Gas seal failure
Gas seal failure
(OP)
Just looking for brainstorming:
What could cause a dual pressurized set of gas seals on a split case pump (7 impellers) to fail the seals, touch off on only one part of the gland plate (shaft rub of about 90 - 180 degrees) and shear off some dog-point set screws. (3 failures in less than a month, 1 drive end 2 thrust end)
Lots of things have already been ruled out: Push bearings are unaffected (not even damaged), shaft is true, alignment is dead on, vibrations are low. The shaft is a softer material, 4".
This is becoming a "look for the unicorn" problem, so any ideas or suppositions are welcome. :)
Thanks.
What could cause a dual pressurized set of gas seals on a split case pump (7 impellers) to fail the seals, touch off on only one part of the gland plate (shaft rub of about 90 - 180 degrees) and shear off some dog-point set screws. (3 failures in less than a month, 1 drive end 2 thrust end)
Lots of things have already been ruled out: Push bearings are unaffected (not even damaged), shaft is true, alignment is dead on, vibrations are low. The shaft is a softer material, 4".
This is becoming a "look for the unicorn" problem, so any ideas or suppositions are welcome. :)
Thanks.





RE: Gas seal failure
Mike Halloran
Pembroke Pines, FL, USA
RE: Gas seal failure
This part doesnt make any sense. It seems impossible that a 3.25" shaft could touch off, run a wear pattern and blue up the gland plate when a set of bearings 10" away are unaffected and show no damage.
RE: Gas seal failure
The gland plate moved out of alignment?
Ted
RE: Gas seal failure
Most probable cause of wear: Gland plate movement (of .022 or more to surpass clearances) to touch off on the shaft/sleave.
Why we dont think thats it: Tight gland fit, good alignment, no bearing wear, no bolt degredation etc. None of the other things that would be wrong if it had shifted.
It LOOKS like a gland plate shift, but no other effects of somthing like that happening.