A sealing assembly for fluidly sealing a roof drain within a conductor pipe has a sealing element and an expansion ring. The sealing element defines an inner wall with a portion that transitions inward and may be disposed on a portion of the roof drain. The expansion ring is disposed within the inner wall. Reciprocation of the of the expansion ring along the inward transitioning portion of the inner wall causes the sealing element to expand outwardly to a sealed position with the sealing element outer wall abutting the conductor pipe inner wall in a fluid tight seal. Opposite reciprocation of the ring allows the sealing element to contract and release from the conductor pipe.