May 2003 ISSUE TONGBAI Page 4/5 COMPACT HYDRO in ...

steels with yield points from 355 to 550
MPa and quenched and tempered
S690Q steel. The total weight of
VA TECH HYDRO’s scope of deliveries
comes to some 2,012 tons. The whole
construction time, including tunnel excavation,
is only 33 months. During
most of the time the power plant has to
be kept operative, and it will be shut
down for the last nine months of construction
only. During this rather short
time, all civil works, pipe installation
and paint work necessary for connecting
the new power conduit with the remaining
structures, have to be completed
– a real challenge for all parties
involved in the project. Installation of
the steel tunnel lining commenced in
July 2002. It started with a section at
the downstream end of the inclined
shaft, followed by parallel work towards
the upstream tunnel portal and the
powerhouse. In the inclined shaft 12 m
pipes are installed. For transport reasons,
however, only 6 m pipes can be
prefabricated. These sections are
transported from the powerhouse to
the upper valve chamber by means of a
cable car, running parallel to the existing
penstocks. In the area of the valve
chamber, and directly on top of the upper
tunnel portal, a temporary winterproof
workshop has been installed.
There, the 6 m pipes are assembled and
welded to form erection units of a
length of 12 m. For welding the field
joints inside the tunnel once again the
fully automatic TIG-HW welding technique
is applied. This technology was
adapted by VA TECH HYDRO for steel
tunnel linings and was successfully
used for the first time in the Goldisthal
project in Germany. In the light of an accident,
which recently occurred in a hydropower
plant in Europe, highest attention
is paid to material, welding and
quality assurance. The client has
placed special and very strict reguirements
for welding and non-destructive
testing. But there is no doubt that all
these conditions are met to the full satisfaction
of the client. VA TECH HYDRO
subcontracted manufacture of the
pipes to the Linz facility works of MCE
VOEST, and, for capacity reasons,
some parts to another MCE daughter
company. MCE VOEST, our traditional
partner in the field of hydromechanical
equipment, is executing the installation
under the overall responsibility of
VA TECH HYDRO. All activities are well
in time and the contractual completion
in June 2004 is secured. With this contract,
VA TECH HYDRO sets another
milestone in its history of high-head
penstock construction.
Roland Starnberger
Phone +43/70 6987 8805
roland.starnberger@vatech-hydro.at
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