Forgings are produced by pounding hot metal into a cavity. This is one of the oldest fabrication methods. They are used for the pressure vessels operating in hydrogen environment. It consists of two types: hand and die forgings. The hand forgings are produced without lateral confinement of the metal during the forging operation. The die forgings are produced by pressing the forging stock between a pair of dies and thus, are also called closed die forging. They are more expensive than castings but they are more feasible if enough parts are needed and strength and ductility are important. This also consists of steel forgings. They are produced by metal shaping by plastic deformation. The forged components are shaped either by a hammer or press. Forging on the hammer is carried out in a succession of die impressions using repeated blows. This is used in refining oil industry operating high temperature, high pressure, as well as high partial hydrogen pressure.