Semi tank trailers are semi - articulated vehicles consisting of a tractor unit and a trailer with a large - capacity tank, used for transporting liquids and gases. The tanks can be made from materials like stainless steel, aluminum, or composite materials, depending on the cargo, such as fuels, chemicals, or food products. These trailers are designed for long - distance haulage and offer high cargo - carrying capacities. Safety features, such as double - walled tanks, emergency shut - off valves, and leak - detection systems, are standard to prevent leaks and ensure safe transit. Semi tank trailers are widely used in industries that require the bulk transportation of fluids, providing a cost - effective and efficient solution for moving large volumes of goods.