va tech hydro in india - ANDRITZ Vertical volute pumps

STALDEN
Our customer Kraftwerke Mattmark
has relied on VA TECH
HYDRO’s products and services
for more than forty years.
Already in 1992, when coating of hydraulic
components was still in its
infancy, VA TECH HYDRO was
awarded a contract to coat runner
C of Stalden power plant using
SXH48. Coating of runner E was
performed in 1995 with the improved
SXH52 material. Runner B fol-
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TECHNOLOGY
Protection of Pelton Runners against Sand Abrasion in Switzerland
lowed in 1999 using state-of-theart
SXH70 coating.
Today, SXH70 is the leading coating
material to prevent abrasive
wear of hydraulic power generation
units. It consists of tiny, ultrahard
tungsten carbide particles
embedded in a corrosion-proof
cobalt-chrome matrix and is applied
in a layer of 0.3 mm by
means of a thermal spraying
process.
Uncoated runner (left) after one year/4,500 hours of operation and coated runner (right)
after five years/17,286 hours of operation.
Stalden power plant (Valais, Switzerland): 2 horizontal double Pelton units.
The coating is suitable for use in
arenaceous water, in particular if it
comprises minerals of a hardness
of more than 5.5 on Mohs’ scale.
These include quartz (6), plagioclase
(6.4), feldspar and albite (6)
or hornblende (5.5). At Stalden the
sand concentration during the
summer months ranges between
0.2 to 0.3 grams per litre on an
average and reaches maximums of
2 grams per litre. Previously, uncoated
runners had to be refurbished
at Stalden by local re-grinding
once a year because of
excessive wear. Every two years,
the runners had to be shipped to
Kriens for general revision during
which the buckets were again given
an acceptable shape by welding,
heat treatment and grinding.
The SXH70 coating, applied for the
first time to cast runner B, allowed
for uninterrupted service of the