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Multi-chamber containers: The mandatory requirements for multi-chamber containers are as follows: 01 The overall design diagram must indicate the test pressure for each chamber; in cases where special requirements apply, it is necessary to specify the allowable pressure difference across shared components, as well as the test procedures and requirements. 02 For multi-chamber containers (such as the tube side and shell side of heat exchangers, as well as jacketed containers), each pressure chamber is classified separately; the design pressure is taken from that of the respective chamber, and its volume is determined by the geometric volume of that chamber. 03 For multi-chamber containers (such as the tube/shell sides of heat exchangers, jacketed containers, coiled-tube containers, etc.), the pressure chamber with the highest category is used as the container’s category for purposes of usage management, but design and manufacturing technical requirements are specified separately for each pressure chamber based on its own category. 04 When there are multiple media in a pressure chamber, they are classified according to the medium with the higher group category. 05 For multi-chamber containers (such as jacketed equipment), the design pressure for each pressure chamber shall be determined separately; the calculated pressure for shared components shall take into account the maximum pressure difference between adjacent chambers. 06 The test pressure for each chamber is determined based on its design pressure; however, it is necessary to verify the stability of the shared components (such as the inner cylinder of a jacketed vessel) under this test pressure. If the stability requirements are not met, a leak check must be conducted first, and only after that can the pressure resistance test be carried out. During the test, a certain pressure level must be maintained in adjacent pressure chambers to ensure that the pressure difference across these components does not exceed the allowable value. This requirement together with the allowable pressure difference value must be specified in the drawings. 07 For vessels with jackets, a pressure test of the inner cylinder should be conducted first; once it passes, the jacket should be welded on, followed by a pressure test of the interior of the jacket. 08 When designing the pressure difference for the heat exchanger tube sheet, the design pressure difference shall be specified in the design documents, and requirements to maintain this pressure difference during pressure testing shall be outlined. 09 For shell-and-tube heat exchangers where the design pressure of the tube side is higher than that of the shell side, the testing methods and pressure for the tube ends shall be specified in the drawings. 10 When the flanged tube sheets, welded tube sheets with internal holes, and flat covers of tube boxes are manufactured from sheet metal, they shall meet the requirements of grade Z35 as specified in GB/T 5313.