A pressure vessel is a closed container designed to hold gases or liquids at a pressure that is different from atmospheric pressure. Pressure vessels are important components in many industries because they allow fluids to be stored, heated, cooled, separated, or processed under controlled pressure. Since failure of a pressure vessel can be dangerous, its design and construction require careful engineering and adherence to safety standards. Types of Pressure Vessels Pressure vessels can be classified according to their shape, orientation, and function. 1. Cylindrical Pressure Vessels: These are the most commonly used pressure vessels. They consist of a cylindrical shell with curved or flat ends called heads. They are used for storing compressed air, gases, chemicals, and other fluids.