#105 Multiport valves for phosgene and other difficult thermal cycling applications.  Problem: At a Baytown, Texas processing plant, engineers needed to replace a number of multiport 3-way valves in a liquid phosgene application. The German manufactured valves that were in use performed adequately. However, parts and replacements for the German valves were expensive and a long lead time was required for delivery. Plant management was also interested in upgrading the stem seals to better control fugitive emissions. Control of fugitive emissions was especially difficult because the process involved thermal cycling. The temperature varied from ambient to –30 F.  Solution: Working with the Tufline Special Products Group, a 3-way Tufline sleeved plug valve was modified with a patented extended stem packing design. The Tufline XP top seal was deemed especially appropriate because of its exclusive and patented thermal shrink-seal lip which helps control fugitive emissions. To control fugitive emissions during thermal cycling, a lip is machined in the interior bore of the bonnet of the Tufline XP Sleeved Plug Valve. Any radial shrinkage of the live-loaded PTFE packing causes the packing to compress tightly against this lip. This patented shrink-seal lip actually tightens the seal as the packing shrinks. Primary top sealing is provided by the interaction of the plug, the full-circumferential PTFE sleeve, and the body. The extended live-loaded packing provides secondary, back-up sealing for superior control of fugitive emissions. The unique design included a special TFE/Grafoil® double-packed stem. It was also a plus that Tufline was able to easily and economically match existing face-to-face dimension and bolt pattern requirements.  Result: The new valves matched or exceeded the performance of the previously used German valves. Also, both plant management and engineers now breathe easier with improved assurance of compliance with EPA air quality regulations. Tufline and plant personnel have also developed a continuing "Partnering" relationship. Plant engineers rely on continued valving support that is nearby, responsive, and economical. Index of all performance report case histories.