Bonded Seal Manufacturers, Suppliers & Exporters In India. A bonded seal, also known as a Dowty seal or a metal washer seal, is a type of sealing washer used to create a reliable and secure hydraulic seal between two surfaces. These seals are commonly used in high-pressure hydraulic systems to prevent fluid leakage. Bonded seals are widely used in hydraulic systems, particularly in threaded connections, bolted joints, and banjo fittings. They are commonly employed in applications where a metal-to-metal seal alone may not provide sufficient fluid-tight sealing.