Special Issue – 2011 Outage Handbook

2011 Best Practices Awards

Four Best of the Best Awards go to NAES-operated plants

Feature Articles

Rotor Life Extension
Beluga personnel install new wheels on Frame 7 turbine rotor at 200,000 hr

> The hot topic at most gas-turbine user-group meetings today is rotor life evaluation. Recall that the OEMs have established life limits on turbine rotors that strongly suggest their replacement at a  prescribed number of operating hours or starts, whichever comes first.  more

Flow-Accelerated Corrosion
Lessons relearned
by David Addison, Thermal Chemistry Ltd (New Zealand)

>  Although the mechanism of flow-accelerated corrosion in gas-turbine-based combined-cycle and cogeneration plants generally has been understood for decades, FAC remains one of the major safety issues for plant management and personnel. It can occur across the feedwater system, from the condensate pump to the economizers and LP evaporator sections of heat-recovery steam generators. It is equally dangerous in both single- and two-phase flow regions.   more

There’s nothing generic about generator failures
by Clyde V Maughan, Maughan Generator Consultants

> Root cause analysis is never easy, but the dearth of true field expertise with generators has led to improper diagnoses, incorrect responses, and significant costs to owners and OEMs, much of which could have been avoided.  more

New Safety Standard
NFPA 56 a ‘game changer’

> Virtually all owner/operators of gas-fired generating facilities will have to change existing plant practices and thinking to meet the requirements of the “Provisional Standard for the Commissioning and Maintenance of Fuel Gas Piping Systems”—this to protect personnel and equipment against explosion and other hazards associated with the use of natural gas. more

Safety Alert
Leaking blank flanges on liquid fuel lines hazardous

> The scene: Simple-cycle 7FA startup on a quiet Sunday afternoon. About 30 minutes after the button is pushed on the gas-only unit, compartment thermocouples read 300F; 15 minutes later, 350F. Operator checked the engine and saw a blowtorch-like flame shooting out from a combustor end-cover. The unit was shut down immediately.  more

Corrosion Primer
Protect underground piping from corrosion: What to do before the outage
by Jerry Weiser, Norton Corrosion Ltd

> You look at your calendar and see that you have 180 days before your planned outage. Looking out the window to where your plant’s fuel lines meet those from the gas transmission and supply system, you are concerned about corrosion, and have to make unscheduled repairs. You want to solve these issues. You also want to make sure your good piping remains that way.  more

HRSG Clinic

When it comes to training plant personnel to operate and maintain heat-recovery steam generators (HRSGs), perhaps no organization is better equipped to handle the assignment than HRST Inc, Eden Prairie, MN. the company conducts its HRSG Academy twice anually and always plays to a full house.  more

Industry First
Ovation replaces Mark V on 7FA

> Owner/operators learned at the recent 7F Users Group Conference (May 9 – 13, Houston) how Xcel Energy replaced an ageing Mark V gas-turbine control system with Emerson Process Management’s (Pittsburgh) Ovation (TM) on Unit 3 of it’s Fort St. Vrain Generation Station (FSV), Platteville, Colo. more

Online, Offline Washing
Rx for compressor fouling: proper ingestive cleaning

> When the performance of your gas-turbine compressor degrades because of fouling, don’t just assume an “over the counter” compressor cleaning will do. Get a prescription that accounts for the specifics of your machine and its operating characteristics. more

Turbine Inspection Reports
Keep up with OEM advisories

> Plant managers are always pressed for time and keeping up with OEM advisories can be challenging. But it’s important to do so. You don’t want to overlook an issue that could cause a forced outage which should not have occurred.  more

Water Chemistry
How to improve your water sample panel

>  PacifiCorp’s Lake Side Power Plant, Vineyard, Utah, completed in 2006, a 545-MW, 2 × 1 combined-cycle facility (Fig 1) was built with an inadequate and unreliable water sample panel. It was difficult to work on, required excessive maintenance, had poor sample-water temperature control, and was poorly arranged. more

Lubricating/Control Oil
Vanquish varnish to improve gas-turbine reliability

> Gas turbine owner/operators know that varnish can have a significant adverse impact on engine performance. However, there had been little formal research conducted on the problem until recently. more

Generator Exciters
How to prevent collector-ring fires

> Flashovers in generator exciters have gotten considerable attention in the last couple of years as powerplant owner/operators have stepped up efforts to make their facilities safer workplaces. Today, the industry generally recognizes that collector-ring fires can be prevented by closer observation of exciter operation on rounds and proactive maintenance. more

Valve Repairs
Don’t forget to inspect your valves

>   It’s easy to leave valves off your outage checklist. There are so many things that must be done and time is limited. Work generated by a seemingly endless stream of advisories from the gas and steam turbine OEMs, generator manufacturers, and regulatory agencies typically gets top priority. more

Long-term Service Agreements
What you need to know about non-OEM LTSAs

>  It took a while for non-original equipment manufacturers (OEMs) to break into the long-term service agreement (LTSA) market for gas turbines, but now they are here to stay. In many cases, the parts and maintenance services offered by non-OEMs are comparable to the OEM’s. more

Air-cooled Generators
Diagnosing partial discharge, spark erosion

> Air-cooled generators are offered today with a rated output of 400 MW and moving higher with voltages at 18 and 19 kV. As with the hydrogen-cooled units that were pushed to the limit in the 1970s and 1980s, the larger air-cooled machines have begun to show their own set of unique problems. more

Control Room Equipment
Ten years in construction, plant upgrades HMIs before COD

> You probably read this headline twice. Strange things can happen in competitive markets.  more

Business Partners

> The Clyde turns 85, threatens retirement … again
> Texas Tech salutes Rentz
> Dodero receives top paper award

From the Editor

> Attend a user-group meeting this fall