Spools are pre-fabricated sections of piping systems that consist of pipes, fittings, flanges, and sometimes valves, all assembled together in a factory or workshop before being transported to the installation site. These pre-assembled units are designed for easy and quick installation, minimizing the need for on-site welding or assembly, which speeds up the construction process and improves consistency in quality control. Spools are commonly used in industrial applications, such as power plants, oil refineries, and chemical plants, where complex piping systems are required.