Clean the equipment carefully, making sure any debris, dust, oil or other material is not in the way on the valve, flanges, gaskets or pipeline. Open the valve and clean the sealing edge of the disc.
Close the valve so that it is installed in this position.
Install the flanges or collars on either side of the section of pipeline on which the butterfly valve is being installed. Flanges or collars create a seal and a place to attach the valve to the smooth ends of the pipeline. The type will depend on the type of butterfly valve you are installing. The flanges or collars mount on the ends of the pipeline and are tightened down, using tension to seal the connection.
Slip the valve between the flanges or collars on the pipeline, making sure not to scratch the gasket sealing surfaces on the valve or flanges. Make sure the bolts and holes are centered and mated before tightening the bolts completely. Tighten the bolts evenly in a crisscross pattern to apply even tension.
Open the valve slowly to check for adequate clearance within the pipeline until you are sure it is operational.