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As the gas turbine morphs from a supplementary source of power to being increasingly responsible for baseload, the aftermarket has become more lucrative. Carlo Luzzatto, President of Chromalloy, estimated that the gas turbine (GT) service business amounts to somewhere around $16 to $17 billion per year. He qualified this by saying that this number may not include upgrades to turbines and replacements of the fleet, so the actual total may be as high as $20 billion annually.

With so much at stake, it is not surprising that more spare part and aftermarket options are becoming available. This applies, in particular, to the F-class market.

“As the installed base matures and existing OEM service contracts expire, the F-classmarket has begun to open up for the independent sector,” said Mick Conway, Marketing Director ofWood Group GTS.

As well as straightforward replacement parts, some suppliers are seeking to improve upon the original components by incorporating design and material innovation.

However, third parties typically are reluctant to offer parts for the very latest machines. “For an engine design less than 10 years in operation, we recommend the operator uses OEMparts, as design integrity, repair history and failure modes are being established and ideally addressed,” said Scott Nicol, General Manager for Turbine Services at Chromalloy.

F-class bonanza

Spare parts comprise the largest slice of the maintenance pie. As a result, there are plenty of choices available for the Frame 5 up through the E, and more recently for Fclass engines, which have been spinning for over 15 years. Their designs have stabilized to a point where third parties provide options aimed at improving life cycle costs. This makes F-class components a hot commodity.

“The biggest part of the GT services market is the F-class,” said Luzzatto. “One year’s average maintenance is four times more for the F-class than the E-class.” For the F-class, spare parts account for 68% of the total aftermarket, repairs 18% and field service 14% (Figure 1). OEMs are finding it harder to renew contracts once their Long Term Service Agreements (LTSAs) expire. They now have to compete with third parties entering the market with good technology and workable designs for F-class machines.

The F-class, after all, is no longer earlystage technology. Users and aftermarket suppliers have had more than a decade to come to grips with the fine points of its operation and maintenance.

As well as copycat parts, some suppliers promote new blade and material types. This is awelcome development due to the changing operating patterns of gas turbines. A decade or so back, many turbines operated at relatively low capacity factors.

These days, they are operated with far greater frequency; and as more coal plants close down they are even transitioning into baseload operation. This could be a recipe for a parts shortage: A steady increase in the number of GTs with each running far longer than originally intended.

Nicol explained that the number of third-party providers of combustion and hot section components has decreased as engine fire temperature has increased. This is driven by the complexity of materials, castings processes, cooling design and coatings.

However, the firing temperatures required in F-class units provide complexities beyond what is required in E class. Factors such as the criticality of materials, casting technology (examples are directionally solidified and single crystal casting), cooling designs, and thermal and hot corrosion coatings combine to reduce the field of suppliers. But that does not mean there are not other possibilities out there.

“Only a handful of players have offered F-class alternative parts in the last 10 years,” said Nicol. “This has primarily been the larger 60Hz fleet in North America. Because of the competitive presence of independents in this space, OEM pricing has largely moved towards thirdparty pricing levels.”

The 50Hz markets, on the other hand, have not had the same volume of independents. But Nicol believes that this space will follow a course similar to the U.S. especially in Asia and Europe.

“Aftermarket parts for land-based engines are becoming increasingly available to operators,” said Nicol. “Availability increases by fleet size and maturity of the engine, and is largely driven by the economics of the marketplace.”

One obvious economic advantage is price. Nicol estimated that Chromalloy parts may yield savings to the operator of thirty or more percent off OEMlist pricing depending on the frame.


Warranty challenges

On the warranty side, he said that third parties are challenged to go further than OEMs.Warranty clauses have to be clear in requirements and terms, and third parties have to largely base the warranty on equivalent operating hours. One example is 9E parts where the end user is guaranteed a stated initial price and refurbishment rate for the life of the part.

Chromalloy, whose customers include the OEMs and operators, has its own casting facilities where it can create large directionally solidified (DS) and single crystal airfoils. Its latest casting facility in Tampa, Florida, is designed to pour up to one million pounds of super-alloy components each year. This includes F-class components.

Quality, cost and fast delivery

Another well established supplier of non- OEM parts is Turbine Services Ltd. (TSL) of Saratoga Springs, NY, which focuses on GE heavy-duty gas turbines. As an ISO 9001:2008 certified operation, it emphasizes quality, cost and fast delivery.

Since 1972, it has engineered more than 600 turbine components including more than 50 rotating blade styles, equiaxed (crystalswith axes of about the same length) and DS. It manufactures 30 different varieties of stationary vanes and diaphragms made of high-strength nickel alloys and corrosion- resistant cobalt alloys.

As touched upon earlier, it is not just about reducing costs and finding cheaper parts. Some non-OEM sources are looking at ways to improve lifecycle costs. TSL’s SL+ combustion components, for instance, are designed to increase unit availability by extending the gas turbine combustion inspection interval. This is achieved by improved clearances, addition of wear resistant materials and addition of thermal barrier coating.

Similarly, Chromalloy is investing in coatings and base materials specifically for multiple-start duty. Jupiter, Florida-based Power SystemsManufacturing (PSM), too, seeks to differentiate itself through innovation. Instead of copying existing systems and components, it analyzes models, redesigns and seeks to improve them. The company offers OEM-compatible airfoils and Dry Low NOx (DLN) combustion components for GE 6B, 7B/EA, 7FA and 9E machines as well as Siemens 501F.

To reinforce its F-class ambitions, PSM has developed airfoil and combustion component reconditioning processes to improve the life of F-class components. It provides long term agreements for 7FA and 501F turbines, which include part supply, reconditioning, monitoring, diagnostics, field services and parts tracking.

For example, PSM has introduced a row zero compressor blade for 7FA gas turbines equipped with a flared compressor design. These blades are intended to overcome failure incidents. These blade sets are a direct replacement installation.

Service perspective

Parts provision is only one part of the picture. The field service element has to be included for O & M success. That is why some parts manufacturers are trying to either partner up with an established field service provider or organically grow their own service division.

A recent example of a parts-field service partnership is Pratt & Whitney Power Systems (PWPS) and Wood Group. While PWPS supports its own FT8 turbines, it has established a joint venture with Wood Group to address its FT4 machines. Out of 1,200 FT4s sold in the 1960s and 1970s there are around 850 to 900 still operating.

PWPS has a repair shop in San Antonio, Texas, that focuses mainly on Fclass turbines, and a Singapore shop that addresses Frame 6Bs and 9Es. “We expect to broaden our portfolio of part and repair services,” said Peter Christman, President of PWPS.

The company formed an alliance with Wood Group GTS for F-class services, whereby both companies jointly service the GE Frame 7FA industrial gas turbine aftermarket. GTS has a ten-year license for sale and distribution of PWPS manufactured combustion hardware, hot gas path components and repair services. In return, GTS will gain access to parts to support power plant owners and operators it serves via LTSAs.

PWPS prefers to stick to its core competency of part manufacture and repair manufacturing. This arrangement enables the company to leverageWood Group GTS expertise in lifecycle management.

“7FA operators demand choice, so this alliance provides a viable OEMalternative and a means for users to control future costs,” said Frank Avery, president of power plant services atWood Group GTS. “With many existing service agreements expiring over the next several years, this presents a big opportunity.”

User group feedback

The subject of aftermarket parts is a common topic at many user group meetings. Even if not on the agenda, it either comes up during Q and A, or is discussed widely in the hallways.At one recent user meeting in the U.S., for example, most people in attendance admitted to having used non- OEM replacement parts.

One attendee spoke about using them to control costs. This included first-stage buckets and shroud blocks, compressor row stationary vanes and carriers, and row 17 rotating blades.

His advice to make such a vendor relationship workable was to start early as the process takes a few months, check customer references thoroughly, evaluate several vendors by going to their sites for a cold, hard look, and to use a consultant or subject matter expert to help find the best solution.

“We did an extensive review of quality documents,” said this user. “While most did real well in this department, we were disappointed in a couple of them.”