DOUBLE MIXER SEAL REPAIR
Sharpe Double Mixer Seal for Tolling Facility
3.500″ Sharpe Double Mixer Seal sent in to Robco of Americas repair facility from a Tolling plant in South Texas. The seal operates under the following conditions: 150psig / 500 F / Product: Phenol. Carbon vs Tungsten / Kalrez o’rings – product end Carbon vs Silicon / Viton – outer end.
Customer stated the rotary seal sleeve had stopped rotating with the mixer shaft and there was a leak coming up between the mixer shaft and the seal sleeve. Upon inspection we concluded that the two setscrews in the seal that are torqued down onto the mixer shaft to make the seal rotate are not providing enough force to hold up under operating conditions. We informed the end user that we would add an extra setscrew into the mechanical seal and that upon re-installation of the seal customer should apply LOCTITE to the setscrews to offset the chance of VIBRATION causing the setscrews to come loose.
End user also sent the stub shaft in with the mixer seal. It had severe wear in the area where the seal sleeve had been “slipping”. We machined a 0.040″ undercut on the shaft in the area where the seal sits and had it metal sprayed back up to the finished O.D. We re-machined the coating & polished for an acceptable o’ring sealing finish.
The seal was repaired and pressure tested to 60psig. This repair was carried out over 5 working days.
Work Rendered
3.00″ Sharpe double mixer seal. Carbon vs Silicon (outer end). Carbon vs Tungsten (product end). Kairez o’rings for high temps.
Back to back T8 Carbon faced seals on the rotary seal sleeve, surfaces covered in oil & Carbon residue.
Due to the fact a new seal sleeve is required. We can look at drilling and tapping an extra hole to utilize a setscrew. The seal only has (2) setscrews to make it rotate with the shaft, we think the seal should have at least (3) setscrews. Also, they should have Loctite applied when the seal is re-installed on the tank.
Rotary seal sleeve has been “slipping” on rotary shaft. I.D. bore is worn and non repairable. The bottom plate, bearing sleeve and the main seal housing require cleanup, polish on o’ring sealing surfaces and re-machine as required to remove indents & scratches.
New rotary seal sleeve with one of the two T8 seals installed with a new Carbon seal face installed.
Old worn sleeve.
New Tungsten Carbide seat installed in the re-machined & polished product end flange plate.
Rotary stub shaft has been re-machined to remove damaged surface caused by the seal sleeve “slipping” during operation. Double Mixer Seal repaired & pressure testedto 60 psig. Ready to transport back to Tolling facility in South Texas.
