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.