Expert service, operation and maintenance: the key to maximizing gas turbine performance

Operators of on-site power plant based on gas turbines will know that expert service and maintenance is essential to keeping plant running and availability and performance high. This article rounds-up the capabilities of some key players in the industry.

Gas turbine generating plant tends to be expensive and complex. It needs careful design, sizing, application, operation, monitoring and control to perform at its best. On top of this, turbine-based plant needs specialist service and maintenance (S&M) attention, as well sometimes, as repair and overhaul services. One obvious route to the former is a S&M contract with the turbine manufacturer, but this is not the only method. A range of specialist companies, both large and small, some in the gas turbine manufacturing business, many not, also offer S&M services.

At one end of the scale are comprehensive, long-term service agreements incorporating performance guarantees. But plant operators may also choose a more piecemeal approach using smaller companies to carry out parts supply, service, repair and operations, both on-site and at off-site workshops.

Today’s economic climate has altered the financial equation around refurbishment of existing plant versus the installation of new, replacement equipment. And, beyond repair and refurbishment, many S&M companies will upgrade plant with new components, thus either increasing its output, or improving its all-important operational efficiency. The service and maintenance industry is already looking forward to being one of the winners in the recession ” in contrast to many other sectors of the industry.

This round-up of some of the key players in gas turbine specialist service and maintenance is sourced from the companies themselves.

MTU Maintenance

Germany’s MTU Maintenance is part of MTU Aero Engines, which designs and builds both aero and aero-derivative industrial turbines, and is also a major independent provider of turbine maintenance services. The maintenance company focuses its work with aero-derivative industrial gas turbines ” with a particular emphasis on the GE LM series of gas turbines ” at its ‘centre of excellence’ at Berlin-Brandenburg where it has one of the world’s largest and most advanced industrial gas turbine test cells.

The company sees the repair and maintenance of industrial gas turbines as a cornerstone of its activities and is gearing up to face substantial growth in this part of the business.

Volvo Aero

Sweden’s Volvo Aero is another company that works primarily with turbines and engines for aircraft, but that also services industrial gas turbines. The company says it has grown into a full-service partner for hundreds of industrial and marine gas turbine operators around the world. It offers turbine operators maintenance services at many different levels, from a complete product programme covering repair and overhaul, to turbine testing, spare parts, etc.

Volvo Aero says it has particular high-level skills necessary for technical upgrades and repairs method development. The company is an authorized maintenance centre for the GE LM1600 and Dresser-Rand DR990 turbines, and has experience covering many types of application, including cogeneration.


Another major network of independent providers of maintenance support to owners and operators of rotating equipment from a range of major manufacturers, is the Turbocare Group. The Group combines a long history of steam turbine service capabilities with the gas turbine service capabilities of several joint ventures. Turbocare, which also looks after compressors, generators and electric motors, says it can provide full service solutions to the customers regardless of equipment manufacture and brand. With 16 businesses around the world the Group works in more than 100 countries worldwide.

Turbocare offers a complete range of component repair, equipment refurbishment, system retrofits, engineering, and parts replacement services for gas turbines ” the company also works with steam turbines, compressors, generators and electric motors.

Sulzer Turbo Services

Sulzer Turbo Services, part of the 175-year old, Switzerland-based Sulzer now provides repair, refurbishment, and maintenance on rotating equipment globally ” claiming to be the leading non-OEM provider of turbine repair services. The Turbo Services company, itself with 30 years experience, specializes in the customer support of gas turbines from all the main manufacturers. Its approach covers repair services, supply of replacement parts, and complete overhauls and maintenance packages of heavy duty and light frame industrial gas turbines.

Sulzer provides scheduled and unscheduled maintenance. Boroscope inspection, combustion inspection, hot gas path inspections and major overhauls are performed by OEM-trained staff and mechanical and electrical inspections are supported by in-house engineering and logistical departments. Turbine control upgrade packages are available.

Thomassen Turbine Systems

Ansaldo Thomassen has over a century of experience on all aspects of GE-type heavy-duty gas turbine technology and, offers a one-stop-shop to serve the owners of turbine systems worldwide. Based at service and sales centres in the Netherlands, Italy, India, South America, Indonesia and the United Arab Emirates, the company says it aims to provide full service solutions that optimize unit availability, minimize maintenance and component costs, and increase operational safety for GE heavy-duty gas turbines.

Rotor of a large gas turbine which was repaired by Sulzer Turbo Services after a severe outage credit: sulzer
Click here to enlarge image

The company also sources GE design heavy-duty gas turbines from clients and re-manufactures and upgrades them at its facility in Rheden in the Netherlands for new owners. As well as service and re-manufacturing, Ansaldo Thomassen will also upgrade turbine systems. Finally, the company says that its long-term service agreement approach assures component availability and fixed turnkey price arrangements over several years.

GE Energy

US-based global company GE offers probably the widest range of heavy-duty gas turbines available, from 26 to 480 MW, within which there ought to be a machine for every industrial user, independent power producer and utility, says the company, from power-only generation to cogeneration and district heating. The company says it has installed more than 6000 gas turbines, more than any other supplier, and has accumulated over 200 million hours of operating experience.

But the company also has over 25 years in the operation and maintenance (O&M) business, making it one of the world’s largest third-party providers of power plant O&M services. GE says it manages more than 22 GW of generation capacity in 24 countries, so claims to be uniquely positioned to provide the latest, cost-effective practices and process improvements to ensure optimal economic performance of turbine plant. The company offers a range of fixed price and ‘cost plus’ O&M contracts to include various levels of maintenance.

Wood Group

Headquartered in Aberdeen, UK, and Houston, US, global energy technology company Wood Group includes a Gas Turbine Services division which offers maintenance, repair and overhaul solutions for heavy industrial gas (GE, Siemens, Alstom and Mitsubishi), aero-derivative (GE, Rolls-Royce and Pratt & Whitney) and light industrial gas turbines (Siemens and Solar) used in the global power generation market. The company offers S&M services for other high-speed rotating equipment and generators, as well as repairing gas turbine accessories and components.

The company says its turbine overhaul and advanced technology accessory and component repair facilities are strategically positioned around the world and are supported by field service teams located around the world. In addition to its global repair and overhaul facilities, the company says it has field service specialists strategically positioned to offer on-site support 24/7 to any location worldwide. On-site services include: gas and steam turbine major inspection and repair, outage and maintenance services, combustion and hot gas path inspection, long-term maintenance management for rotating equipment, and operational and technical support for rotating equipment.

Information compiled by COSPP magazine.

GE’s Operations and Maintenance Advisory Services

Last year, GE Energy launched a first-of-its-kind service, designed to help customers who operate and maintain their own power plants achieve the highest possible levels of efficiency and performance.

The new offering, ‘Operations and Maintenance Advisory Services’, will assist customers in creating processes and procedures based on GE Energy’s own extensive O&M experience. It enables customers who want to operate their own power plants the ability to utilize GE Energy’s experienced staff to provide on-the-job training and advice using GE Energy power generation technology.

Under the new programme, customers will be able to utilize many of the same O&M tools used by GE Energy in power plants around the world. GE Energy experts will be available to advise customers on performance, offering solutions that could help increase productivity and reduce costly downtime. Workforce optimization, robust procedures around administration, operations, maintenance and reporting and managing workflow, are just some of the areas where customers can benefit.

The O&M Advisory Services offering is derived from ISO 9000-certified processes and procedures.

Sulzer case study ” uprating a German-designed 120 MW gas turbine

It is normal for a gas turbine, during the lifetime of the model, to increase its performance both in terms of efficiency and output. The easiest way to improve both efficiency and output is to simply increase the firing temperature of the gas turbine. The simple rule of thumb is that for every 10à‚°C increase in firing temperature, the lifetime of the parts is reduced by 50%. To combat a loss of life and increase maintenance costs, Sulzer Turbo Services has been working on new and improved turbine components for this gas turbine.

The full gas path consists of four rows of stationary vanes and rotating blades. The original unit gave a nominal output of 120 MW, with 32.5% simple cycle efficiency and a maintenance cycle based on 25,000 equivalent operating hours. Today, it is anticipated that the efficiency will increase to around 34.3% and the output to approximately 165 MW, generating an additional US$20 million per year of revenue (based on 6500 hours and price of $70/MWh).

Sulzer engineers worked on a redesign of the parts that would provide increased capacity or allow for extended maintenance intervals. The parts can be operated at either 1060à‚°C or 1075à‚°C with a different ‘cost of maintenance’ and different unit output, based on the chosen firing temperature. This owner is able to optimize his costs and revenues based on market conditions. Three major changes were required:

  • Improved cooling ” the easiest way to improve the performance is to increase the air flow to the part. The toughest issue is to make best use of the air flow that exists by incorporating new airflow designs to the cooled blades.
  • New materials ” new materials have become available. New casting technologies have also helped and it is now possible to cast large parts, allowing materials with better creep and oxidization resistance to be used.
  • Better coating systems ” Sulzer found the most effective way to cool parts is to apply a preparatory MCrAlY thermal barrier coating (TBC) system ” a ceramic layer that insulates the metal from the full temperature of the hot gas path. The TBC coating extends maintenance intervals without increase in output, and increases capacity and efficiency.

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