How to Install Wafer Butterfly Valves

Remove all rust and other contaminants from both pipe flanges by rubbing them with sandpaper. A pipe flange mounts to the end of each pipe that connects to a wafer butterfly valve. Each pipe flange contains a series of bolt holes.

Wipe all grease and other contaminants from the wafer butterfly valve's ports with a rag. Some wafer butterfly valves have a rubber gasket surrounding both ports. Use the rag's edge to clean grease and other contaminants from the void between each gasket and its port.

Turn the wafer butterfly valve's handle or worm gear counterclockwise until its disc is in the closed position.

Slip the wafer butterfly valve into the space between the two pipe flanges, keeping the valve handle or worm gear facing upward. Rotate the valve until its alignment holes match the bolt holes in the pipe flanges.

Push a flange bolt into one of the pipe flange's bolt holes. The flange bolt slips through the first flange's bolt hole, through one of the wafer butterfly valve's alignment holes and into the second flange's respective bolt hole. Use your hand to tighten a flange bolt nut onto the threaded end of the flange bolt. Repeat this procedure for the remaining flange bolts.

Open and close the wafer butterfly valve several times using the valve's handle or worm gear to work the valve's disc. If the disc binds, loosen the flange bolt nuts, and reposition the valve between the pipe flanges. Use your hand to tighten the flange bolt nuts, and retest the valve's operation.

Place the correct size of wrench on one of the flange bolts. Place a second wrench on that flange bolt's nut. Hold the flange bolt still with its respective wrench, and turn the flange bolt nut clockwise one full turn. Repeat this procedure with the remaining flange bolts and nuts, tightening the nuts in a crisscross or star pattern.