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(1) Scope of application: Applicable to pipes with a design pressure p within the following operating range. ①Pipes for pressure pipelines in the range of 0 MPa (G) ≤ p ≤ 35 MPa (G). ②A vacuum pipeline is a pipeline with p < 0 MPa (G). ③Suitable for pipelines transporting all types of fluids, including fluidized solids. (2) Principles for determining the design pressure of pipelines: ① The design pressure of pipelines shall not be lower than the maximum operating pressure. ②For pipes equipped with safety relief devices, their design pressure must not be lower than the operating pressure (or burst pressure) of those relief devices. ③The design pressure of all pipes connected to the equipment shall be no less than the design pressure of the equipment to which they are connected. ④Pipes used to transport refrigerants, liquefied gases, and other media with low boiling points are designed based on the maximum saturated vapor pressure that the medium can reach when the valve is closed or when no flow of the medium occurs. ⑤When the path between the pipeline or pipeline components and the overpressure relief device may become blocked or severed, the design pressure is determined to be no less than the maximum operating pressure that may occur. ⑥For pipes for which engineering design requirements dictate the calculation of wall thickness, the calculated pressure listed in the pipe wall thickness table represents the design pressure of that pipe, and the operating temperature corresponding to that calculated pressure is the design temperature of the pipe. (3) Selection of the design pressure for pipelines: ① For pressure pipelines equipped with safety valves: p is greater than or equal to the opening pressure of the safety valve. ②Pressure pipelines connected to equipment without safety valves: p is greater than or equal to the design pressure of the equipment. ③Centrifugal pump outlet pipe: p is greater than or equal to the pump’s shut-off pressure. ④Reciprocating pump outlet pipeline: P is greater than or equal to the safety valve opening pressure at the pump outlet. Compressor discharge pipeline: P is greater than or equal to the safety valve opening pressure plus the pressure drop from the compressor outlet to the safety valve under the maximum normal flow rate. ⑥Vacuum tube: p equals complete vacuum. ⑦For pipes that do not fall within the aforementioned range, p is greater than or equal to the maximum value of the variations in operating pressure.