atmengr
Mechanical
- Sep 2, 2005
- 14
Looking for advice in what we could be happening in our 650# BFW system, and how to correct it.
We recently ran a parallel line to our current 650# BFW supply to our 650# steam drum. It is identical to the original line, which will be abandoned due to washed out CV and bypass globe valve. We liquid filled the line and pressure tested, then closed the upstream block valve on the CV line and the globe valve on the bypass. The pressure on the upsteam side was ~1120 psi and on the downstream ~650 psig. As the globe valve was cracked open it began vibrating severely, backing the nut off of the handwheel, then developing a packing leak. The packing bolts were tightened but the leak did not stop, and vibration would not allow the valve to be opened more. The line was isolated from the system until we can solve the problem.
I assume we were flashing across the valve, accompanied with cavitation. I don't know the exact cause of the packing leak. Should the globe valve handle that pressure drop without developing the packing leak? Was the packing leak because of the vibration? How can I get the valve open enough to decrease the pressure drop and get the vibration down? I assume I can get the system stable enough to operate since the parallel line has operated without extreme vibration (but has chewed up the valves). I know I know, lots of questions with little data and no answers, but any observations will be appreciated. Thanks!
We recently ran a parallel line to our current 650# BFW supply to our 650# steam drum. It is identical to the original line, which will be abandoned due to washed out CV and bypass globe valve. We liquid filled the line and pressure tested, then closed the upstream block valve on the CV line and the globe valve on the bypass. The pressure on the upsteam side was ~1120 psi and on the downstream ~650 psig. As the globe valve was cracked open it began vibrating severely, backing the nut off of the handwheel, then developing a packing leak. The packing bolts were tightened but the leak did not stop, and vibration would not allow the valve to be opened more. The line was isolated from the system until we can solve the problem.
I assume we were flashing across the valve, accompanied with cavitation. I don't know the exact cause of the packing leak. Should the globe valve handle that pressure drop without developing the packing leak? Was the packing leak because of the vibration? How can I get the valve open enough to decrease the pressure drop and get the vibration down? I assume I can get the system stable enough to operate since the parallel line has operated without extreme vibration (but has chewed up the valves). I know I know, lots of questions with little data and no answers, but any observations will be appreciated. Thanks!
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