CLOSET FLANGE-METAL RING 3-4INloset flanges solvent welds over 3" Sch. 40 DWV pipe or inside 4" Sch. 40 DWV pipe. The metal ring provides added strength and cracking resistance to the flange and can be rotated to allow precise allignment of bolts and screws. Welds inside of 4" or over 3" Sch. 40 DWV pipe.