#112 Where nickel-chromium valves fail, Tufline Lined Plug Valves succeed.  Problem: At the DuPont adipic acid plant in Victoria, Texas, sleeved nickel-chromium alloy plug valves often failed in just six months. Failure was due to corrosion and sleeve slippage. The flow media was 56% nitric acid at temperatures up to 248° F. Valve sizes ranged from one-half inch to twelve inches.  Solution: More than 250 Tufline Lined Plug Valves were installed. The valve lining material was Teflon® PFA. Unlike alloy valves, Tufline fully-lined valves are virtually unaffected by changes in processing temperature or chemical concentration. An alloy valve may meet the nominal specifications for handling a corrosive fluid. However, small changes in processing conditions can significantly affect the valve material and the valve can fail due to corrosion. Tufline fully-lined valves can be used with almost all corrosive fluids, so there is no need to stock and carefully match different alloy valves for every application. In Tufline fully-lined valves, the fluorocarbon lining is locked into the valve body. It resists blow out and collapse. 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. 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 lining more porous. 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.  Results: Based upon preliminary evaluations, DuPont plant engineers predict a ten year service life for the Tufline Lined Plug Valves. This represents a huge savings in valve costs as well as greatly reduced downtime. Teflon® is a DuPont registered trademark. Only DuPont makes Teflon. Index of all performance report case histories.