AUTUMN 2019
WELDING
>>
vessel maintenance, repair and revamps.
Sean Hegarty, BWSC plant manager at
Lisahally Power Station, explains: “The
tendering process was very competitive, and
Sulzer stood out from the competition, as
it offered an outstanding service package.
The company was selected on the basis of
its ability to deliver cost-effective and highquality
solutions for boilers.”
Delivering corrosion
protection
As an economical and sustainable alternative
to replacing the existing structures within
the boiler, Sulzer and BWSC decided to
cover the damaged membrane walls with
layers of Inconel 625 to repair and protect
the membrane wall. This is an austenitic
nickel-chromium-based superalloy that
is particularly resistant to corrosion and
oxidation, even in harsh environments with
elevated temperatures, such as in furnaces.
The additional Inconel layer would enable
the boiler to efficiently maintain high steam
pressure whilst protecting the surfaces from
future corrosion and erosion.
The homogeneous deposition of Inconel
onto the corroded and eroded surfaces
was carried out onsite by automated weld
overlay. Using its expertise in this process
Sulzer has developed an advanced automated
technology, CladFuse, to perform highly
accurate welding operations for structures
such as boilers, furnaces, vessels and towers.
CladFuse uses a carriage that travels
along a laser-levelled track system fixed
to the wall that needs repairing. On the
carriage, a robotic index arm moves the
welding torch and the oscillator in order to
create weld Inconel beads with an overlap
Sulzer’s advanced automated CladFuse technology can perform highly accurate welding operations for structures
such as boilers, furnaces and towers.
of approximately 50% between adjacent
weld beads. All the weld overlay process
parameters, e.g. carriage speed or bead
thickness, are controlled by a programmable
logic controller (PLC). Operators can
communicate with it and adjust the
parameters manually using a humanmachine
interface (HMI).
In addition to offering a cost-effective
and high-quality method to repair damaged
metal surfaces, the solution developed
by Sulzer is extremely fast. This was
particularly important for managers and
operators at Lisahally Power Station, who
needed the welding to be completed by
the end of a scheduled outage for regular
maintenance activities.
Hegarty says: “Adhering to a strict
timeline and coordinating this repair with all
our operations was a must. Whenever weld
overlay is performed within the boiler, large
volumes of different gasses are generated.
Therefore, it is necessary to segregate the
boiler, and it is not possible to carry out any
other maintenance work in its immediate
vicinity. As the power station needs to
run continuously, extended shutdown and
downtime would have greatly affected the
plant. To ensure that this didn’t happen,
Sulzer’s experts set up a number of measures
and controls to ensure we could carry on
conducting planned maintenance activities
along the steam path.
“The project was challenging, and
Sulzer’s knowledge and expertise provided
a great and outstanding execution. We are
extremely happy with the outcome.”
Andrew Petticrew, business development
manager at Sulzer Tower Field Services,
concludes: “Sulzer’s extensive capabilities
in automated weld overlay were crucial to
complete this project. The application proves
how the correct repair operation can not only
reduce maintenance costs, but also improve
the efficiency of power stations, delivering
sustainability whilst reducing the expenses
to generate energy.”
SULZER
01908 632775
www.sulzer.com
38 www.fastening-solutions.co.uk
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