Valves are used in a variety of applications including industrial, military, commercial, residential, and transportation. Oil and gas, power generation, mining, water reticulation, sewerage and chemical manufacturing would constitute the majority of valves used by industry. The body material is grey cast iron, ductile iron or carbon steel. check valves are mechanical device allowing fluid to flow through it in one direction. These valves have two ports or two openings. From one opening the fluid enters while from the other the fluid leaves. These valves have many applications.