A cylinder is a kind of pressure vessel. The cylinder is cylindrical, with a convex or concave bottom at one end and a spherical shoulder with neck at the other end. Above the neck there is a bottle opening with conical thread for fitting the bottle valve. The advantage of our cylinder is as following :serious control of raw material; the strength is superior to the standard requirements, and metallographical organization meets the standard requirements; our gas cylinder bottom size is superior to the standards and design requirements, each cylinder will mill the bottom forming, then can directly visual observation of the bottom fusion situation; both of the inside and outside surface adopt the shot peening treatment to ensure no rust when using.