HOUGHTON INTERNATIONAL was commissioned by Sabic, a Teesside-based
petrochemical manufacturing company, to overhaul a 250kW, 3.3kV 4-pole Ex N GEC motor used in its Olefins 6 plant, the second largest liquid naphtha cracker plant in Europe.
Initially, the customer requested an
inspection and report on the condition of
the motor. The motor was received from
the customer in poor condition externally
with substantial corrosion across the
entire surface of the unit, but upon
dismantling, the internal components
were found to be clean, with little ingress
evident in the windings. It was suspected
that this was the first time the motor
had been dismantled since the original
installation other than for routine bearing
oil changes.
Based on these findings, Houghton
International recommended a complete
in-depth overhaul of the motor at its
IECEx certified facility by a team of
experienced electromechanical engineers.
The overhaul consisted of stripping down
and steam cleaning the motor, stoving
the stator windings and dynamically
balancing the rotor to ISO grade 2.5. Being
an Ex motor, the mandatory hazardous
area checks were also carried out, with a full report produced at the end.
Remedial repairs to the covers were
also carried out, and they were shot blasted
and primed. A new sound baffle cover,
cooling fan locking nut and new gaskets
were manufactured to specification, and
the entire unit was rebuilt.
Following the rebuild, the motor
underwent full testing, including a
Baker test which ran a complete cycle
of tests to ensure the integrity of all
motor windings, an overall broad test
run, and monitoring of vibration and all
bearings before being returned to the
customer's site.
To begin with, the customer
thought the existing motor was
beyond economical repair because
of the external damage, and a new
motor would be required. However,
the overhaul minimised the cost
implications and disruption to the
customer.
Furthermore, midway through the
overhaul, the customer requested a
much quicker turnaround. Houghton
International was able to meet the
customer's demands and deliver the
overhauled motor on time, ahead of the
original schedule.