Misalignment of the Rotary Joint
The greatest cause of pre-mature carbon seal ring failure is misalignment of the rotary joint or union. This is evident when the rotary joint wobbles during operation. When such a wobble takes place, the carbon seal ring (the internal sealing surface) is pinched against the l.D. of the joint housing and unusual wear or breakage may follow.
It is imperative that the rotary joint be installed with flexible metal hoses (inlet and outlet). As seal ring wear takes place, a non-compensated rotary joint will move away from the journal end. The hoses will allow for this movement. The hoses are to be of proper length to allow flexibility.
All associated flanges/bolts must be tightened evenly on all sides so as not to force the rotary joint out of alignment. Tighten bolts 180° from one another in a gradual manner. Check the opening at the back side of the joint housing to verify that the clearance around the circumference of the nipple is even. If not, adjust support brackets and piping to and from the rotary joint. All parts should either be parallel or perpendicular to the rotary joint centerline for proper operation.