Ahead of a scheduled 36,000-hour
overhaul, one of Trinidad and Tobago
Electricity Commission's (T&TEC)
Wartsila 18V50DF dual fuel generators
experienced a failure on crankpin #9.
The generator's OEM was brought in to
inspect the damage and provided a report
that resulted in the generation of a public
tender for the completion of the repairs
and the 36,000-hour overhaul.
Goltens travelled to the plant to
complete an inspection of the engine,
which had been completely disassembled
by plant personnel at the maker's
recommendation. Goltens determined
that the 450mm diameter journal had
surface cracks and excessive hardness
(as high as 568HB) from the bearing
failure and proposed in-place machining
and annealing repair in addition to the
overhaul.
After the tender was awarded, Goltens
first machined the crankpin to -4.5mm
to remove all surface cracks leaving a
250mm x 120mm hard spot. The team
then performed the annealing process
and reduced the crankshaft hardness
from 568HB to a maximum of 300HB. A new radius was
cut for the final
undersize of -6.0mm,
and final machining
and polishing were
completed with a
surface finish of
0.4Ra.
While the
annealing was
being carried out,
Goltens deployed
diesel teams to
begin the overhaul
of components in
parallel. The 36,000-
hour scope was
comprehensive
and included the
calibration and
overhaul of all pistons and connecting
rods, honing the cylinder liners, replacing
all crankpins and main bearings, and
overhauling the cylinder heads. In addition,
all cam bushings were removed and
replaced, and the vibration damper was
overhauled along with the turbochargers
and fuel equipment before the engine was completely rebuilt and tested.
Goltens then flushed the engine,
completed system checks and
commissioned the engine before it
was turned over to T&TEC powerhouse
personnel.
www.goltens.com