How do you seal a drain pipe on a flat roof?

To seal a drain pipe on a flat roof, first, clean the area around the drain to remove any debris, dirt, or old sealant. Apply a high-quality roofing sealant or waterproof membrane around the base of the drain pipe, ensuring it forms a tight seal with the roof surface. Smooth the sealant with a putty knife or your finger to create an even finish and ensure no gaps are present. Allow the sealant to cure as per the manufacturer's instructions before exposing it to water.