Head is used to close the end of the container so that its internal and external media isolation components, also known as the end cover. The head of a cylindrical vessel is usually a rotary shell. According to the shape of the head surface can be divided into convex, conical, flat and combined shape. Convex head refers to the outer surface shape of the convex head, such as hemispherical, oval, disc and no flanged spherical seal. Some gas cylinders adopt convex inward combined bottom head, which can not only ensure the strength, but also meet the needs of safe use.

The head is a part of the container to which the barrel is welded. According to the different geometrical shapes, it can be divided into spherical, elliptical, disc, spherical crown, conical shell and cover, among which spherical, elliptical, disc and spherical crown head are collectively referred to as convex head. In the welding is divided into butt welding head, socket welding head. Used in all kinds of container equipment, such as storage tanks, heat exchangers, towers, reactors, boilers and separation equipment, etc. The material includes carbon steel (A3, 20#, Q235, Q345B, 16Mn, etc.), stainless steel (304, 321, 304L, 316, 316L, etc.), alloy steel (15Mo3 15CrMoV 35CrMoV 45CrMo), aluminum, titanium, copper, nickel and nickel alloy, etc.