVC-U pipes is now
about 70 years old. This is a period
very close to the predicted service lifetime
of 100 years for PVC pipe applications.
This 70 years long-term experience
permits a comparison to be
made between the theoretical lifetime
of pipes (based on extrapolation of
results from long-term hydrostatic
burst pressure tests of up to 10,000
hours with the application of safety
factors), with real life experience and
actual test results.
After the reunification of East and
West Germany in 1989 and the
involvement of Omniplast with pipe
production in Bitterfeld, it was possible
to excavate and test PVC-U pipes
from the early production years, as
they were still in use in 1992/1993.
A comprehensive series of tests on
several of these old pipes was carried
out in the 1990s against the current
norms. The results provide an excellent
database to compare the data from the
original pressure tests with actual
results from 60 year old pipes.
This is not only an interesting
reflection of the history of PVC pipe
production and application as well as a
confirmation of the long-term performance
predicted
60 years
ago, but it is
also an important
contribution
to future
PVC pipe developments.
Beside the
data from the
Bitterfeld pipes,
the report also
includes data
from PVC pipes
produced at
Troisdorf in the
1930s and tested
in the 1960s after 25 years of use.
The comparison shows that the
actual performance of the pipes has
comfortably exceeded the performance
predicted by the long-term pressure
tests more than 60 years ago. The conclusions
which can be drawn are that
the extrapolation of 10,000 hour pressure
testing is, in fact, very conservative
and that the actual service life of
PVC-U pipes is likely to be more than
double the original 50 year design life.
The article above is a summary of a
presentation being made in April at the
13th World Pipe Symposium in Milan,
Italy.
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