MH Power Systems Belgium approached Maintenance Partners to inspect and repair auxiliary pumps and motors for a customer in Italy. The pumps and motors are auxiliaries of a 660 MW MHI steam turbine which are used in in the turbines’ oil systems.
The assignment was part of a scheduled shutdown of the 660MW MHI steam turbine. Mitsubishi Hitachi Power Systems conducted an inspection, during which the uppercasing of the turbine was lifted and the rotor could be inspected to guarantee the reliability and safety of the steam turbine. By utilizing Maintenance Partners for the auxiliary rotating equipment, the competencies available within the Mitsubishi Hitachi Power Systems group were used to provide the end customer a complete solution for the shutdown of the steam turbine.
Scope: Inspection & Overhaul of 22 rotating machines
In total, 22 rotating machines were covered during this assignment: 13 AC electric motors with capacities ranging from 5.5 kW to 110 kW, 2 DC motors and 7 pumps. Although the pumps and motors have relatively small capacities, they are essential for the operation of the steam turbine. The rotating machinery is used to pump lubricating oil, to lubricate the journal bearings and to condition oil.
All rotating machines were inspected, the standard inspections included:
- Mechanical measurements
- Cleaning & drying
- Replacement of bearings
- Electrical test
- Vibration measurements
- Drawing up report
- Packing for transport
With a number of motors and pumps the inspections showed that repairs were needed, for instance machining and purification of collectors (DC motors), rebushing of bearing housings, repair of mechanical seals and shaft repairs.
Shortening of schedule: 12 working days –> 9 calendar days
For operational reasons, the end customer was forced to adjust the schedule. This meant that the original schedule of 12 working days was shortened to 9 calendar days. Furthermore, there was a holiday weekend within the new planning which implied that the ‘standard’ work suddenly became a challenge. To maintain the overview, the entire job was carried out in our workshop in Naninne.
The short and fast communication made it possible to finalise these standard inspections within 9 calendar days, including the repair of the mechanical seals, rebushing of bearing housings and a visit by the end customer for the inspection of motors, pumps and approval of repairs.
In addition to the inspections, repairs and no load testing of 22 rotating machines in our workshop, the assignment also required to test these pumps and motors under operating conditions. Therefore, one of our reliability engineers performed all necessary electrical and mechanical measurements on site while the steam turbine was back in operation.
Measuring overhauled machinery after installation under operating conditions is not only essential to ensure a smooth operation, but offers two other advantages:
- Compare data after overhaul with factory specifications and tolerances
- The possibility to establish preventive maintenance programs
Flexibility & Customer Orientation
Due to the flexibility and customer orientation of the team in Naninne, this assignment could be performed quickly. Therefore the schedule of the shutdown could be respected so that the steam turbine could start on time, with great satisfaction of the customer (MH Power Systems Belgium) and the Italian end customer.
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