Articulated pigs are primarily used in small-diameter applications (6″ to 14″) with tight-radius bends. Articulated pigs are connected in the center with a urethane chain (a solid steel chain molded in urethane). They are equipped with brushes for cleaning operations such as pre-commission and on-stream cleaning where rust, mill scale, sand, wax, organic growth, mud, oxides, and other foreign matter exist. Various brush designs include wire-wheel, split-ring, and spring-loaded, as well as polyurethane blades. When equipped with a gauging plate, the pig can be used to prove pipe roundness and to ensure excessive weld penetration or debris does not exist. Articulated pigs can also be used to prove minimum bend radius prior to intelligent pig use.