Emerson’s Rebecca Turner shared her expertise on control valve selection considerations in hydrofluoric acid alkylation units.

Rebecca noted that alkylation units tend to be older units not found in more modern refineries. Hydrofluoric acid is highly hazardous and requires protective gear for plant personnel when performing valve maintenance in the area.

Fisher A-Body valves have been used in this application. These valves are supported but no longer actively sold. The construction of the valve includes a screwed in seat ring. Valve disassembly requires protective gear and vibration in unit may cause the seat ring to being to unscrew.

Modern control valve selections included double ported control valves for 1 to 4 inch lines. For larger pipe diameters Fisher Vee-Ball, carbon steel or Monel valve body with Monel trim provide a good solution.

Other considerations include control valve capacity, face-to-face dimensions, pressure relief cases, and flange styles.

Rebecca shared cases where Vee-Ball valves replaced A Body valves. Making sure the actuator had sufficient capacity to operate the valve was another consideration for this replacement.