API 650 welded storage tanks siphon-type drains

The main reason of "small breathing" loss of API 650 welded storage tanks is the change of atmospheric temperature. When the temperature rises with the increase of solar radiation from dawn, the temperature of oil in the API 650 welded storage tanks also changes, resulting in the acceleration of evaporation speed and the increase of evaporation pressure. When the pressure exceeds the positive pressure rating of the breathing valve, the oil-gas mixture in the API 650 welded storage tanks is discharged into the atmosphere through the breathing valve, which is the "exhalation" process of the oil tank.

Any joints between the adjacent sections of API 620 oil storage tank stiffening rings, as shown in Figure Q-1, shall be made so that the required moment of inertia of the combined ring-shell section is provided. Weld joints between adjacent sections shall be made with full-thickness and full-penetration butt-welds. Stiffening-ring butt-welds may employ metal backing strips. Backing strips and the associated welding shall be made in a manner that provides a smooth contour in the rat hole and all other weld joint ends. All weld passes shall be started at the rat hole and other weld joint ends and shall be completed by moving away from these ends. Passes shall be overlapped away from edges to provide a smooth continuous weld.

Welded steel API 650 welded storage tanks storage tanks that are designed, manufactured and installed on the ground are classified according to the API standard system. The three API standards API 650 welded storage tanks all adopt on-site production and installation of storage tanks.