An end cap is a component used to seal the end of a container, isolating it from the internal and external media; it is also called an end cover. Based on their geometric shape, they can be mainly divided into spherical, elliptical, dished, spherical crown, conical, and flat cap types, among which spherical, elliptical, dished, and spherical crown end caps are collectively referred to as convex end caps. In terms of welding connection methods, they are mainly divided into butt-welded end caps and socket-welded end caps. Commonly used materials include carbon steel, stainless steel, alloy steel, aluminum, titanium, copper, nickel, and nickel alloys.
End caps with different geometric shapes have different structural characteristics and mechanical properties. Hemispherical end caps have the best stress distribution and use the least material, but are difficult to manufacture and are mostly used in high-pressure vessels. Standard elliptical end caps have good stress distribution and shallow depth, making them easy to process and the most widely used. Dish-shaped end caps have edge stress at the junction of the spherical surface and the transition zone. Conical end caps facilitate material collection and unloading, but have poor stress distribution, requiring careful design of the transition structure at the large and small ends. Flat plate heads have the simplest structure, but require the largest thickness for pressure bearing and are generally used for low-pressure, small-diameter containers.