#115 Tufline Sleeved Plug Valves succeed where gate valves fail.  Problem: A gulf coast processor was having problems with gate valves in a hydrofluoric acid application. Iron fluoride scale accumulated in the seat ring area of the HF gate valves. This prevented proper shutoff.  Solution: The failing gate valves were replaced with Tufline Sleeved Plug Valves. The Tufline Sleeved Plug Valve has no cavities so there is no area for solids in the fluids to accumulate and interfere with valve operation. In addition, as the plug is rotated during operation, the plug is "wiped" clean of any accumulated solids. These features provide greatly extended service life compared to gate valves. The Tufline Sleeved Plug Valve also offered better stem sealing characteristics than the gate valve. Some of these valves were used in emergency evacuation lines. To assure swift, safe evacuation of tanks and lines, the full-port model of the Tufline valve was chosen for this portion of the application  Results: The Senior Inspector at the plant said, "Tufline is the only valve which shuts off effectively over time." Index of all performance report case histories.