The one-piece spun aluminum body has a plastisol coated flange for direct hot air welding of PVC type roof membranes. The drain flange has a depressed sump area to facilitate the easy drainage of all water from the roof surface. The drain is equipped with a heavy duty cast aluminum strainer dome for durability and strength. The Heavy Duty AlumaWeld RetroDrain incorporates the technology of the U-Flow® Seal technology providing a mechanical watertight connection to cast iron pipes or PVC. Also available with a plastic strainer dome.