we are operating 8Gas Turbine Generator frame 7E GTG machines. These machines were installed in early '80s, and have been operated and maintained. Mostly, these units are operated on natural gas as primary fuel, and are currently it is in good working conditions as well as all condition monitoring equipments are in good working condition in all the units. however, All these GTG units are now about to reach 200K hours of its operation.

we seek the advice for the following:

1. What precautions would be recommended for such extended operation?

2. Is there any special monitoring required during operation?

3. what if we operate these units beyond 200K hours.

thanks

 

>1. What precautions would be recommended for such extended operation?
Really there are no extra precautions required. As long as the machines are being properly maintained at the correct intervals, all you need to do is what you have been doing in the past.

>2. Is there any special monitoring required during operation?
As machines get older they can get a bit more fragile. Any strange occurrences should be investigated immediately and corrective action taken.

>3. what if we operate these units beyond 200K hours.
Again, I really don't think there is any problem, I have seen machines still running with +250,000 Hrs. Just keep doing what you have been doing and keep monitoring and maintaining the machines.

Good Luck

 

Dear All;

I agree with glenmorangie , I'm seeing 70's machines which are running very VERY smooth. Some of them have been upgraded and they are more powerful than they used to be.

But Are you aware about <b>RLM</b> and/or <b>RLE</b> (Rotor Life Management or Extension)?

There are a lot of GE publications about this topic. And GT customers/Owners, like my company, are just furious about the idea that a lot of their machines have exceeded or approached the 200.000 fired hours. And for some turbine like the MS5002D his rotor life is just 100.000 FFH (<b>Factored</b> Fired Hours) to extend rotor life some inspections need to be performed.

Another Worldwide GE talk is about the GT casing. Turbine Casing also need to be inspected and to extend its life.

Regards
Karim

 

I would only add a couple of things--and thanks to bkarim55 for mentioning the rotor/casing issues.

First, 200,000 hours is a lot of hours--and there are many machines which wouldn't last even that long without major refurbishment. To that end, GE is still learning about the lives of various machines and the components. Also, some of the methods for determining cracks and the effects of stress and long-term usage have only been recently developed. Many NDE (Non-Destructive Examination) methods have only recently been developed to allow early detection.

In other words, even GE is still learning about the capabilities of their machines. Many gas turbines were only expected to last 20 years or so, and MANY have greatly exceeded that (200,000 hours is 22+ years, and that doesn't include planned outages). There are still many GE-design heavy duty gas turbines with very old (50+ years) control systems operating in Base Load service, though many have had one, two or even three control system upgrades. (And, new control systems can help to prolong the life of turbines, also.) So, a lot of things have greatly exceeded estimates and expectations--and the manufacturer learns from the fleet experience because they don't operate machines; they just build and service them and want to sell a lot of spare parts.

Second, GE-design "B/E" class gas turbines, including all the venerable Frame 5 models, and the Frame 3s, were built with LOTS of engineering- and engineering margins. Many would say they were "over-built", and I would agree--they "take a licking and keep on ticking" (to quote a USA advert from decades gone by). And, that's what allows them to be upgraded over the years--some times multiple times--because they are so strong and durable and robust because of the margins used in their design and construction. (Not like many of the newer technology heavy duty gas turbines, which are designed to run at the very limit of the materials used to build them--HA class excepted!)

If 7E heavy duty gas turbines are operated within design parameters and don't experience excessive starts mainly due to avoidable trips (and most trips are very avoidable), they will last a very, very long time. As glenmorangie says--as units age, it's important that any trips or increased vibration/spreads be dealt with in a timely fashion and not allow to persist. Good maintenance practices are also important, as is control system maintenance (including field devices and instruments).

But, do avail yourself of the various GE publications with their recommendations--just remember, many of the inspection techniques are recently developed, and the OEM wants to sell more spare parts (there is a huge profit in spare parts, and the service for installing them). So, many of these newly developed inspection technologies are identifying "issues" that have gone largely undetected, and may, in time, turn out to be non-issues--who knows? Technology is a wonderful thing, but it can lead to "false positives" and revised guesstimates, all in an effort to sell more parts and service.

I'm not saying to ignore new recommendations and inspection techniques and -technology; but I am saying time changes perception. And, there will still be some crashes and catastrophic failures--with the old or the new service recommendations; most of it depends on operational factors which are unknown.

This is where the IIoT--the Industrial Internet of Things--the OEM is talking about and promoting so much these days is going to change things tremendously. All of the operational data they have been able to gather from F-class and newer B/E class heavy duty gas turbines via the Internet has allowed them to greatly improve the design of components and predict with much more precision when things are in the process of failing in order to avoid catastrophic failures. And, to extend operation between maintenance outages.

Anyway, I digress; if the machines have been well taken care of--they will continue to provide years, perhaps decades, of continued service. But, do pay close attention to developing problems before they lead to trips and bigger problems. And, do read the new publications with something of a critical perspective (especially those which employ new inspection techniques resulting in newly revised maintenance recommendations).

I'm just saying....

GE machines of this vintage are among the most reliable and robust machines around--with proper operation and maintenance!

 

Dear CSA;

> Anyway, I <b>digress</b>; if the machines have been well taken care
> of--they will continue to provide years, perhaps decades,

Your digression is much appreciated!

It looks like you are reading in my mind and I'm NOT the only one who is thinking that there are a huge business behind Rotor/Casing life management. YES! 200.000 FFH (Factored Fired Hours) is a long period but what about MS5002D & E, GE5 & 10 et PGT10 (single and double shafts), PGT25 Their HP and LP rotors life is 100.000 FFH?

There is another GE talk; it's about <b>to upgrade components to new standards</b>. The example I'm living is about the Frame 5, the standard is the D model (MS5002D). So when you request spare parts (capital parts) for the B or C model you will get a response that those parts are not more manufactured and they will propose to you the upgraded version which is a D model but <b>with an extra price </b>and this extra may be the double of what you used to pay for AND you will be lucky if NO more parts are required to install the upgraded version (to install the first stage nozzle D model on the Frame 5 B or C model you need also to order its support ring) ?!!.

> CSA has said: GE-design "B/E" class gas turbines, including all the venerable Frame 5 models, and the Frame 3s,"

To be honest, I never known which design class are Frame 5 models, What I know that 6B, 7E & 9E are B/E class and 6F, 7F & 9F are F class. Would you please, respected CSA, confirm that all Frame 5 models and Frame 3 are also B/E class?

Thanks in advance and kinds Regards
Karim

 

bkarim55,

> To be honest, I never known which design class are Frame 5
> models, What I know that 6B, 7E & 9E are B/E class and 6F,
> 7F & 9F are F class. Would you please, respected CSA,
> confirm that all Frame 5 models and Frame 3 are also B/E class?

To be honest, also, I believe the Frame 3 and Frame 5 models are kind of grouped in with B/E class machines when talking about non-F-class (and now non-HA-class) machines. There probably aren't too many new single-shaft Frame 5 machines sold these days; the cost-per-MW and efficiency compared to even the 6B probably makes the 6B more economic sensible.

Those are ALL my own personal observations and opinions, not based on any actionable data. I think the B/E class units are mostly based on scaled up designs of the venerable Frame 3 & -5 machines, and there are LOTS of models of the- 3 & -5 machines, many of which haven't been produced for years BUT are still in service decades after installation. So, it's just easier to group them together with the Non-F-class machines (though now there's yet another class, the huge HA machines).

I was hoping otised it glenmorangie would help with this answer, as their extensive experience and knowledge of mature machines is much greater than mine.

Also, one kind of has to consider the OEM's situation, with the proliferation of new designs and manufacturing methods. They don't derive revenue (profit) from machines which have long ago outlived their projected lifespans. They make money selling parts and new machines, and maintaining old production equipment and methods and training people to produce mature parts can get costly.

Lastly, 100,000 hours is a LOT LONGER than some of the first F-class rotors lasted. Again, sometimes design and and materials aren't maintained with the proper, or even intended, safety margins. And, sometimes Marketing gets to drive the ship (which can lead to unintentional groundings close to shore).

Take care!