PVC Sanding Files Stick sandpaper to cutoff pieces of PVC water pipe with spray-on adhesive and you'll be able to sand concave curves to perfection. PVC pipe is labeled by inside diameter; here's an index for the outside diameter of useful pipe sizes. 1/2-in. i.d. = 7/8-in. o.d. 3/4-in. i.d. = 1-in. o.d. 1-in. i.d. = 1-1/4-in. o.d. 1-1/4-in. i.d. = 1-5/8-in. o.d. 1-1/2-in. i.d. = 1-7/8-in. o.d.