JEC COMPOSITES MAGAZINE - Issue #85 - November/December 2013 - 21

More green energy in Sri Lanka
The flourishing small hydro power
industry in Sri Lanka saw a further
green accomplishment in the south of
the country approximately 2 km from
Dehilanda in Wellawaya at the river
Kuda Oya. With a capacity of 1.2 MW
and approximately 5.7 GWh output
per year, which will be fed into the
national grid of Sri Lanka Water, the
hydropower plant will supply about
6000 households. The owner, the private company Wellawaya Hydro Power
Pvt Ltd., opted for a sustainable and
environmentally sound penstock solution using Hobas CC-GRP pipes.
Environmental considerations played
a crucial role in the decision making
process for the best suitable pipe
material. "Since the plant is situated
Year of construction
Construction time
Total length of pipe
Diameter
Pressure class
Stiffness class

2011 - 2013
18 months
1460 m
DN 700 - 1100
PN 1 - 12.5
SN 5000
and 10000

Curved alignment of the hydropower
plant penstock Sokolna in Bulgaria

of joints with angular deflected or angular cut pipes,
stringent tests to ISO 8639
have been conducted at the
TÜV and governmentally
(ISO 17025) accredited
TechCenter in Wietersdorf,
Austria.

in the jungle, we wanted to make sure
to protect flora and fauna as best possibly. We decided to bury the penstock
because it would have otherwise
crossed and divided animal trails,"
says Roshan Prabatha Wickramasinghe, Director of Wellawaya Hydro
Power Pvt Ltd. As it was possible to
optimally adapt the line to the terrain,
only a 3-metre-wide section had to be
cleared for trenching. The tested and
approved method of angular deflection accommodated in the couplings
and angular cut pipe ends reduced the
number of necessary bends.
The construction of the 1460-m-long
GRP pipeline leading to the turbine
at a head of 95 metres began in 2011.
Hobas delivered pipes designed for
different pressure classes ranging from
PN 1 to PN 12.5. While gravity pipes
were utilized for flatter parts of the
route, pressure pipes were installed in
Head
Capacity
Installation method
Client
Designer

Apart from the pipe system
itself, external factors play
an equally decisive role and
need to be carefully checked
to verify if curved installation is suitable for the
respective project. Drawing
from numerous laboratory
tests and more than half
a century of experience,
Hobas experts provide support for such feasibility studies and make sure that each
project receives a hydraulically and economically optimized pipe solution. Special
attention also needs to be

95 m
1.2 MW
Open trench
Wellawaya Hydro
Power (Pvt) Ltd.
Munex (Pvt) Ltd.

especially steep sections, where the
comparably light pipe material considerably benefited pipe transportation
and handling. Some parts were in fact
so steep that a mechanically operated
winch had to be employed to pull the
pipes to the trench. This would have
proved very difficult if not impossible
with other pipe materials which are by
far heavier.
After 18 months construction time,
the pressure test was conducted and
successfully passed so that the plant
could be put into service. Shrubs and
trees were quickly replanted along the
backfilled trenches so that soon there
will be no trace of construction works
and nature can take its usual course.
Not only is the operator content with
the result but also the villagers: Apart
from electricity, locals received the
opportunity to be trained to operate
the hydropower plant.
Construction
company
Advantages

paid to the correct installation of the line, that should
always comply with the individually prepared method
statement by Hobas and
with the latest respective
standards. For underground
constructions, appropriate
pipe trenching and bedding,
soil conditions (groundwater interference, soil type,
etc.) and field conditions
(slope, traffic, frost heave,
etc.) need to be ensured. For
penstocks mounted above
ground, the saddle design
and the fixation of the pipe
or coupling need to be taken

No85 November - December 2013

Dolphin Marine Lanka
(Pvt) Ltd.
Environmentally sound
solution, easy handling
thanks to light weight,
long service life

into consideration. During
every project phase, Hobas
experts will provide support
and know-how.
The approved long life, low
maintenance and outstanding hydraulic properties
of Hobas GRP pipes will
bring out the best of every
hydropower plant in terms
of safety, efficiency and
profitability - to stay ahead
of the curve. n
More information:
www.hobas.com

/ jec composites magazine 21
http://www.hobas.com
JEC COMPOSITES MAGAZINE - Issue #85 - November/December 2013

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