Prediction Gas Turbine System Reliability

[LewisCallaway]

I am doing a reliability study for a Solar MARS 90 vintage 1980ish. The MTTF/MTBF data that I have been able to get my hands on is somewhat suspect. Does anyone know a good source of reliability data?

 

[MikeHalloran]

Can you get the historical service/ maintenance/ outage/ failure data for that particular turbine in that particular installation?


Mike Halloran
Pembroke Pines, FL, USA

 

[LewisCallaway]

The maintenance data I have been able to put my hands on is very limited. I have been doing standards based reliability prediction with mediocre, in my opinion, results. Is there a good mechanical reliability prediction standard?

 

[TPL]

MTTF/MTBF data is just about site specific - depends largely on fuel type and quality (gas/liquid), quality of air filtration , duty (power gen/gas compression). Wash regime contributes as well.

These factors can vary enormously from site to site and give widely varying MTTF/MTBF

 

[ccfowler]

TPL's comments are as valuable as you can get. The actual duty experienced by the machine is all-important. Compared to "utlity size" machines, this is a small unit, but it is subject to the same problems. A gas turbine that is never heavily loaded can run indefinitely (multiple years) with little accumulated wear and thermal damage, but just a few minutes at excessive loads and temperatures can be the equivalent of months or even years of otherwise "normal" operation. Very rapid loading from a cold start is hard on these machines, too. If you don't have all of the actual instantaneous load, fuel consumption, and exhaust temperature recording charts (or their electronic equivalent), complete with calibration records, for the specific machine, there is no coherent basis for any meaningful formal evaluation. If you are lucky enough to be able to get credible testimony about the unit's operating history from operators and mechanics who are familiar with the actual machine, this would be the next best basis on which to make a judgement. Any attempt to use nominal factors for the engine series as a basis for a formal evaluation will be little more than an exercise in "fun with numbers."

Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.