PVC pipe and fittings technology
PVC
was discovered as early as 1835, but the first definite report of the
polymerization of vinyl chloride did not come until about 35 years later. At
that time, the material was reported to be an off-white solid that could be
heated to 130 degrees C without degradation.
PVC
remained a laboratory curiosity for many years, probably because of its
intractable nature. The polymer was inert to most chemicals and very tough
(strong). These properties eventually led scientists to consider PVC for
applications where durability and toughness were desirable.
In
1912 the first industrial developments were initiated in Germany. Throughout
the 1920’s, attempts were made to use PVC copolymers that were easier to process
than PVC. These early attempts were only marginally successful.
By
1932, the first tubes made from a PVC copolymer were produced. Nearly three
years later the first PVC pipes were produced using a roll mill and hydraulic
extruder. This two step process involved melting the PVC powder on a roll mill
and rolling the sheet produced up to a billet. The PVC could then be processed
in a discontinuously working ram extruder to make pipe. This process was
adapted from that used for celluloid and was really ill-fitted for PVC. As a
result, the products were often of dubious quality.
Never-the-less,
these early PVC pipes were deemed suitable for drinking water supply piping and
waste water piping because of their chemical resistance, lack of taste or odor
and smooth interior surface. From 1936 to 1939 over 400 residences were
installed with PVC drinking water and waste pipelines in central Germany.
Various test pipelines of PVC were laid in Leipzig, Dresden, Magdeburg, Berlin,
Hamburg, Cologne, Heidelberg and Wiesbaden during the period of 1936 to 1941.
Both
the pipelines for chemicals and those for water supply and waste water came up
to expectations, as did the test pipelines in the cities mentioned above, apart
from damage caused by World War II. The PVC pipes installed in central Germany
are still in use today without any major problems.
In
retrospect, these first PVC pipes had been made before their time, before the
material compounds and machines for their manufacture had been perfected. It
was not until 1950 that the systematic development of extrusion technology
began. Prior to this, the manufacture of PVC pipe remained makeshift and the
use of PVC pipes did not become widespread.
The
1950’s and 1960’s were decades of dramatic advances for PVC pipe and fittings
technology. Encouraged by the results obtained from primitive pre-war PVC
pipelines, several European and American companies realized the enormous
potential for PVC pipes. These companies pursued the technology, both in
formulation and processing. Systematic research and trials were successful in
the development of effective stabilizers, lubricants and processing aids,
together with processing machinery engineered specifically for PVC. During this
time period, PVC pipe began competing with traditional products in a number of
major markets, such as: gas distribution; sewer and drainage; water
distribution; electrical conduit; chemical processing; and drain, waste and
vent piping.
World demand for plastic pipe is projected to rise 6.7 percent
per year though 2019 to 19.3 billion meters, according to a new study by a
research group
Strong construction activity, particularly in the large markets
of China and the United States, will boost demand as plastic pipe sees
intensive use in both building and non-building construction applications.
Plastic’s performance, cost, and installation advantages will also spur its
increasing use over competing pipe materials such as concrete, copper, and
steel. PVC is the leading resin used in plastic pipe.
The energy, agriculture, and industrial sectors tend to be less
intensive users of plastic pipe than construction. However, improvements in
technology and plastic materials have helped plastic pipe increase its share in
many of these markets.
Although construction spending will decelerate in China, the
world’s largest plastic pipe market, demand for plastic pipe in the country
will still rise over nine percent annually through 2019, according to
Freedonia. In the U.S., the world’s second-largest market, continuing recovery
in construction spending and housing completions will support rapid advances
for plastic pipe demand.
Growth in plastic pipe demand will also be robust in the
developing countries of Africa, Asia, and South America due to efforts to
expand access to potable water and sewage systems. According to Freedonia Group
analyst Mariel Behnke, “The market opportunity for water and sewer systems is
large, as a considerable share of the population in these regions does not have
reliable access to drinking water supply or improved sanitation.” The
comparatively low cost and ease of installation of plastic pipe gives it advantages
over other pipe materials in these regions.
Advances in plastic pipe demand in the more developed regions of
Eastern and Western Europe are expected to accelerate through 2019, supported
by recovering construction spending. Demand in both regions contracted
following the global economic recession, but began to recover in 2013.
No comments:
Post a Comment