Sulzer is the leading worldwide,
independent service provider
for the repair and maintenance
of rotating machines including
turbomachinery, pumps and
electro-mechanical equipment.
Although more
common in Europe, radial turbines are
also used in marine applications due
to their relatively compact dimensions,
compared to an axial turbine with a
similar power output. Their design means
that they are limited to a maximum
output of approximately 30 MW, making
them more suitable to small industrial
generating sets rather than power
generation for the grid.
In-depth assessment
Initially, the customer contacted
Sulzer asking for assistance with
investigating a vibration issue on
the steam turbine. Working with the
customer, the Sulzer team examined the
vibration data and also conducted a visual
inspection of the rotors during a brief
shutdown period.
Analysis of the inspection showed that
the RH rotor had helical linear cracks
on all of the steam inlets, both rotors
had excessive steam seal clearances
and both of the rotor couplings would
need to be replaced. Due to the design
of the turbine, the only way to repair
the steam inlets would be to completely
remanufacture the right-hand stub shaft.
As the depth and complexity of the
repair became apparent, it was clear
that the project would require some of
the specialist facilities in the Edmonton
Service Center, which has considerable
experience in reverse engineering
complex components.
With the aim of delivering a more reliable
and efficient turbine, Sulzer instigated a
metallurgical root cause failure analysis
of the damaged shaft to determine if
there were any design modifications
that could be implemented before
remanufacturing began. Even the repair
of conventional steam turbines requires a
considerable amount of high specification
machine tooling and large capacity over-
head cranes as well as a highly skilled
workforce. When the repair involves an
almost unique design, the experience and
skill of the engineers really come