Abstract: Based on periodical test results obtained from spherical tank in recent years, this paper describes the relative solutions to various defects arisen from in-line pressure spherical tanks. It is considered that starting from decreasing structure stress of spherical tank and concentration of corrosive media, controlling residual stress of welding, material hardness and concentration of hydrogen sulfide should be an important job to do to reduce the stress corrosion during maintenance of spherical tank, which can be an effective measures to safe operation for the tank.