Pipe cap is a part of pipe fittings, which is connected by welding. According to different geometric shapes, it can be divided into spherical, elliptical, dish-shaped, spherical cap, cone shell and flat cap. Among them, spherical, elliptical, dish-shaped, spherical cap-shaped pipe caps are also collectively called convex pipe caps. . In welding, it is divided into butt welding Pipe cap and socket welding Pipe cap.