Turbine Generator Maintenance (TGM) was contracted by an industrial customer in the United States to perform a valve and bearing inspection on their General Electric (GE) condensing steam turbine and hydrogen-cooled generator. The turbine and generator set is of a four bearing design.
During the project, a Safety Meeting was held prior to the start of any work. The Safety Meeting topics were based on work activities to be performed during the shift. In addition, hazardous observations which could impact the safety of the team were discussed and resolved. Prior to performing work, a Job Safety Analysis (JSA) form was completed by the work team. This project had no accidents and no first aide incidents.
The generator rotor remained in the stator and both of these components, the generator rotor and generator stator, received visual inspections and electrical testing. The journal bearings were removed and visually and dimensionally inspected. The pedestal oil deflectors were removed and visually and dimensionally inspected. The #3 outboard (OB) and #3 and #4 inboard (IB) oil deflectors showed to have excessive clearance. These deflectors were conveyed to a local machine shop for repairs. The remainder of the deflectors were cleaned and returned to service.
The inlet control valves (CV) were removed, cleaned and inspected. The valve seats and poppets were found in acceptable condition, CV’s 3, 4, 5 and 6 received new stems sourced from customer spares. The valve bushings showed to be worn and were recommended for be replacement at the next planned outage. The main stop valve (MSV) and operator were disassembled, cleaned and inspected. All components were approved for reassembly and were returned to service.
The lube oil system main, AC and steam driven oil pumps were disassembled and received inspections. The main oil pump (MOP), which is driven by the turbine rotor, was returned to service with no repairs being necessary. The steam driven auxiliary oil pump (AOP), was found to have acceptable clearances and was reassembled and returned to service. One row of carbon steam packing was found to be damaged and was replaced. The AC driven oil pump was found to have acceptable clearances and was reassembled and returned to service. The lube oil reservoir was opened and cleaned.
The generator coolers and air ejector condensers were opened on the water side for inspections. The tubes were rodded out, flushed and vacuum tested. All were OK and the components were reassembled. The lube oil coolers were opened and cleaned. The system trip devices were cleaned and received visual inspections; all linkages were checked for wear and proper freedom of movement. The devices were latched and checked for tripping operation. The governor speed control trip latch oil pressure trip cylinder piston rings were found to be seized. New rings were manufactured and installed.
Upon startup, the unit operation was accepted and the unit placed online. Our personnel demobilized the job site and were released to travel the following morning.
Another successful project and satisfied customer.