Frame-VI Gas Turbine Mark-V Control

From what you have stated, it appears that the oil used in the governing system is impure. Have you checked the contamination level of the oil? if not, please check the contamination level. If it is just over the permissible level, run the filtering system continuously and check again whether the impurity level has come down. If not, change the oil and observe the performance

I have dealt exhaustively with governing systems installed for hydro turbines and invariably the moog valve was the culprit for faulty operation of the governing systems since moog valves require oil with impurity levels less than 10 to 12 microns which is not possible in Indian conditions

There is a long history of moog valve on GE industrial turbines malfunctioning due to oil coking. The oil is exposed to very high temperatures while while cooling the #2 bearing assembly. This causes coking of the oil that clogs the servo valves. There are numerous companies now that can provide external filtering sytems to clean the oil. If you join the Frame 6 users group you will find many users with similar problems.

http://www.frame6usersgroup.com/

Sir, Thank you very much for your reply and giving me a site name which is very useful for me @ Lube oil quality related information. We are going to detailed analysis of Main Lube oil (SP-32) as per guide line given in site mentioned by you. We have still not resolved the problem of machine load (MW) VARIATION @ 5-8MW without changing in FSR1 (Liquid fuel FSR). (2) We have also facing the problem related to IGV. Out of 9 M/C we have faced problem of IGV in 3 M/c. We have a 9 m/c running in Droop control and all are operated at Part load operation. During Ambient temp. Increased IGV modulate but we have faced that IGV stuck up at 62-64 DegAngle. (Normal operation 57 - 84 degA). To avoid this problem we operate M/C at IGV OFF mode (84DegA). We have checked IGV cylinder, Mood assembly, and Moog filter. We found moog filter chocked, and also found IGV cylinder alignment slightly mismatches. We resolve this problem in one of m/c, but still we faced IGV related problem in other 2 machines. Sir, please guide us or giving related document to resolved this problem. If any site name knowing by you related to GE make controlled machine for gas turbine trouble shutting and advanced Operational knowledge of Gas turbine.

For IGV, best people to ask for is Young & Franklin, USA. They are the one who have manufactured IGV for GE turbines for past 6 dacades & are OE to GE & its licensees. In fact BHEL also bought sometime from them before replacing it with indigenous stuff. I have come across issues related to this.

Y&F has come out with better design of IGV where there is seal leakage issues. GE is also supplying new design IGV actuators after June 2006. You can get in touch with Mr Eric Sohne. VP. Sales of Young & Franklin at esohne@yf.com He will put you to their engineering deptt.

Sir our Gas turbine we have replaced lube oil (IOC brand SP-32). We have analyzed lube oil for sediment and Color test we found color 6.5ASTM (mostly designed value are 2-3, confirmed value I don't know). I have required advised for future for which kind of Lube oil test to be carried out for early detection of Oxidation, Rust, sediments etc. At present we was done routine monthly test like Moisture, TAN, Viscosity, Flash point. We have analyzed all of our GTs lube oil analyses, most of are color number 5 to 6 ASTM.

In case of high purity requirements, we in our equipments recommend electrostatic filter - this can be put direct on line if flow is low and in kidney loop on tank if the flow is high.

You may consult one of the filter suppliers quite a few are there in India. Just google for it.

This is supposed to remove the solid particulates upto sub-micron level and additionally has the de-humidification capability

Alternative may be putting a centrifuge in kidney loop.

Having worked for MOOG distributor in Middle East for couple of years & into powergen field for 8 years, being aware of contamination issues leading failure of MOOG valves, can suggest following.

1. Approach MOOG India. They recommend certain set of filters only. Also they recommend flushing before commissioning MOOG valves.

2. Moog has nozzle-flapper design which is not much flexible with contaminant size. However, you can try Parker Abex servo design which is Jet-pipe design & allow higher level of contamination than MOOG valves. I have seen that people who uses Abex never switch to MOOG. They do not face issue of contamination. It costs double the MOOG valve & is drop-in replacement. MOOG also has similar design under Ashley Pegasus brand. This should solve the issue.

3. Electrostatic filter or cleaning the oil systems by companies like ISOPur / Kleantek is well placed to tackle this issus. It is a very simple principal & doesnot cost much. But takes 8-9 months before your system starts behaving the way you desire.

4. There is a company in Qatar called Qatar Vinyl Company having 4 x Fr 6. 3-4 years back they used to send almost 10-12 MOOG valves for repair. But they installed proper purification system & now not even looking at MOOG valves in 2 years.

5. If problem still persists, look at option of switching to Young & Franklin, USA Electrically actuated GCV & Liquid Fuel Bypass Valve. It eliminates hydraulic circuits itself & you donot have any servos now. Actuation is by DC brushless servo motors. It is working very fine with some of the companies here & they are converting their hydraulic valves to electric valve. Maintenance free & reliable. Recently GE Oil & Gas changed one of their turbines to Electric turbine & technology is gaining pace. FYI, Y&F has been OE to GE for more than 50 years with installed base on more than 10000 turbines for GCV / SRV / Bypass Valve / Stop valve / IGV Actuator / Ratchet sequencing valves.

Hope this should address the issue of MOOG valves.

Trying PARKER valves doesnot solve servo valve failure due to contamination.

MOOG valves are GOOD and are prone to failure only of highly contaminated oil.

For your information MOOG recommends Oil Contamination level to NAS level 5

even if valve fails they have world class after sales support.

Few MOOG valves in my plant working fine for the past 8 years without any problems.

Just one note, Y&F is not the current supplier of either IGVAs or gas valves to GE. You may want to investigate other suppliers who also have hydraulic and electric solutions for the problem.

I see that someone is recommending against trying Parker EHSV's for this application. The flapper nozzle design on the Moog valve is subject to fowling by contamination and worse, it typically fails in a hardover position causing a system trip. I know that Parker has installed numerous EHSV valves that have now run several years without any failures. Dominion, Florida Power and Light, and several other utilities, have added the Parker valve to their specs as a direct replacement to the Moog.

The Parker EHSV's utilize the "jet pipe" technology that can handle surprisingly dirty conditions without problem. If the valve should fail, it will fail in a passive position (or in a spring biased position.) which will allow the unit to remain in service without tripping and causing downtime. The Parker units are essentially plug and play with the Moog. Depending on your GPM requirements, Parker offers four different models, all of which have been fully qualified. Model 410 through 450. Filters and other solutions will always help, but the flapper nozzle is the root problem here...

Try a Parker, you will be glad you did.

Guys, lets not make this for your product marketing forum...Grow up!

GE has long history with Nozzle/Flapper (MOOG) for its servo requirements on its GT.

Earlier it tried Jet Pipe (ABEX, now acquired by PARKER) design and later switched to Nozzle/Flapper design over its fast response time.

While Jet pipe pilot stage may me more contaminant tolerant, if you look at the whole valve, both the Nozzle Flapper and Jet pipe valves have similar type of Spool assemblies and contamination in the oil will have the same effect on the spool of both these type of valves.

- Jet Pipe valves are still affected by contamination due to fine particles that wear the jet, receiver, bushing, and spool. Jet Pipe parts are the same materials as Nozzle/Flapper design valves.

Jet Pipe design valves are just a susceptible to electron streaming corrosion that is common in Power Gen Applications.

In short, if you look at the valve as a whole, there are no advantages of using Jet pipe technology valves over a Nozzle/Flapper type one. If the oil is contaminated, the Spool of a Jet Pipe valve also will be eroded just like a Nozzle/Flapper type valve spool.

Also the internal pilot filter of Jet Pipe valve could get choked due to contamination creating problem in valve working.

There are also many Nozzle/Flapper valves working for many years without problems.

In addition to this, Jet pipe comes twice the price of Nozzle/Flapper

For both Nozzle/Flapper Type and Jet Pipe valves, oil cleanliness is critical for longer life. (NAS 5 or below) Contact GE Customer Care for more details.

Hope this Helps. Cheers!