In the early 2000’s, a Canadian Oil Sands facility was using knife gate valves to modulate slurry from their Primary Separation Cells. At that time, the service life of these heavy-duty valves was measured in days (typically 2-3 weeks).
When throttling a knife gate valve, higher flow velocities will occur within the acute angles formed at gate to body interface. Upon failure, the system was shutdown, the valves removed, and new units were installed.
These expenditures in labor and product were significant; however, they were minimal compared to the lost production revenue. The frequent shutdowns were costing the company millions annually. There had to be a better way.