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Containers that cannot undergo pressure testing have the following mandatory requirements: 01 The design drawings must indicate the calculated thickness as well as the special requirements for manufacturing and use. 02 Safety measures to be adopted to exempt the voltage withstanding test: (1) Raise requirements for raw materials (special smelting methods, strict chemical composition specifications, higher impact energy requirements, increased frequency of mechanical property tests, etc.) ； (2) Perform local stress analysis on the critical areas ； (3) Optimize the structure to reduce the effects of secondary stresses and peak stresses caused by overall structural discontinuities and local structural discontinuities ； (4) Adopt a strictly evaluated welding process ； (5) Adopt high-quality welding methods ； (6) Increase the proportion of non-destructive testing to raise the qualification level ； After approval by the technical supervisor of the design unit, it shall be indicated on the drawing. Containers requiring internal inspection: For containers that need internal inspection after use but for which such inspection cannot be carried out, the following requirements are mandatory: 01 The design drawings must indicate the calculated thickness as well as the requirements for regular inspections during use. 02 For containers where inspection holes need to be created but cannot be installed (such as those with an excessively small inner diameter, where the insulation layer cannot be removed, or in the shell side of fixed-tube plate heat exchangers), the design team should propose additional specific measures: increasing the number of inspection tasks or the proportion of inspections during manufacturing (such as full non-destructive testing), and specifying the key inspection items and methods to be used for regular inspections during the equipment’s operation. 03 For pressure vessels that require internal inspection after use but for which such inspection is not possible, their Class A and Class B weld joints shall undergo 100% non-destructive testing (RT/UT/TOFD). 04 Weld joints of classes A and B shall undergo 100% non-destructive testing (RT/UT/TOFD).