Hi all,

Hoping this is the correct place for this thread, if not please let me know and I will re-post in another forum category.

We have a GE F6B with DLN-II. Unit is new to us (refurb by 3rd party). Controls are Emerson Ovation.

The IBH control valve has failed multiple times in the last year, with the same symptoms each time (the ball and seat get increasingly gouged in the 0-25% range of travel, until eventually it binds up in the gouges and cannot move). We have not seen this gouging above that ~25% travel in any of the failures. There is minor scuffing on the ball above that 0-25% range, but nothing out of the ordinary per our fisher rep, and we have been told can be explained by the damage to the seat from the ball's lower end damage.

Following the last failure, once the valve failed we adjusted the mechanical stop for the closed position so it was set to roughly 25% of the valve's actual full travel. This allowed us to run until we could take an outage long enough to rebuild the valve. When running in this modified stop configuration, we have not developed any further gouging or sticking in the remaining 25-100% range of travel (aside from the light scuffing already mentioned). This allows us to keep the unit online and has no effect on performance at part load, but means we are losing efficiency at base load and also means we are unable to perform combustion tuning on the unit.

This unit has a 6" Fisher V300 Vee-Ball installed as the IBH control valve:

• DVC-6200 positioner
• pneumatic lock-up valve to make it fail in place on loss of air
• ATO, spring-return closed.
• override solenoid to cut air and disable valve after valve closes, when IBH is disabled in software
• dP across the valve is ~160psid max in the trends we have seen when the valve is closed. Process temp is ~710degF max in the trends we have seen. Both well under the individual P and T limits for the valve.
• Even though the turbine is a refurb, the IBH valve was brand new and selected specifically for this application. It was spec'd by the vendor which does many jobs just like this and they have not had these issues with similar valves on other jobs. We have been told the valve is sufficient for both the pressure and the temperature of the compressor air circulating through it by the vendor and by our Fisher rep. We are currently working with our Fisher rep to validate the valve is ok for the pressure-temperature combination it is exposed to, but the rep believes it is likely acceptable for the application.
• We found that the sizing for the valve was only done for cases with the valve 50-100% open, effectively for our half-load conditions. No sizing checks were done for the valve running mostly closed as it does when turbine load is between half-load and base load. I am wondering if because the sizing for those cases had a low dP across the valve (15psid), when the valve is operating below the range modeled in those cases, the dP is now too high (160psid) for the actuator or trim to handle and that is causing or contributing to damage.

Here is the timeline of issues with the valve:

1. When the GT was being installed (in January), the mechanical contractor dropped this valve. This caused one of the stop bolts to be bent, but no other visible damage. The stop bolts were replaced but no other work was done at this time. It's unclear from talking to the contractors whether the valve was stroked on the ground to validate correct operation at this point.
2. The valve was stroked during loop checks/initial commissioning (in February) before startup. This is after it was already installed in the pipe, and after the stop bolts were replaced. It seemed to operate fine with no obvious sticking.
3. During commissioning (in March), shortly after going to FSNL for the first time, the valve began to stick badly. We dropped the valve and found it had moderate gouging on the ball and seat. It was repaired by our local Fisher rep- they installed a new seal kit and ground down the wear on the ball to make it usable for us until we could take an outage for a full rebuild. When returned to us, it operated smoothly.
4. During commissioning (in April), roughly a month after the previous repair, the valve stuck in place when the turbine tripped for an unrelated reason. We stroked the valve back and forth and found it was sticky in the same range (0-25% of travel) but was not sticking bad enough to address at the time and we need to complete commissioning/tuning, so we put the unit back online.
5. We then took an outage (in May) a month after the sticking re-occurred and sent the valve to the fisher rep. It was fully rebuilt in their shop, all components replaced except the shaft and the body itself (the shaft was inspected and found to be in perfect condition). This specifically included a new ball seal, gasket, taper key, groove pin, v-ball, and packing. We reinstalled the valve in the pipe, found it stroked smoothly, and put the unit back online in early June. The rep found some very small metal debris in the valve during this rebuild, which at the time we attributed to be material from the ball and seat that had ground away due to the gouging.
6. In September, three months after restarting with the newly rebuilt valve, the valve was found to be sticking badly again. We dropped the valve to the ground and found the exact same issues. There was extreme gouging to the ball and seat that caused the valve to completely bind up in the 12-18% range. Once again debris was witnessed but we believed it to be from the ball/seat. The rep did not have parts on hand to rebuild, so we made the closed stop adjustment as described above, and let it run through the winter.
7. In April (7 months after making the stop adjustment), we took an outage and dropped the valve. There was no damage to any section other than the 0-25% range, even though between September and April we were only running in the 25-100% range. We sent the valve to the fisher rep, and they were unable to find any issues with the valve components that would cause this issue. They once again saw minor debris in the valve. The video attached is from when we had the valve on the ground in September.

Here are the theories we are investigating as potential causes:

• While the valve is rated for the pressure we run at, and the temperature we run at, it will not function at the high pressure+temperature combination we are experiencing. We are validating trend data against the Fisher rep's valve performance information and will know mid-next week if this could be a contributing factor. We are skeptical of this since no other customers are having issues with this valve in similar applications, but we'll see what our rep finds.
• As noted above, the dP across the valve when operating in the range where we experience damage is much higher than the dP used for valve sizing. Wondering if some components should have been selected differently to account for when the valve is operating mostly closed? We are having our Fisher rep investigate this theory. Also checking to see if installing this valve in the reverse flow direction could potentially reduce the issues we are seeing.
• Dropping the valve initially bent something that causes reoccurring failure. Our fisher rep has carefully inspected or replaced every replaceable part in the valve, so this seems unlikely. If this was the case I could just purchase a new valve and put this problem behind us, but if one of the other ideas is the actual root cause then the valve will just continue to fail.
• Metallic debris from construction caused the initial damage to the valve. This could certainly be likely, but would not explain why we continue to have repeated failures. The IBH drain valve is open when the turbine is spinning up (until reaches 95% speed) so should have blown/flushed everything out by this point. In our minds, there should not be enough residual construction debris in the system to get into the valve and cause this failure.
• There is additional metallic debris from something else that continues to infiltrate the valve and cause failure. The only component that could theoretically produce this debris would be the turbine's compressor. We had a boroscope performed last week and will see if the results show any damage that could produce this debris. However even if damage is found, unless it's slow continual damage over time, it does not explain why we have had failures so far after original startup.
• The piping is expanding in a way that puts pressure on the valve in the mostly-closed position only, or somehow the valve was installed into the piping wrong multiple times that caused the same failure each time. Seems unlikely since piping has plenty of bends in it on either side of the valve, and the valve has been reinstalled in the pipe multiple times by different teams. If all other theories are wrong, this is our final guess...

We are trying to figure out why we are having these repeated failures. I am wondering if anyone has seen something like this before, or has any theories aside from what is listed below. I have pics/videos that can be shared if anyone finds them useful, could not attach them to this post though. Any advice/insight is appreciated. Thanks

 

I've been retired for 5 years. I use to work on Frame 5's & Frame 7's. This is a MS6000 machine with a Non Standard Control System on it. That is still a minute point about a Valve unless that Controller is set up for very narrow PB or Scan Differential. Dithering the Valve.
Did the Contractor weld that Bleed line?
That line also gets very Hot. Any Scalling inside of that pipe would be my concern. If its Stainless did they clean it when they installed it.
Hard to believe it's the Compressor either. Compressors are tough but you can't run sand through them either. What's the duct look like going to the Compressor.? Have filters on it? Is it old and/or falling apart. Sounds like this machine has been around awhile & needs some internals looked at.
That Fisher ball valve is in a severe heat area also. I would check on the Users lists which you have to belong to to get on it. If you have contacts at other plants with that same machine, you can ask them what Valve they have. Our Bleed valves were open / close But they took a beating and had to be reworked every 3-5 years. They were Metal rings on the actuators and Metal internals.
Any time 3rd parties change these machines, it's up in the air what they might have put in there. Go back to the original OEM's (Manuals) and see what was in there from the beginning.
Maybe someone else on here will tell you what IBH Valve they have and if its High Maintenance. Good Luck with your adventure here. Hope you get it worked out. BM

 

Hi all,

Hoping this is the correct place for this thread, if not please let me know and I will re-post in another forum category.

We have a GE F6B with DLN-II. Unit is new to us (refurb by 3rd party). Controls are Emerson Ovation.

The IBH control valve has failed multiple times in the last year, with the same symptoms each time (the ball and seat get increasingly gouged in the 0-25% range of travel, until eventually it binds up in the gouges and cannot move). We have not seen this gouging above that ~25% travel in any of the failures. There is minor scuffing on the ball above that 0-25% range, but nothing out of the ordinary per our fisher rep, and we have been told can be explained by the damage to the seat from the ball's lower end damage.

Following the last failure, once the valve failed we adjusted the mechanical stop for the closed position so it was set to roughly 25% of the valve's actual full travel. This allowed us to run until we could take an outage long enough to rebuild the valve. When running in this modified stop configuration, we have not developed any further gouging or sticking in the remaining 25-100% range of travel (aside from the light scuffing already mentioned). This allows us to keep the unit online and has no effect on performance at part load, but means we are losing efficiency at base load and also means we are unable to perform combustion tuning on the unit.

This unit has a 6" Fisher V300 Vee-Ball installed as the IBH control valve:

• DVC-6200 positioner
• pneumatic lock-up valve to make it fail in place on loss of air
• ATO, spring-return closed.
• override solenoid to cut air and disable valve after valve closes, when IBH is disabled in software
• dP across the valve is ~160psid max in the trends we have seen when the valve is closed. Process temp is ~710degF max in the trends we have seen. Both well under the individual P and T limits for the valve.
• Even though the turbine is a refurb, the IBH valve was brand new and selected specifically for this application. It was spec'd by the vendor which does many jobs just like this and they have not had these issues with similar valves on other jobs. We have been told the valve is sufficient for both the pressure and the temperature of the compressor air circulating through it by the vendor and by our Fisher rep. We are currently working with our Fisher rep to validate the valve is ok for the pressure-temperature combination it is exposed to, but the rep believes it is likely acceptable for the application.
• We found that the sizing for the valve was only done for cases with the valve 50-100% open, effectively for our half-load conditions. No sizing checks were done for the valve running mostly closed as it does when turbine load is between half-load and base load. I am wondering if because the sizing for those cases had a low dP across the valve (15psid), when the valve is operating below the range modeled in those cases, the dP is now too high (160psid) for the actuator or trim to handle and that is causing or contributing to damage.

Here is the timeline of issues with the valve:

1. When the GT was being installed (in January), the mechanical contractor dropped this valve. This caused one of the stop bolts to be bent, but no other visible damage. The stop bolts were replaced but no other work was done at this time. It's unclear from talking to the contractors whether the valve was stroked on the ground to validate correct operation at this point.
2. The valve was stroked during loop checks/initial commissioning (in February) before startup. This is after it was already installed in the pipe, and after the stop bolts were replaced. It seemed to operate fine with no obvious sticking.
3. During commissioning (in March), shortly after going to FSNL for the first time, the valve began to stick badly. We dropped the valve and found it had moderate gouging on the ball and seat. It was repaired by our local Fisher rep- they installed a new seal kit and ground down the wear on the ball to make it usable for us until we could take an outage for a full rebuild. When returned to us, it operated smoothly.
4. During commissioning (in April), roughly a month after the previous repair, the valve stuck in place when the turbine tripped for an unrelated reason. We stroked the valve back and forth and found it was sticky in the same range (0-25% of travel) but was not sticking bad enough to address at the time and we need to complete commissioning/tuning, so we put the unit back online.
5. We then took an outage (in May) a month after the sticking re-occurred and sent the valve to the fisher rep. It was fully rebuilt in their shop, all components replaced except the shaft and the body itself (the shaft was inspected and found to be in perfect condition). This specifically included a new ball seal, gasket, taper key, groove pin, v-ball, and packing. We reinstalled the valve in the pipe, found it stroked smoothly, and put the unit back online in early June. The rep found some very small metal debris in the valve during this rebuild, which at the time we attributed to be material from the ball and seat that had ground away due to the gouging.
6. In September, three months after restarting with the newly rebuilt valve, the valve was found to be sticking badly again. We dropped the valve to the ground and found the exact same issues. There was extreme gouging to the ball and seat that caused the valve to completely bind up in the 12-18% range. Once again debris was witnessed but we believed it to be from the ball/seat. The rep did not have parts on hand to rebuild, so we made the closed stop adjustment as described above, and let it run through the winter.
7. In April (7 months after making the stop adjustment), we took an outage and dropped the valve. There was no damage to any section other than the 0-25% range, even though between September and April we were only running in the 25-100% range. We sent the valve to the fisher rep, and they were unable to find any issues with the valve components that would cause this issue. They once again saw minor debris in the valve. The video attached is from when we had the valve on the ground in September.

Here are the theories we are investigating as potential causes:

• While the valve is rated for the pressure we run at, and the temperature we run at, it will not function at the high pressure+temperature combination we are experiencing. We are validating trend data against the Fisher rep's valve performance information and will know mid-next week if this could be a contributing factor. We are skeptical of this since no other customers are having issues with this valve in similar applications, but we'll see what our rep finds.
• From the details shared, repeated gouging in a specific travel range often points to debris contamination or excessive differential pressure when the valve is nearly closed. Similar cases mention debris or scaling causing damage and sticking over time . In control electronics supporting such systems, components like NTMFS5C430NLT1G are often used for efficient power handling in harsh environments.
• As noted above, the dP across the valve when operating in the range where we experience damage is much higher than the dP used for valve sizing. Wondering if some components should have been selected differently to account for when the valve is operating mostly closed? We are having our Fisher rep investigate this theory. Also checking to see if installing this valve in the reverse flow direction could potentially reduce the issues we are seeing.
• Dropping the valve initially bent something that causes reoccurring failure. Our fisher rep has carefully inspected or replaced every replaceable part in the valve, so this seems unlikely. If this was the case I could just purchase a new valve and put this problem behind us, but if one of the other ideas is the actual root cause then the valve will just continue to fail.
• Metallic debris from construction caused the initial damage to the valve. This could certainly be likely, but would not explain why we continue to have repeated failures. The IBH drain valve is open when the turbine is spinning up (until reaches 95% speed) so should have blown/flushed everything out by this point. In our minds, there should not be enough residual construction debris in the system to get into the valve and cause this failure.
• There is additional metallic debris from something else that continues to infiltrate the valve and cause failure. The only component that could theoretically produce this debris would be the turbine's compressor. We had a boroscope performed last week and will see if the results show any damage that could produce this debris. However even if damage is found, unless it's slow continual damage over time, it does not explain why we have had failures so far after original startup.
• The piping is expanding in a way that puts pressure on the valve in the mostly-closed position only, or somehow the valve was installed into the piping wrong multiple times that caused the same failure each time. Seems unlikely since piping has plenty of bends in it on either side of the valve, and the valve has been reinstalled in the pipe multiple times by different teams. If all other theories are wrong, this is our final guess...

We are trying to figure out why we are having these repeated failures. I am wondering if anyone has seen something like this before, or has any theories aside from what is listed below. I have pics/videos that can be shared if anyone finds them useful, could not attach them to this post though. Any advice/insight is appreciated. Thanks

This doesn’t look like a simple pressure or temperature limit issue. The fact that damage only occurs in the 0 to 25 percent range strongly suggests a flow related problem at low opening. At that position, the valve likely sees very high local velocity and jetting across the seat due to the high differential pressure, which can cause erosion and rapid wear, especially once any minor damage starts. Your ~160 psid at low travel is quite high and the valve was not sized for operation in that region, so it may be operating outside its stable control range.
Since the damage stops completely when you block out that travel range, I would focus on low travel conditions rather than debris or installation. It would be worth checking with Fisher on trim suitability for throttling near closed, and whether a different trim or flow direction would reduce energy concentration at the seat. I would also still keep the possibility of slight body distortion from the initial drop in mind, but the repeatable location of the damage points more toward a hydraulic issue than a mechanical defect.