Keep a supply of flat washers on hand to avoid down time during assembly, construction or maintenance jobs. Flat washers protect surfaces by evenly distributing torque when tightening a bolt or screw and prevent corrosion between a steel screw and an aluminum surface. A nylon washer is often placed under a machine screw to reduce noise and abrasion and offer electrical insulation. Sealing washers are used in plumbing and hydraulic projects. Grainger has the right flat washer for every application, from aerospace to general construction.