Vacuum testing is one of the most adaptive method to test for any defects or leaks in the bottom. Vacuum box is used to clear for any leaks or faults in the welding of bottom and annular plates of the tank, and sometimes it is used on roof plates welding test. The vacuum pump attached creates a vacuum in the vacuum box, which shows bubbles in the soap water applied in the weld in case of any leaks or weld defects.