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Associate Editor, Turbomachinery International Magazine
Technologies are emerging to perform maintenance, repairs, retrofits, and overhauls while gauging asset health remotely. Drones are being deployed for inspections. Some parts can be scarce, so plant operators are increasingly seeking alternatives.
There’s no app for this. There are no shortcuts. In the 21st Century, turbomachinery requires just as much repair and maintenance as ever, only now those repairs can be more accurately predicted and planned in advance.
The name of the game is efficiency. Technologies are emerging to perform maintenance, repairs, retrofits, and overhauls while gauging asset health remotely. Engineers are adopting video calling to train other engineers and operators to perform their duties. Drones are even being deployed for inspections. Part availability, too, is a hot issue. Plant operators increasingly seek alternatives for parts.
Meanwhile, several shops note a slowdown in overhauls and retrofits as cash-strapped utilities kick the can down the road. Fewer projects and more competition could spell trouble for smaller service companies in the months ahead. In some cases, residual life assessments are replacing traditional maintenance outage windows. Information gathered from continuous diagnostics and monitoring dictate if and when an outage takes place.
As grids grow more reliant on renewables, combined cycle plants in the U.S. have largely shifted from base load to cycling operation. Faster, more frequent cycling and harder duct firing wreaks havoc on heat recovery steam generator (HRSG) gas- and water-side components.
But let’s hear what the experts have to say. Those interviewed include HRST, Doosan Škoda, EthosEnergy, Rotating Machinery Services, Rotoflow, Sulzer, John Crane, Siemens Energy, MAN Energy Solutions, Riverhawk, and BRG Machinery Consulting. They offer insight into engineering and technical advisory services, OEM and non-OEM retrofits and upgrades, field services, repair/replacement of parts, 3D scanning, and on-site machining.
Liburdi Turbine Services
Liburdi Turbine Services is a specialist engineering and repair company for turbine flow-path component repairs, compressor airfoils, fuel nozzles, combustor parts, turbine blades, and vanes and shrouds. Most of its repairs involve bringing a part back to the form, fit, and function of the original. Any change, even in the coating applied, could affect the part to a degree that could require testing, which adds cost.
Liburdi relies on an institutional understanding of metallurgy and the various competing damage mechanisms in any gas turbine. The company created rejuvenation and reconstruction processes to refurbish and fortify parts to mitigate against future damage.
“Operators do not want to scrap their components, and neither do we,” said Robert Tollett, Director of Marketing at Liburdi.
There’s an inherent contradiction in the trends identified by Liburdi engineers. As the next generations of gas turbines are commercialized, components will be progressively optimized for efficiency. The achievement of efficiency generally adds complexity. Yet complexity is unforgiving in terms of design margin and reparability.
“There could be a time when most turbine parts become one-use expendable,” said Tollett. “That will be an unfortunate waste of resources akin to the cellphone industry.”
In response to COVID-19 restrictions, Liburdi noticed shortages of available parts as well as deferral of outages. Yet its shop has operated close to full capacity for a year.
HRST has observed a significant uptick in high-pressure drum weld cracking due to steam drums bearing the brunt of cyclic operation damage. This often requires nondestructive examination and analysis to determine if the unit is fit for service and what repairs are necessary. Aging duct burners and superheaters/reheaters are also impacted by cycling and duct firing.
The company is embracing new technologies to address these problems, as well as the need for more frequent inspections of turbine exhaust ducts, expansion joints, liner systems, catalysts, and silencers. HRST now uses drones as part of its inspection routine.
“During offline inspections, duct burners, catalysts, silencers, and stack dampers can be inspected by a drone at a fraction of the price of erecting scaffolding,” said Sam Shaw, Systems Engineer at HRST. “Drone technology allows for high resolution photography of these components while maintaining a safe distance for the inspector.”
Drones can also be equipped with Forward Looking InfraRed (FLIR) cameras to perform online thermal inspections. This can prove useful in detecting pen seal failures, expansion joint failures, casing hot spots, and insulation degradation on HRSGs and simple cycle exhaust duct work. Weeping pressure safety valves on some HRSGs, for example, can be detected this way as the silencers run at an elevated temperature.
Another market shift noticed by HRST is that peaking units see more run time and starts as more renewable generation comes onto the grid. This sharpens the requirement for reliability and preventive maintenance. It can mean more frequent inspections for peaking turbines and related duct work.
EthosEnergy has seen greater focus on a risk-based maintenance strategy and away from traditional OEM recommendations. This results in increased demand for condition-based maintenance programs and fast response to unplanned outages. The company has adapted by enhancing its engineers’ capacity to handle technical or commercial concerns.
The company is one of many reporting a slow, steady return to pre-pandemic business activity. This includes the gradual return of normal outage planning and repair and maintenance service requests.
Even before the pandemic, cost cutting measures had created higher demand for remote access to shops and technical personnel. Now, the company says that has become a standard necessity. EthosEnergy now has a live video feed for customers to interact with engineers in real time. Additionally, the company’s life extension and rotor solutions address changing asset demands and duty cycles, as well as energy security and grid stability challenges.
Rotating Machinery Services (RMS)
RMS is an OEM provider of AC-brand axial, centrifugal, and oil-free screw compressors, and Conmec-brand axial and centrifugal compressors, as well as gas and steam turbine repair and maintenance services. The company performs overhauls, repair and refurbishment, upgrades, spare parts and kit boxes, and nondestructive testing and analysis. As maintenance budgets tighten over time, RMS customers are increasingly cost-conscious of spare parts, overhauls, rerates, and redesigns.
“We serve as the OEM (for AC Compressor) but have always been a service provider to all nameplates of equipment,” said Alex Tetlow, Vice President of Sales at RMS. “This mix of OEM and non-OEM knowledge allows us to be creative in our solutions.”
Staying current with the latest technology in 3D printing, CFD, FEA and CAD is a priority for RMS, as well as the integration of remote communication and measurement into field maintenance routines. Over the past year, it has been difficult to schedule field crews to perform planned turnarounds. But now, there is more urgency in the market to conduct urgent repairs due to unplanned outages.
Rotoflow, an Air Products business, is a manufacturer and operator of rotating equipment, offering turbo expander repair, field service, machine rerates, root cause analysis, nondestructive testing, and reverse engineering. As well as repairing and maintaining turbomachinery, the company develops strategies to improve uptime, including proper sparing, site assessments, and condition-based monitoring.
During the pandemic, Rotoflow adopted video calling to show customers test data in real-time as an alternative to an in-person mechanical spin test. The company also redeployed field service technicians who were no longer able to travel to customer locations. As travel restrictions eased, the field service team is now performing work at customers’ sites, both planned and emergency maintenance and repairs, while following strict safety protocols.
MAN Energy Solutions
MAN Energy Solutions offers services for spare parts, turbomachinery maintenance and repairs, modular service agreements, and individual consulting and field service. For non-MAN rotating equipment, the company offers services under its Omnicare brand through a global repair shop network. It also safeguards equipment with remote machine diagnostics and provide training for operational and maintenance skills with a service called PrimeServ.
Like others, MAN has noticed a shift from time-based to condition-based maintenance.
“Customers seek higher uptime and reliable, uninterrupted operation with longer maintenance intervals,” said Oliver Tromm, Head of Product Center Zurich/Berlin, MAN Energy Solutions, MAN PrimeServ. “Optimization of residual lifetime is key today so high equipment reliability must be ensured.”
MAN is adjusting to the same trends as the rest of the industry. Turnarounds were shifted, investments into upgrades and modifications were questioned and delayed, a higher degree of remote services was requested, stock inventory was checked, and risks were minimized with higher stock levels.
Siemens Energy services drivers and driven equipment, including aeroderivative gas turbines, medium and small gas turbines, steam turbines, generators, all types of compressors, and gas engines. It provides OEM services for parts, field service, repairs, overhauls, inspections, and remote operational services. The company listed several trends: customers want no repairs to go unplanned, minimal outages time, lower emissions, reduced inventory over time, and higher employee productivity, with a tendency towards using its own employees and teams rather than subcontracting.
“Customers are keen to adopt new technologies, like additive manufacturing, sensors and remote monitoring,” said Erhard Eder, Senior Vice President, Industrial Applications Services for Siemens Energy. “They also want more predictive maintenance options, like asset performance management to transition to condition-based maintenance.”
Since the COVID-19 pandemic, the company invested more in its remote offerings. This begins on the factory floor, with remote testing, then to the field with remote performance monitoring and diagnostics, and field service when needed. Accordingly, Siemens Energy trained its regional field teams to carry out maintenance with remote tools. Remote Inspection and Testing Acceptance (RITA) allows customers to be virtually present when its turbomachinery is being tested. Cameras film the components during actual test procedures. Footage and critical data are transmitted in real-time.
Riverhawk designs and manufactures bolt tensioning solutions and is a full-service diaphragm coupling manufacture and repair center that specializes in refurbishing OEM diaphragm couplings. Along with its coupling offerings, the company supplies all the installation tooling to install couplings and torque management solutions. The biggest challenge it faces is the demand need for service within weeks rather than months.
Most users shut down for only a brief period of preventative maintenance. If there is no spare coupling, they need an existing coupling serviced and returned before completion of the turnaround
“Returning a coupling in as-new condition with a short lead time can be a challenge, especially if parts are damaged beyond repair and need replacement,” said Riverhawk’s Pat McCormack, Business Development Manager.
Over the years, the company has seen formal safety standards shift. Sometimes it means showing a simple video on a facility’s safety requirements. In other cases, it requires an all-day class before entering the facility. In addition, the company has seen a growing demand for detailed documentation of repair work such as Material Certifications, Calibration Certificates and pictures of certain portions of the repair.
Riverhawk has no plans to abandon face-to-face meetings. But they are being supplemented by video conferencing software and high-resolution cameras to provide proper guidance in the use of tooling. Overall, McCormack said maintenance spending was down about 20% from initial 2020 projections. Nevertheless, he remains optimistic that 2021 will be a good year for those in maintenance and repair.
BRG Machinery Consulting
C. Hunter Cloud, Ph.D., President of BRG Machinery Consulting, a Virginia-based provider of rotating machinery technical services, commented on a long-term trend of fewer experienced machinery engineers being present in plants. As a result, he often sees repairs made without addressing the root cause of problems. The rush to return critical machinery to full operation can contribute to a lack of due diligence that should include a thorough failure analysis by internal or external technical experts.
As margins in operating plants shrink, Cloud said, decisions to refurbish aging equipment are being delayed. Repairs attempt to extend the life of inefficient equipment, often beyond the original design. Cost reductions have also led to the use of third-party repair shops who can be unfamiliar with the equipment’s design, placing more reliance on the user to determine which repairs are necessary.
Some large manufacturers, Cloud added, are evolving into global organizations. At times, this can create barriers to having the right people involved with a repair or failure investigation. Further, field support may now involve quarantine before and after, which affects timing and costs. Oversight of shop work requires more detailed documentation along with virtual inspections, such as for bluing contact checks and witness of rotor balancing.
Sulzer is an OEM for pump parts and offers maintenance and repair services for pumps, turbines, compressors, motors, drives and generators. The company is constantly keeping up with customer demand for alternatives for spare parts. This is especially important for a non-OEM service provider like Sulzer, whose main focus is increasingly seal reliability.
Since the start of the pandemic, Sulzer has seen fewer overhauls in a more competitive market. Fernando Romero, VP Engineering at Sulzer, said clients often want a re-rate until they know the cost.
Sulzer has invested in automation in the form of computerized numerical control capabilities to support manufacturing, dimensional inspections and, welding.
“With remote maintenance, you lack control over the capabilities, workmanship, and resources of the party at the other end of the line,” said Romero. “Care is required in the division of responsibilities.”
John Crane offers project management services for turbomachinery performance restoration as well as pre-commissioning and commissioning services. The company manufactures gas seals, separation seals, conditioning, and asset monitoring systems. It works constantly to raise seal, speed of rotation, diameter, and resistance to process gasses, in addition to running at colder temperatures.
“We have made progress of late raising the understanding of seal health dry gas seal lifespan,” said Mike Weegenhausen, Director, Turbomachinery Products & Services at John Crane.
He gave examples of the type of projects the company is engaged in. The operational lifetime of centrifugal compressors, for example, can be cost-effectively extended by upgrading components such as motors, impellers, seals, bearings, and control systems. A common upgrade is a dry gas seal retrofit for oil-seal-equipped centrifugal compressors.
Doosan Škoda Power
Turbomachinery services are a key line of business for Doosan Škoda Power. All types of overhauls and inspections of machines in combined cycle power plants have remained the key driver in turbomachinery services. The company also sees growth in the waste-to-energy industry and in the nuclear segment.
Doosan Škoda Power can perform online remote borescopic inspections of turbine internal parts and remotely access turbogenerator control systems as part of long-term service agreements. This enable tuning and adjusting of operating parameters and alarms.
“We can manufacture spare parts in the original quality in the same workshop used for new build installations,” said Stanislav Šnejdar, Director of Service at Doosan Škoda Power. “Our service team is located under one roof along with all subject matter specialists and R&D engineers.” ■