A boiler end cap is a component of a boiler pressure vessel. Typically used at both ends of a pressure vessel. Additionally, it refers to the closed end of welded pipe products made of pipes. There are many different forms.

The head is a component of the container that is connected by welding to a cylindrical body. Depending on different geometric shapes, it can be divided into spherical, elliptical, conical, spherical cap, conical shell, and flat cover types. Among them, spherical, elliptical, disc-shaped, and spherical-headed ones are referred to as convex heads. The heads are joined by butt welding or plug welding. Containers are used in various equipment, such as storage tanks, heat exchangers, towers, reactors, boilers, and separation equipment. Materials include carbon steel (A3, 20#, Q235, Q345B, 16Mn steel, etc.), stainless steel (304, 321, 304L, 316, 316L, etc.), steel (15Mo3, 15CrMoV, 35CrMoV, 45CrMo), aluminum, titanium, copper, nickel, and nickel alloys.