Coordination and comprehensive planning and scheduling were the pivotal keys to success of this complex work that included rings-off generator fields, diaphragms, steam turbine rotors, valves and actuators, and a variety of related items including parts supply.

Consolidated scheduling, communication, accurate reporting and corporate-wide commitment flawlessly united to ensure customer and MD&A-wide confidence in this landmark achievement.

Multiple Divisions

The focal point was the one-stop shop, MD&A’s Turbine Generator Repair Facility in St. Louis, MO, and encompassed various divisions including Generator, Steam Path, Machining Services, as well as the Ohio-based Bearings, Seals and Hydraulics Division.

The precision-based and long-established service and manufacturing capabilities of MD&A joined forces to seamlessly complete each detail of this multifaceted and time-dependent outage.

Scope

Overall scope of work included inspection and repair of 9A4 and 7FH2 generator fields, two HP rotors, HP and IP diaphragms, spill strip supply and installation, two sets of valves and two sets of actuators, and critical parts supply.

Generator

Upon arrival in St. Louis, MD&A completed rings-off testing, inspection and permanent blocking replacement of two steam turbine generator fields. Electrical testing showed unsatisfactory results and mechanical inspection indicated noticeable dishing of the collector rings. These would be honed and polished. Existing amortisseurs showed heat damage and axial cracking, requiring replacement by MD&A.

Existing blocking was replaced with the MD&A strap and tie design. These unique axial blocks have spring forces acting in opposite directions to add interference to prevent any unwanted axial or radial movement of the blocking after installation.

After repairs, the fields were moved to our high-speed balance facility in St. Louis where heat runs with electrical testing were successfully completed. Fields were then moved to machining services for collector ring work scope, including hone and polish. The fields were then final inspected by the Generator Division before returning to site.

Detailed recommendations were prepared for ongoing operation. In addition, MD&A recommended a full rewind at the next rings-off opportunity.

The two gas turbine generator fields also received complete inspection and repair. Mechanical testing indicated noticeable dishing in the collector rings. Slot spring misalignment was found.

Blocking would be replaced with the MD&A strap and tie design. Inspection showed that vent holes for the coils were partially blocked, which can result in reduced hydrogen gas cooling flow, leading to thermal instabilities with the rotor leading to excessive rotor vibration and forced outages.

Our experts performed a unique, patented 7FH2 generator field repair process (top hat modification) that eliminated the axial migration of slot leaf springs that restricted the air flow. Collector rings were honed and polished to correct the dishing.

The following components received non-destructive examination: snap rings, retaining rings, and field wedges. Because these gas-turbine units are hydrogen-cooled, pressure decay testing was performed.

After machining services work was completed, fields were released to the high-speed balance facility, then to the Generator Division for final inspection and shipping preparation.

Steam Turbine Rotors

MD&A conducted detailed inspection and repair of the steam turbine rotors in St. Louis. Upon arrival the rotors were visually, dimensionally and non-destructively inspected. Repairs were conducted and detailed recommendations were made for long-term operation.

Dimensional, run out and non-destructive evaluation (NDE) inspections (including metallurgical evaluations) yielded minor findings that were addressed. Minor indications were identified, reviewed and dispositioned. Low speed balance and a full quality inspection was completed prior to return to service.

Minor repairs completed consisted of:

• Rabbet fit restoration via peening and machining
• Minor bucket repairs were completed by MD&A’s expertly trained bucket technicians
• Deburring and cleaning to remove any stress riser concerns, and
• Low speed balance

All detailed data inspections, repairs and as left conditions, including future repair recommendations were included in final reports to support future planning.

Valves

Example valve repairs, following complete inspection, included the following:

1. Main Stop Valve
   1. Installed new stem & anti-rotation key
   2. Lapped the pressure seal head backseat to achieve a 100% blue contact check
   3. Installed a new stem/disc nut anti-rotation pin and staked, torqued and blue checked to the disc
   4. Machined the pressure seal head gasket face to correct runout and true it to the bushing bore
   5. Ground & polished the main disc seating surface to remove runout and surface imperfections

2. Control Valve
   1. NDE revealed indications in the nitride around the disc OD, a new disc was purchased and installed
   2. New disc nut anti-rotation pin for the was installed and staked into the new disc

3. Turbine End Reheat Stop Valve
   1. Honed pressure seal head bushing tight spots to restore design clearance to the stem
   2. Lap the pressure seal head backseat to achieve a 100% blue contact check
   3. Performed a weld buildup on the pressure seal head casing fit and machined to restore clearance to the steam chest on-site
   4. Machined the pressure seal head gasket face to correct runout and true it to the bushing bore
   5. Ground & polished the main disc seating surface to remove runout and surface imperfections
   6. Installed a new stem anti-rotation pin
   7. Installed a new disc cap bolt

4. Generator End Reheat Stop Valve
   1. Honed the disc bore to restore design clearance to the stem
   2. Honed pressure seal head bushing tight spots to restore design clearance to the stem
   3. Lap the pressure seal head backseat to achieve a 100% blue contact check
   4. Machined the pressure seal head gasket face to correct runout and true it to the bushing bore
   5. Ground & polished the main disc seating surface to remove runout and surface imperfections
   6. Installed a new stem anti-rotation pin

5. Intercept Valve #1
   1. Honed the disc bore to restore design clearance to the stem
   2. Restored the split ring ID to stem OD design clearance and verified
   3. Ground the split ring face in the surface grinder to restore the design stem lift
   4. Stoned the seal ring face to restore the axial clearance upon valve reassembly
   5. Ground & polished the main disc seating surface to remove runout and surface imperfections

6. Intercept Valve #2
   1. Honed the disc bore to restore design clearance to the stem
   2. Restored the split ring ID to stem OD design clearance and verified
   3. Ground the split ring face in the surface grinder to restore the design stem lift
   4. Stoned the seal ring face to restore the axial clearance upon valve reassembly
   5. Ground & polished the main disc seating surface to remove runout and surface imperfections
   6. Installed a new seal ring bolt

At MD&A’s Bearings, Seals and Hydraulics in Ohio, two sets of steam turbine valve actuators (Rexroth and MOOG) were completely refurbished. The refurbishment included disassembly, cleaning, and inspection of all components. All soft parts and sealing parts were replaced, and in some instances some critical components were replaced, and this includes the following: large disc springs, piston shafts, servos, solenoids, LVDT components, packing glands, bushings, piston rings. Additionally, some components were restored using chrome and grind restoration methods to reestablish critical dimensions.

After repairs were complete the actuators were re-assembled, fluid flushed and tested at 110% operating pressure with the same fluid used at site. This ensures that the actuators function properly and ensures that the actuators are leak free during operation.

This testing greatly reduces the need for field troubleshooting and adjustment on site during start-up.

Explore the Benefits of MD&A

These Steam Turbine-Generator Majors and repairs led to their life extension, continued operation and longevity of the plant in the future.

Mechanical Dynamics & Analysis enjoys a firmly-established global reputation as a reliable and trustworthy non-OEM service firm with deep roots in all major OEM products and developments. MD&A’s professionals are up to date on all industry issues and offer these benefits:

• Comprehensive service and precise coordination.
• Multi-talented MD&A personnel in multi-faceted long-established facilities.
• One-stop gas turbine, steam turbine and generator point of contact for estimating, scheduling and project execution.
• Long-term operating assurance and operating guidelines for the owner/operator.
• All backed by MD&A’s world-class corporate commitment.

No job is too complex for MD&A. To discuss and schedule your next turbine generator service and repair project, contact the experienced professionals at MD&A. Call us at (518) 399-3616 today or use our contact form.

The post Quadruple Steam Turbine-Generator Majors with Precision, Breadth, and Coordination appeared first on MDA Turbines.

The HPIP section features six high-pressure impulse stages, and six intermediate-pressure reheat stages in an opposed flow configuration. Over time, thermal cycling, mechanical stresses, and environmental conditions had contributed to severe cracking in the integral valve chest of the lower half shell, along with additional minor and moderate indications throughout the upper and lower shells.

Comprehensive Scope of Work

MD&A’s experts began by preparing a detailed “as-found” inspection of the HPIP outer shells. This initial assessment revealed not only the originally defined severe cracking in the valve chest but also several additional minor and moderate internal and external shell indications. The scope quickly expanded to include:

• Excavation and weld restoration of the original valve chest severe cracks.
• Grinding, blending, and welding of newly discovered moderate indications across both shell halves.
• Employing proven and proprietary distortion control measures during the welding.
• Post weld heat treatment (PWHT) to relieve residual stresses and restore metallurgical integrity.
• Final nondestructive surface and subsurface examinations (NDE) and hardness testing to validate the repairs.
• Dimensional inspections to assess shell geometry and fit-up conditions.
• Reinstallation and welding of small bore piping, removed to gain access for the major weld repairs.

This multi-phase repair required precise coordination, advanced welding techniques, and rigorous quality control to meet OEM specifications and ensure safe and reliable operation.

The lower half shell presented the most significant challenges. In addition to the original valve chest severe cracking, MD&A identified eight minor internal indications and four moderate external indications. While the minor indications were accepted and documented for future evaluation, the moderate ones were excavated and prepared for weld restoration.

The valve chest indications were excavated and prepped for welding.  The welding was performed utilizing a GTAW welding process for the root passes and a SMAW welding process for the subsequent layers. In-kind weld filler materials were selected for their compatibility and mechanical properties. Each weld layer was cleaned, inspected using a hot magnetic particle testing process, and control measures were employed to minimize distortion.  The team applied approximately 350# of weld between the two sides of the valve chest.

Once welding was complete, the shells were wrapped and insulated for PWHT. The heat treatment cycle included a ramp-up to 1225°F, soak at temperature, and a controlled cool-down. This step was essential to relieve residual stresses and restore the mechanical integrity of the repaired areas.

The upper half shell also revealed additional indications during inspection—one internal and three external. These were addressed through localized grinding and blending to clear the indications, and in one case, weld restoration using GTAW with local flame preheat. Per ASME code, no PWHT was required for this minor repair, but all locations were subjected to final NDE to confirm the absence of defects.

Following the repairs and heat treatment, MD&A conducted comprehensive dimensional inspections. These revealed improvements in shell flatness and roundness, particularly in the lower half shell. However, the lower half valve chest flange face, bonnet bores, and seat bores remained out of specification due to the legacy distortions from previous weld repairs.

MD&A provided detailed recommendations for machining and alignment to correct these conditions, including boring bar sweeps and machining of valve seat bores, bonnet bores, gasket pockets, and flange faces. These steps were critical to ensure proper fit-up and alignment during reassembly, and the final machining was performed by Mitsubishi.

In conclusion, this project underscores why MD&A is a trusted partner for utilities facing complex turbine repair challenges. With decades of experience in turbine-generator systems, MD&A brings unmatched technical expertise, agility in the field, and a commitment to quality that ensures successful outcomes, even when unexpected issues arise.

Their ability to adapt to evolving site conditions, execute precision repairs, and deliver comprehensive documentation gives plant operators confidence in the long-term reliability of their assets. Whether it’s a planned outage or an emergent repair, MD&A’s team is equipped to respond with speed and precision. Call us at +1 (518) 399-3616 today or use our contact form.

The post HPIP Outer Shell Valve Chest Weld Restoration Onsite appeared first on MDA Turbines.

During full-load operation, the steam pressure differential between the HP and IP turbine section forces the packing casing towards the IP section. The outer perimeter main axial locating fit of the packing casing resists this unbalanced steam force.

At full operating temperature, the casing material is vulnerable to cumulative creep rupture damage. Radial circumferential cracking has occurred within the industry and has led to loss of axial positioning of the N2 packing casing, potentially causing internal damage to the turbine rotor and diaphragms.

Inspection and Engineering

Incoming disassembly, blast cleaning and detailed inspections were performed by component specialists at MD&A’s Turbine Generator Repairs Division facility in St. Louis, MO.

Following incoming inspections, the original geometries of the casing main axial fits were reverse engineered, a key activity by MD&A’s experienced and precision-oriented professionals. This process measured the main axial fit widths, main axial fit fillet radii and chamfers, and fit faces critical axial positions.  MD&A experts found evidence of distortions, galling and fretting damage.

A complete and clear listing of recommended repairs and hardware replacements was then prepared and reviewed with the owner/operator.

Findings and Resolutions

Initial recommendations focused on the lower half and upper half N2 packing casings.

For the lower half casing, inspection revealed rough surface and erosion on the outside diameter main axial locating fit steam seal face. MD&A experts would restore the steam seal face by welding and machining. For the upper half casing, findings included rough surface and erosion on the OD main axial locating fit steam seal face. Also, the fillet radius-to-steam seal face showed visible intermittent liner crack indications. They removed the crack indications and restored the original geometry by welding and machining.

Further investigations revealed additional requirements. For the upper half casing, OD left and right-side dowel pin though holes would need repair due to excessive clearance.

Horizontal zero-clearance joint packing groove key pocket threaded holes, both left and right sides, showed thread damage and excessive tap wobble. This appeared on both the turbine and generator ends. MD&A actions included removal of the damaged threaded hole, weld restoration and machining for all four locations, followed by post-weld heat treatment.

Horizontal joint studs, softened during the original work scope, were removed by destructive machining and replaced with new hardware. Selected new hardware would also be required for horizontal joint steam dam springs and screws; left and right-side elevation block bolts, clearance keys and key screws; horizontal joint nuts; and horizontal joint studs.

Restoration

The packing casing halves were welded and post-weld heat treated. The main axial locating fit was weld restored, as was the zero-clearance groove keeper block screw holes.

Post-weld heat treatment was performed, utilizing distortion control bars, which were removed, followed by blast cleaning of both casing halves.

Final machining and grinding were then performed. This included the main axial fit geometry, and final grinding and blending to clear all NDE indications. In addition, the back-side boss surface of the main axial fit steam seal face was welded to increase thickness and improve stiffness.

Inspections, Assembly and shipment

Final inspections, and final NDE and dimensional checks were then performed by MD&A Quality personnel.

Full 100 percent magnetic particle inspections revealed no findings. Casing upper and lower halves were laser mapped to confirm flatness. Final diameters and vertical radial drops were also completed.

MD&A then completed final assembly of the upper and lower halves in preparation for return shipment.

MD&A successfully completed the inspections, engineering, repairs, restoration and improvement of the N2 packing casing at its St. Louis facility. This project enters the MD&A portfolio as another example of the company’s global response as a premier, non-OEM service provider to the worldwide steam and gas turbine generator industry.

Call us at +1 (518) 399-3616 today or use our contact form.

The post Steam Turbine N2 Packing Casing Repairs appeared first on MDA Turbines.

Industrial steam turbine/generators are used globally in chemical and petrochemical plants, refineries, pulp & paper mills, and mining operations. They are also used in biomass and waste-to-energy facilities, combined heat and power plants, geothermal and concentrated solar power installations, and desalination operations, including many others.

Ongoing operation of these units ensures stable, reliable use of proven technologies to convert the expansive power of steam into useful mechanical work. The processes are both fundamental and critical as the world exploits all available resources to meet its present and future needs for heat and power.

The professionals at MD&A are uniquely qualified to serve these needs by applying their deep and time-tested experience with steam turbine/generators, regardless of OEM.

For this particular industrial unit, onsite work was performed by MD&A’s Outage Services division, Generator division and our Turbine & Generator Controls division. All valves were sent to MD&A’s Turbine-Generator Repair Facility in St. Louis, MO for inspection and repair. MD&A’s Bearing, Seals and Hydraulics Division in Euclid, OH, inspected bearing assemblies, thrust pads and oil deflectors.

ST-660 Industrial Steam Turbine Major Inspection

After mobilizing, MD&A’s experts removed the upper-half shell and turbine rotor, then performed blast cleaning for complete non-destructive examination. The rotor, packing carriers and blade carriers were aligned to OEM specifications. The nozzles were blast cleaned and NDE’d in place.

Inspection revealed evidence of steam cutting that was photographed and recorded, as well as some deformed bolts. Various other specifics were recorded in the Recommendations Report.

Upper half and lower half shells were also cleaned and inspected.

A key benefit of MD&A’s inspections is written and photographic documentation of lessons learned that can assist the owner/operator in future outages. One lesson learned was on the rotor lift. For this inspection, the turnbuckles were removed and chain falls were used in their place. For future outages, two 15-ton and two 10-ton chain falls should be on hand due to minimal lift clearances.

This recording would benefit both owner/operator and contractors involved in future work.

In-depth inspections then proceeded. This included axial and radial blade clearances, rotor radial runout checks, nut rotation and tightening, thrust bearing clearances, and complete visual and NDE inspections (general, HP impulse wheel, and all 36 rotor stages).

Generator

For the Siemens® conventionally air-cooled generator (71.18 MVA), the coolers were cleaned, visually inspected and pressure tested. The field was removed and generator inspection and testing were performed.

MD&A completed major inspections of both the generator field and stator including visual, borescope and electrical testing. Minor contamination was found on the field turn windings beneath the retaining ring. Signs of field turn migration were also identified and addressed.

One field ground detection bolt was found already removed prior to the MD&A Generator Team’s arrival. It was reinstalled according to OEM specifications. To complete electrical testing, the field winding was isolated from the brushless excitation components. Testing then proceeded on the generator field (IR with PI, DLRO and AC Impedance), rotating armature and rectifier wheel, stationary field, and stator.

At completion, field windings were reconnected to the shaft-mounted brushless excitation equipment and a final IR test was performed.

Conductive paint was applied to the affected partial discharge areas to reduce sparking effect and increase stator bar life.

With testing complete, MD&A issued a recommendation for power factor testing at yearly outage intervals to monitor health of the insulation system.

Brushless Exciter

The brushless exciter was cleaned, inspected, and realigned. The ABB Unitrol 6000 Exciter Regulator Cabinet was also cleaned and inspected.

Steam Turbine Valves

MD&A’s facility in St. Louis disassembled, cleaned and inspected the control valve, main stop valve and other valves. The emergency stop valve was also disassembled, cleaned and inspected during the outage.

For all, a final blue check was performed, 100% blue contact was achieved. New rope packing, supplied by MD&A, was installed during valve reassembly.

Other Key Elements

All turbine bearings were replaced due to wear. Generator bearings were NDE’d and reused. Replacement thrust bearings were installed at reassembly due to wear, New RTDs were installed at MD&A’s Bearing, Seals and Hydraulics facility.

Auxiliary system work included the lube oil tank which was drained and cleaned under MD&A supervision. MD&A performed additional cleaning of the tank and baffle plates. Two lube oil coolers were unstacked, washed and disassembled.

Alignment

Topless laser alignment was completed before startup. This method utilizes laser accuracy to eliminate the time-consuming and expensive process of reassembling a steam turbine for “Tops-On” alignment measurements, saving hundreds of man-hours labor per turbine section. This included horizontal joint measurements, bolt roundness checks, stationary component position verification, and side slip readings among others using laser equipment. Our alignment engineers have the expert knowledge needed to interpret the data.

Why MD&A?

The experts at MD&A are not only dedicated to the fundamentals of turbine and generator longevity. They apply their vast experience in all OEMs to understand and import precise lessons learned throughout the industry, then direct their knowledge and skills to the ongoing development of using steam effectively and efficiently for the long-term benefit of owner/operators throughout the world.

MD&A’s technical directors and service technicians bring decades of experience to each industrial and utility project regardless of OEM, a process now proven in more than 20 countries worldwide. Committed to both industrial and utility customers.

We invite you to discuss any industrial steam turbine major inspection or other steam turbine, generator or gas turbine issues with us today. Call us at (518) 399-3616 or use our Contact Form.

The post Siemens ST-600 Industrial Steam Turbine Major Inspection appeared first on MDA Turbines.

As a result, over 40 years later, MD&A has evolved from a small firm to a large service provider with over 600 employees reaching more than 100 customers each week during outage season.  The reputation for outstanding service in the US has enabled MD&A to spread globally with parts, repairs, and services on large turbine-generator sets.

Watch our company video!

The post MD&A Company Video appeared first on MDA Turbines.

MSV/CV Replacement

Replacement of the combined main stop / control valve (MSV/CV) was requested by the customer in response to a technical memo issued by the OEM relating to a material deficiency. The valve’s original body was a casting, which is prone to stress fatigue and cracking. As a result, the OEM recommended that the valve be replaced with one that has a forged body.

MD&A’s experts completely replaced the combined main stop and control valve assembly. The team provided engineering services for the MSV/CV replacement and outlet pipe modification work to accommodate the new valve assembly.

A new monorail beam was installed to facilitate future CV actuator removal.

After installation, MD&A’s technicians performed several tests and inspections on both main stop and control valves to verify proper installation and assembly.  They also performed HP shell arm loading tests before and after the valve assembly was replaced. Radiography inspections were also conducted after the valve casing was installed, revealing some deficiencies that were remedied immediately.

LP Rotor Inspection, Bucket Replacement, and Related Repairs

As part of planned work for this outage, MD&A’s experts removed and shipped the steam turbine LP rotor to MD&A’s Turbine-Generator Repair Facility for inspection and bucket replacement (which had been previously recommended by MD&A’s major inspection of the unit in 2020). The team performed visual inspection, blast cleaning, dimensional inspections, and NDE inspection of the entire rotor. The rotor was found to be in very good condition overall. Steampath inspection revealed minor FOD, minor moisture erosion, and minor rubs on packing seal lands.

MD&A’s experts installed new buckets for rows L-1 and L-0 rows, according to the moment weight chart provided with the buckets. They required replacement due to wet steam erosion and OEM TIL recommendations.

Rather than replacing them with conventional components, our Advanced Continuous Cover Blades (CCB) were utilized. These blades are constructed using a mono-block blade structure, leaving fewer locations for corrosive deposits. They are less susceptible to stress corrosion cracking and demonstrate excellent vibration characteristics. These long blades provide up to 8% stage efficiency increase, without requiring diaphragm replacement. As part of their installation, MD&A’s technicians reamed all dovetail pinholes, and installed new pins.

After installation, covers for both stages were final machined as required to meet the stated requirements. The team also conducted minor repairs for stages 13 TE & GE to resolve FOD/impact airfoil damage.

Upon completion of the work, a high-speed balance of the rotor was performed at our Repairs Facility.

Once the LP inner casing was removed, NDE inspection was performed on the struts located in the center flow area to verify the strut repairs from a previous outage. The LP inner casing horizontal joint was also inspected, and minor erosion was found on the upper half. During reassembly, high temperature sealant was used in the eroded area.

IP & LP Admission Control and Stop Valves were also disassembled and inspected during the outage.

Lastly, at startup, a vibration analysis was performed and the vibration levels were found to be low and met the requirements for acceptable operation.

CV and IP Admission Actuator Repairs

As part of the planned outage, MD&A’s team removed one Rexroth® Extraction CV actuator, two Mafag® IP admission valve actuators, and two Mafag® LP admission valve actuators.  They were shipped to MD&A’s Bearing, Seals and Hydraulics facility for disassembly, inspection, repair, reassembly, and testing.

For the CV actuator, our experts rebuilt the servo, and tested, flushed, reinstalled the poppets, and replaced shaft seals and O-rings. All other main components of the actuator were found to be in good condition and reused.

For the IP and LP admission valve actuators, our technicians performed various repairs including chroming and grounding two of the shafts, polishing two of the cylinders, replacing a poppet valve on one unit, and installed new RVDT and packing glands on all.

Upon completion of reassembly, all actuators were tested and found to be properly functioning and free of leaks. The actuators were pressure tested at 110% and stroked and tripped several times.

Bearing, Seals and Hydraulics experts also repaired the T4 bearing because onsite the upper half bearing showed indications of lack of babbitt bonding at the horizontal joint. They blended some babbitt and additional PT was performed with no indications found.

Controls

MD&A’s technicians performed a wiring inventory of the DEHC and distributed IO channels. Several observations were made including old wiring that should have previously been removed, and issues with wiring that was not wired to the manufacturer’s documented specifications. The shields for four RVDT position feedback triad cables were also not landed at the EHC cabinet. MD&A’s technicians worked with the on-site electrician to resolve these issues.

The team also noted that the CV junction box did not have a properly connected ground cable. Further, LVDT jumper settings in the EHC cabinet were found in to be in “as-shipped configuration”, and therefore not properly configured. MD&A’s team resolved the issues by adjusting the settings to match the manufacturer’s drawings.

Summary

The extensive scope and successful completion of this engagement demonstrate MD&A’s ability to provide expert service on a wide range of steam turbine systems and components. From inspection and routine repairs, to more extensive work, such as Main Stop Control Valve and Bucket Replacements, MD&A’s technicians completed the work on time and to the customer’s satisfaction. This case perfectly demonstrates why MD&A is respected as a full-service, one-stop source for turbine operators worldwide. Call our us at (518) 399-3616 or use our Contact Form.

The post Main Stop Control Valve and Bucket Replacements appeared first on MDA Turbines.

High Pressure Turbine

HP/IP – MD&A’s Outage Services Division disassembled and inspected the HP/IP rotor onsite, as well as reassembly. The HP/IP rotor, HP inner casing, nozzle, N1 and N3 packing cases, and all diaphragms were sent to the MD&A’s Turbine-Generator Repair Facility for inspection, testing, NDE, blast cleaning, and repair. MD&A’s technicians replaced the spill strips and shaft packing. They also drilled out and tapped all diaphragm elevation key screws and clearance key screws. The clearances were good radially and axially.

Bucket Replacements – The team also replaced both stage 6 and stage 7 buckets. Rotor NDE revealed concerning crack-like indications on two of the blades on stage 6, the last of the HP section. Excavation was attempted, but unsuccessful. A decision was made to replace the row of blades with new buckets, which were expeditiously manufactured during the outage. The replacements were produced by reverse engineering the existing ones, to help ensure proper functioning and fit. Once received, MD&A’s experts then machined and installed the new buckets.

Stage 7 buckets were replaced as part of the original scope of work for the planned outage. In addition to the buckets, new covers, axial lock keys, and grub screws were installed as well. The wheel dovetail showed minor mechanical damage in two locations, which were polished prior to installing the new buckets.

Diaphragms / Nozzle – Severe erosion was found on stage 7 at opening inspection. FOD was also noted.

At our Turbine-Generator Repair Facility, dimensional inspection revealed no major findings. NDE revealed some typical issues, such as impact damage, rubs and other relatively minor damage.

Other repairs included blending mechanical damage, removing impact damage, and resolving some indications. The team also machined the T1 and T2 journal surfaces.

MD&A’s Topless Laser Alignment (TLA) specialists aligned all diaphragms. Once complete, diaphragm clearance keys were measured and adjusted. The nozzle keys required significant scraping for contact. Large indentations were also noted and corrected. The nozzle clearance keys were adjusted to proper clearance, and the hold down bolt clearance was also adjusted. Minor repairs were performed on nozzle box components.

Alignment

Stationary component alignment for the HP/IP turbine section was conducted using our Topless Alignment® service. This method utilizes laser accuracy to eliminate the time-consuming and expensive process of reassembling a steam turbine for “Tops-On” alignment measurements, saving hundreds of man-hours labor per turbine section. Our alignment engineers have the expert knowledge needed to interpret the data. Coupling alignment was performed as well.

Outer Shells – Several issues were found on HP/IP outer shell as follows:

Severe dishing and indentation was noted on the steam inlet flanges, which were machined. Cracking in the reheat bowl was identified in the HP/LH casing crush pin appendage. These were drilled and mapped.

The blowdown pipe was found seized in the LH/HP casing. The seal rings were cracked locking rings and distorted seal rings and were replaced. The blowdown pipe was also machined to correct out of roundness.

The TC pipes were found to be severely bent during disassembly and were replaced with new pipes fabricated by MD&A’s Machining Services division.

Inner Shells – The HP inner shells were inspected at MD&A’s Turbine-Generator Repair facility. They performed visual and dimensional inspections, as well as NDE. The team prepared a report detailing observations and repair recommendations, and then conducted certain repairs.

On visual inspection, the HP inner shell, both lower half and upper half, revealed typical conditions including galling, scoring, dinging, fretting, thread damage, and the presence of raised material. The lower half blowdown seal rings were noted to be bound up and loaded to one end. No significant issues were otherwise noted.

Dimensional inspections were conducted on the snout pipe, blow down pipe, diaphragm grooves, and various critical fit widths. Dimensions were found to be mostly within range, except for a snout pipe diameter and float. Recommendations were made to remedy these issues.

MD&A performed repairs on the HP inner shells, including destructive removal of broken bolts & screws, stoning and blending of various indications and surfaces, and replacement of the blowdown seal rings.

Oil Deflectors – MD&A Bearings, Seals, and Hydraulics Division inspected and refurbished T1 and T2 oil deflectors. The team noticed that both were rubbed hard in the vertical plane. After evaluating the clearances with the customer, and previous experience with increased clearances in areas with 750 degree temperature potentials, T1 and T2 clearances were increased.

Boiler Feed Pump Turbine

MD&A’s experts at our Turbine-Generator Repair Facility removed and inspected boiler feed pump turbine (BFPT) A and B valves. For BFPT A, the LP SV stem was found and replaced. The team refurbished the LP SV disc and replaced the seat. The HP SV and CV were both replaced, and the HP SV strainer basket was repaired.

For BFPT B, MD&A’s experts refurbished the LP SV disc. Bushings on the LP SV rack were noted as oversized and had severe wear. The bosses were refurbished so OEM bushings could be installed. The HP SV was replaced, and the Machine Services team repaired the HP SV strainer basket. They also machined the bonnet to resolve excessive clearance.

Conclusion

Impressively, all of this was completed three days ahead of schedule! This is despite the challenge of resolving the unforeseen bucket replacement, which included manufacturing.

Several of MDA’s divisions participated including Outage Services, Generator, Steampath, Machining Services, Bearings Seals & Hydraulics division, Topless Laser Alignment, High Speed balance and Turbine & Generator Controls Division. This engagement underscores MD&A’s extremely diverse range of turbine inspection and repair capabilities, in-house expertise, and the ability to get the job done on time.

These are exactly the reasons why operators worldwide rely on MD&A for exceptional steam turbine inspection and repair services as a full-service, OEM-alternative. Call us at (518) 399-3616 today or use our contact form.

The post Full-Service Steam Turbine Major appeared first on MDA Turbines.

Work was divided among MD&A’s teams including the Bearings, Seals & Hydraulics (BSH) team and the Valves Team of MD&A Machining Services Division and conducted as follows:

Valves

MD&A’s Valve Team performed inspection, replacement, and repair on various valves and related components. These included control, main stop, reheat stop and intercept valves, as well as a blowdown and a ventilator valve. Each valve was disassembled, blast cleaned, dimensionally checked and repaired as required. All valve work was completed at MD&A’s Turbine-Generator Repair Facility in St. Louis, Missouri.

Control Valves – All four control valves failed the incoming inner valve blue check which was corrected by lapping the pilot valve seats.  The team honed the bushings on valves #1 and #2 to correct stem to bushing clearance issues. They also replaced several components as needed, including the disc and balance chamber, anti-rotation screws, stems, bushings and pins. Disc to balance chamber clearance issues and out of tolerance run outs were noted on valves #3 and #4. Clearance was restored by hand working the blue blush from the balance chamber IDs and grinding the disc ODs. Several other clearance issues were found and resolved by honing, grinding, or lapping. MD&A supported vendor performed NDE, revealing indications on two valves, which were excavated and hand blended by the team.

Reheat Stop Valves – New stem nut pins were installed on both valves during reassembly. Further, the stems were machined, and backseats were lapped to achieve acceptable blue checks. The valve disc seating surfaces were ground and polished as well. MD&A’s valve technicians also replaced the stem, inner/outer bushings and back seat on the R/S valve.

Intercept Valves – The two intercept valves were found to have similar issues among them. Both had several clearance deficiencies, which were remedied by grinding, honing, or machining. Component replacements included the crosshead guide busing, as well as disc bolts on both valves. The stem on the L/S valve was machined, drilled, and pinned; while the R/S valve had the backseat machined and lapped to achieve acceptable blue checks.

Ventilator Valve – This valve required the stem OD to be lapped. To ensure proper contact, the main disc seating was ground and polished. MD&A’s Valve team replaced the air cylinder gasket, the balance chamber, and corrected the valve lift during reassembly.

Blowdown Valve – Our technicians reset the gap between the piston stem and valve stem and restored the inner valve lift. They also polished the pilot valve and lapped the valve seat in the main disc. The main disc seating surface was ground and polished. Replacements included the air cylinder gasket and piston rings, air cylinder fitting and the bushing.

Main Stop Valves – For both valves, the team cut the stem back seat and lapped the pressure seal head backseats to achieve a good blue check. They ground and polished the disc contact seating surfaces, skim cut the gasket faces and restored the disc cap peening lips. Further, on the R/S, the bypass valve and disc seat were skim cut, and the stem was replaced.  On the L/S, various clearances were restored as required.

Compression Rings

MD&A’s experts inspected and repaired two compression rings. Damage including corrosion was observed and remedied on both rings. The rings were oxide blast cleaned to bare metal.  The I.D. and O.D. of the lower face were then weld repaired. The rings were then machined.

EHC Actuators & Spring Cans 

MD&A’s Bearings, Seals & Hydraulics (BSH) team disassembled, inspected, repaired, and tested ten GE® EHC actuators and spring cans. The coil springs were shot peened, mag particle inspected, and painted. The spring cans had several components replaced including seals, bushings, and bearings. The cans were bead blasted and painted. The team tested the actuators to confirm they were functioning properly and leak-free prior to leaving our BSH repair facility.

Additional Components

The BSH team also inspected and repaired several additional components including the overspeed trip, two tilt pad bearings, eight journal bearings, eleven oil deflectors, four hydrogen seal bronze assemblies, and two hydrogen seal housings.

Overspeed Trip was disassembled, cleaned, and inspected. Several components were replaced including the spindle, upper and lower bushings, eccentric ring, and lock plates. Weld repairs were performed on the body, spring seat, and spring shim. Trip speed was set and the unit was test.

Tilt Pad Bearings were in acceptable condition. Babbitt pads were cast and bored. New seal teeth were installed and also bored. One bearing required boring on several anti-rotation pin holes.

Journal Bearings underwent centrifugal cast repair. The inspection revealed that several dowels were no longer acceptable, and were replaced. Bearing T8’s body bolts were also not acceptable, and re-fit.

Oil Deflectors – all units received new teeth. One deflector required modification to accommodate insert-style teeth. Several required new body bolts.

Hydrogen Seal Bronze Components were machined to be within manufacturer’s specifications.  As for the housings, the dowels were replaced on one unit, while the other required bolt replacement.

Conclusion

The extensive range of work and complexity involved in this project highlights one of MD&A’s greatest strengths: being a dependable one-stop solution for virtually any power-generation repair need. The scope demanded the expertise of two teams of experienced engineers and technicians, who performed quickly and properly, to the customer’s satisfaction.  As the go-to service provider for power generation asset owners across the globe, call MD&A today at +1 (518) 399-3616 or use our contact form to learn more about MD&A’s steam turbine control component repair services.

The post Repair and Replacement of EHC Actuators, Valves, Hydrogen Seals and Additional Components for a Large Steam Turbine appeared first on MDA Turbines.

Here are the significant initiatives we have in place to ensure continuous growth and development within our organization.

Mentoring Program and Succession Planning

Kristin Esterby, our Human Resources Director, addressed the critical need for effective succession planning, particularly as many of our seasoned professionals approach retirement. “We’re facing a unique challenge with our workforce,” Kristin noted. “Not only are we navigating the aftermath of the COVID-19 pandemic, but we also have an aging workforce.” This demographic shift necessitates proactive measures to maintain our high standards of service and expertise.

To address these challenges, MD&A has implemented several strategic initiatives:

• Succession and Talent Planning: Our approach focuses on evaluating individual performance, setting clear goals, and creating tailored development plans. This ensures that our employees are prepared to step into critical roles as they become available.
• Mentoring Programs: We are in the process of developing both formal and informal mentoring programs. These initiatives aim to facilitate knowledge transfer between experienced leaders and newer employees, fostering an environment of continuous learning and growth. Technical-specific mentorships are also being established to address the unique challenges of our industry.

Kristin emphasized the importance of these programs in bridging the knowledge gap and ensuring a smooth transition of expertise. “Mentorship is not just about transferring knowledge; it’s about building relationships and creating a culture of support and mutual growth,” she explained.

Learning and Training (LEAP)

One of our most impactful initiatives is the Leading Effectively at Power (LEAP) program. This week-long training event brings together 20-25 leaders from various divisions to enhance their leadership skills. The curriculum covers crucial topics such as finance, legal considerations, and change management. Participants engage in interactive sessions that promote cross-functional learning and collaboration.

Kristin highlighted the dual benefits of the LEAP program: “Participants not only gain insights from our expert instructors but also learn from each other, which is invaluable for their development as leaders.” This collaborative learning environment helps build a cohesive leadership team equipped to handle the complexities of our industry.

In addition to LEAP, we are launching a pilot series called Leadership and HR 101. This program aims to equip our leaders with foundational knowledge in key areas such as human resources and basic management principles. By providing this training, we ensure that our leaders are well-prepared to manage their teams effectively and foster a positive workplace culture.

Engineers in Training (EIT) Program

Charles Monestere, our General Manager of Technical Services, provided insights into the Engineers in Training (EIT) program. Initially, MD&A focused on hiring experienced engineers. However, in 2009, we shifted our strategy to recruit recent graduates, recognizing the value of fresh perspectives and new talent. This structured program combines intensive classroom training with hands-on, on-the-job experience under the mentorship of our seasoned engineers.

Charles outlined the program’s objectives: “We aim to hire about ten new engineers each year. Our goal is to provide them with a comprehensive understanding of our operations and prepare them for long-term careers with MD&A.” The EIT program has grown significantly since its inception, reflecting its success in developing well-rounded engineers who are ready to contribute to our mission.

Personal Experience: Colin Baker

To provide a personal perspective on the EIT program, Colin Baker, a Field Engineer and recent EIT program graduate, shared his journey. “I joined MD&A straight out of college with minimal turbine experience,” Colin recounted. “The EIT program allowed me to learn from experienced engineers and apply that knowledge in the field.” He emphasized the importance of networking and continuous learning, which are integral components of the program.

Colin’s story is a testament to the program’s effectiveness. He highlighted how the EIT program not only provided technical training but also fostered a supportive environment where he could grow both professionally and personally. “The mentorship and hands-on experience I received were invaluable. It helped me build confidence and develop the skills necessary to excel in my role.”

Looking Ahead

At MD&A, we believe that investing in our people is crucial to our long-term success. Through our comprehensive mentoring and training programs, we are preparing our workforce to meet future challenges head-on while fostering a culture of continuous learning and development. These initiatives ensure that we remain at the forefront of the power industry, delivering excellence and innovation.

View Open Positions & Apply

The post Building A Powerful Future: Insights from Our Mentoring and Training Programs appeared first on MDA Turbines.