Westinghouse 251B Gas Turbine Inspection

We were recently contracted to perform a modified Combustion Inspection on a Westinghouse 251B Gas Turbine by a customer in the United States.  Below is a summary of the activities we completed during this inspection.  All activities were completed with an attention to safety, and our quality processes, to ensure a successful outage completion.

Upon arrival for setup of tools the unit was shut down and locked out to perform the inspection. The necessary roof sections were removed for crane access to disassemble the components. All combustion parts were removed and replaced with new/refurbished during the inspection – pilot nozzles, support housings, baskets and transition pieces.

During this outage, the upper half compressor case was removed for the inspection of the R1 – R7 in the compressor section.

During this inspection, due to the condition of the compressor it was decided to remove two bottom R-1 vanes (#21 & #22) for a visual inspection and then reinstall.

The inlet access door was removed for inspection of the inlet scroll and the Inlet Guide Vanes. The Inlet Guide Vane angles were checked and verified. The row #1 compressor blade tip clearances were also checked. The Inlet Guide Vanes were greased after inspection. The inlet was cleaned and visually inspected by the plant personnel and our Technical Field Advisor prior to closing.

The exhaust was opened, and the bullet cone inspection cover was removed for inspection of the exhaust bearing pedestal. The exhaust struts were inspected, and cracks were repaired as needed by the site welding contractor.

The end result was another successful turbine inspection – zero safety incidents, quality work, and an on-time and on-budget outage completion.

Valve & Bearing Inspection

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.

Running Condition Assessment

We performed a running condition assessment (RCA) inspection on an industrial GE Steam Turbine, in which we performed a variety of inspection processes to determine the overall running condition of the steam turbine generator and its auxiliary equipment at a facility located on the East Coast, USA. This RCA was completed as an annual inspection to determine the condition of the turbine and generator and to better prepare and schedule the next major inspection for this unit.

We met with the customer and discussed the goals of the Running Condition Assessment, how the unit was operating, and the plan to inspect and evaluate the unit to help determine a time frame for the next major inspection of this unit.

A walk down of the turbine and the visual survey portion of the RCA was completed. The detailed findings were included in a comprehensive 400 page final report. A vibration survey, thermal imaging survey and ultrasonic survey of the unit was performed while on site. The underside of the turbine was surveyed for the condition of the thermal insulation and other visual defects. The auxiliary equipment which included the generator and coolers, lube oil tank, pumps, gland exhaust system, steam traps, and pipe hangers was also surveyed.  Running readings were obtained from local instrumentation as well as from the units control system.

The end result provided the customer with an assessment of how their turbine generator set was currently operating, as well as the trending data from previous years’ assessments.  This data was analyzed and discussed at the customer meeting, allowing the customer to budget and tentatively schedule their next Major Inspection based on the year over year trends and recent assessment findings.  The goal of the RCA program is to help customers extend the duration between Major Inspections, while assessing and correcting minor issues on an annual basis.

 

 

 

Shaft Machining

Our Field Machining Division was dispatched to repair an inboard fan shaft for a Utility customer in the Midwest.  We mobilized a total of 4 specialty field machining personnel, and began the process of machining the inboard fan shaft which had severe shaft damage and hard spots.  We cleaned up 100% of the shaft, had hardness checks performed, and then proceeded to final hone and polish.

The total duration of the project was 3 days from start to finish, and the end result was another satisfied customer.  The photos below will give you an idea of the severity of the original shaft damage, as well as the final condition upon completion.  Another great project by our Field Machining Division!

 

As Found:

 

Upon Completion:

Steam Turbine Major Inspection

We’re lifting the LP upper half casing on a Westinghouse Steam Turbine.   Great attention to detail and planning is required to perform a safe, quality lift of this nature.  Nice job team!

D-11 Turbine Inspections

We are seeing many inspections scheduled on the D-11 fleet of steam turbines all across the United States.  This fleet has very specific needs when it comes to maintaining and repairing them, and we have solutions for many of the common repairs needed.  From the diaphragms to the packing boxes, and every other component on this machine, we offer repair solutions that will provide you with an efficient and reliable turbine for the foreseeable future.  We will execute a turnkey field service inspection at your site with our qualified Technical Field Advisors and turbine execution teams, perform any of the steam path repairs (rotor, diaphragms, etc.) at our Midwest Steam Path Repair Facility, as well as inspect, repair, and manufacture new components for the associated steam valves at our Southeast Valve Repair Facility.  If you have any inspections scheduled on your D-11 steam turbines please contact us today to learn more about what we can offer.

Emergency Stop Valve Inspection

We recently received a call from a paper & pulp producer in the Southern U.S. to assist them with an emergency stop valve they were having issues with.  Obviously an important safety component to any turbine, we immediately mobilized a Technical Field Advisor to assist in identifying the root cause and developing a path forward.  The inspection revealed a broken retaining ring inside the stop valve.  We had a new retaining ring manufactured, stop valve re-assembled, and assisted with unit start-up all in just over 24 hours, allowing the plant to get back online as soon as possible.  This was another example of our quick emergency response times when there is a customer in need.

Project Spotlight – Steam Turbine Diaphragm Restoration

During the spring outage season Power Services Group was contacted by an Industrial Steam Turbine Owner in the Midwest with the intent to purchase a new diaphragm assembly (upper and lower halves). The customer was advised by the OEM that their existing diaphragm assembly was beyond economical repair. The lead time and price provided by the OEM to manufacture a new diaphragm assembly would have put the customer over budget and beyond the allotted schedule for their planned outage in progress.
In response to the customer purchase inquiry, we requested photos of the damaged areas of the existing diaphragm. After a detailed review we informed the customer that the existing diaphragm assembly could be repaired at a reasonable price and schedule.
After the customer reviewed our detailed repair plan and schedule, they accepted the proposal and personally delivered the diaphragm assembly to our Midwest Repair Center of Excellence located in Pevely, Missouri.
After incoming inspection, our technicians executed a major weld repair of the admission and exhaust side inner and outer setback faces of both diaphragm halves. Upon completion, final dimensional inspections were performed. After thorough quality verification, the diaphragm assembly was expedited back to the customer’s facility, successfully installed, and returned to service.
The total schedule for all work completed – from receipt of initial phone call to a fully-repaired, delivered diaphragm assembly – was 11 days. This timeline was not considered possible by the customer when they initiated that first call.
PSG provided the customer an alternative, attractive solution they thought was unattainable. The diaphragm assembly was restored, instead of replaced, at much lower cost than a new diaphragm assembly. Even more importantly, extensive repairs were completed within 11 days of initial contact, versus the long lead time of new component manufacturing. PSG saved the customer significant downtime and associated lost production revenue. We are proud to have a satisfied customer we were able to help through an extremely difficult situation.

“As Found” Photos:

Exhaust-Side Erosion

Admission-Side Erosion

“As Left” Photos:

Admission Side Final Machined

Exhaust Side Final Machined

Horizontal Joint Final Machined

Horizontal Joint Final Machined

Finished Diaphragm

Stationary Blade Restoration

During the most recent outage season, PSG was contracted to perform the in-place restoration of stationary blades on an 800MW Steam Turbine for a large power producer in the United States.  The customer was looking for a solution where the blades could be restored without completely disassembling the unit and sending the components to a shop – enabling them to save valuable generation time and significant expense.  Our Field Machining Division mobilized our specialized technicians and equipment and began the detailed process of restoring the blades, ultimately returning them to operating specifications.

The customer was extremely pleased with the outcome of the project and commented on the high-quality craftsmanship displayed by our technicians.  This is another example of the complicated turbine repairs we can perform on-site, and a testament to the quality of our execution personnel.

Spill Strip Installation

We are in the process of installing new spill strips for an industrial GE Steam Turbine. Very nice work by our Steam Path Repair facility in Pevely, Missouri.