Pipe Scrub Brushes Crossover Pipe Scrubbing Wire Brush is used to brush and clean the ID of the casing and remove scale, rust, mud residue, and any other particles of debris. These brushes are generally run on Rotary Shoulder Drill String to Brush the inside of Casing Down Hole. These brushes will remove rust, scale and other contaminates that build up on the inside diameter (ID) of the casing. Usually run in preparation of running a packer or some other piece of equipment that needs a fairly uniform ID to set.