A boiler end cap is a component of a boiler pressure vessel, commonly used at both ends of pressure vessels. It also refers to the closed end of pipe products made of pipes. There are many different forms.

The head is a component of the container, connected and welded to the cylindrical body. Depending on different geometric shapes, it can be classified into spherical, elliptical, conical, spherical cap, conical shell, and flat cover, among which spherical, elliptical, disc-shaped, and spherical-headed ones are referred to as convex heads. The heads are joined by socket welding or plug welding. The containers are used for various equipment such as 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.