A synthetic rubber manufacturer was having constant seal leakage problems with their SBR agitator seal for the past 5 years. The Flowserve BRO double seal would leak instantly on the outboard seal while the internal seal would leak inside the agitator after approximately 2 months. Customers incurred massive disruptions in their manufacturing process and product loss as a result of this.
The seal was sent to the PSS Seal Service Center for examination and repair. There were clear problems of concentricity and misalignment. PSS replaced the mechanical seal faces and other soft parts. We sent the seal back to the customer with our suggestions to check agitator shaft concentricity.
Customer agreed with our suggestions and asked the PSS Service team to perform the work. As this is a large agitator with a 6 meter shaft, we started by examining the shaft inside the agitator. We also had to install lifting supports for the shaft as the lantern and gear on the top had to be removed.
Next we checked the concentricity at the top flange end of the agitator and found it out of spec at 0.3 mm. It became quite apparent that the lantern gear had to be examined. PSS removed the lantern gear at the site and moved the equipment to PSS workshop for disassembly and inspection. After inspection, we found there were many problems – bent shaft, damaged coupling, and distorted lantern top.
We got customer approval to machine the lantern surface to the right flatness. We straightened the shaft and repaired the coupling. After assembling the unit again, the concentricity was reduced to 0.05 mm, a huge improvement.
We installed the equipment back at the site. Customer has now been operating the equipment for the last 6 months without any problem. There is also no leakage on the external seal. Customer is extremely satisfied with the result and will now be asking to solve all their agitator seal leakage problems on site – there are another 5 units.