Seal washers are used as sealing components in mechanical and equipment applications, as well as in pipelines where fluids are present. They are made of metal or non-metallic sheet materials, cut, stamped, or trimmed into shape, and serve to seal connections between pipes and between parts of machinery. They are categorized into metal and non-metal seal washers. Metal types include copper, stainless steel, iron, and aluminum washers. Non-metal types include asbestos, non-asbestos, paper, and rubber washers.