Plumbing duct is a type of PIPE used in plumbing systems. It is typically made of metal and is used to transport water, gas, or other fluids. Plumbing ducts are often used in residential and commercial buildings to provide a safe and efficient way to move water and other liquids. They are also used in industrial settings to transport hazardous materials. Plumbing ducts are designed to be durable and long-lasting, and they come in a variety of sizes and shapes.