recomendations after over speed event
recomendations after over speed event
(OP)
would you roll a STG unit (10MW air cooled) that exceeded 150% speed with out opening it up and inspecting.
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recomendations after over speed event
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RE: recomendations after over speed event
Before deciding on inspection, there are some factors that would definitely warrant opening the unit:
1. Was the coast down time normal?
2. Did the turning gear engage and the unit cooled down nomally? Abnormal vibrations during coastdown?
3. Is the shaft free to turn with no binding or strange noises?
4. Any debris found in the oil?
5. Any debris found in the exhaust?
6. Any opportunity to inspect the last stages without opening?
7. Any opportunity to borescope?
Depending on the criticality and downtime cost i would first exhaust all alternatives to do an educated assessment.
If the manufacturer's recommendations are that after such event the unit shall be opened and inspected then there is no room for argument. But if the instructions are silent or it is at the operator's discretion, I would try to avoid fixing something that is not broken.
What do yo think?
saludos.
a.
RE: recomendations after over speed event
I was not involved in the event. so I can't answer
But the main concern was to set the valves and try again
I just declined to assist and wonder if I'm too concerned.
I recall that 15% above OST was where things started to give on utility size units
hey, 30 years with out being at a "blow up" and don't want to ever
RE: recomendations after over speed event
To add to Tick's list, were there any concerning vibrations during the overspeed event? Did it spend any time in a resonance range? How long was the duration of the overspeed?
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If we learn from our mistakes I'm getting a great education!
RE: recomendations after over speed event
Since my decline to assist, I doubt I will hear any more from them
RE: recomendations after over speed event
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If we learn from our mistakes I'm getting a great education!
RE: recomendations after over speed event
- Figure out what caused the overspeed event in the first place.
- Figure out what automatic controls failed to stop the unit before it got much above 100pct, and fix them.
Mike Halloran
Pembroke Pines, FL, USA
RE: recomendations after over speed event
RE: recomendations after over speed event
RE: recomendations after over speed event
E.g.: For the Diesels that my outfit sells, a single overspeed event ends your warranty. Period. Not negotiable. End of discussion.
Perhaps the STG manufacturer has a similar policy about overspeed events, in which case the perpetrators have career incentives to sweep such events under the rug, and to find someone else to throw under the bus when it arrives.
Mike Halloran
Pembroke Pines, FL, USA
RE: recomendations after over speed event
rmw
RE: recomendations after over speed event
I think you might gather my question for recomendations following event was not for the excellent confirmations of items to inspected, but as a self check for me since it seemed I was the only one concerned. Since I've declined to assist, Im pretty sure I will not hear from them what they do one way or the other
RE: recomendations after over speed event
I concur with your decision.
Sometimes a man has to do what a man has to do. You gotta live with yourself. If one of those retaining rings comes unglued and shreds the generator, at least it won't be on your watch. It looks like they had their minds made up but needed a scapegoat in case they were wrong.
rmw
PS: I assume you are a man.
RE: recomendations after over speed event
www.u
RE: recomendations after over speed event
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If we learn from our mistakes I'm getting a great education!
RE: recomendations after over speed event
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If we learn from our mistakes I'm getting a great education!
RE: recomendations after over speed event
I agree with previously stated concerns that the generator is a greater issue--air-cooled generators can catch fire quite readily.
You certainly were wise to stay clear of that obvious set-up. Any short-term compensation would almost certainly have been quickly overshadowed by less than pleasant events.