Keeping power plants profitable

Keeping power plants profitable

by Eugene R. Reinhart

Nondestructive evaluation enables power-plant operators to make their own decisions on equipment replacement and upgrades

With deregulation of the utility industry becoming a reality, some utilities are developing procedures and databases that allow independence of OEM support and keep maintenance and replacement costs to a minimum. A utility's ability to control these costs may become one of the keys to its survival.

NDE techniques were used to examine blade-attachment areas from the bore at the Connecticut Light & Power Co's Devon station. The process allowed access to the lock-slot blade-attachment areas without disassembly of the casing

Of particular concern has been utility managers’ inability to seek second opinions on OEM recommendations to repair and replace critical, costly plant components such as turbines, generators, or piping. Some utilities have developed the ability to make these decisions independently. Nondestructive evaluation (NDE) has become a focus of these efforts.

Pennsylvania Electric Co. tried an innovative eddy-current system in Johnstown, Pa., to detect stress-corrosion or corrosion-fatigue cracking in the inner rows of turbine blades without a turbine teardown, saving the owners approximately $2.8 million. NDE inspection of rotors’ tenon areas resulted in considerable savings to Southwestern Public Service in Amarillo, Tex.

After hundreds of rotors were retired on OEM recommendation, EPRI and independent groups developed inspection and analysis technology for use by utilities, and many rotors were returned to service. Recently, these NDE techniques have been expanded to include examination of blade-attachment areas from the bore, so the blades can be examined in place. The Connecticut Light & Power Co. was estimated to have saved more than $1.5 million using this technology at its Devon station.

Bid packages for NDE services have no detailed requirements for training, experience, or certification in NDE methods. This may result in missing failure-causing defects, thereby negating the objective of the inspection.

Experienced utility engineers are often key to cost savings and will be invaluable in evaluating new devices and techniques. Instead of retiring these experienced engineers, it would appear best to increase their training in new technologies. Otherwise the independence of action critically needed by utilities in a competitive world may actually be reduced.

The above was adapted from an article by Eugene R. Reinhart, president of Reinhart & Associates Inc. in Austin, Tex. The full text may be found in the April 1997 issue of Mechanical Engineering magazine. © 1997 ASME International.© To obtain a copy of this issue, click here.