#111 Tufline Lined Valves far outlast alloy valves with substantial reduction in lifetime costs.  Problem: At the DuPont hydrogen fluoride plant in LaPorte, Texas, valve corrosion was a problem. Flow media included abrasive fluorspar slurries as well as sulfuric and hydrofluoric acids. Processing temperatures ranged from 13 degrees F to 257 degrees F. Corrosion-resistant nickel-chromium alloy valves failed after a relatively short time.  Solution: Plant engineers installed more than 100 Tufline Lined Plug Valves. The valve lining material was Teflon® PFA. Valves lined with PFA are clearly superior to valves lined with PTFE. Dovetail recesses in the valve body lock the lining into the valve body. The lining resists blow out. PTFE lined valves are susceptible to lining collapse because the PTFE cannot be locked into the valve body. PTFE lined valves are also more susceptible to corrosion. This is because the micro-fissures that develop in the PTFE during the blow molding process make the PTFE more porous.  Results: With the Tufline Lined Plug Valves there were substantial long-term cost savings. They lasted four times longer than the alloy valves DuPont previously used. The PFA lining also provides lubricity. This lubricating effect permits lower operating torques. For assured in-line sealing in this difficult application, the plug valve has a large, full-circumferential sealing area. Teflon® is a DuPont registered trademark. Only DuPont makes Teflon. Index of all performance report case histories.