API plan 53A

[PracticalEngr]

Hello All:
I'm operating a thermic oil centrifugal pump at 350 deg C, the pump has a double mechanical seal with API plan 53A (pressurized reservoir with pumping ring. The barrier fluid is same as thermic fluid
The pump and the seal runs fine for few months then after we've noticed a sudden drop in the reservoir level i.e. from 70% to 65% in one day, then the level is steady for few weeks and then it drops 5-10% again in a single day. Due to frequent loss of the fluid, it is our and (john crane's) hypothesis that barrier fluid accumulates on the outboard seal and forms a crusty layer due to oxidation. After formation of the layer to a significant extent the bellows no longer can close the seal faces and then eventually the seal starts leaking outside
Any operational experience in this regards?
Any help would be greatly appreciated
Regards,
PracticalEngr

 

[JJPellin]

Is the fluid leaking to the outside or into the process? A seal drawing would be very helpful.

Johnny Pellin

 

[CH5OH]

possible causes:
hanging of seal (can be observed if seal is renewed) investigate old seal, look for carbon deposits
is seal buffer tank connected to N2 net? any process parameters available (pressure buffer tank constant?)