TPi September 2016

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46 Tube Products International September 2016
products & developments
20 years of surface
protection for
steel pipes
The introduction of GRP coating for
steel pipes 20 years ago, marketed as
the BWB system, was a success story
for BKP Berolina. Since then, more
than 110,000m of gas pipes (DN 100
to DN 1,400) have been coated with
this special and highly resistant GRP
coating.
The BWB system contains resin-
impregnated glass fibres tangentially
and axially wound on the PE coated steel
pipe. Meanwhile an environmentally
friendly and styrene-free resin is cured
by using UV-light. The coating protects
the steel pipes from being damaged
by obstacles in the soil when being
installed by horizontal drilling or similar
methods that might cause corrosion.
The on-site protection of welded
joints is applied by attaching glass
fibre mats combined with resin and
cured by UV-light. The BWB system is
not sensitive to the pulling direction,
giving the contractor more flexibility
when putting the pipeline together, and
avoiding mistakes on-site. In the case of
stuck drillings, pulling back the pipeline
is still an option as far as soil and
equipment conditions allow it.
In 1995, the first test was performed
in cooperation with the former Wingas
GmbH. A special
testing device
was developed
to determine the
mechanical level
protection. The
results showed
that the protection
of a steel pipe
coated with the
BWB system is three times better than
a polypropylene coating and eight times
better than a polyethylene coating.
BKP Berolina replaced the formerly used
styrenated resin with an environmentally
friendly and styrene-free resin. For
special applications where the pipeline
is winched into an existing host pipe, in
2011 the company developed additional
GRP spacers already applied with the
BWB coating.
The advantages of these 50mm-thick
spacers were demonstrated during
the exchanging of a gas pipeline near
Schlüchtern, Germany, last summer.
On a section of the MIDAL (Mitte-
Deutschland Anbindungs-Leitung) – a
connecting gas pipeline in the centre
of Germany – some divergences in
the galvanic protection had been
determined through routine monitoring.
The PE-spacer rings had caused
damage in the PE-coating of the existing
pipeline. The affected section had to be
removed and replaced by DN 800 BWB
system-coated pipes with additional
GRP spacers.
To winch the 90m-long pipe section into
a DN 1,200 casing tube, a 40mm-thick
steel rope was pulled by an 80-ton winch
through a 45° deviation. Michael Muth,
manager at Gascade Gastransport
GmbH, commented, “The BWB system
combined with the factory-installed
spacers withstands any situation and
proved its reliability by 100 per cent.”
BKP Berolina Polyester GmbH & Co
KG – Germany
Holding the 90m-long pipe section in the right position
DN 1,200 casing tube (black), and BWB-coated steel pipe (green) with
GRP spacer (brown)
The target pit, close to a highway ramp