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Stress corrosion-resistant containers: The mandatory requirements for stress corrosion-resistant containers are as follows: 01 The design documents must specify the appropriate corrosion resistance measures, testing methods, and other technical requirements. 02 For storage containers prone to stress corrosion, the design drawings shall specify the limited content of corrosive media. 03 When copper end caps may experience stress corrosion cracking under specified operating conditions, they should be subjected to annealing or stress-relief annealing in accordance with the design specifications and product standards. 04 The corners at the inner diameter of the take over should be rounded, with the radius of the fillet generally taken as min{δnt/4, 19mm}. 05 There shall be no undercut on the surface of the container welds. 06 If any welding repairs are carried out after post-weld heat treatment, the repaired area should be heat-treated again. 07 For cold-formed steel pressure members, if the deformation rate exceeds the range specified in Table 4 for p330, heat treatment to restore the material properties should be carried out after forming. 08 Post-weld heat treatment is required. 09 For spherical tanks subject to stress corrosion, all weld joints are subjected to surface magnetic particle or penetrant testing. 10 In stress-corrosion service conditions, strength expansion joining shall not be used. 11 For heat exchange tubes that require resistance to stress corrosion, flexible expansion jointing should be used. 12 When stress corrosion resistance is required or when it is necessary to eliminate residual stresses, the bent section of the U-tube and at least 150 mm of the straight section shall be heat-treated. 13 The LPG storage tank should have H2S levels limited to ≤50ppm.